# DIY PAR meter, Yeah you heard me



## mistergreen

*Edit *5-10-13*
NOTICE - Firmware has been updated for outdoor lighting.

Final product list: 

Photodiode: VTB8441BH 
price: $4.660
http://www.alliedelec.com/search/productdetail.aspx?SKU=70219652

Cosine diffuser: 1/8" thickness, 2447 white plexiglass 
price: varies, get the sample or buy a big sheet of it.
http://www.eplastics.com/Plastic/Plexiglass_Acrylic_Sheet_Black_and_White
http://www.usplastic.com/catalog/item.aspx?itemid=23681

Basic 16x2 Character LCD - Black on Green 5V
price: $14 but you can get it cheaper on e b a y
http://www.sparkfun.com/products/255

Arduino Uno
price: $30
http://www.sparkfun.com/products/10356
http://www.sparkfun.com/products/11021 (newer model)


Diagram


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## CptanPanic

mistergreen said:


> I made my order in for my DIY peristaltic pump and I bought this guy too
> 
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> http://www.sparkfun.com/commerce/product_info.php?products_id=9541
> 
> cost $1.50
> 
> It's sensitive to visible light and a little IR as well so I hope it won't throw the
> reading too much. So yeah, it's not super accurate but maybe good enough
> for the regular hobbyist.
> 
> 
> I've already started building the waterproof body to hold the photo cell. The case
> doesn't have a diffusor like a real PAR sensor but hopefully it'll be fine.
> 
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> It a little plastic paint jar and wires are threaded through the tubing. The signal
> will be read with my handy all purpose ardiuno...
> 
> 
> Thanks to Hoppy's PAR chart, I can calibrate the signals to a rough guessimate.
> 
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> Compared to a $300 PAR meter & sensor, this might be a deal.


Neat project, but that is a light sensor not just PAR, so would measure lumens.


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## Hoppy

The little photodiode might sense PAR or it might sense nearer to lumens, or anything in between. Considering the cost, that slight disadvantage isn't that important. It could work well for adjusting the height of T5 lighting, checking how much shading the plants are doing, noting bulb deterioration, etc. But, for getting data that can be compared to other's data, it wouldn't be that great.


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## mistergreen

Good point.

I think taking the average of all of the readings per second would make it PAR?
All of the math can be done through my microprocessor.


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## Baadboy11

Someone send this man a par meter so he can see how close they are! STAT!


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## mistergreen

No need to send me a PAR meter although I wouldn't mind having one for a while 

Once it's built I can post some standard readings like sunlight at noon and people with a real meter can confirm the readings.


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## mistergreen

I found some neat µmol m-2 s-1 conversions and some standards like full sun is 2000 PAR on Apogee's website.

http://www.apogeeinstruments.com/faq_solar.htm#Q3

Posting for posterity.

1 µmol = 6.02 × 10^17 photons


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## Jim Miller

Different light sources have different spectral output characteristics. I think to make this work you'd need to put a filter which combined with the silicon sensor response would approximate a PAR curve.

Sounds like an interesting project.

Good luck!

jim


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## mistergreen

Here's the spectral sensitivity of this photodiode. As you can see, not the best match 











I did find a photodiode that fits the bill though
http://sales.hamamatsu.com/en/produ...ound-semiconductors/gaasp,-gap/part-g1118.php









It's $17 , I think. Maybe I'll get it one day... I couldn't pass up a $1.5 photodiode.


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## Jim Miller

Try getting a light modifier for theater lights, a piece of gel, with a spectrum near what you are looking for. I bet you can get a "goodnuf" match. 

Jim


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## mistergreen

Is there a gel that blocks InfraRed?

Well, hopefully, calibrating the output based on Hoppy's chart might be 'goodnuf'.

I went ahead and contacted Hamamatsu on how to get their photodiode.


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## Jim Miller

If you're measuring underwater I don't think you'll need to worry about infrared. In a dry tank you probably need something but I'd try the green gel first before working on the infrared part. In an otherwise subdued light room you'd be measuring the output of flourescents which don't have any significant IR output to measure. If you're measuring incandescent or MH that's a completely different story with lots of heat output.

Good luck!

Jim


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## keithy

mistergreen, what's the difference between relative spectral sensitivity and photo sensitivity? If they're the same, the trend of the graph looks similar however, the peaks are very far off(1.0 and 0.3). If there is a scaling factor/calibration, it would be worth looking into before spending $17 bucks. 

Sorry if my questions/comments sounds dumb, I am no light expert, just want to contribute and point out what I though to be a little bit of inconsistency. Overall, I think you have got brilliant idea rolling!

Edit: I looked at it again and seems like the photo sensitivity/peak of photo sensitivity = relative spectral sensitivity. Is this correct? If it is, it may fit pretty well.


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## mistergreen

Oh, I'm just looking into the Hamamatsu diode... Haven't bought it yet until I played around with the cheaper diode.

photo sensitivity is a electrical engineering term referring to photodiodes:
http://en.wikipedia.org/wiki/Photosensitivity#Interpretation_in_electronic_engineering

And spectral sensitive is another term for photo sensitivity ( another unit of measurement like inches & centimeters ).. I assume they measure the same thing.


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## mistergreen

I received the photodiode yesterday. Got to play with it a little. In this picture, I'm trying to find the right resistor for this set up.









A 4.6K resistor seems to work. I'm calibrating the max output to sunlight.. 1024 (5V) is the max reading and sunlight through a window gives a reading of ~900. So I think I got it.

Mounted the photodiode on a electrical cap









Assembled the jar... This nub in the jar is a problem. It casts a shadow on the photodiode.









I moved the diode to the side and gave the plastic a little frost with fine grit sandpaper to scatter the light a little.










Next step is to calibrate these numbers to the PAR readings.


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## Dave-H

Truly some pioneering DIY action! Great job!


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## mistergreen

Thanks. Trying to make the hobby more accessible.


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## mistergreen

I don't think I showed you how I'm reading the values so far.










It's all through USB... It's supplying the ardiuno power and a way for the ardiuno to communicate to my computer...
This is my serial monitor outputting the values.









The values jump/dance around like it's being hit by photons, kinda cool. So I wrote the code to find the average within every second...

NON-PAR code...(NOT FINAL)


Code:


unsigned long average = 0;
unsigned long time;
int counter = 0;

void setup() {
  Serial.begin(9600);
  time = millis();
}

void loop() {
  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
    average = average/counter;
    Serial.println(average);
    
    //reset timer & counter to get ready for the next second.
    time = millis();
    counter = 0;
    average = 0;
  }
}

Oh, I double checked the readings by going outside... Full sun will give me the maximum value of 1023.. In the shade, around 100-120.


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## mistergreen

For those wanting to play with a microprocessor, check the Texas instrument one. It's only $4.50!!!
http://processors.wiki.ti.com/index...G2)?DCMP=launchpad&HQS=Other+OT+launchpadwiki

I haven't played with it but my dad got one for me.


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## Hoppy

I think PAR in full sun at midday is around 2000. That suggests your readings may be about half of the true PAR values.


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## mistergreen

Yeah, I'm mapping out the values now to see the relationship...

Hoppy, I have a question about your PAR - distance chart.
Your graph implies a parabolic curve, meaning the closer you get to the bulb, the more it gets to infinity or to the max value (the sun 2000 PAR). This is assuming your bulb is outputting at the level of the sun? It doesn't seem right.

I'm definitely getting a fixed value no where near the maximum with my DIY meter.


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## bsmith

Super awesome DIY. Keep your findings coming.


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## mistergreen

Here you go..









The proportions doesn't look like a x2 constant calibration... It looks like a gaussian curve (bell curve).... Will work on the equation unless some math wiz out there beat me to it


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## mistergreen

Ok,
I found the equation... There were some guessing going on because I didn't know what hoppy's chart start value is.

It looks like these bulbs output are bell curves rather than parabolas.

f(d) = A * (11e^(-d^2/(2*35^2)))
A is the value from my DIY sensor, d is distance.

I'll graph this out to see how close they fit.


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## malaybiswas

Great idea. This might be my next dig as well.

Sent from my DROIDX using Tapatalk


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## Hoppy

The inverse square relationship of PAR and distance only works within a relatively small range of distances. When you get close to the bulb it breaks down. I determine relationships like this by just plotting the data on log-log graph paper. If the points form a straight line, it demonstrates that one variable is a function of a power of the other variable, with the slope of the straight line being the power.

It is very hard to measure distances very accurately with tests like this, and PAR meter readings can fluctuate as you read the meter, and vary from hour to hour. So each data point can be assumed to have a pretty large uncertainty. Considering all of that, if a line with a slope of minus 2 will fit the data points reasonably closely within the distance range that is relevant for aquariums, it is a good approximation to assume the inverse square relationship. Then, when you toss in values for multiple bulb fixtures, using the PAR number divided by number of bulbs, and those data points follow the same line, you can see that it is a good approximation to say that n bulbs give n times the PAR of one bulb.

It makes no difference to us, when we are looking for an aquarium light, whether or not the PAR varies with square of distance at distances of 1 inch to 4 inches, so I never bothered to measure it at those distances, except with single LEDs. Single LEDs are so near a point source that the inverse square relationship will hold true at even 3-4 inches from the single LED. It gets much more complicated when you have an array of LEDs.


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## mistergreen

Doh! there's no way to tell the sensor what the distance is to the light source... will have to rethink the equation.


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## mistergreen

Hoppy said:


> The inverse square relationship of PAR and distance only works within a relatively small range of distances. When you get close to the bulb it breaks down. I determine relationships like this by just plotting the data on log-log graph paper. If the points form a straight line, it demonstrates that one variable is a function of a power of the other variable, with the slope of the straight line being the power.
> 
> It is very hard to measure distances very accurately with tests like this, and PAR meter readings can fluctuate as you read the meter, and vary from hour to hour. So each data point can be assumed to have a pretty large uncertainty. Considering all of that, if a line with a slope of minus 2 will fit the data points reasonably closely within the distance range that is relevant for aquariums, it is a good approximation to assume the inverse square relationship. Then, when you toss in values for multiple bulb fixtures, using the PAR number divided by number of bulbs, and those data points follow the same line, you can see that it is a good approximation to say that n bulbs give n times the PAR of one bulb.
> 
> It makes no difference to us, when we are looking for an aquarium light, whether or not the PAR varies with square of distance at distances of 1 inch to 4 inches, so I never bothered to measure it at those distances, except with single LEDs. Single LEDs are so near a point source that the inverse square relationship will hold true at even 3-4 inches from the single LED. It gets much more complicated when you have an array of LEDs.


hmm. In that case, I use a simpler equation like a regular parabola.


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## Hoppy

I plotted your data for the 3 bulb unit on log log paper and got:








The line is the slope if the data follows the inverse square rule. You can see how much scatter there is, and that the close to the bulb readings diverge from the other data. This isn't much different from the data I got from other sources. And, it is why the charts I made are only good for approximating the PAR - you have to measure in your tank with your lights to get really accurate measurements.

If I were to add your data to my charts I would read off data points from that line, not your actual data. That reduces the scatter a great deal, and makes it possible to do this.


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## mistergreen

This is the best I can do, with my sensor
(multiply 8 to the single bulb data)










But as we know I went outside into the sun I'd get 8000 PAR 

I'm curious to see if the mamamatsu photo diode would give me a better output. I think the Infra Red is affecting the readings.


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## aaronbrown

this might help you all out at least to make the sensor http://www.colorado.edu/eeb/facultysites/melbourne/Publications/Mel_Dan03/Melbourne_Daniel03.pdf


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## Hoppy

aaronbrown said:


> this might help you all out at least to make the sensor http://www.colorado.edu/eeb/facultysites/melbourne/Publications/Mel_Dan03/Melbourne_Daniel03.pdf


Thank you! That is a very good report. It almost makes me want to justify buying a milivoltmeter.....but, not quite.


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## aaronbrown

well i thought this would help alot of ppl out and so i thought i would do a lil research to help further this along and if it can be built cheaper than buying one thats great cause we all know how expensive the world of fish keeping is wether it be freshwater or saltwater


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## mistergreen

Hey, guys, I think I found a better photodiode.
http://www.alliedelec.com/search/productdetail.aspx?SKU=9800079#tab=Specs
Cost: $3.19

It's basically, the photodiode I have but it has a IR filter in it and the resulting spectrals are:









But the problem is minimum order is 25... that's like $70+.....
hmmmm. Maybe I can look for a IR filter instead or just call up hamamatsu.


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## keithy

mistergreen,
what data does the ardiuno gave you as an output and how do you translate that to PAR reading? I am new to electronics but would like to learn and prehaps provide some input to help out.


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## keithy

the $3 photodiode data you provided does looks better and somewhat matches the $17 photodiode. good find. 

I am very interested to find out how everything turns out. I have been reading this thread every day since it started. With Hoppy providing useful input, I have a strong feeling it will turn out good.


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## mistergreen

aaronbrown said:


> this might help you all out at least to make the sensor http://www.colorado.edu/eeb/facultysites/melbourne/Publications/Mel_Dan03/Melbourne_Daniel03.pdf


I looked around for the photodiode used here... I don't think they make it anymore or anything like it. The maker got bought up or something.


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## mistergreen

keithy said:


> mistergreen,
> what data does the ardiuno gave you as an output and how do you translate that to PAR reading? I am new to electronics but would like to learn and prehaps provide some input to help out.


All photodiode will output a small voltage when excited by light but the voltage alone is not not good enough in terms of resolution.
So what you do is apply 5Volts through it and gather the output signal from the diode (0V-5V).
Here's a typical setup (photoresistor/photodiode)












keithy said:


> the $3 photodiode data you provided does looks better and somewhat matches the $17 photodiode. good find.
> 
> I am very interested to find out how everything turns out. I have been reading this thread every day since it started. With Hoppy providing useful input, I have a strong feeling it will turn out good.


Yeah, I think it'll turn out well. I'll go ahead and get the hamamatsu diodes. I think I'll get 5 diodes for that $17. I can sell off the rest to you guys.


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## keithy

ah... now I see how its done! thanks for the quick answer. I will follow closely on the developement of the DIY PAR meter.


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## mistergreen

I called up Hamamatsu, wow what a hassle. I think they'll do a background check hah...

And I had to order at least $50 worth. I think I might wind up with 15 diodes so I'll have plenty to share.


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## keithy

mistergreen said:


> I called up Hamamatsu, wow what a hassle. I think they'll do a background check hah...
> 
> And I had to order at least $50 worth. I think I might wind up with 15 diodes so I'll have plenty to share.


hmm......... first they did a 'background check' on you and then asked you to make a minimum of $50 purchase? That is outrageous!


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## mistergreen

HEh, They needed me to fill out a form on the intent of my purchase... I think it's regular policy these days to make a safer world.


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## keithy

mistergreen said:


> HEh, They needed me to fill out a form on the intent of my purchase... I think it's regular policy these days to make a safer world.


For photodiodes??... maybe its more of a marketing strategy to look into new avenues they can market their products.......... just my 2 cents. Anyways, how is the design and calibration coming along? Any new developements?


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## Hoppy

Aha! A good photodiode and and some oxidized hydrogen, and you have the makings of a powerful thermonuclear device! (Let me double check my old college physics book to confirm that.)


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## mistergreen

Hah, I have no idea what kind of weapons you can make but I know photodiodes are used regularly to detect lasers.. I have heard news stories of people buying cheap components from the States and shipping them to NATO embargoed countries which is a big no-no.

In my research, I found out that a green LED, can read PAR visible light pretty darn well. The spectrum matches up but the resolution is so low I'd need an expensive millivolt meter.


Well, the conclusion on this so far is that the current photodiode is not reliable because it reads Infra Red as well. Different bulbs will have different IR output and will skew the readings. Since a photodiode is the key foundation for this, I'll wait for the correct diode to arrive and restart the calibrations.

I can worry about the cosine corrections and such later. I wouldn't even know where to get a cosine correction filter ... But from looking at the charts & graphs, I can leave it out and call it 'goodnuff'.


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## mistergreen

I got tired of the Hamamatsu runaround and by chance I was rechecking if alliedElectronics sold anything similar to that photodiode but don't have a minimum order.

They do
http://www.alliedelec.com/search/productdetail.aspx?SKU=9800078#tab=Specs

So, I canceled my account with Hamamatsu and ordered this instead.


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## keithy

I have been away a few days. Sweet, another new source for photodiode. Keep at it mistergreen.


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## mistergreen

Yup, the new photodiode just arrived today actually.


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## mistergreen

I soldered in the new photodiode. It took 10 seconds; a snap. It's reading my desk lamp and it looks good.

Now I need the sun to come out so I can set the maximum parameter.


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## mistergreen

Ok, I got to make some readings









And this is the result.









So, toward the end there, it doesn't look like it falls off correctly. THe values are too high.


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## mistergreen

I'm starting to think that cosine correction filter is pretty important to shift that line curve into place.
Readings can shift if I tilt the sensor slightly.


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## keithy

mistergreen, 
I think you are almost there. The graph seem to have the same order of magnitude.


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## Baadboy11

looks like its getting close!!! keep up the good work!


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## mistergreen

I was looking around the web for a company that sells cosine correction filters. I finally found one but prices are a bit steep.



> T UV-Vis Internal Diffuser
> $67
> Used in addition to the W for improved cosine response, especially with thin film filters. For spectral ranges 250- 700nm.
> TD Low Cost UV-Visible Diffuser
> $67
> Domed teflon diffuser for use with IL detectors for spectral ranges 250- 700nm.
> W Quartz Wide Eye Diffuser
> $144
> Internal hemisphere of solid quartz for use with IL detectors for cosine response
> A312 Opal Diffuser
> $144
> Opal Diffuser, Mounted in A310 Ring
> A313 Flat Quartz Diffuser
> $167
> Flat Quartz Diffuser, Mounted in A311 Ring


A cheaper router would be go onto ebay and buy a cheap light meter and harvest the diffuser.


Or maybe look around hobby and art store for anything spherical and can act as a diffuser.


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## mistergreen

aaronbrown said:


> this might help you all out at least to make the sensor http://www.colorado.edu/eeb/facultysites/melbourne/Publications/Mel_Dan03/Melbourne_Daniel03.pdf


Oh! thanks to aaron, a sheet of opal acrylic will work as the diffuser. I think HD carries it..


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## mistergreen

Well, it's harder to find opal acrylic than I thought. There are suppliers in China but I'm not going that route.

I used a regular piece of white plastic instead...

















And the result is quite funny.









A linear line, no inverse law what soever  . Very strange.... I'll have to remove the piece of plastic.

I did learn one thing though. My initial reading from the very beginning might have been affected by the tank and water... I remember reading where hoppy said the water and sides of the tank might act to reflect and magnify the light. I'll have to remove my light and test it outside the tank.


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## mistergreen

Latest readings









Good nuff.... Now to go measure stuff. I have a feeling my 75G tank has too much light and that's the source of my minor algae issues.

Oh, I'll build a JAVA app that'll output the 'PAR' too. It's cross platform for anybody that wants it.


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## Hoppy

That's looking good now, probably as accurate as you will need it to be. How did you get the data to fall where they do now?


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## mistergreen

I took the white plastic off the sensor and measured the light outside the tank.

I noticed measuring in the tank full of water was giving me higher readings that didn't fall on the inverse law curve.

over all cost:
~$10 - photo diode + S&H
~$.50 - plastic paint cup 
~$4 - electrical cord
~$30 - ardiuno MP (there's a $20 version too, and there's a $5 texas instrument one)
~$.50 - 27K resistor

total: $45.00


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## !shadow!

mistergreen is a secret agent from north korea  
^^refering to post 45


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## mistergreen

!shadow! said:


> mistergreen is a secret agent from north korea
> ^^refering to post 45


Ugh, you know what? I'm probably on the 'flag' list whenever I go to fly now; going to have to get to the airport extra early.


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## mistergreen

Ok, I built an app to output the 'PAR' data.








Big numbers for us old folks.









And an option to choose which port for it to listen to. You can do a wireless connection if you hook a bluetooth radio to the arduino 
**Admendment**

If /dev/tty.usbserial-a9007muf is not the first item on the list, choose that... On windows, it might be COM1.

***************
You can download the app on my forum.
http://aquatictechtank.net/viewtopic.php?f=11&t=150&p=390#p390


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## keithy

mistergreen, I was busy for a few days and you're done building the diy par meter already? I am loving the way the data looks now.


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## macclellan

impressive, MG.


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## mistergreen

Thanks, It was pretty easy; all in a Sunday afternoon.


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## mistergreen

Oh! Just thought of making this more portable: Attaching a $14 LCD screen and use batteries.... 

I've always wanted to play with lcds.


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## Dave-H

Hoppy said:


> Aha! A good photodiode and and some oxidized hydrogen, and you have the makings of a powerful thermonuclear device! (Let me double check my old college physics book to confirm that.)


You must have graduated from MCU.

That's Mac Gyver University! (thank you very much, that was the most useful thing I've contributed to this thread so far).


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## Noahma

Now you can find a way to recoup your costs by building and selling these in the swap and shop? hehe


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## NJAquaBarren

Noahma said:


> Now you can find a way to recoup your costs by building and selling these in the swap and shop? hehe


I'd buy one!


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## mistergreen

I've thought about it 

I need to find a way to design the sensor better. It's clumsy with the epoxy, maybe a heyco grip cord is better.
The LCD is a better way too but obviously $14-$15 more expensive. And the microprocessor needs to be designed too. It can't be left exposed where water can get at it 

Unless, I can just get all the parts, program it and let you guys handle the assembly. That would keep cost down.


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## mistergreen

Holy cow,
I was wondering where my order was on the lcd was and it turned out I never placed the order last week.. It was just sitting in the shopping cart.

One of those days.


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## bsmith

mistergreen said:


> Holy cow,
> I was wondering where my order was on the lcd was and it turned out I never placed the order last week.. It was just sitting in the shopping cart.
> 
> One of those days.


Been there done that bro.


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## keithy

bsmith said:


> Been there done that bro.


same happened to me whan I was doing my christmas shopping online, bro.


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## mistergreen

A big update....
I redesigned the sensor with new parts; using an ethernet cable instead of a chuncky electrical cord and using a 1/4" heyco gripcord.

















looks half professional doesn't it?


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## mistergreen

And I received my LCD and battery holder today and couldn't wait to hook things up.. What else to do on a cold rainy day?

















First 'hello world' test run.

And hooking everything up, batteries included.... Sorry for the self promotion there.









The next part is to figure how things will fit together and make all those wires look not so scary.


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## bsmith

Very nice. How much would yOu say you have in just this generation of meter? How accurate is it?


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## mistergreen

Meter AND sensor (minus ship & handling) looks to be under $50.

Accurate? hmm. tough question... It is by no means as accurate as a PAR meter mainly because of the photodiode used and lack of cosine correction.

There was a chart in past posts where I compared my readings to Hoppy's readings. It came close enough.. I can't really give a +- percentage error. In Hoppy's chart, the curves are margins and not lines. I don't think reading light is an exact thing, correct me if I'm wrong.


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## Hoppy

You don't need an exact reading, and even a PAR meter doesn't give you that. All it takes is slightly tilting the PAR sensor and the reading changes, plus there is an error range for the distance between the sensor and the light to consider also.

Ideally you will borrow a commercial PAR meter and calibrate yours against that, but I can understand that not being easy to do.


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## mistergreen

Does anybody know if I can crimp a RJ connector without the crimper?

I'm adding a RJ (phone jack) connector at the end of my sensor.

I guessing I need to spend $20 on a crimper.


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## HolyAngel

yeah, short of getting lucky and finding something that will fit nicely inside the slot that needs to be crimped and using pliers.. you'll most likely have to get a hold of some actual crimpers to make sure it won't pull out on accident.


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## mistergreen

Hoppy said:


> You don't need an exact reading, and even a PAR meter doesn't give you that. All it takes is slightly tilting the PAR sensor and the reading changes, plus there is an error range for the distance between the sensor and the light to consider also.


Yeah, kind of make sense not to spend $300 on a par sensor & meter then.



HolyAngel said:


> yeah, short of getting lucky and finding something that will fit nicely inside the slot that needs to be crimped and using pliers.. you'll most likely have to get a hold of some actual crimpers to make sure it won't pull out on accident.


Yeah, I'm going to The Home Depot later to grab a crimper. Maybe I'll make a few of these to sell to recover the cost of the crimper


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## HolyAngel

oh, happened to come across this just a minute ago, not sure if it'd be of use or anything, but thought i'd pass it on just in case:

http://www.kippzonen.com/pqs1


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## mistergreen

HolyAngel said:


> oh, happened to come across this just a minute ago, not sure if it'd be of use or anything, but thought i'd pass it on just in case:
> 
> http://www.kippzonen.com/pqs1


yeah, I ran into them when I was doing research... I think they cost more than agogee.


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## aaronbrown

id be interested in one depending on cost


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## mistergreen

Ok,
Here it is, the unveiling.

It fits comfortably in your hand.









It just made sense to have the sensor detachable and not soldered into the board. I used a telephone jack as the interface.









And the underside.







[

The only thing is I forgot or never bothered to design it with an on/off switch .... To turn it off, I yank a battery out... I'll have to think about a switch.


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## bsmith

Very cool. You just need to figure out how much to charge and how long until you can ship and I think you might be in business!


----------



## mistergreen

I added an on/off switch!

But I almost blew up the whole thing 

I was confused on how to wire up a switch and then the machine started feeling warm/hot. You know you're in it deep when it turns into a heater. Basically, I created short circuit.

Can't wait to try his out tomorrow.


----------



## HolyAngel

Don't blow it up! lol

Thats pretty ingenious with the phone jack tho ^^ I like it!

I would definitely buy one if you wanna make extra's


----------



## mistergreen

Ok, when I have time, I'll make another one and post it up in the swap 'n shop. No pre-orders, forum rules. I'm guessing $50 will be the cost of the thing.

In the meantime, I'll keep testing it and making refinements.


----------



## mistergreen

Really interesting to see all of the par values in the tank.

*substrate area*
22 PAR - (under large plants) smaller plants will not grow, they die off actually.
60 PAR - plants grow slowly
180 PAR - (open area) plants will grow but with algae 

I'm seeing GSA at the top of my crypts where I'm getting 280 PAR. I might get a glass cover for my 75G and see how the PAR will drop. I need something for stopping the fishes from jumping anyway.


----------



## mistergreen

I just checked my Low-tech 10G tank. 
The lights are DIY, 3 x 14W(I think) spiral fluorescent... Wow, it's throwing out hi-tech numbers 300 - 200 PAR... Good thing I designed it in parallel where I can turn off whichever bulb I want.. Got the PAR down to 200 - 80 by turning off one bulb.

This tank has a glass cover. Seems glass will cut down the PAR by 50-80.


----------



## HolyAngel

interesting numbers, very nice to be able to check! 

What kind of light are you running on the 29?


----------



## mistergreen

It's a 75G actually... I have 3x54W T5HO hanging 12+" above the tank.


----------



## HolyAngel

Ah sorry, but very nice! ^^

I'll be interested to check these odno'd t8's vs a coralife fixture or two that I may be picking up soon here.


----------



## artemm

Here is the idea. I did it for IR, but i am sure it works for visible light.
Get a 1 red at 660nm led, one blue, one deep blue, one green, one yellow and one orange led all with known light wave length.
These leds can be easily used as photodiodes and each responds best at the wave length
it emits. Put them into an array, put a diffuser on top and do some very nifty math to get PAR reading from the voltages each generate (you would need a bunch of opamps to amp the voltages for sure). Even better is to put a pass-through filter on each led, so, it will see only its own wavelength peak. This, i bet, will make the math and calibration a lot more simple. Furthermore i am sure this setup will provide a lot better PAR reading, i mean a lot closer to real sensitivity curve. The overall cost would something like 30 bucks (mainly because of the 10$ 660nm red led) in retail prices for the sensor and the amp.
I wonder why the heck no company tried that before. This setup has a lot more potential and also allows corrections to be made in software.


----------



## mistergreen

artemm said:


> Here is the idea. I did it for IR, but i am sure it works for visible light.
> Get a 1 red at 660nm led, one blue, one deep blue, one green, one yellow and one orange led all with known light wave length.
> These leds can be easily used as photodiodes and each responds best at the wave length
> it emits. Put them into an array, put a diffuser on top and do some very nifty math to get PAR reading from the voltages each generate (you would need a bunch of opamps to amp the voltages for sure). Even better is to put a pass-through filter on each led, so, it will see only its own wavelength peak. This, i bet, will make the math and calibration a lot more simple. Furthermore i am sure this setup will provide a lot better PAR reading, i mean a lot closer to real sensitivity curve. The overall cost would something like 30 bucks (mainly because of the 10$ 660nm red led) in retail prices for the sensor and the amp.
> I wonder why the heck no company tried that before. This setup has a lot more potential and also allows corrections to be made in software.


Actually, you only need blue and red. Photosynthesis is strongest with these lightwaves.


----------



## artemm

No, you need green too, all the rest are overkill. The green is needed to subtract green actually, because even selective photodiodes (see google) have response curves which go into neighbor regions. So, to get green out of the blue and sometimes out of the red (depend on the sensor) you need green value. 
The whole idea seems to me more and more nice especially after looking at datasheet for selective spectrum photodiodes. They already have the color filters built in and are still relatively cheap.
The only disadvantage is that they cannot be used at small distances, because all three of them must be covered evenly with the same light.


----------



## artemm

A suggestion for your DIY par meter.
Add something like http://www.adorama.com/BW55YGW.html
this can give better response curve, closer to the real thing which should make calibaration easier.


----------



## mistergreen

Make sense but a bit expensive.

The scientific papers don't make use of color filters so I'm following their lead.


----------



## MosMike

Guys, I found an excellent sensor for a PAR meter.
It is an RGB photodiode

There are 2 models with very selective bandwidths
1) 390-680nm http://jp.hamamatsu.com/resources/products/ssd/pdf/s10917-35gt_kspd1078e04.pdf
2) 400-720nm http://jp.hamamatsu.com/resources/products/ssd/pdf/s9032-02_kspd1067e06.pdf

They even sell them by 1 piece: http://sales.hamamatsu.com/en/produ...odiode-series/si-photodiode/part-s9032-02.php


----------



## Usil

I have been considering doing a project like this and when I saw this I was blown away. Great job. My project is comparing aquarium bulbs and specifically LED lighting but can't afford a PAR meter. I am using a Light meter to get EV values and calculating Lumens which gives me general total light output but can not address frequency ranges for plants specifically. I found a low cost waterproof strip from a Chinese company 

http://www.dealextreme.com/p/waterproof-1-meter-30-led-4-5w-light-strip-white-dc-12v-900116211

and it works perfectly. I just wanted to test it to see how it compares to florescent and other lamps. Can you send me the applet/code for reading the PAR values from your device? I might try the RGB photodiode but will have to think about how to proceed. 

Thanks for the all the work you have done. 

Usil


----------



## mistergreen

MosMike said:


> Guys, I found an excellent sensor for a PAR meter.
> It is an RGB photodiode
> 
> There are 2 models with very selective bandwidths
> 1) 390-680nm http://jp.hamamatsu.com/resources/products/ssd/pdf/s10917-35gt_kspd1078e04.pdf
> 2) 400-720nm http://jp.hamamatsu.com/resources/products/ssd/pdf/s9032-02_kspd1067e06.pdf
> 
> They even sell them by 1 piece: http://sales.hamamatsu.com/en/produ...odiode-series/si-photodiode/part-s9032-02.php


It's difficult to buy a hamamatsu part here in the States but awesome that you found those.




Usil said:


> I have been considering doing a project like this and when I saw this I was blown away. Great job. My project is comparing aquarium bulbs and specifically LED lighting but can't afford a PAR meter. I am using a Light meter to get EV values and calculating Lumens which gives me general total light output but can not address frequency ranges for plants specifically. I found a low cost waterproof strip from a Chinese company
> 
> http://www.dealextreme.com/p/waterproof-1-meter-30-led-4-5w-light-strip-white-dc-12v-900116211
> 
> and it works perfectly. I just wanted to test it to see how it compares to florescent and other lamps. Can you send me the applet/code for reading the PAR values from your device? I might try the RGB photodiode but will have to think about how to proceed.
> 
> Thanks for the all the work you have done.
> 
> Usil



oh, I never posted the code?

here it is. It outputs to an LCD but you can output it to your monitor if you want. I'll have to buy a PAR meter to do more experiments... I'm thinking a green photodiode might do too.




Code:


#include <LiquidCrystal.h>

float average = 0;
unsigned long time;
int counter = 0;
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);


void setup() {
  time = millis();
    // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("2noodles PAR");
  
}

void loop() {
  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
     //corrections to fit par : change the calibrated output here
    average = average/counter * 1.5;
   
    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(average);
  
    //reset timer & counter to get ready for the next second.
    time = millis();
    counter = 0;
    average = 0;
  }
}


----------



## Usil

How do I use the code through computer and it's monitor? Insert into HTML? What port should be used? Can this work for a USB port? Sorry, I need a little more on how to use this code through a computer.

Usil


----------



## mistergreen

You have an arduino? Yes through USB. And I have a java app the reads the output. I thought I posted it. I'll look for it.

http://flowerandmonster.com/index.php?option=com_content&view=article&id=15&catid=2&Itemid=3

The code you install on your arduino and java app is there


----------



## reybie

Cool, very interesting. I'm going to have to check out the whole thread. I just bought an arduino board and this looks like a good first project to mess with.


----------



## mistergreen

yeah, It's an easy first arduino project. Get yourself an LCD if you want to get more complicated.


----------



## EdsterG

mistergreen said:


> Latest readings
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Good nuff.... Now to go measure stuff. I have a feeling my 75G tank has too much light and that's the source of my minor algae issues.
> 
> Oh, I'll build a JAVA app that'll output the 'PAR' too. It's cross platform for anybody that wants it.



Looking at this graph, a little adjustment to your formula and you'll be virtually spot on!

Try:
average = (average/counter * 3) - 100;

I came up with this guesstimating values from the graph above, and it could use a little tweaking.
Can you tell me the new values using this formula and how they compare to Hoppy's data?


----------



## mistergreen

Output * 3 - 100 might work. I'll play with the graph.


----------



## HolyAngel

What kind of t5ho are you using to get the readings from? It would have to be a tek or Catalina fixture to be a direct comparison as other HO fixtures can put out a lot less par than what the graph reads for them.


----------



## mistergreen

well, well well,
it looks pretty good.









I'll change the code and dust it off the shelf.


----------



## Hoppy

That chart is worthless for evaluating a PAR meter. It isn't that accurate to start with, and as HolyAngel noted, you would have to use a Tek or equivalent one bulb light before the chart could even be assumed to be accurate. If someone has taken data with the specific light you are using, you can use their data to calibrate with. For example, look at http://www.plantedtank.net/forums/lighting/154807-fish-need-but-do-plants-need.html if you have either of the two lights it shows data for.


----------



## mistergreen

Yeah. I always knew to make this as accurate as possible, I'd have to get a par meter to do some comparisons. But this is a good starting place.


----------



## O2surplus

Mistergreen

If you could post up a complete wiring schematic for your Par-meter, including all component values and pin assignments for the Arduino, I could create a Printed circuit board that would roll everything into a nice compact package for you. I could fit all the components needed to make a working Par-meter onto a small board that could mount directly under your LCD. Let me know what you think.


----------



## mistergreen

wow, nice. I'd have to deconstruct the prototype to get all of the pins. It depends on what arduino board you buy too. The pins and placements are different on different boards so that could be an issue.

I think I'll have to go ahead and buy a par meter, bite the bullet to get some confirmations.


----------



## EdsterG

Once I get some cash, I'd like to test out different types of senors too see how they compare, maybe do some more research on IR interference and IR filters. And since I live in Sacramento, I'm sure there's someone that lives here who can let me borrow a PAR meter, or if not borrow, let me use it in their presence.


----------



## mistergreen

Oh! I can just buy the apogee sensor to keep cost down. I might be able mod my arduino PAR meter to accept an apogee sensor.


----------



## O2surplus

mistergreen said:


> wow, nice. I'd have to deconstruct the prototype to get all of the pins. It depends on what arduino board you buy too. The pins and placements are different on different boards so that could be an issue.
> 
> I think I'll have to go ahead and buy a par meter, bite the bullet to get some confirmations.


Are you using a Duemilanove or an UNO? I believe the pins are inter-changeable between the two, as I've interchanged them both without issue. All I need is the pin assignments to create the board and your sketch should run everything perfectly. A batch of 10-12 pcbs can be made for as little as $10. That's $1 or less per board. The Atmel 328 chip can be purchased for $5 and an LCD for $5. All the remaining parts needed would probably be another $5-$10 The whole project could be built from scratch for less than the cost of an off the shelf Arduino.
I built my own solid state LED Pwm controller (based on Arduino) and LED drivers using the same approach, saved a few bucks, and learned a lot about electronics in the process. 
If your able to eventually get reliable/accurate PAR values from your prototype and want to clean up your final design, let me know and I'll help you out with the custom PCB . Here's a photo showing my LED controller. It's just a really stripped-down Arduino UNO with an LCD attached.


----------



## mistergreen

O2surplus said:


> Are you using a Duemilanove or an UNO?


Good to know. I'm using the Duemilanove. I was even thinking about using a smaller/cheaper board for future models.

I think I got ripped off on the LCD. I got mine for $14. Where can you get $5 ones?


----------



## O2surplus

mistergreen said:


> I think I got ripped off on the LCD. I got mine for $14. Where can you get $5 ones?


Yep, you got hosed. I'll send you the link via PM.


----------



## mistergreen

I went ahead and bought the SQ-120 (electric) sensor, $150.


----------



## DarkCobra

Saw an interesting sensor today that made me think of this project, the Taos TCS3200D:










It's an 8x8 array of identical photosensors, with a filter grid evenly divided between red, green, blue, and clear. Each group of 16 identically filtered pixels are averaged together to eliminate position-dependent errors. Specs seem nice, though it might benefit from the addition of an IR filter.

It's used in both the ColorHug open-source monitor calibration device, and a Parallax module which includes LEDs and a lens for sensing color of a non-illuminated surface. So example code is available.

There's several other devices in the Taos color sensor lineup too.

I've also been curious if an acceptable cosine filter could be stolen from a cheap lumen meter, since they don't appear to be available separately at any reasonable price.


----------



## EdsterG

I did some research on Opal acrylic. It's actually widely available in the UK at a decent price.


----------



## dundadundun

mistergreen said:


> I went ahead and bought the SQ-200 sensor, $150.


typo, maybe? did you mean SQ-120?

forgive me. i'm trying to follow along and that threw me off.


----------



## mistergreen

dundadundun said:


> typo, maybe? did you mean SQ-120?
> 
> forgive me. i'm trying to follow along and that threw me off.


oops, sq-120, electric.  . I'll fix it so others won't get thrown off.


----------



## mistergreen

I received my apogee sensor today. I'll have fun with it.

Some notes for posterity.
5 PAR / 1 mV
red wire +
black wire -
clear ground

I'm going to take the day off 
I'll go jogging and will play with the sensor when I get back.


----------



## mistergreen

Hoppy is right, that chart was way off. The actual PAR was closer to my original reading without math calibration.


----------



## mistergreen

I did some more test on a regular spiral CF.










I've noticed this with the help of the new PAR sensor that the values are off above 300 PAR.. A diffuser is *necessary* to flatten out the readings. I'm using a regular piece of thin white plastic light diffusor. I might have to hunt around for a consistent piece of white or opal acrylic.


----------



## mistergreen

I think I found some affordable diffusers.

http://www.eplastics.com/Plastic/Plexiglass_Acrylic_Sheet_Black_and_White

and opal acrylic but no pictures.
[strike]OA-PRIS2X4[/strike]
* I asked the sales rep, this is textured like this product
http://www.eplastics.com/Plastic/Lighting_Diffusers/CA-PRIS2X4


----------



## mistergreen

I received my sample of diffusing acrylics. I'll try to make small discs out of the 2447 sheet with a hole drill bit. If you have a better idea, let me know.

cost: $4.95 + $10(SH)


----------



## mistergreen

The diffuser seems to work great. I think we have a winner.










It allows light to come through and corrects the curve. I'll do more testing when the sun comes out for higher PAR readings. The closer I got to the light bulb, the more erratic the readings. So I can live with the gap in the beginning of the graph there.


----------



## mistergreen

More readings
The readings are random locations. I taped the 2 sensors together so they're the same angle etc...










It looks like the coefficient needs to change with par over 900.
Something like 


Code:


if (output <= 900) coefficient = 1.53
else 
coefficient = 1.34


----------



## Katch

I've been following this thread for a while now and have 3 of these sensors sat on my desk (samples  ).

Are you still using a 27k resistor? I'm going to build mine later I think. Do you also have your current code for the arduino?

Much respect for your work here! Looking forward to finding out how much PAR is coming out of my DIY LED setup.


----------



## mistergreen

Here you go. Make sure to get the same cosine diffuser (2447 acrylic) too. I'm still using the 27K resistor.


Code:


#include <LiquidCrystal.h>

float average = 0;
float output = 0;
float factor = 1.52;
unsigned long time;
int counter = 0;
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);


void setup() {
  time = millis();
    // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("2noodles PAR");
  
}

void loop() {
  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
     //corrections to fit par
   average = average/counter;
   
   if(average <= 560) {
     factor = 1.55;
   } else {
     factor = 1.36;
   }
   //corrects for high PAR
   output = average * factor;
   
    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(output);
  
    //reset timer & counter to get ready for the next second.
    time = millis();
    counter = 0;
    average = 0;
  }
}


----------



## Katch

Thanks. I'm trying to get some of that acrylic but it doesn't seem to be available in the uk... I have a flat diffuser from a photography light meter I'm going to try.

Sent from my HTC Desire using Tapatalk


----------



## mistergreen

Katch said:


> Thanks. I'm trying to get some of that acrylic but it doesn't seem to be available in the uk... I have a flat diffuser from a photography light meter I'm going to try.
> 
> Sent from my HTC Desire using Tapatalk


The diffuser will affect the readings. Post your readings of the sun outside without the diffuser and with the diffuser. I can figure out the factor for you so you can change the code.

I think we're around the same longitude so the sun could be a constant we can use and I have an apogee PAR sensor


----------



## Katch

Heh, that's if we ever see the sun here again. Cold wet and dark months are upon us.

Can't find a 27k tonight. Will go have a rummage around my old mans study tomorrow and then post some findings.

Sent from my HTC Desire using Tapatalk


----------



## mistergreen

Katch said:


> Heh, that's if we ever see the sun here again. Cold wet and dark months are upon us.
> 
> Can't find a 27k tonight. Will go have a rummage around my old mans study tomorrow and then post some findings.
> 
> Sent from my HTC Desire using Tapatalk


Whenever the sun does come out, make note on the time of day you took the reading. PAR is affected by that as well.


----------



## Katch

ok, not sure I've got mine working right at all...

here's the code I use. I've put the serial output back in because I'm not using an LCD.



Code:


#include <LiquidCrystal.h>

float average = 0;
float output = 0;
float factor = 1.52;
unsigned long time;
int counter = 0;
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);


void setup() {
    Serial.begin(9600);
  time = millis();
    // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("2noodles PAR");
  
}

void loop() {
  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
     //corrections to fit par
   average = average/counter;
   
   if(average <= 560) {
     factor = 1.55;
   } else {
     factor = 1.36;
   }
   //corrects for high PAR
   output = average * factor;
   
    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(output);
    
        Serial.println(average,1);
  
    //reset timer & counter to get ready for the next second.
    time = millis();
    counter = 0;
    average = 0;
  }
}

I get 1023 outside in full sun (1:45 pm GMT) without the diffuser and 385 with.

Hmmm also just noticed my diode is a VTB8440BH - not 1BH but the datasheet looks near identical (they are both on the same sheet - http://www.alliedelec.com/Images/Products/Datasheets/BM/PERKINELMER/980-0078.PDF)


----------



## mistergreen

They do look similar. PM me your address. I'll send you a little piece of my acrylic. You'll have something known to compare against your diffuser.


----------



## Katch

tnx - pm sent

Am I also right in saying the meter only reports values from 0 - 1023?

Is the idea that we won't ever be measuring above 1023 PAR in our tanks so we only need to measure in that range?


----------



## jccaclimber

1023 makes me think you're maxing out the chip. That is the max return value for a 10 bit register.


----------



## Katch

I agree


----------



## jonny88888

*Awesome DIY*

Mistergreen, This is a great DIY, and I'm going to give it a shot, I'll be able to post numbers to help your data. I just ordered the silicon photo diode from allied electric. I like how you integrated the network cable.

Where did you find that watertight fitting, and the housing for your sensor? It looks like in your rebuild that you are no longer mounting the diode on a cable tie. what are you mounting it on?


I might have a couple follow up questions for you too if you don't mind.


----------



## mistergreen

Katch said:


> tnx - pm sent
> 
> Am I also right in saying the meter only reports values from 0 - 1023?
> 
> Is the idea that we won't ever be measuring above 1023 PAR in our tanks so we only need to measure in that range?


It should theoretically go fro 0 - 2000 PAR. The code adjust the 0 - 1023 input signal to the arduino. It's winter no so you should get around 1500 PAR. Full sun in the summer should get you 2000 PAR. But yes, you don't typically get readings up in the thousands in an aquarium setting.


----------



## mistergreen

jonny88888 said:


> Mistergreen, This is a great DIY, and I'm going to give it a shot, I'll be able to post numbers to help your data. I just ordered the silicon photo diode from allied electric. I like how you integrated the network cable.
> 
> Where did you find that watertight fitting, and the housing for your sensor? It looks like in your rebuild that you are no longer mounting the diode on a cable tie. what are you mounting it on?
> 
> 
> I might have a couple follow up questions for you too if you don't mind.


The container is a small paint cup from an art store









It's not water tight, so I silicon the lid to the cup









If anybody has a better design, please give me ideas.


So far this DIY par meter is pretty darn good. It's almost on PAR (pun) with the APOGEE PAR meter. I use it to measure everything now like for my new 10G tank and I've noticed I need new t-5 bulbs for my 75G tank.


----------



## stephenpence

How close are we to a big S&S unveiling?? the only thing that i can see that may help your design would be to make it so it can sit flat with the sensor facing upwards. I was on the verge of breaking down and blowing the $300 on a PAR meter, so needless to say.. pins and needles over here to find out if you're close to selling some of these bad boys!!


----------



## demonr6

Man I love reading these threads. Way over my head on some parts but I can appreciate the hard work, perseverance and determination to get this thing down right. I would have saved up and bought the PAR meter but you took the creative approach and decided making one was more enjoyable than shelling out the $300. How much are you into it financial wise since you took this on? 

I can't wait to see the final product, I want to get one not only because I want one and can use it.. but to say I bought something actually _made_ by someone.

Props to you on this one.


----------



## stephenpence

so i've decided to follow in your footsteps sensei. although having read the thread, i was a little confused as far as which photo sensor you ended up using? actually, if i could be even more demanding, could you post a full equipment list?? I'm so excited for this!!!!


----------



## The A Dog

This thread is awesome, so exciting to track your progress seeing others getting involved!!! It does seem a little daunting for someone who doesn't know how to code and is a beginner with electronics, but it is inspiring and might be a good learning project!!! I am thinking of getting one of the budget TI boards to practice on


----------



## mistergreen

stephenpence said:


> so i've decided to follow in your footsteps sensei. although having read the thread, i was a little confused as far as which photo sensor you ended up using? actually, if i could be even more demanding, could you post a full equipment list?? I'm so excited for this!!!!


I changed the 1st post... I'll list all the the components there. For now the photo diode is listed.


----------



## Chlorophile

I think I may have something of interest for you. 
It is a part off of a photography light meter - there are two different kinds and either may be of interest. 
Sekonic L - 398 M Lumidisk 
or
Sekonic L - 398 M Lumisphere

The lumisphere provides cosine corrected light readings for individual light source measurements. 
I don't know what the lumidisk does, it might be good for readings with multiple light sources? 
There is also a lumigrid which has lots of small holes in it, which on the light meter is useful for measuring reflected light, but probably not useful to you. 










This is the lumisphere

You could probably find a way to silicone it to the rest of the housing and make it waterproof, and maybe you could find a way to make the cable come out of the side so it could lay flat.


----------



## mistergreen

Chlorophile said:


> I think I may have something of interest for you.
> It is a part off of a photography light meter - there are two different kinds and either may be of interest.
> Sekonic L - 398 M Lumidisk
> or
> Sekonic L - 398 M Lumisphere
> 
> The lumisphere provides cosine corrected light readings for individual light source measurements.
> I don't know what the lumidisk does, it might be good for readings with multiple light sources?
> There is also a lumigrid which has lots of small holes in it, which on the light meter is useful for measuring reflected light, but probably not useful to you.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> This is the lumisphere
> 
> You could probably find a way to silicone it to the rest of the housing and make it waterproof, and maybe you could find a way to make the cable come out of the side so it could lay flat.


Can people buy this component?
I'm limiting to parts people can buy cheaply.

The piece of acrylic I'm using seems to work pretty well.


----------



## Chlorophile

http://www.adorama.com/SKL398LS.htm...ping Site&utm_campaign=Other&utm_source=gbase


----------



## Chlorophile

Here is a picture of mine next to a quarter. 
its fairly deep and hollow too. 
Would certainly look more similar to a real par meter if you care about looks ;]

P.S. Doesn't the angle of this photograph make you feel upside down? Muahahaha


----------



## mistergreen

Ok, I finally got around to drawing out the diagram for this.










Does anybody want to design the printed circuit board?


----------



## O2surplus

mistergreen said:


> Ok, I finally got around to drawing out the diagram for this.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Does anybody want to design the printed circuit board?


I'll take a crack at it. Did you want an Arduino compatible "shield" or better yet, a Stand alone board with it's own AVR, LCD display, and on board Battery power? I could build you a PAR meter with similar construction to the LED controller that I built last year. Here's a photo of the "guts" and another with the LCD attached. I could probably shrink everything needed for the PAR meter to fit on a board no larger than the LCD. Let me know what you think.


----------



## mistergreen

Thanks!



O2surplus said:


> Did you want an Arduino compatible "shield" or better yet, a Stand alone board with it's own AVR, LCD display, and on board Battery power?


Whichever is the cheaper/easier route. Let's mobilize this thing!


----------



## stephenpence

having recently had some experience with O2's boards, i say we go for the all inclusive one. I'm doing some builds off of his work for my LED drivers, and it's, well, legit. if we (using the we term FAIRLY liberally here  can eliminate the arduino, and slot in the LCD screen, this thing would be much more manageable to encase and use. but that's just my vote


----------



## O2surplus

Mistergreen-

I'm going to design the PAR meter Pcb to be as small as possible and power it off a standard 9v battery. I'll probably use the ATMEL328-AU, as I have 20 of them already flashed with the Arduino "Optiboot" - Bootloader. I'll include a connection for a FTDI adapter as it will be needed for the initial programming. If you could do me a favor- please post your wiring diagram with a little more info as it will save me some time. I need to know what size jack plug you want ( 1.8mm, 2.1mm, 2.5mm ect.) Also a copy of your "sketch", so that I can confirm the exact pin/wiring configuration used. I'll get to work on this and send you PM's if further questions arise.


----------



## mistergreen

O2surplus said:


> info as it will save me some time. I need to know what size jack plug you want ( 1.8mm, 2.1mm, 2.5mm ect.)


The Jack is a bulky home depot 6 pin phone jack. Not sure what you mean by 1.8mm,2.1mm etc... It can be any jack, ethernet etc..

Here's the code for you to confirm pins.

What's the cost estimate on this?



Code:


#include <LiquidCrystal.h>

float average = 0;
float output = 0;
float factor = 1.52;
unsigned long time;
int counter = 0;
// initialize the library with the numbers of the interface pins
[B]LiquidCrystal lcd(12, 11, 5, 4, 3, 2);[/B]


void setup() {
  time = millis();
    // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("2noodles PAR");
  
}

void loop() {
  [B]int sensorValue = analogRead(0);[/B]
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
     //corrections to fit par
   average = average/counter;
   
   if(average <= 560) {
     factor = 1.55;
   } else {
     factor = 1.36;
   }
   //corrects for high PAR
   output = average * factor;
   
    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(output);
  
    //reset timer & counter to get ready for the next second.
    time = millis();
    counter = 0;
    average = 0;
  }
}


----------



## O2surplus

mistergreen said:


> What's the cost estimate on this?


I'm shooting for around $20 not including the PAR sensor, project box, and battery. 

1. Custom PCB - $2-$4
2. ATMEL 328 Micro-controller $5
3 16x2 LCD - $5
4. 16Mhz crystal - $1
5. 5 volt regulator - $1
6. dc power jack, resistors,capacitors, ect..$4


----------



## mistergreen

Hey, that's pretty good. Cheaper than the actual arduino uno.


----------



## O2surplus

This should work. I modified the wiring diagram and the code for the LCD a bit, and included a 1ok pot for the screen contrast adjustment. The Par sensor will connect to the bottom side of the PCB, through a 2.1mm DC barrel jack. Power will be provided through a remote mounted switch, by a 9V battery. The PCB measures 83mm x 40mm and will mount directly to the underside of a 16 X 2 LCD.
I'm going to re-flash one of my led controllers as a test, just to make sure the circuit will work before ordering some boards. Please let me know if you Guys see anything that I may have missed, as I cranked this one out in a hurry.


----------



## mistergreen

Looks pretty darn cool.

You know better than I but pin 5 on the LCD-header isn't used?

Oh, I found a barrel jack male on sparkfun.
http://www.sparkfun.com/products/10287

I think it's cleaner than a phone jack.

I should grab a USB to FDTI cable while I'm at it.
http://www.sparkfun.com/products/9718


----------



## Chlorophile

O2surplus said:


> This should work. I modified the wiring diagram and the code for the LCD a bit, and included a 1ok pot for the screen contrast adjustment. The Par sensor will connect to the bottom side of the PCB, through a 2.1mm DC barrel jack. Power will be provided through a remote mounted switch, by a 9V battery. The PCB measures 83mm x 40mm and will mount directly to the underside of a 16 X 2 LCD.
> I'm going to re-flash one of my led controllers as a test, just to make sure the circuit will work before ordering some boards. Please let me know if you Guys see anything that I may have missed, as I cranked this one out in a hurry.


Hmmm.. Looks like it's missing a TI-83 input, and your Exhaust-Gas Solenoid port doesn't link up to the blugger valve...


----------



## O2surplus

I think I must have done something right. After making a few mods to Mistergreen's code to match the lcd circuit that my controller uses, I uploaded the code and SHAZZAAAAM! It works-










Here's the modified code-


Code:


#include <LiquidCrystal.h> // modified by O2surplus

float average = 0;
float output = 0;
float factor = 1.52;
unsigned long time;
int counter = 0;
// create the LCD
LiquidCrystal lcd(8, 7, 5, 4, 16, 2);
// set up backlight
int bkl = 6; // backlight pin

void setup() {
  time = millis();
    // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("2noodles PAR");
  pinMode(bkl, OUTPUT);
  digitalWrite(bkl, HIGH);
  
}

void loop() {
  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
     //corrections to fit par
   average = average/counter;
   
   if(average <= 560) {
     factor = 1.55;
   } else {
     factor = 1.36;
   }
   //corrects for high PAR
   output = average * factor;
   
    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(output);
  
    //reset timer & counter to get ready for the next second.
    time = millis();
    counter = 0;
    average = 0;
  }
}

Next will be to order some boards, put a couple together, and send'em to Mistergreen for evaluation and testing.


----------



## HD Blazingwolf

when this gets done. i will buy one to support the hobby. i can't do math, or coding, or decide whci hway to wire and code a microprocessor. i understand these principles well, just don't have the knack for actually making a system. but i can take anythign apart and replicate anything done efficiently which includes prewritten code, and fully assembled systems


----------



## mistergreen

I'll make sure it's calibrated to actual PAR numbers and then will post it on the S&S probably. It'll probably be $40 - $50 over-all... Not sure about encasing this in a project box or not for the sake of cost and assembly time. Maybe we'll leave that up to you guys.


----------



## O2surplus

Mistergreen- Can you think of anything, component wise, that should be added to the PCB? I was wondering if it would be prudent, to add another 1kohm pot inline with the 27kohm resistor, to allow for fine tuning of the signal coming from the photo diode? It's a simple matter to make any additions now, prior to the board production run.


----------



## mistergreen

O2surplus said:


> Mistergreen- Can you think of anything, component wise, that should be added to the PCB? I was wondering if it would be prudent, to add another 1kohm pot inline with the 27kohm resistor, to allow for fine tuning of the signal coming from the photo diode? It's a simple matter to make any additions now, prior to the board production run.


That's actually a pretty good idea. I was going to adjust the code for fine tuning


----------



## aaronbrown

i want one when you get them up and operational just let me know the price and where to send it


----------



## O2surplus

Ok - I added a 5kohm pot in line with the resistor. I dropped the value of the resistor to 24.9k ohms so that with the additional resistance provided by the pot, total circuit resistance can be varied from the 27k Ohm target + or - 2.5k. This should allow for an increased PAR sensor calibration range. Here's the latest PCB. I'll send the files out for production and have some boards by next weekend.


----------



## Chlorophile

O2surplus said:


> Mistergreen- Can you think of anything, component wise, that should be added to the PCB? I was wondering if it would be prudent, to add another 1kohm pot inline with the 27kohm resistor, to allow for fine tuning of the signal coming from the photo diode? It's a simple matter to make any additions now, prior to the board production run.


I have no idea what that might do, but I am wondering if that is something that maybe the end user shouldn't be able to tweak? 
What would the effect be of adjusting the potentiometer? 
It seems it would be nice for us all to have identical equipment so our readings are comparable. 
Again I don't know what the heck it does, but I am wondering.


----------



## mistergreen

When you build applications, you try to be flexible so not to paint yourself into a corner. Things are rarely fixed so a little calibration is needed but the end product should be standardized.

For instance, a 27k resistor isn't really 27k. It can vary from 26.6k to 27.2k or something like that. That affects the read out. So, having a pot, I can calibrate the read out to match actual par readings.

I have an apogee par sensor.


----------



## O2surplus

Ok everyone- I sent the PCB design files to SeeedStudio this morning. If everything goes smoothly, I should have 10 of the Pcb's in my hands in about 9 days. I'll then solder some of them up and send them out to Mistergreen for testing.

Mistergreen- Please send me a PM with your mailing address, when you have time.


----------



## audioaficionado

Subscribed.

It will be nice for a DIY alternative to the $$$ least expensive units I've looked at.


----------



## mahko

Same. Subscribed. This looks really cool.


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## mistergreen

Let's give this a name. How about "Close enough PAR".
O2Surplus, If you're going to upload the binary, can you change the 2noodles to that? It's 16 characters exactly


----------



## O2surplus

mistergreen said:


> Let's give this a name. How about "Close enough PAR".
> O2Surplus, If you're going to upload the binary, can you change the 2noodles to that? It's 16 characters exactly


I can do that. I was going to name mine " H&H PAR" which is short hand for "Horse shoes & Hand Grenades". since you only have to be "close enough" with either to win .:icon_mrgr


----------



## tentacles

How does a person get a place on the waiting list for these?


----------



## mistergreen

No waiting list. I'll post the item on the swap & shop.


----------



## tentacles

I'll be trying to watch the SnS like a hawk then.. Are you only making 10 of these, or more than that? 

Also, have you had an opportunity to compare your photodiode to the apogee with reef type lighting or blue/RB leds? It would be nice to know if it could also be useful for checking reef lights as well as planted tank stuff.


----------



## mistergreen

We'll start with 10. Baby steps 
Theoretically it should work with any fluorescents.


----------



## h4n

Very interesting!
Subscribed too!!


----------



## O2surplus

Update - PCB's have been manufactured and shipped and I have enough parts on hand to build the first batch of ten. I'll start soldering just as soon as the boards arrive :biggrin:


----------



## O2surplus

Well everybody, so far so good. The PCB's arrived last night, so I spent a few minutes this evening soldering up a unit and flashing it with MISTERGREEN'S Firmware. I'll be mailing this one out to MISTERGREEN for calibration and testing.

Take a look- the first photo shows the main board and the LCD. The second shows the completed unit up and running. Pretty cool huh!


----------



## mistergreen

That's very tight looking.
Don't forget the barrel jack 
If not, I can find one at radioshack or something.

It took you a few minutes! That's mighty good. It took me an hour to solder up the prototype.


----------



## O2surplus

mistergreen said:


> That's very tight looking.
> Don't forget the barrel jack
> If not, I can find one at radioshack or something.
> 
> It took you a few minutes! That's mighty good. It took me an hour to solder up the prototype.


Haha - Maybe more like 15 minutes! That's what makes using an actual printed circuit board worth the money! The barrel jack is out of view because it's mounted to the bottom of the PCB. I used a 2.1mm DC barrel jack because they're a fairly common size and easy to source. I think we'll have to standardize the length of the sensor cable (I'm thinking 6' should be plenty) prior to calibration, so that PAR readings will not vary (between par sensors), due to differences in cable length, #of wire strands, ect.. 

I'll be dropping this unit and an appropriate cable in the mail for you sometime this week. All you have to do is attach the diode and calibrate the unit. Let me know if we have a winner and I'll "spend a few minutes" soldering up some more.


----------



## mistergreen

Good point on the cable length. I have a roll of ethernet cable I can use. The cable is round so I can use a cable grip on it when attaching the sensor housing, makes a water-tight seal.


----------



## aaronbrown

looking good cant wait till there for sale i need one for my fresh and saltwater tank


----------



## tentacles

I'm pretty excited too. I was thinking about how these would react to blue LEDs (like checking reef tank PAR), and I bet they'll be pretty close. No way to tell until somebody tries it, though.


----------



## rollntider

i am looking forward to how this turns out. I would not mind a low cost meter.


----------



## audioaficionado

This is amazing how well this project is turning out. I'll have to set aside some bux to jump on one as they'll go fast once listed in the SnS.


----------



## JohnnyAirtime

Subscribed!!

And I only registered to this site, to get in on one!! I'm salty (Reef Tanks) 

ANY Chance you can let everyone know when they are posted as "available"??


----------



## mistergreen

JohnnyAirtime said:


> Subscribed!!
> 
> And I only registered to this site, to get in on one!! I'm salty (Reef Tanks)
> 
> ANY Chance you can let everyone know when they are posted as "available"??


Nice!

O2Surplus sent one in the mail. I'll get it by next week.
I'll let you (all) know when it's available on the S&S. Or maybe I'll keep the first one for sentimental reasons


----------



## audioaficionado

I'll have the bux in a couple of weeks.
I'll gladly take #2 or 3 off your hands :icon_mrgr


----------



## O2surplus

SSSSSSHHHHH! You didn't hear it from me, but.......we're getting really close ("close enough" that is)


----------



## jccaclimber

Cool, I'm looking forward to this.


----------



## mistergreen

Well, working on this I learned something. The 27K resistor isn't some magic number. It will vary from device to device which affects the output. These are fairly sensitive sensors. Without a real PAR meter to calibrate it'll be hard if not impossible. And good thing O2surplus had the idea of putting in a potentiometer as a resistor so it can be calibrated.


----------



## O2surplus

So If I understand the situation correctly, Each photo diode has to be treated as an individual because there's variations between diodes, even if they're from the same manufacturer's batch. We'll have to lower the value of the standard resistor and raise the value of the potentiometer to compensate for such differences. Plus we'll need an actual Apogee PAR meter to reference to, for setting up the initial calibration of our little DIY meter. The situations not impossible- just a little more challenging. SO who's got an Apogee meter that they're willing to loan to MISTERGREEN?:icon_excl


----------



## mistergreen

I got one ( an apogee sensor )!
That's how I can move forward 

We're good. I was giving a head up for any body else who wants to build this.


----------



## O2surplus

Cool! So we're not really stuck? Do you think it would be a good idea for me to finish assembly of the remaining units and send em' to you, so they can all be calibrated to match each other? I'll have some free time this weekend for soldering the rest, if needed.


----------



## mistergreen

No we're not stuck. We just need more range on the resistance. Your 10K - 40K plan is good.


----------



## audioaficionado

How much range do you need?
Is there going to be any drift on one large pot?
Would a precision resistor with a small precision pot in series work better?


----------



## mistergreen

I don't think we need to be super precise. It is a 'Close enough PAR' meter


----------



## mistergreen

Here are some pictures.

Up & running, perfectly.









Some minor corrections to get it running perfectly.









Shrink tubing is a wonderful thing.


----------



## audioaficionado

Payday is tomorrow :icon_mrgr


----------



## galabar

mistergreen said:


> Here are some pictures.
> 
> Up & running, perfectly.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Some minor corrections to get it running perfectly.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Shrink tubing is a wonderful thing.


Ok, now its time to get a Chinese manufacturer to put it in a fancy box and start shipping these out to us.


----------



## jccaclimber

I've actually worked with a couple off shore (and domestic) circuit manufacturing places if it ever comes to that.


----------



## O2surplus

jccaclimber said:


> I've actually worked with a couple off shore (and domestic) circuit manufacturing places if it ever comes to that.


I had the PCB's made in China. The rest of the build was soldered by hand, as it should be with a DIY product. We'll probably leave the installation into an enclosure to the people who buy them. That way everyone gets some satisfaction for "Doing it themselves" and the cost is held down to boot.


----------



## jccaclimber

Sounds good. Do you have any thoughts on how casual hobbyists like myself should go about calibrating the unit on a cloudy winter day?


----------



## O2surplus

*Great Job MISTERGREEN!*

What do you think about using a 1k ohm resistor in line with a 30k pot? Do you think a 30k ohm adjustment range will cover all the photo diode variances, or should it be higher than that? I'll probably switch the pot out from a single turn to a multi-turn, so you don't loose adjustment resolution with such high resistances.


----------



## jccaclimber

^At that point why do you have the 1k Ohm resistor? It seems like a large and small pot, or just one large multi turn one would work better with less parts.


----------



## O2surplus

jccaclimber said:


> Sounds good. Do you have any thoughts on how casual hobbyists like myself should go about calibrating the unit on a cloudy winter day?


You don't need to calibrate the unit before use. Mistergreen will be calibrating each unit against his apogee sensor before sending them out to buyers. That way everyone gets a PAR meter that will behave exactly like all the others that we build.


----------



## O2surplus

jccaclimber said:


> ^At that point why do you have the 1k Ohm resistor? It seems like a large and small pot, or just one large multi turn one would work better with less parts.


We still need a small fixed resistor in line with the pot to protect the unit from a short circuit in the event that the pot were turned to its minimum value. Think of it as a safety item that helps "keep the smoke in the wires where it belongs".


----------



## mistergreen

O2surplus said:


> *Great Job MISTERGREEN!*
> 
> What do you think about using a 1k ohm resistor in line with a 30k pot? Do you think a 30k ohm adjustment range will cover all the photo diode variances, or should it be higher than that? I'll probably switch the pot out from a single turn to a multi-turn, so you don't loose adjustment resolution with such high resistances.


I don't think it needs to be that big... I have a feeling it'll hover around 20K total. I'll make another sensor over the weekend to see what the variances are.


----------



## mistergreen

jccaclimber said:


> Sounds good. Do you have any thoughts on how casual hobbyists like myself should go about calibrating the unit on a cloudy winter day?


Yeah, I'll calibrate them before I ship them out.


----------



## jccaclimber

I like keeping the magic smoke inside, the magic tends to leave with the magic smoke. I used to have pots that had a minimum resistance, but looking around it seems like those are pretty rare.


----------



## O2surplus

mistergreen said:


> I don't think it needs to be that big... I have a feeling it'll hover around 20K total. I'll make another sensor over the weekend to see what the variances are.


Ok, Just let me know what you find. I think I've got some 15.6k ohm resistors and 10k pots that can be soldered in to the remaining units. That way you'll have a 10k adjustment range + & - of the 20k target value.


----------



## mistergreen

I've tested this on fluorescents, and now just tested on a LED. All I had was an LED flash light. It's on PAR, 
PAR: 72.5
CEP: 74.0
(Close Enough PAR)


----------



## O2surplus

mistergreen said:


> I've tested this on fluorescents, and now just tested on a LED. All I had was an LED flash light. It's on PAR,
> PAR: 72.5
> CEP: 74.0
> (Close Enough PAR)


WOW- I'd call that "close enough". Let me know when you're totally satisfied with the performance of the meter and I'll solder up the rest.


----------



## Chlorophile

Dang, only thing that would make this look any sweeter would be using the cosine corrected lumisphere from sekonic instead of that plastic cup!!


----------



## audioaficionado

Where do I send my money for one? :icon_mrgr


----------



## O2surplus

Well folks, After scanning this whole thread, it seems that there's a lot of interest by members who want to purchase this little creation. I'm going to try my best to build out the remaining 9 examples and send them off to MISTERGREEN for calibration. I'm sure he'll post them up on the S&S forum, and they'll be up for grabs - first come first serve. MISTERGREEN and I are not in this to make a profit. The "Close enough PAR Meters" will be sold for our COSTS ONLY. (I'll post receipts with a breakdown of parts costs) If all the units sell out quickly and there is still demand for more, I'll be happy to do another production run, provided that MISTERGREEN is still willing to provide his time to build the sensor, calibrate the units and post them for sale. I've already designed the next version. It will use the larger DIP version of the ATMega328 micro-controller IC. Here's a picture of the Board.


----------



## mistergreen

Chlorophile said:


> Dang, only thing that would make this look any sweeter would be using the cosine corrected lumisphere from sekonic instead of that plastic cup!!


The little acrylic piece inside the cup does a pretty darn good job at cosine correction at fractions of the cost...around $0.80 at piece for now.
Will be cheaper when I buy a big sheet of it.


----------



## audioaficionado

I'm subscribed to this thread. Could you make an announcement here so those of us who have followed this project thread can have a chance of finding the SnS thread in time? I don't troll the SnS 24/7 like some seem to do, but I do check my subscribed threads a few times a day.


----------



## mistergreen

yup, will make an announcement here first then I'll post it in the S&S.


----------



## h4n

I can't wait!!


----------



## darkside212

subscribed!


----------



## mistergreen

O2surplus is shipping me some units. I'll have some out in a couple of weeks.

This looks to be $40 - $50 without shipping, probably $50.


----------



## h4n

Yayy!! I definitely want one!!!


----------



## daveonbass

Are you saying that the parts for you are 50 bucks, or that the unit is for sale to us for 50 bucks? Im extremely interested in one of these. If its cheaper than an apogee then I'm totally in, especially because of how close it seems to be to the PAR readings from other meters. Put me down for a meter.


----------



## crowconor

I saw an apogee par cable and it came with computer software. Maybe I am wrong but I was under the impression you could get PAR readings like this through your computer. And that was only $61


----------



## mistergreen

daveonbass said:


> Are you saying that the parts for you are 50 bucks, or that the unit is for sale to us for 50 bucks? Im extremely interested in one of these. If its cheaper than an apogee then I'm totally in, especially because of how close it seems to be to the PAR readings from other meters. Put me down for a meter.


The unit with sensor will be $50. Parts are around $38. The rest is for labor and shipping between me and O2Surplus. Still cheaper than a LUX meter 




crowconor said:


> I saw an apogee par cable and it came with computer software. Maybe I am wrong but I was under the impression you could get PAR readings like this through your computer. And that was only $61


$61? I think your might have the wrong info. I bought the apogee cable & sensor for $150.


----------



## wet

mistergreen! 

I just got my first Arduino this weekend, googled for aquarium projects for ideas, and ran across this wonderful thread. So much awesome.

O2Surplus and you are married to leaving off a USB/Serial output? I ask because the capability of logging output is important to me and would be a deal breaker for purchasing instead of DIYing this rad project.

Thanks!


----------



## audioaficionado

Less bells and whistles = low/affordable price


----------



## mistergreen

wet said:


> mistergreen!
> 
> I just got my first Arduino this weekend, googled for aquarium projects for ideas, and ran across this wonderful thread. So much awesome.
> 
> O2Surplus and you are married to leaving off a USB/Serial output? I ask because the capability of logging output is important to me and would be a deal breaker for purchasing instead of DIYing this rad project.
> 
> Thanks!


Hey,
O2Surplus would know better than I. There is FTDI interface. You can get a usb to ftdi cable. Maybe you can get output through that?

I can check really quick.

Actually, O2surplus will come out with a new design with a new chip where your can mount it onto your arduino to reprogram. You'll need a serial.print instead of the current code to print to the LCD.


----------



## O2surplus

I don't think we need to add the USB adapter to the circuit board, The FTD1 interface adapter can be used to log data through the serial monitor in the Arduino IDE. I think all that would be needed is a few tweaks to the Firmware "Sketch" to make serial output possible.


----------



## darkside212

Yeah the sensor/cable is about $150 through apogee, so $50 for something that is relatively close is AWESOME. Also my understanding is the apogee measure par 400-700 and most of that is not utilized by plants, and coral. What I'm saying is even if it's a little off, where it is off is probably not in a range that is important (or at least it's wishful thinking)


----------



## mistergreen

The funny thing about a par sensor is the closer you are to a light source, the more erratic the readings. Also you can be a few millimeters closer, farther, or the angle is slight off, and the readings are different. So the case for a cheap, close enough sensor is a good one.


----------



## darkside212

yes I currently have an apogee on loan from my local club and it behaves the same way.


----------



## wet

Thanks for the followup re: serial, mistergreen and O2surplus


----------



## mistergreen

O2surplus just wrote in code for a serial output so you bon't have to reprogram the meter. All you need is the USB to FTDI adaptor. You can get it at sparkfun.com. We'll test it out for you.


----------



## wet

Awesome. I'm blanking on additions or good ideas to add for most folks, but hope to contribute some code or ideas back once you're shipping. Maybe I'll just pick up some probes and start looking into a logging solution, or relays and a per-outlet control for the Uno that's still lonely here.


----------



## audioaficionado

I know you guys have RL responsibilities and pursuits so I don't want to bug you too much. Do you anticipate the first batch to go out to SnS around the first week of April? What extras or improvements will the next redesigned batch have over this initial group?


----------



## O2surplus

audioaficionado said:


> I know you guys have RL responsibilities and pursuits so I don't want to bug you too much. Do you anticipate the first batch to go out to SnS around the first week of April? What extras or improvements will the next redesigned batch have over this initial group?


The first week of April may be a bit soon. I sent out the first batch to MISTERGREEN on Friday of last week, so it should arrive any day now. He still has to build all of the sensors and calibrate each unit, so that will add additional time.

I'm working on the design for the next batch as time permits. The overall design won't be changing much. I may use some different components, but the functionality will remain the same.


----------



## audioaficionado

I guess I'll have to install some auto PM bid software to monitor the SnS LOL.


----------



## mistergreen

I can put up 1 or 2 by the first week of April. They're the units we used to experiment with.


----------



## audioaficionado

OK next week I'll start tolling the SnS 24/7 LOL.


----------



## Chlorophile

mistergreen said:


> The funny thing about a par sensor is the closer you are to a light source, the more erratic the readings. Also you can be a few millimeters closer, farther, or the angle is slight off, and the readings are different. So the case for a cheap, close enough sensor is a good one.


If PAR takes into account light in a given area, like flux, but not like lumens, then the sensor size probably plays a role in the weird readings when you get close to the light source.

Maybe a 1 square meter sensor would be less erratic regardless of the distance.
Useless though.


----------



## Chlorophile

mistergreen said:


> The little acrylic piece inside the cup does a pretty darn good job at cosine correction at fractions of the cost...around $0.80 at piece for now.
> Will be cheaper when I buy a big sheet of it.


Hmm... When I buy a meter from you I will want to swap the cover for the domed lumisphere from sekonic, for looks and for the diffusion effect of the white domed plastic, but wont be able to compare the readings I get with the lumisphere.

Any chance you'd buy one to test/compare it with the lumisphere compared to real par meter?
If not I may send you one if you'd try it and let me know the difference in readings with it.

I think it would be quite helpful because the covering your using seems like it would cast specular hotspots that would really mess with the consistency of the readings.


----------



## mistergreen

I'd have to calibrate the par meter with the lumisphere. I might have to change out a resistor if need. 

Sorry for the delays folks. I'm getting slammed by work and sickness in the family and I still have to do my taxes ;eek;

Maybe things will clear up after tax seasons. I definitely have 1 ready for sale but I'd want to build a bunch of them first so more people can get them.


----------



## audioaficionado

That's OK, My daughter's birthday present and a new 20L shrimp setup is wiping out the funds I had set aside, so please take another 3 weeks and I'll have more money in and a chance at one of those units. Thanx again guys for working on this project.


----------



## mistergreen

I'm sitting here doing mind numbing copy and paste work. I can't stand it!
I'm a problem solver by trade.

Money is money I guess.


----------



## mistergreen

Chlorophile said:


> If PAR takes into account light in a given area, like flux, but not like lumens, then the sensor size probably plays a role in the weird readings when you get close to the light source.


Yeah, I'm guessing those whacky photons are more active closer to the light source.


----------



## audioaficionado

mistergreen said:


> I'm sitting here doing mind numbing copy and paste work. I can't stand it!
> I'm a problem solver by trade.
> 
> Money is money I guess.


Could be worse. I'm currently employed cleaning brown paste off porcelain bowls for a living. :eek5:

Pays for the med insurance that keeps my wife alive.



Chlorophile said:


> If PAR takes into account light in a given area, like flux, but not like lumens, then the sensor size probably plays a role in the weird readings when you get close to the light source.


Sounds like you are putting the sensor too close to the source. This is going to be merely a close enough meter. :icon_mrgr


----------



## mistergreen

Ok, I'm back. No more going to the doctor till next week. Taxes are done and paid  
My days of getting refunds are over.
I'll finish up a project today and will have time to start building some sensors this week.


----------



## audioaficionado

Cool!


----------



## Ryi

Subscribed!

I'll be checking SnS for the initial offering. I'm pretty sure you'll have enough response for a second round if I miss out. 
I just picked up a led driver kit (Catalog # 277-029) from Radioshack this weekend, just to learn how to build. I'm like so many others: I can build it if you hand me directions. If you make this in a kit form so all we have to do is some soldering and stuff it in a project box I'll snap one up!


----------



## mistergreen

I scheduled in Sat & Sun to make some sensors.

Yeah, I was in Radioshack buying some supplies and saw that they sell Arduino kits too. They know their audience.


----------



## zavikan

*Simplify for the simple mind*

Alright, read through a lot of this... But a lot of techno over my head talk...

How close is "close enough"? Do we have data on a curve like hoppys old chart comparing the real against the close enough?

What would we be buying? Do I need computer/programming knowledge or is it a self contained meter like the apogee, with it's little digital read out?

Would it be "tricked" by certain lighting? As in, it's good for t5ho, but the spectrum from t8/metal halide (arbitrary examples) would make it far less then 'close enough'?

Is it only effective at a certain distance, or can it do the curve like hoppys chart? Does it get further and further off like the speedo in a car?


----------



## mistergreen

It doesn't seem to be 'tricked'. It only cares about photons with wavelengths between 400 - 800 nm, or something like that.

Hoppy's chart is off so that's not the standard for comparison. It's calibrated to an actual par sensor.

***** update. I have wires cut, cups made. All I need to do for this weekend is to solder in the photo diode, and the barrel jack. I'm pumping out 6 sensors.

Total price seems to be $53.

You'll be getting this









No programming or nothing. It acts like a par meter.

******
Oh shoot, my niece and nephew are visiting this weekend. Will have to find some other time.


----------



## tentacles

Where do I send the money? ;P 

This is such a cool project, if I don't manage to snag one of these, I may just build my own and calibrate it from sunlight or something. Mistergreen, what do you think of having some sort of calibration standard that's easy to get, like a particular LED or CF light, too much batch to batch variation?


----------



## mistergreen

tentacles said:


> Where do I send the money? ;P
> 
> This is such a cool project, if I don't manage to snag one of these, I may just build my own and calibrate it from sunlight or something. Mistergreen, what do you think of having some sort of calibration standard that's easy to get, like a particular LED or CF light, too much batch to batch variation?


If you build one you can send it to me and I'll calibrate it for you. Learning from experience (Hoppy's chart), the only way is to use an actual PAR sensor to calibrate accurately. There are too many variables that would throw off the reading like light bulb BRAND, not only the type etc...


----------



## jcgd

I wish we could give reps on this board. Mistergreen, you'd be way in the green.


----------



## sundragon

Where do we send money?


----------



## Ryi

Fourteen "I want one!" responses so far:

Post# Name
69 NJAquabarren
84 aaronbrown
88 Holyangel
147 demonR6
167 HD Blazingwolf
180 tentacles
192 rollntide
193 audioaficionado
194 JohnnyAirtime
231 h4n
232 daveonbass
251 Chlorophile
259 ryi
266 Sundragon

I didn't count the "wow that's cool" responses. 

Mistergreen, looks like you've got the start of a thriving cottage industry


----------



## Pickled_Herring

Make that 15 I want one too.


----------



## jccaclimber

You can't count PMs to him either. Make that 16.


----------



## jcgd

I want one. 17


----------



## audioaficionado

You guys can count all day long. I don't think it's going to work that way. If all the 2am SnS lurkers with the bux pounce on these and beat me out as they frequently do, I'll just utilize the OP's nice linked parts list to DIY my own and arrange for it to be calibrated later.


----------



## mistergreen

lol, I'm not taking reservations.
I'll put them up on the Swap & shop when I'm done so everybody get a chance.

I'll make an announcement here first so you don't have to lurk in the SnS all the time.

I have to go to a 2 day meeting next week. It's going to kill me. Who meets for 2 days?! It's ridiculous so time is tight for me again.


----------



## Ryi

lol!!


I didn't mean it as a reservation list (or I would have moved myself up a couple spots!) I just meant it to show members with serious interest. I wouldn't be surprised if you are flooded with requests once more people know what you are working on. 
If the marine guys find out? Run!! Run fast!! 
:biggrin:


----------



## audioaficionado

Yeah, right... :icon_mrgr



> SnS lurker: Watch mistergreen's profile page/Statistics tab/'Find all threads started by mistergreen' 24/7 -> "Refresh once a minute until it's mine"


I hope I can get in on one, but my world won't end if I get beat out by dedicated SnS lurkers LOL.


----------



## DrGonzo




----------



## Ryi

http://hackaday.com/category/led-hacks/page/2/


You've made the big time  


HackaDay has a link to your par meter project in their Arduino Aquarium Light article.


----------



## dshel1217

mistergreen said:


> lol, I'm not taking reservations.
> I'll put them up on the Swap & shop when I'm done so everybody get a chance.
> 
> I'll make an announcement here first so you don't have to lurk in the SnS all the time.
> 
> I have to go to a 2 day meeting next week. It's going to kill me. Who meets for 2 days?! It's ridiculous so time is tight for me again.


 
I have been look over the whole thread and I noticed that you guys changed PCB a few times. 

- What PCB did you end up going with? 
- Also did you add a internal pot so it would be easier to make calibration adjustments?

Thanks and you guys are doing a great job!


----------



## wgraham

pm me on how to pay for one of these


----------



## mistergreen

Ryi said:


> http://hackaday.com/category/led-hacks/page/2/
> 
> 
> You've made the big time
> 
> 
> HackaDay has a link to your par meter project in their Arduino Aquarium Light article.


I don't see it but cool. 



dshel1217 said:


> I have been look over the whole thread and I noticed that you guys changed PCB a few times.
> 
> - What PCB did you end up going with?
> - Also did you add a internal pot so it would be easier to make calibration adjustments?
> 
> Thanks and you guys are doing a great job!


The first batch used this one.








But there's a error at the barrel jack connection which we fixed by hand. O2Surplus just designed another PCB and it looks pretty good. That'll be out in the next batch.

I'll spend this Evening soldering up the barrel jack connector in. These things are hard!


----------



## O2surplus

I sent out the design files for another batch. This time there will be two versions of the PCB. The only difference between the two will be the package of the Atmega 328 chip. I also deleted the barrel jack and cleaned up the overall design a bit on both versions. I should have 20 more PCB's ( 10 of each design ) in a week or so. I also designed and ordered a custom PCB that will work as an Arduino Shield for burning Bootloaders onto blank chips. That way I'll be able to use raw chips purchased for a lot less money, in future projects. Here's some photos of the latest PCB's

PAR METER SMDversion












PAR METER DIP Version











"ARDUINO as ISP" Shield


----------



## mistergreen

Hey O2surplus,
So What's the connector now that you deleted the barrel jack?


----------



## O2surplus

mistergreen said:


> Hey O2surplus,
> So What's the connector now that you deleted the barrel jack?



Well it could be made with 2 male pins (soldered to the board) and a female 2 pins connector on the PAR sensor cable - OR - If you want to get super cheap - solder the PAR sensor cable directly to the PCB. 

The change should drop "our costs" by $3 - $4 per unit. roud:


----------



## mistergreen

oh, ok. should we leave this up to the buyer?


----------



## O2surplus

mistergreen said:


> oh, ok. should we leave this up to the buyer?


The way I see it- most buyers will want to mount the PAR meter PCB into some type of enclosure. If we solder the wires or mount it to the PCB using a cheaper plug type of connection our costs are lower. The end user can always cut the cable and install their choice of interconnect for a pass through into their enclosure. I think it's the best way to produce the Meter as buyers will not be paying for a barrel connection on the board that they might not be able to reuse with their own enclosure.


----------



## Ryi

Here's a better link
http://hackaday.com/2012/03/26/arduino-aquarium-lights/
Then look for:


> *But Arduino enthusiasts don’t have to look far to find offerings like this PAR meter build*


----------



## Ryi

wgraham said:


> pm me on how to pay for one of these


Watch SnS like a hawk and hope the rest of us carnivores don't beat you to it


----------



## mistergreen

Ok, all the sensors are soldered. I'll calibrate them all over the weekend. I'll post them up in the SnS on Monday.


----------



## O2surplus

SnS Lurkers are doing this-







and this -


----------



## jccaclimber

I'm just trying to figure out how to get in on this while at work. I can't check the forum from there.


----------



## mistergreen

jccaclimber said:


> I'm just trying to figure out how to get in on this while at work. I can't check the forum from there.


Ok, I'll post the Sns after work. I have some stuff to design and a phone meeting anyway.


----------



## O2surplus

Uhhhh I hate to "split hairs" but.......... What time do you get off work? and in what time zone? I only ask because.......... People need to know what time to line up for the race.


----------



## mistergreen

Let's shoot for 6pm est. That should be 2,3pm pst..


----------



## tentacles

mistergreen said:


> Ok, I'll post the Sns after work. I have some stuff to design and a phone meeting anyway.


This is hardly fair! I took the whole week off to stalk the SnS for one of these! Well, that and help with my newborn son (#2)


----------



## Mr. Fish

Some of you here amaze me on how smart you are.. good work Mistergreen!


----------



## mistergreen

Sounds like all 6 meters will be gone the minute I post them 

I probably want to restrict 1 per user.


----------



## h4n

Got my alarm set for a bit before 6pm est Hahha.
Yes one per user or the first will buy all 6!! 

-Sent from my Samsung Note, a "Phablet"


----------



## audioaficionado

mistergreen said:


> Sounds like all 6 meters will be gone the minute I post them
> 
> I probably want to restrict 1 per user.


Same would be true if you had two dozen.


----------



## mistergreen

Well, I posted the sale and all 6 were gone in 1 minute.
Those who purchased, please PM me you contact info. I'll pm you my paypal.


----------



## h4n

Dam.. Went to go to the bathroom and missed it!!! Ahh

-Sent from my Samsung Note, a "Phablet"


----------



## O2surplus

h4n said:


> Dam.. Went to go to the bathroom and missed it!!! Ahh


Not to worry- I'm stocking up on enough parts to build 20 more, but I'm assuming that MisterGreen is still willing to build the sensors and calibrate the units?


----------



## h4n

O2surplus said:


> Not to worry- I'm stocking up on enough parts to build 20 more, but I'm assuming that MisterGreen is still willing to build the sensors and calibrate the units?


cool~! I hope so!!!


----------



## Hoppy

Hmmm, 10 sales in one minute, equals 600 sales per hour, equals 10000 sales per day, roughly. MisterGreen will be busy for a few days!


----------



## audioaficionado

Thanx, no more PAR level guess work in my tanks :icon_mrgr

I had my bullet preloaded in the gun and finger was on the trigger since 1400 and I still barely got in on the deal.


----------



## tentacles

Damn having kids, I totally forgot about this. Now I have to go pay for an apogee sensor...


----------



## jccaclimber

I guess I shouldn't have gone biking tonight, I guess I'll try to get in on the next batch.


----------



## O2surplus

1 minute- That's got to be record for the S&S. Unbelievable! I hope MIsterGreen has some more diodes and paint bottles laying around, that way he can get a head start on the next batch. I intend to start soldering the next batch this week end and hopefully blow out another 20 units.


----------



## mistergreen

OH man, You guys know how long it took me to make the first batch. I still have plenty of diodes but will have to find other components.

Calibrating is super easy. I just finished an hour ago and now to get some usps priority boxes


----------



## h4n

mistergreen said:


> OH man, You guys know how long it took me to make the first batch. I still have plenty of diodes but will have to find other components.
> 
> Calibrating is super easy. I just finished an hour ago and now to get some usps priority boxes


I hope you guys make more!!

I still can't believe i got up to go use the bathroom and missed it lol!!!

-Sent from my Samsung Note, a "Phablet"


----------



## DENNISF

Well I missed out on the first batch! I have been following this for several months in the background to see if it would really come to be and it did. Congratulation! Now to my point, I am on the BOD of the Dallas/Fort Worth Marine Aquarium Society and we are always looking for presentors for our monthly meetings. I was wondering if mistergreen would be interested in putting together a 40 minute powerpoint presentation on this operation for presentation at one of our monthly meeting in the not to distant future? We are a salty group but we like light too.:icon_smil If you are interested, respond here. I will check back.


----------



## O2surplus

mistergreen said:


> OH man, You guys know how long it took me to make the first batch. I still have plenty of diodes but will have to find other components.
> 
> Calibrating is super easy. I just finished an hour ago and now to get some usps priority boxes



It's too bad that "life" always gets in the way of having fun. Bills, relationships, and other commitments have to be taken care of first and often. That leaves little time for other pursuits- other than sleep.
Should we try to find another way to create the sensor that is less labor intensive? - if there is one? Should we use something "off the shelf"? Any solution that would free-up Mistergreen's time to simply solder a few connections and calibrate the units would be appreciated.
I can build each unit in as little time as 15 minutes, but I have to stay up late to do so. I'm limited to a few hours on weekends to do the work, so progress will be slow- but I'll continue building these if the demand is there.


----------



## mistergreen

Well, not having to solder in the male barrel jack will save a lot of time. I'm not sure if there's any 'off the self' solution.

I'm going to run out of the 1/4" ethernet cord soon. Home depot stopped selling them by the roll. Do you know of a better solution? It'll be cheaper by the roll.


----------



## jcgd

mistergreen said:


> Well, not having to solder in the male barrel jack will save a lot of time. I'm not sure if there's any 'off the self' solution.
> 
> I'm going to run out of the 1/4" ethernet cord soon. Home depot stopped selling them by the roll. Do you know of a better solution? It'll be cheaper by the roll.


Electrical wholesalers would probably be cheaper than HD or lowes. I'm sure teu could cut you a few dozen meters of wire at a time.


----------



## O2surplus

jcgd said:


> Electrical wholesalers would probably be cheaper than HD or lowes. I'm sure teu could cut you a few dozen meters of wire at a time.



We only need a 2 conductor cable with round insulation correct? I found this - seems kinda pricey though @ $45 for a 100' roll?

1172C SL005 Alpha Wire | A120-100-ND | DigiKey 

I'll take a look at my local electrical supply houses and see what they've got. I'm sure that I could find some more Ethernet cable for cheap, but shipping it to you would negate any cost savings.


----------



## mistergreen

O2surplus said:


> We only need a 2 conductor cable with round insulation correct? I found this - seems kinda pricey though @ $45 for a 100' roll?
> 
> 1172C SL005 Alpha Wire | A120-100-ND | DigiKey


yup, 1/4" in diameter. Yeah, I'm looking local to save on those shipping cost. I'll look around for a local electrical supply co.


----------



## jccaclimber

I'd have to go get a decent soldering iron (been meaning to for a while), but I can do soldering if you send me the parts.


----------



## Jeff52478

I'm going to run out of the 1/4" ethernet cord soon. Home depot stopped selling them by the roll. Do you know of a better solution? It'll be cheaper by the roll.[/QUOTE]


I have a few thousand feet in my garage, it would be kinda costly to send a hole box thru the mail. But I could probably get 1 or 2 hundred feet into a flatrate box if you want.


----------



## tentacles

Digikey wire is silly money, try monoprice - http://www.monoprice.com/products/p...=10239&cs_id=1023904&p_id=4045&seq=1&format=2 100ft, $10. I use the 4 conductor version for LED fixtures.


----------



## mistergreen

Hey, those are pretty good prices. Worth the shipping.
The bigger the AWG, the thinner the wire right? It's probably best to have least resistance.


----------



## Jeff52478

mistergreen said:


> Hey, those are pretty good prices. Worth the shipping.
> The bigger the AWG, the thinner the wire right? It's probably best to have least resistance.


Yes the "higher" the number the thinner the wire is. 24 awg is thinner than 18 awg. Cat 5 is normally 24 awg. The thinner the wire the more resistance u will have, and stranded wire will also have more resistance than solid.


----------



## jcgd

Your volt drop over the wire is the current through the wire multiplied by the wire's resistance. So keep in mine that if those photo diodes don't put out much current than you won't need very large wire. A guess would be that the smallest diameter wire you can find will be much bigger than needed.

I used #18 for my led fixture and I'll be pumping 1.5+ amps through it. I can't see those diodes pushin more than a few hundred milliamperes. Got the data sheet for them?


----------



## jccaclimber

Let me know your current draw (and acceptable voltage drop) along with length and I can spec a wire gauge needed. I know I have a bunch of twisted pair phone wire around, but I might have a lead on some free 'scraps' (less than 50 feet) of Cat5. I'll check in to that tonight and should know by the end of the week. Often places that wire buildings throw away the 'short' leftovers.


----------



## mistergreen

I'm getting free cat5 cable from jeff52478. You can't ask for a better deal than that.


----------



## jccaclimber

That does sound like a pretty good deal, cool.


----------



## O2surplus

My new PAR Meter PCB's arrived yesterday along with more parts from DigiKey, so needless to say- I'm ready to build another batch. One of the PCB's that came in is an Arduino shield that I designed to allow me to burn boot loaders and program blank Atmega 328P-au micro-controllers directly from my Duemilanove. The burning process is fully automatic and doesn't ever require a computer. I managed to assemble one and burn 25 chips last night!The shield is set up to accept chips in the DIP28 and DIP32 package and has a FIT1 input for burning the main sketch. I have a few of these shields left over and will share them with anyone interested in having one. 
Here's a photo of the Programming shield/TQFP adapter on top of my Duemilanove.


----------



## mistergreen

That's very cool. Send me a shield with the next shipment.


----------



## O2surplus

mistergreen said:


> That's very cool. Send me a shield with the next shipment.


Hey Thanks! I'll send you an assembled one with the next batch. All you'll have to add is a ZIF adapter or a TQFP adapter like mine- and you'll be ready to go.


----------



## Ryi

I'm not above bribery 
Are there any other components that are in short supply I could provide in exchange for a spot on the waiting list? I was going to throw in some cat5 but you've got that covered. I'm not arduino-gifted but I bake a mean oatmeal cookie and my brownies are pretty good.


----------



## mistergreen

Ryi said:


> I'm not above bribery
> Are there any other components that are in short supply I could provide in exchange for a spot on the waiting list? I was going to throw in some cat5 but you've got that covered. I'm not arduino-gifted but I bake a mean oatmeal cookie and my brownies are pretty good.


Bribe away but there's no waiting list  We all enjoy cookies & brownies.
First one to buy off the swap & shop. That's all.


----------



## audioaficionado

I used these when I was still a test tech at an assembly house programing embedded firmware in various products for customers.


----------



## mistergreen

Hey, what do you guys think of this new sensor design; less parts, cheaper, faster to make.
I don't think it's as durable as the one with the cup housing but 'good enough'?
The shrink tube is holding the diffuser in place.


----------



## jccaclimber

I think the old design with the cup is much more robust. What is the cost change?


----------



## O2surplus

Will it still be water proof? Have you tried it out yet?


----------



## mistergreen

Just tried it out in water. No short.
I think it saves $5 but more importantly, assembly time.


----------



## O2surplus

Here's an idea- Why not sandwich the diode between two layers of plastic. You could use two different colors so people would know the "blue side" faces the light source and make them about 2"x2" so they would lay flat on their own. You could water proof the sensor by sealing the two halves of the "sandwich" with aquarium safe epoxy. Whatcha think?


----------



## mistergreen

Not sure what you mean. What's the purpose of the sandwich?

I have silicone underneath the diode. It keeps it from shorting and waterproof maybe.


----------



## tentacles

I think the heatshrink method should work fine, but I recommend upgrading to adhesive lined heatshrink, it's a thick walled polyolefin but lined with some hot melt adhesive, stuff sticks to almost anything extremely well. It should stick to that acrylic diffuser as long as you get it nice and hot. Remember, silicone doesn't bond well to acrylic.


----------



## toksyn

Weld-on bonds acrylic very nicely.


----------



## O2surplus

Another issue - unless the silicone is spec'd for electrical use it can be *corrosive* when used as a potting compound. 

I'll have draw up a picture of how I would construct the sensor. I'm just looking for a sure fire way to provide a long lasting= water proof seal for the sensor, that's easy to construct. Drying time for the epoxy would not be an issue since you could pre=solder all the diodes to the wiring, prior to encapsulating all the sensors in 1 final step.


----------



## audioaficionado

I believe GE RTV silicone works with electronics/electrical parts. We used it in the Navy sealing up the mag amp boxes on the flight deck.


----------



## O2surplus

Here's what I had in mind-


----------



## toksyn

O2surplus said:


> Another issue - unless the silicone is spec'd for electrical use it can be *corrosive* when used as a potting compound.
> 
> I'll have draw up a picture of how I would construct the sensor. I'm just looking for a sure fire way to provide a long lasting= water proof seal for the sensor, that's easy to construct. Drying time for the epoxy would not be an issue since you could pre=solder all the diodes to the wiring, prior to encapsulating all the sensors in 1 final step.


There is silicone conformal coat spray you could use for PCBs as well, comes in aerosol cans.


----------



## mistergreen

O2surplus said:


> Here's what I had in mind-


Cool design but it might take a bit of time to assemble. Plus, I'm worried about the wires coming out of the sandwich. There's no support and can easily break. We can give it support but then it complicates things more.

Fixing it would be impossible as well. You'd have to throw away the whole unit.


----------



## tentacles

Problem is, epoxy doesn't bond to acrylic, the best you can do with it is a mechanical fit but that won't seal all that well long-term. Epoxy also doesn't bond to vinyl or whatever thermoplastic they use in cat5 to insulate the individual strands of wire.


----------



## mistergreen

tentacles said:


> Problem is, epoxy doesn't bond to acrylic, the best you can do with it is a mechanical fit but that won't seal all that well long-term. Epoxy also doesn't bond to vinyl or whatever thermoplastic they use in cat5 to insulate the individual strands of wire.


yeah, that's true too.


----------



## Pickled_Herring

Be careful with the shrink tubing. While it's a good insulator it;s not very durable and the properties change once its been heated. If you decide to pot the sensor in epoxy you can supply strain relief with short pieces of tubing over the wires just make sure the back ends are surrounded by the epoxy so the water doesn't wick into the wires. You can get epoxies that will adhere to Acrylics and polycarbonates. Try Loctite Epoxy plastic bonder it looks like it may work.


----------



## mistergreen

Let us know how the 'cup' version works out.


----------



## audioaficionado

How water tight are the first batch of sensors? It's not like I'll leave it in a tank more than a few minutes between uses.


----------



## mistergreen

It's watertight. The cup is sealed with silicone. If it leaks in you can see it and fix it yourself.


----------



## wintu

just got the meter today  and ofcourse tried it right the way. but have one question, how should i hold the sensor ? if i hold it bottom up the readings are way to high for my light so looks like horizontal position is way to go. it gives more sensible readings. any tips?


----------



## O2surplus

"Somebody" got busy with the solder again- only 10 more to go!


----------



## jcgd

wintu said:


> just got the meter today  and ofcourse tried it right the way. but have one question, how should i hold the sensor ? if i hold it bottom up the readings are way to high for my light so looks like horizontal position is way to go. it gives more sensible readings. any tips?


Jealous, I won't get mine for at least another week! Darn customs... Darn countries and borders!

Mistergreen, maybe you could show us a few photos of how to use the meter?


----------



## mistergreen

wintu said:


> just got the meter today  and ofcourse tried it right the way. but have one question, how should i hold the sensor ? if i hold it bottom up the readings are way to high for my light so looks like horizontal position is way to go. it gives more sensible readings. any tips?












What lights do you have? What were the readings? How far away is the sensor to the light source?

It's a good chance you do have high readings.


----------



## mistergreen

jcgd said:


> Jealous, I won't get mine for at least another week! Darn customs... Darn countries and borders!
> 
> Mistergreen, maybe you could show us a few photos of how to use the meter?


Yup, I had to fill out a customs form for your package.

I should print out a 1 page instruction with each package too.


----------



## wintu

my light is fishneedit 2x24 sitting on top of 14 high tank and reading are: at the surface (2.5") about 240 and sustrate level (12.5")about 120 . using bottom up method


----------



## jcgd

mistergreen said:


> Yup, I had to fill out a customs form for your package.
> 
> I should print out a 1 page instruction with each package too.


I really appreciate that. Hopefully it wasn't a lot of inconvenience. You and O2 have really helped me out.


----------



## mistergreen

wintu said:


> my light is fishneedit 2x24 sitting on top of 14 high tank and reading are: at the surface (2.5") about 240 and sustrate level (12.5")about 120 . using bottom up method


These are t5 bulbs? That sounds on the money. Do you have algae issues?


----------



## In.a.Box

seeing this make me miss the old days


----------



## wintu

> These are t5 bulbs? That sounds on the money. Do you have algae issues?


no algae issues which is kind of surprising because i think with 120 PAR on the substrate would be a algae farm. according to this thread http://www.plantedtank.net/forums/lighting/154807-fish-need-but-do-plants-need.html this light is T5NO and its got really bad reflectors so thats why is so strange to see PAR like this. i will also try to put in old bulbs to see if there is any change . (curently using GE starcoat 6500k)


----------



## wintu

ok, readings with the old bulbs are about 10PAR less on both


----------



## mistergreen

It sounds right. Bulb brand have different outputs, some much stronger than others.
I'm not sure what bulb brand they tested that's why those par charts are misleading. I found that out the hard way.


----------



## wintu

> I'm not sure what bulb brand they tested that's why those par charts are misleading. I found that out the hard way.


that is why i'm trying to figure this out. its pretty big diference also ican't imagine that such cheap light pulling 120 par at about 13". is there anything universal such a 60w regular light bulb should have xx par at lets say 6"? so i can test it on something else


----------



## jcgd

Go outside and test the sun maybe? That reading should be pretty uniform.


----------



## mistergreen

I'm getting 150 par at 12" away from my old t5ho. Outside at 4pm on a partially cloudy day I'm getting 1300 par in the sun and 200-300 par in full shade.


----------



## mistergreen

Oh, you can test it out on regular spiral cf
http://www.plantedtank.net/forums/lighting/85667-par-data-spiral-power-saver-bulbs-2.html#post837592


----------



## wintu

full california sun 1400
full shade 200
so looks like meter is ok :biggrin: , but than that fishneedit light is much stronger then everybody think it is
thanks mistergreen


----------



## wintu

good link will play with that as well now that i have this cool gadget :icon_lol:


----------



## audioaficionado

I'm looking forward to getting mine next week. First tank I'll check is my cycled but flora/fauna empty 20L to see what I'll need to keep plants happy at a medium-low lighting level so I can start planting it asap. Then I'll get some shrimp. My 45 tall is over grown and I'll check what things I can tuck in the shade and what needs clear cutting around it.


----------



## ecotanker

*tested it today*

Kudos to Mistergreen and O2surplus, and others who have contributed, for all the wonderful work put into making this device!

I finally got some time to test it this weekend on some of my fixtures.
On my 2x24 watt 24" T5HO Nova Extreme with 2 year bulbs, measured in air , I got the following PAR values:

8" from light => 150 

15" from light => 50 

Tried to measure in water, but notice some water in the diode cup.
Now meter is off line until cup is made air tight.


----------



## O2surplus

ecotanker said:


> Kudos to Mistergreen and O2surplus, and others who have contributed, for all the wonderful work put into making this device!
> 
> I finally got some time to test it this weekend on some of my fixtures.
> On my 2x24 watt 24" T5HO Nova Extreme with 2 year bulbs, measured in air , I got the following PAR values:
> 
> 8" from light => 150
> 
> 15" from light => 50
> 
> Tried to measure in water, but notice some water in the diode cup.
> Now meter is off line until cup is made air tight.



Hey- Thanks for the compliments! I'm glad to hear that you like the meter.

I got busy again today and built 6 more! This brings the total to 16 so far. I'm still waiting for some parts to arrive to finish the full 20. 
Here's a photo of the meter using the DIP version of the Atmega Chip.


----------



## mistergreen

ecotanker said:


> Tried to measure in water, but notice some water in the diode cup.
> Now meter is off line until cup is made air tight.


Whoops 
Good catch. Good thing these sensors are easily fixed.

Let's see who can bling the meter the best!


----------



## mistergreen

O2surplus said:


>


We're going to have to give you a new nickname/handle. How about ,'2quickWithSolderGun'.


----------



## AirstoND

Can I get these parts at a local Radio Shack?

Anyone have locally available source store?, I don't order online


----------



## mistergreen

AirstoND said:


> Can I get these parts at a local Radio Shack?
> 
> Anyone have locally available source store?, I don't order online


Yes, you can. They sell an arduino kit at radio shack. Your only problem is getting the diffuser and photodiode. It's online only.


----------



## O2surplus

mistergreen said:


> We're going to have to give you a new nickname/handle. How about ,'2quickWithSolderGun'.


HaHa That's a good one! Can you do that? I like 'Addicted to Solder Fumes' for my handle. I finished soldering 4 more last night! All I need now are the pin headers for the LCD screens and I'll be done with this batch of 20. :icon_smil


----------



## Pickled_Herring

Anybody have any ideas on a good DIY case for the meter? Still working good no leaks.


----------



## mistergreen

O2surplus said:


> HaHa That's a good one! Can you do that? I like 'Addicted to Solder Fumes' for my handle. I finished soldering 4 more last night! All I need now are the pin headers for the LCD screens and I'll be done with this batch of 20. :icon_smil


Speaking of which, Do you know if they still add lead in the solder?



Pickled_Herring said:


> Anybody have any ideas on a good DIY case for the meter? Still working good no leaks.


I haven't seen a nice looking case except these
http://www.sparkfun.com/products/8632
http://www.sparkfun.com/products/8601

but It's too small height wise.


----------



## O2surplus

Pickled_Herring said:


> Anybody have any ideas on a good DIY case for the meter? Still working good no leaks.



Project boxes are easy to find, but finding one designed with a bezel for a 16x2 display has not panned out. I plan one using a plastic project box, cutting a hole for the display and using one of these to clean up any "rough edges" around the display. It may take some work but it should look clean when done. 16x2 Lcd Bezel


----------



## O2surplus

mistergreen said:


> Speaking of which, Do you know if they still add lead in the solder?



I use "lead free" solder paste and hot air for all the surface mounted components and good, old fashioned 60/40 *LEAD/TIN *on all the through hole stuff. Adequate ventilation / respiratory protection is required. Because of the nature of my day job (Petro-chem) I get tested nine ways to sunday - all the time, and no lead detected so far! HaHa- God knows I can't afford to be lose any more IQ points!


----------



## wintu

i was looking at this http://www.serpac.com/ looks like pretty good selection and they will even customize all the opening you need of course for $$


----------



## audioaficionado

http://www.serpac.com/cleartop.aspx


----------



## mistergreen

Ok, so O2Surplus will make the sensors too. This will make it slightly cheaper where he doesn't have to ship it to me and a smaller risk of damaged or lost packages full of meters.
He's also way faster than I am at making these things too


----------



## In.a.Box

Good thing the sale is going to be online, Haha 
Just think what could happen if it was a walk in buy.
People will step on people just to get inside the store. Lol


----------



## outcast

Awesome work! I've finally decided to take the plunge and buy a probe, but surprised to find this diy project to turn out so polished. I'll definately be keeping an eye out on the SnS to get one. If im happy with the results i may commit for more of them (when we are able to buy more than one) for a few buddies locally here into planted tanks.


----------



## hamato

I'm looking to build one of these sensors myself since I like DIY and already have an arduino based controller for my tank, but I have a few questions.

Did you end up using blue acrylic similar to the apogee sensor or is that just a protective coating in the photo? A link to the exact material/thickness you used would be helpful!

Also I doubt I will have access to a real PAR meter for calibration, but if you have an average resistance value you are getting for the devices I think that would be "close enough" for me


----------



## mistergreen

We're using the 2447 acrylic sheet. It's is 1/8th thick. You can find it at your local plastic warehouse. O2Surplus found some and got free samples.
It's a nice deal.

You can use this to calibrate
http://www.plantedtank.net/forums/lighting/85667-par-data-spiral-power-saver-bulbs-2.html#post837592
It's pretty close.


----------



## O2surplus

I'm gonna do some experiments with acrylic for a new, water proof sensor design. I just scored a nice, new 6' x 4' x 3/8" sheet of acrylite GP for FREE! I'm going to see how much work it will take to embed the sensor diode and diffuser between two fused pieces. Since the acrylic is 3/8" thick, I'm pretty sure that I'll be able to grind out a small recessed area for the diode/diffuser and still be able to fuse the two pieces together. I'll post some pictures later, after I've had a chance to try it out. Worst case scenario - I see a few 12"x12"x12" rimless tanks in my future. Oh yeah, I've got the next batch of twenty pretty much done, I'm just waiting for some LCD's to show up in the mail. MISTERGREEN's gonna send me his diodes and I'll get to work on the sensors. Once they're done- IT'S OFF TO THE SWAP-N-SHOP.:thumbsup:


----------



## 2wheelsx2

Yay, I'm all over that!


----------



## jcgd

Just got my meter today. This thing is awesome and easy to use too. I'm getting way higher readings on everything than I would expect, until I measure some standard lights like halogens. The efficiency difference is incredible. LEDs are definitely the kings now.


----------



## mistergreen

jcgd said:


> Just got my meter today. This thing is awesome and easy to use too. I'm getting way higher readings on everything than I would expect, until I measure some standard lights like halogens. The efficiency difference is incredible. LEDs are definitely the kings now.


Now you (not you personally) know why you get algae 
Bump up those CO2 or lower your light intensity!


----------



## 2wheelsx2

Wow, I finally read the whole thread. Amazing.

Just one suggestion, or maybe I missed it. Why don't you guys charge a little bit more per unit, say $75 and take pre-orders so that you can get yourself new soldering irons, etc. etc. to make it a bit easier. Then you just have to do the one batch and it's over.


----------



## h4n

O2surplus said:


> I'm gonna do some experiments with acrylic for a new, water proof sensor design. I just scored a nice, new 6' x 4' x 3/8" sheet of acrylite GP for FREE! I'm going to see how much work it will take to embed the sensor diode and diffuser between two fused pieces. Since the acrylic is 3/8" thick, I'm pretty sure that I'll be able to grind out a small recessed area for the diode/diffuser and still be able to fuse the two pieces together. I'll post some pictures later, after I've had a chance to try it out. Worst case scenario - I see a few 12"x12"x12" rimless tanks in my future. Oh yeah, I've got the next batch of twenty pretty much done, I'm just waiting for some LCD's to show up in the mail. MISTERGREEN's gonna send me his diodes and I'll get to work on the sensors. Once they're done- IT'S OFF TO THE SWAP-N-SHOP.:thumbsup:


Yes that's what i like to hear!!! 
This time no more bathroom breaks ill piss my self first lol!!!!!!

-Sent from my Samsung Note, a "Phablet"


----------



## mistergreen

2wheelsx2 said:


> Wow, I finally read the whole thread. Amazing.
> 
> Just one suggestion, or maybe I missed it. Why don't you guys charge a little bit more per unit, say $75 and take pre-orders so that you can get yourself new soldering irons, etc. etc. to make it a bit easier. Then you just have to do the one batch and it's over.


Pre-order is bad business practice and is against forum rules. If we make it too expensive, I think we lose the hobby side of things.

Beside, we make it when we have free time and when we want to. Nobody to bug us when their order is done. It's a pretty good plan.


----------



## 2wheelsx2

mistergreen said:


> Pre-order is bad business practice and is against forum rules. If we make it too expensive, I think we lose the hobby side of things.
> 
> Beside, we make it when we have free time and when we want to. Nobody to bug us when their order is done. It's a pretty good plan.


Right. Forgot about that rule on tpt. Oh well, it's still good for everyone and hopefully, eventually, everyone who wants one can get one.


----------



## outcast

Maybe we can luck out and both make the cut on the next batch and save on shipping 2wheels  (neven btw)


----------



## O2surplus

I got a big box of stuff from MISTERGREEN in the mail today. Looks like I'll be busy working on sensors this weekend.


----------



## 2wheelsx2

outcast said:


> Maybe we can luck out and both make the cut on the next batch and save on shipping 2wheels  (neven btw)


Sounds good. I can even pick up in Pt. Roberts so there is no customs.


----------



## mistergreen

O2surplus said:


> I got a big box of stuff from MISTERGREEN in the mail today. Looks like I'll be busy working on sensors this weekend.


Good thing you're making them. I'll be on the road for a little bit.


----------



## DarkCobra

Looks like a lot of progress since I last checked. Cool.

But so far as I can tell, these are still using the Excelitas VTB8441BH sensor.

As I understand, a PAR meter has spectral response like an "M" - sharp cutoff of UV/IR, rejection of green in the middle, and strong sensitivity to red/blue.

But the VTB8441BH's peak sensitivity is 580nm, which is yellow; and it tapers off towards red/blue. That resembles the response of a LUX meter more than PAR.

Granted the results may "close enough", but then wouldn't a $20 commercial LUX meter, adjusted by the closest correction factor, be only a little further off?

Back on page #9 I suggested a RGBW sensor, which is available in single quantity from Mouser and Digikey. Combined with a bit of cheap IR filter material, this would provide a better PAR reading by summing red/blue (and possibly subtracting some amount of green/white). By displaying raw RGB values, it would also allow a user to determine spectrum, and shift over time, of their lighting; a capability which would set this PAR meter apart even from commercial ones, and provide additional info to help users decide when a bulb replacement is really necessary. It even costs less than the Excelitas part. I was surprised that no one even commented on it.

And it's not the only sensor that would have been superior in the same price range, like this one from Sparkfun. Either one would interface to the Arduino with the CAT5 cable you're already using.

Seems a darn shame to have put so much time and effort into a PAR meter, when it could have offered more accuracy and capabilities; with no increase in hardware or price.


----------



## mistergreen

DarkCobra said:


> As I understand, a PAR meter has spectral response like an "M" - sharp cutoff of UV/IR, rejection of green in the middle, and strong sensitivity to red/blue.


Not necessarily true. As long as the diode is sensitive to 400-700 spectral range, it'll work. Scientists have made a similar DIY sensor so I'm going off their research. It is entirely possible to take a lux meter and do some math to find the PAR value. The big question is what is the photodiode in the lux meter reading exactly and can vary from manufacturer to the next. It's a big question.

The color sensor you showed is awfully hard to work with. It's tiny. It might work though.


----------



## toksyn

While I agree with you on your points, I think the sensor from Sparkfun is a little out of the reach of the general hobbyist. Even though it's a ridiculously simple BGA (ball grid array) part, it's still a BGA part and I don't think a lot of people possess hot air rework units to solder that properly (yes, I suppose you could do it with an iron but you can't guarantee that it will seat evenly and correctly). I also think that the technicians and electrical engineers that would have had experience doing any amount of miniature SMT soldering are in the minority in the general hobbyist population, even in this forum.

Despite the sensor selection and limitations, and the Arduino-based nature of the project (I'm not a fan of Arduino for my own endeavors), I'm still pretty impressed at how good of an approximation it turned out to be compared to "the real thing". 

[EDIT]
I don't mean to accidentally relegate anyone involved in the active development of this project to a "mere hobbyist". I was just trying to make a point. I don't intend any offense.



DarkCobra said:


> Looks like a lot of progress since I last checked. Cool.
> 
> But so far as I can tell, these are still using the Excelitas VTB8441BH sensor.
> 
> As I understand, a PAR meter has spectral response like an "M" - sharp cutoff of UV/IR, rejection of green in the middle, and strong sensitivity to red/blue.
> 
> But the VTB8441BH's peak sensitivity is 580nm, which is yellow; and it tapers off towards red/blue. That resembles the response of a LUX meter more than PAR.
> 
> Granted the results may "close enough", but then wouldn't a $20 commercial LUX meter, adjusted by the closest correction factor, be only a little further off?
> 
> Back on page #9 I suggested a RGBW sensor, which is available in single quantity from Mouser and Digikey. Combined with a bit of cheap IR filter material, this would provide a better PAR reading by summing red/blue (and possibly subtracting some amount of green/white). By displaying raw RGB values, it would also allow a user to determine spectrum, and shift over time, of their lighting; a capability which would set this PAR meter apart even from commercial ones, and provide additional info to help users decide when a bulb replacement is really necessary. It even costs less than the Excelitas part. I was surprised that no one even commented on it.
> 
> And it's not the only sensor that would have been superior in the same price range, like this one from Sparkfun. Either one would interface to the Arduino with the CAT5 cable you're already using.
> 
> Seems a darn shame to have put so much time and effort into a PAR meter, when it could have offered more accuracy and capabilities; with no increase in hardware or price.


----------



## O2surplus

Yeah, I call that sensor "a little small" for even people with advanced SMT soldering skills!


----------



## DarkCobra

I agree the BGA part would be a major PITA. It was included just to show that such RGBW sensors are available from multiple vendors. Sparkfun does have a pre-soldered breakout for it, though for more $$$ of course. And the bare part may be available in other packages, I haven't checked.

But don't forget my original recommendation from page #9, the Taos TCS3200D, which is more hobbyist-friendly:










Even for the SMT-phobes (I'm one of them), SOIC-8 is easy.

As for the current sensor being used, I didn't see a spectral response graph in the data sheet. We don't know how rapidly response drops off at red/blue, only that it detects yellow best. I'd be curious to see how it performs against a real PAR meter with a more extreme case - light sources like fluorescent/LED grow lights (with primarily red/blue and lacking green/yellow); rather than sunlight or bulbs which approximate it, against which it appears to be software-calibrated. If it still comes close, it's earned my trust.


----------



## toksyn

Shame about the SMT phobia. I hate through hole components, too much wasted land area.

Since we intend to convert the output into a digital format anyway, why not just get a digital part? TCS3471, also from TAOS (now ams), provides a digital output over I2C. Removes the frequency to level conversion requirement, and has the same spectral responsivity. In fact, it's also cheaper and has built in gain control (though admittedly, it isn't as configurable as a full on analog solution but neither is the light-to-frequency component.


----------



## mistergreen

You know what, if you want this to be more accurate, put a green light gel above the photodiode we have now. It'll now capture red and blue only and you'd need to change the code a bit because it'll restrict the light intensity.

I don't think it's necessary but for those of you who want to play with the notion.


----------



## audioaficionado

Since it was calibrated with a PAR meter and white light, I'm satisfied. I don't plan on anything other than mostly white light over my planted tanks. Even if the thing was 50% off on some frequencies, it's a lot closer than my eyeballs and chart guesstimates that I would otherwise end up doing.

Thanx roud:


----------



## mistergreen

audioaficionado said:


> Since it was calibrated with a PAR meter and white light, I'm satisfied. I don't plan on anything other than mostly white light over my planted tanks. Even if the thing was 50% off on some frequencies, it's a lot closer than my eyeballs and chart guesstimates that I would otherwise end up doing.
> 
> Thanx roud:


Have you played with it? How is it working out?


----------



## audioaficionado

mistergreen said:


> Have you played with it? How is it working out?


Yeah I played with it some. I gotta get some kind of case for it and a switch to turn it on/off. Also need a rod or long handle so I can hold and orient it underwater in filled planted tanks. I thought my 45 tall tank was high light with two T5 lamps laying on the glass cover. Nope, it's only low at the bottom and barely high at the surface. Maybe it's time for a relamp. Those spirals in a reflector are pretty high. You can't really tell with your eyeballs even if the different tanks are in the same room.


----------



## outcast

just remember that the switch needs to be installed only on one wire of the battery clip, for some strange reason people often make the mistake and connect it across both power lines. Also an algae scraper shaft would be great way to control where the probe goes, unless you want to spend money on an expensive set of long spring tension tongs


----------



## O2surplus

I just received an order of 20 LCD's in the mail today, so now I have enough to finish out the next batch. I'm 2 days in to a 4 day weekend right now and have a lot of things to do, but i'll try to spend some time on Monday working on sensors for the completed units.


----------



## mistergreen

audioaficionado said:


> Yeah I played with it some. I gotta get some kind of case for it and a switch to turn it on/off. Also need a rod or long handle so I can hold and orient it underwater in filled planted tanks. I thought my 45 tall tank was high light with two T5 lamps laying on the glass cover. Nope, it's only low at the bottom and barely high at the surface. Maybe it's time for a relamp. Those spirals in a reflector are pretty high. You can't really tell with your eyeballs even if the different tanks are in the same room.


Yup, a glass cover will bump the par down by 10-20. 



outcast said:


> just remember that the switch needs to be installed only on one wire of the battery clip, for some strange reason people often make the mistake and connect it across both power lines. Also an algae scraper shaft would be great way to control where the probe goes, unless you want to spend money on an expensive set of long spring tension tongs


Good idea on the algae scrapper. Creative use of PVCs tubes would work too.



O2surplus said:


> I just received an order of 20 LCD's in the mail today, so now I have enough to finish out the next batch. I'm 2 days in to a 4 day weekend right now and have a lot of things to do, but i'll try to spend some time on Monday working on sensors for the completed units.


Take your time.


----------



## DarkCobra

mistergreen said:


> You know what, if you want this to be more accurate, put a green light gel above the photodiode we have now. It'll now capture red and blue only and you'd need to change the code a bit because it'll restrict the light intensity.


Leave it to me to miss the low-tech solution.  You're right, that would probably do the trick.

Though I'll stick with the RGB sensor recommendation. A couple more things I can think of where raw colorimetry data would be useful:

1) Determine how dimming affects the spectral distribution of my dimmable T5HO fixture (maybe LEDs too, since they're also phosphor-based). Also determine quantitatively if running them at less than full power results in longer life and less spectral shift over time.

2) Make an alternate, opaque sensor head to connect to the main board that accommodates a test vial, and shines a white LED through it. Pick a test (like nitrate) and run a few reference tests with varying ppm, recording the RGB values for each. Real test results can then be interpolated for any test you want, allowing it to replace the entire line of Hanna Colorimeters. I've successfully tested the basic proof of concept with a scanner and Microsoft Excel, and it works; though reflective colorimetry on the test solution isn't as good as transmissive.


----------



## jcgd

I'm gonna make a DIY lily pipe, but instead feed the sensor cable through it. It'll form a J that will have the sensor pointing up and then markings all the way down the long leg that will tell me my depth when I line them up with the water line. That way the sensor is upright, I don't get wet, and my depth is exact. Plus the holder wont block any more light than the cable.


----------



## ecotanker

*some readings for the finnex ray II 24" DD*

Finally got some more time to do some readings with the meter:

full sun at 2:30 -> 1391
shade at 2:30 -> 225

Finnex ray II 24" DD, measured in air

D

6" -> 206 -> 175 -> 96
12" -> 89 -> 87 -> 70
18" -> 48 -> 47 -> 43
24" -> 31 -> 30 -> 28
-------| 0" | 3" | 6" 

For comparison, the official finnex chart 
D

6" -> 179 -> 155 -> 116
12" -> 87 -> 85 -> 73
18" -> 55 -> 53 -> 43
24" -> 36 -> 35 -> 33
-------| 0" | 3" | 6" 


It seems that 12"-24" depth readings are relative close, but the 6" seems off. A week or so ago my diode became wet, could this have any effect on the calibration?


----------



## audioaficionado

FTW!


----------



## mistergreen

> It seems that 12"-24" depth readings are relative close, but the 6" seems off. A week or so ago my diode became wet, could this have any effect on the calibration?


Those are pretty good numbers. Nah, you're fine.. The closer you are to a light source the more erratic the numbers. I wouldn't count the 6". If you were a millimeter closer or farther, the numbers would be exact. This is true with an Apogee meter too.


----------



## Hoppy

DarkCobra said:


> Granted the results may "close enough", but then wouldn't a $20 commercial LUX meter, adjusted by the closest correction factor, be only a little further off?


Of course there are more ways to DIY a PAR meter than this one. But, whether the end result will be as accurate, usable or reliable is an unknown. I'm buying a $20 Lux meter now, intending to make an acrylic waterproof container for the sensor to make it usable as a crude PAR meter. If it works out I will post something about it in another thread.


----------



## audioaficionado

The bottom line in any DIY PAR meter is if it tracks well with a commercial version.


----------



## mistergreen

Hoppy said:


> Of course there are more ways to DIY a PAR meter than this one. But, whether the end result will be as accurate, usable or reliable is an unknown. I'm buying a $20 Lux meter now, intending to make an acrylic waterproof container for the sensor to make it usable as a crude PAR meter. If it works out I will post something about it in another thread.


Cool. Can't wait to see the results. Be careful that the acrylic isn't too thick. It'll throw off your reading by 10-20 par.


----------



## Hoppy

mistergreen said:


> Cool. Can't wait to see the results. Be careful that the acrylic isn't too thick. It'll throw off your reading by 10-20 par.


Yes, and waterproofing one of the cheap luxmeter sensors isn't going to be a picnic either, especially if you want to be able to remove it from the waterproofing enclosure. I'm only doing this as a fun challenge.


----------



## NutZilla

been reading for two straight hours, this thread is amazing. really thanks especially to mistergreen for the innovation, and also to o2surplus for the production side. I really hope to have one of this, been wishing to have a PAR meter for years. thanks again guys.


----------



## audioaficionado

I'm gonna get mine set up in a decent project box later this month. I'll post up pics when it's done. I was thinking of a cheap VOM case with the guts stripped out.


----------



## stevieo

I'm hoping I'll be able to get my hands on one of these. Algae is taking hold again and I'm thinking it's my lights being too close b it I'm not too sure.


----------



## NutZilla

any updates on the second batch production? can't wait to place order


----------



## O2surplus

I still have to find the time to build the sensors, but I've got 19 tested units up and running so far. I've been working a lot of overtime lately, so I hope to find enough time to complete these in the next few weeks.


----------



## NutZilla

O2surplus said:


> I still have to find the time to build the sensors, but I've got 19 tested units up and running so far. I've been working a lot of overtime lately, so I hope to find enough time to complete these in the next few weeks.


Wow that's awesome! Thanks for all the hardwork. I really don't mean to rush you, I'm just so eager to have one of those LOL thanks again O2surplus.


----------



## wgraham

also would love to get one and how


----------



## mistergreen

Wow, that's a lot 
Those will be gone in a minute in the S&S.
Wish I could help. I'll be traveling again soon.


----------



## mistergreen

Just for giggles, I put a purple/magenta cellophane over the sensor. The hope is to eliminate any variance in color bulbs. All it would look for is blue and red light.


















I gave my apogee senor to O2Surplus but I still have my original prototype and 1 CEP.
The cellophane cut the signal roughly in half so I x2 the signal in the code without changing any hardware.

Now I'll have to find a yellow bulb and test that and see. Who has a yellow bulb any more


----------



## Hoppy

It would be interesting to have a yellow-green bulb, and see how much the reading drops with the lavender filter. I think it would be best not to drop it more than 50% - eliminating 90% of the yellow green light would distort the PAR readings too much, I think. I have no idea how to find a yellow-green bulb, but where you got the lavender cellophane might also have yellow green. Also, you can still buy yellow "bug lights", which might work, if they produce enough light to get a meaningful reading with and without the lavender filter. I saw some colored CFL bulbs at Home Depot yesterday, but didn't pay enough attention to remember what colors they had.


----------



## tentacles

The 4100k "cool white" spirals may do the trick, or an old "cool white" T12, those definitely have an awful green miasma to them.


----------



## mistergreen

I bought a 13W green spiral florescent from HD.

At 4 inches away I'm getting:

with magenta filter: 6.9
without: 14.8

The magenta filter definitely is filtering out green.
Normally with a day light 13W I would get 80+.


----------



## Hoppy

The cellophane filter removed about 100% of the output from the photo diode between about 500 and 600 nm, based on the spectral sensitivity curve that came with my luxmeter. That would almost totally eliminate any contribution to the reading from that spectral area. I doubt that that is desirable. A weaker lavender colored cellophane should be better.

Maybe I am mis interpreting this, but this is my 3rd try at trying to understand it. (My brain seems to be stuck in low gear tonight!)


----------



## mistergreen

Honestly I'm not exactly sure what this means either. It's not filtering out 100% of 500-600nm. Looks like ~50% yes? The magenta sensor isn't registering zero, roughly half of the one without whose peak is 550 nm.

So the spectral graph would be an 'M' shape.


----------



## O2surplus

You guys are making my brain hurt. I'm glad that I haven't got around to build the sensors yet as it seems that it would behoove me to wait until there is some consensus on this filter thingy.


----------



## mistergreen

O2surplus said:


> You guys are making my brain hurt. I'm glad that I haven't got around to build the sensors yet as it seems that it would behoove me to wait until there is some consensus on this filter thingy.


... You can go ahead and build the sensors. This filter isn't a big deal since Nobody has odd color bulbs. It's out of curiosity. The range of human perception seems to work fine.


----------



## Chlorophile

I wonder what you could do with 3 sensors, each with their own cellophane color filter on them!


----------



## Hoppy

mistergreen said:


> ... You can go ahead and build the sensors. This filter isn't a big deal since Nobody has odd color bulbs. It's out of curiosity. The range of human perception seems to work fine.


I agree. Since you calibrate the meter it will be plenty accurate for all of the commonly used planted tank bulbs. If this was for lab use, where very accurate measurements of nearly equal PARs was needed, then it could be a problem. When I was playing with the PAR meter two days ago I noticed just how sensitive it is to very small mistakes. I don't think I could do a calibration that I would swear was accurate to better than 10%. To do that I would want some kind of fixture that held the PAR sensor very precisely where it was supposed to be.


----------



## O2surplus

OK, I'll go ahead and build them with the original materials. I've got a 5 day weekend coming up, so I should have some time to get a few built.


----------



## theblondskeleton

If you wanted more precision in the filter, check out Rosco gel filters (or GAM for that matter). If you check out the website, you can order a swatchbook that has small samples of each filter with a card showing the spectral energy distribution curve for each filter. Takes the guesswork out. These should also be available at any stage/film/DJ lighting outlet. The swatch is about 2"x4" so you could probably equip all 20 units with one of these from one swatch book. Here's a link: 

http://www.rosco.com/filters/roscolux.cfm#colors


----------



## O2surplus

theblondskeleton said:


> If you wanted more precision in the filter, check out Rosco gel filters (or GAM for that matter). If you check out the website, you can order a swatchbook that has small samples of each filter with a card showing the spectral energy distribution curve for each filter. Takes the guesswork out. These should also be available at any stage/film/DJ lighting outlet. The swatch is about 2"x4" so you could probably equip all 20 units with one of these from one swatch book. Here's a link:
> 
> http://www.rosco.com/filters/roscolux.cfm#colors



Hey thanks for that link. They've got a ton of color choices there and good documentation. Now the question becomes what color filter would be the best choice? If PAR is normally found in the red and blue regions of visible light, wouldn't we want to use a green/yellow filter to reject NON Par producing wavelengths? Or is it the other way around and we'd use red/blue?


----------



## mistergreen

You'd want the magenta or lavender filters like the cellophane I used. That spectral graph is what plants look for.

But since we don't use yellow and green light bulbs over our tanks, the regular sensor without the filter will work fine, not super accurate.


----------



## O2surplus

We don't use yellow and green bulbs per se, but those two colors are included in sources of "white light". So don't they contribute enough energy to raise the output of the photo diode and throw off the actual PAR value?






mistergreen said:


> You'd want the magenta or lavender filters like the cellophane I used. That spectral graph is what plants look for.
> 
> But since we don't use yellow and green light bulbs over our tanks, the regular sensor without the filter will work fine, not super accurate.


----------



## theblondskeleton

You would use a lavender colored filter, which filters out green and amber to a higher degree than the red and blue. A low saturation filter would likely be best, as it maintains a higher amount of red/blue, but the compromise is more green/yellow gets through. Typical balancing act


----------



## mistergreen

O2surplus said:


> We don't use yellow and green bulbs per se, but those two colors are included in sources of "white light". So don't they contribute enough energy to raise the output of the photo diode and throw off the actual PAR value?


Yes, they are included in white light but only a portion and not the total. That's why I wanted to play with the cellophane. Could the sensor be more accurate with the lavender filter? Sure.
Does it need it for the hobby? Not sure. Depends on cost and such.


----------



## mistergreen

Oh, if you want to play with it, go for it. You have the apogee sensor to do some comparisons.


----------



## theblondskeleton

Rosco's R52 "light lavender" looks like it would be an excellent choice. 

http://www.rosco.com/filters/SED.cfm?titleName=R52:%20Light%20Lavender&imageName=../images/filters/roscolux/52.jpg

It retails around $7.00 for a single 18"x24" sheet. That would go a very long way, haha... I have some lying around somewhere as I use this color a lot. I could send a small sample if you want to play around and see if it makes any difference.


----------



## mistergreen

Here's the photosynthesis spectrum for comparison


----------



## Hoppy

This looks like the one that would work best. Green and yellow add to the PAR, and they should do so. Removing all of those two colors leaves you with a number that isn't PAR. It looks like this filter removes about the right amount to make this comparable to the Quantum meter.


----------



## Jeffww

What modifications would I need to make to measure PAR under relatively blue reef lighting?


----------



## mistergreen

Jeffww said:


> What modifications would I need to make to measure PAR under relatively blue reef lighting?


none.. it might be wonky if you have yellow or green light.


----------



## NutZilla

any updates of the production? thanks.


----------



## mistergreen

O2surplus is super busy so I'm making them now. I'm busy too but should have one or 2 out soon.


----------



## ReluctantHippy

Amazing thread. Like many others I just spent the last several hours reading through it all. Well done everyone.


----------



## NutZilla

mistergreen said:


> O2surplus is super busy so I'm making them now. I'm busy too but should have one or 2 out soon.


great. it would be a tough competition though since only one or two units will be released LOL especially for me because i have a different timezone


----------



## brainwavepc.com

I'd be interested in one of these. I want to do a lot of testing on new lighting options


----------



## NutZilla

any updates?


----------



## mistergreen

Sorry, I've been swamped with work and travel. I'm ordering the parts I need though. I ran out from the last batch.


----------



## shinycard255

Yes, please keep us posted. I would love to get my hands on one of these if possible!


----------



## HD Blazingwolf

Okay, a while back i had said i was going to seal a lux meter probe.. its done and waterproof. i need to get it calibrated against a PAR meter. who's up for the task?


----------



## mistergreen

I should have a batch of 5 or six done at the end of this month. 

I got tired of getting allergies and tearing out carpeting at the moment so I'm preoccupied.


----------



## ugn

Sorry if this has been answered before, haven't read the whole thread 

Is there any smart way to calibrate a DIY PAR meter?


----------



## thelub

Outstanding! I love seeing DIY projects like this. Have you considered doing an open-source license of some sort for this project? Its great that you guys are doing this for non-profit but it would be good to see you gentleman get some sort of extended recognition for all your work. I'll be keeping an eye on this as I want one myself! 

I saw how long ago this whole thing started and at first I had lost hope that I might be able to get my hands on one, but it looks like I might get a chance!


----------



## mistergreen

ugn said:


> Sorry if this has been answered before, haven't read the whole thread
> 
> Is there any smart way to calibrate a DIY PAR meter?


1. Calibrate against a par meter: best
2. Calibrate against known reading to a lighting fixture. Some manufacturer provide this, and there's a thread providing some par numbers: ok.
3. Set the resistance to 27k: not so good but it's something.


Sent from my iPad using Tapatalk HD


----------



## sundragon

Kudos to you for this undertaking! Considering how expensive PAR meters can be, this is a nice cost savings!


----------



## HD Blazingwolf

I still need to get my meter calibrated.... anyone up for grabs????!!!! i know someone has a PAR meter, hoppy. green!!!


----------



## mistergreen

HD Blazingwolf said:


> I still need to get my meter calibrated.... anyone up for grabs????!!!! i know someone has a PAR meter, hoppy. green!!!


I have one but how do you even calibrate your lux meter?


----------



## HD Blazingwolf

Measure it against known par values and divid to get correct par. I believe it to be at 61 lux/par. Going against manufacturer numbers. Id measured against my light and hoppy's chart it seems pretty accurate as well


----------



## mistergreen

ah, you're doing with mathematically. I can't send you my PAR sensor (you need a volt meter) but if you want to send me you lux meter, let me know.


----------



## HD Blazingwolf

I have a volt meter but i understand. Me shipping a 20 dollar meter and potentially not getting it back is much better than u losing a par meter 

Shoot me an address


----------



## Hoppy

The ratio between PAR and Lux readings, for 6500-10000K fluorescent lights is more like 76 than 60. But, if you are measuring the light from a pink bulb, the sun, incandescent bulbs, etc. the ratio can be much different. Lux meters are very useful for rough measurements to see if a light fixture/bulb is going to work well for you, but they are not useful for actual research type measurements - determining how effective an actinic bulb is compared to a 6700K bulb, for example.


----------



## HD Blazingwolf

Well i have a 6 k, 6500k a purple bulb and a red one.. does that help LOL!


----------



## mcarroll

Hoppy said:


> Lux meters are very useful for rough measurements to see if a light fixture/bulb is going to work well for you, but they are not useful for actual research type measurements - determining how effective an actinic bulb is compared to a 6700K bulb, for example.


Unbelievably well said! There's a lot of truth in that statement and I think it bears repeating. 

(Yes, I meant it....everyone read that again!  )

Having a $20 LUX meter to go by is so eye opening (no pun) - *so much* better at showing you what the light really does as it radiates from your light source, as it overlaps with other light sources, etc, than "eyeballing it". If you're someone who DIY's or experiments with your lighting at all in any way, it would seem a shame not to have one of these to use. Even without being calibrated to anything (which just makes a LUX so much more informative).

-Matt


----------



## Whitebeam

Any chance you could post the latest Arduino sketch for this please? I have the sensor and an Uno and would love to have a play.

Also, has anybody made a unit using the TCS3200D sensor that was suggested?

Peter


----------



## O2surplus

Here's the actual sketch that we used for the "Close Enough" PAR Meter.




Code:


// CLOSE ENOUGH PAR Written in Arduino 23 By MISTERGREEN

#include <LiquidCrystal.h> // modified by O2surplus to include correct LCD pinout for "CLOSE ENOUGH PAR Meter" V1.0
                           //  Code also includes provision for seial output of PAR values to a PC.
float average = 0;
float output = 0;
float factor = 1.52;
unsigned long time; 
int counter = 0;
// create the LCD
LiquidCrystal lcd(8, 7, 5, 4, 16, 2);
// set up backlight
int bkl = 6; // backlight pin

void setup() {
  time = millis();
  // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("CLOSE ENOUGH PAR");
  pinMode(bkl, OUTPUT);
  digitalWrite(bkl, HIGH);
  // initialize the serial communication:
  Serial.begin(115200); // Max for Arduino Uno
}

void loop() {

  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
    //corrections to fit par
    average = average/counter;

    if(average <= 560) {
      factor = 1.55;
    } 
    else {
      factor = 1.36;
    }
    //corrects for high PAR
    output = average * factor;

    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(output);
    // send PAR data to the Serial output.
    Serial.println(output, BYTE);
    
  }
  //reset timer & counter to get ready for the next second.
 // time = millis();
  counter = 0;
  average = 0;
 delay(1000);
}


----------



## Whitebeam

Superb - my thanks.

I just want to take relative readings between my current T5s and my new multi-chip leds, once I've assembled them, so I won't need to worry too much about calibration.

Peter


----------



## bhazard451

mistergreen said:


> I should have a batch of 5 or six done at the end of this month.
> 
> I got tired of getting allergies and tearing out carpeting at the moment so I'm preoccupied.


I absolutely must have one of these when they are ready. I rarely use my Apogee now, but a need for it always randomly pops up. This would help me tremendously.


----------



## mistergreen

bhazard451 said:


> I absolutely must have one of these when they are ready. I rarely use my Apogee now, but a need for it always randomly pops up. This would help me tremendously.


huh??  If you have an Apogee, why would you need this?


----------



## bertyboy69

mistergreen said:


> I should have a batch of 5 or six done at the end of this month.
> 
> I got tired of getting allergies and tearing out carpeting at the moment so I'm preoccupied.



just wondering if you finished these up yet. im very intrested in one i was going to build one myself but the semester is starting up on monday and ill be way to busy.

just wondering if i missed these units or if they arent ready yet.


----------



## bhazard451

mistergreen said:


> huh??  If you have an Apogee, why would you need this?


I don't need $350 of apogee hanging around for the few times I use it, when this can do the job for much less.


----------



## dzaninov

*Construction and testing of an inexpensive PAR sensor*

Construction and testing of an inexpensive PAR sensor:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.62.7109&rep=rep1&type=pdf


----------



## mistergreen

dzaninov said:


> Construction and testing of an inexpensive PAR sensor:
> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.62.7109&rep=rep1&type=pdf


yup, that's where this project started, or something similar.

Hey, I built 6 sensors over the past weekend. I'll calibrate them this weekend.


----------



## bhazard451

mistergreen said:


> yup, that's where this project started, or something similar.
> 
> Hey, I built 6 sensors over the past weekend. I'll calibrate them this weekend.


Looking forward to seeing the results.


----------



## dzaninov

*Hamamatsu G1118*

Do you know where to buy Hamamatsu G1118 in the USA ?



mistergreen said:


> yup, that's where this project started, or something similar.
> 
> Hey, I built 6 sensors over the past weekend. I'll calibrate them this weekend.


----------



## mistergreen

dzaninov said:


> Do you know where to buy Hamamatsu G1118 in the USA ?


read from this post down
http://www.plantedtank.net/forums/showpost.php?p=1201259&postcount=40

you have to call up the US Hamamatsu division. They're in Jersey but it's not practical dealing with them. That's why I used the publicly available photo diode instead.


----------



## mistergreen

Hey, I'll post 5 meters up in the 'For Sale' sometime in the afternoon tomorrow EST when I'm back from a meeting


----------



## dzaninov

*Hamamatsu G1118*

I just got a quote for minimum quantity of Hamamatsu G1118 from Hamamatsu in Middlesex, NJ. Minimum quantity is 5 pieces for $18.80 a piece + shipping. They also have to order it from Japan which will take additional 2 to 8 weeks. I do not want to buy 5 pieces and I wanted to check if you want to buy 3 and I would take 2 for myself. If not I will just tell them to cancel the order as $100 for this is too much for me.



mistergreen said:


> read from this post down
> http://www.plantedtank.net/forums/showpost.php?p=1201259&postcount=40
> 
> you have to call up the US Hamamatsu division. They're in Jersey but it's not practical dealing with them. That's why I used the publicly available photo diode instead.


----------



## mistergreen

dzaninov said:


> I just got a quote for minimum quantity of Hamamatsu G1118 from Hamamatsu in Middlesex, NJ. Minimum quantity is 5 pieces for $18.80 a piece + shipping. They also have to order it from Japan which will take additional 2 to 8 weeks. I do not want to buy 5 pieces and I wanted to check if you want to buy 3 and I would take 2 for myself. If not I will just tell them to cancel the order as $100 for this is too much for me.


No, I don't need it anymore. They are a hassle. I think you need to be a business to buy them too from what I can remember.

The sale is up.


----------



## dzaninov

Ok.
They did not seem to care that I am not a company and did not ask to do a background check. The only problem for me is that the price is way to high unless somebody needs it too. At this price I would rather just buy the Apogee sensor.



mistergreen said:


> No, I don't need it anymore. They are a hassle. I think you need to be a business to buy them too from what I can remember.


----------



## mistergreen

Oh, I don't think we mentioned this but O2Surplus build in a FTDI connection into the meter. You can get a usb/ftdi adaptor and read the values from your computer, or read from your favorite microcontroller.


----------



## O2surplus

mistergreen said:


> Oh, I don't think we mentioned this but O2Surplus build in a UART connection into the meter. You can get a usb/uart adaptor and read the values from your computer, or read from your favorite microcontroller.



Actually- A USB/FTDI adapter is what's needed to make the connection. The adapters are widely available anywhere that Arduino parts/shields are sold.


----------



## mistergreen

right, oops, I got uart in the brain with another component.

Set the serial baud to 115200 to get the data through.


----------



## Wolf19

Hey gents,

When is the next batch on for sale?


----------



## mistergreen

Wolf19 said:


> Hey gents,
> 
> When is the next batch on for sale?


Whenever I'm free. I still have ~14 more to build. After that, that's it for me.


----------



## O2surplus

mistergreen said:


> Whenever I'm free. I still have ~14 more to build. After that, that's it for me.


14 more to go.... LOL. We've created a monster, and I'm sorry. I won't point a soldering iron in your direction again.... unless you ask me to! LOL


----------



## mistergreen

O2surplus said:


> 14 more to go.... LOL. We've created a monster, and I'm sorry. I won't point a soldering iron in your direction again.... unless you ask me to! LOL


lol, it's actually pretty easy now. It should go pretty fast. By the way, the meter you build is quality stuff.


----------



## O2surplus

mistergreen said:


> lol, it's actually pretty easy now. It should go pretty fast. By the way, the meter you build is quality stuff.


Hey thanks! I just keep practicing. Design....build.....re-design.....re-build. I find my mistakes at each design iteration and keep going. Eventually I'm able to create something that actually works.LOL... I really want/need to learn how to write software though, but that may never happen, as this "Old dog" is finding it harder to learn "new tricks".


----------



## Wolf19

mistergreen said:


> Whenever I'm free. I still have ~14 more to build. After that, that's it for me.


Start turning a small profit on it  I'm sure these would comfortably still sell at $80. Just personal opinion tho hah


----------



## mistergreen

Wolf19 said:


> Start turning a small profit on it  I'm sure these would comfortably still sell at $80. Just personal opinion tho hah


Nah, profit was never the goal. If you add shipping it's up around $80. Oh, I just saw the paypal fee. It's pretty high.


----------



## tippeecanoe

Very neat project. :thumbsup: Thanks for sharing. I began reading this thread a little over a year ago when you first started this project and promptly lost track. After catching up, things have really progressed nicely! I may have to run down to the local RShack to see if I can pick up one of these Arduino things, an LCD display, etc., and build one of your PAR meters myself now! It doesn't seem terribly difficult, but at least I can always come here if I have any questions, I hope. Thanks again for all your hard work, both of you, and for sharing.


----------



## NutZilla

missed the sales, sigh......


----------



## bhazard451

NutZilla said:


> missed the sales, sigh......


same here. bummed


----------



## Whitebeam

How much tweaking of the calibration pot are you guys having to do to get the thing calibrated against the real PAR meter? Is the circuit still as the first post, but with a pot inline with the fixed resistor? If so, what's the typical pot setting when in cal?

Peter


----------



## mistergreen

Whitebeam said:


> How much tweaking of the calibration pot are you guys having to do to get the thing calibrated against the real PAR meter? Is the circuit still as the first post, but with a pot inline with the fixed resistor? If so, what's the typical pot setting when in cal?
> 
> Peter


I just measured the resistance of a calibrated meter. I got 24.7 k ohm.

There's an inline 15k and the pot is 10 or 15k.

Sent from my iPad using Tapatalk HD


----------



## Whitebeam

mistergreen said:


> I just measured the resistance of a calibrated meter. I got 24.7 k ohm.
> 
> There's an inline 15k and the pot is 10 or 15k.


My thanks for that. Any idea how consistent that 24.7 from one meter to the next?

Peter


----------



## mistergreen

not sure. I'll measure more when I make them but they all should be around that.


----------



## tmclane

*Final build howto?*

Mistergreen,

I was wanting to build myself one of these 'good enough par' meters.
But I am having a bit of trouble imagining how you incorporated the diffuser plastic (2447) into the build. Would building an acrylic box out of it and mounting the diode inside be a good plan?

Any chance you can do a writeup of the final build howto including the plastic diffuser?


----------



## mistergreen

You just need the light to be filtered. It's up to you how you waterproof it. The black thing is a 1/4" Heyco cord grip. It makes the wire coming into the cup waterproof.


----------



## tmclane

Thanks for the pictures!


----------



## Benoitm234

Gents,

I've stumbled across this thread while searching Google for Arduino Quantum Light Sensors. After a pretty thorough read let me extend my congratulations. Your ingenuity inspired me to get on this form and see what other types of neat things are happening. 

I'm a hydroponic tomato, cucumber, lettuce, daisy grower. Measuring PAR (400-700nm) is super important, especially with our lettuce. I'm curious, you're measuring PAR underwater or are you utilizing it above, or both? I'm looking to place this sensor 12" above canopy height.

This is going to be my first arduino project as well so wish me luck. Is there a list of the most updated parts that need to be purchased? I noticed a few posts going back and fourth about changing particular things for final production. I have an expensive quantum sensor at the university I can use to calibrate this with as well. Would be happy to post videos and pictures! 

CHEERS!


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## genocdex

mistergreen, 
this is a very interesting read, for that i thank you very much. i have to admit i got about half way threw this thread before posting this but, did you ever find a way to callibrate these without going out and buying/barrowing an off the shelf unit?
i think id hate myself to buy something like this when i enjoy building it myself XD. at this point i just need a way to calibrate anything i come up with....

edit:
i saw you offered to calibrate another member's par meter, is that an open offer? when i build mine would you be willing to do the same for me?

again thanks so much for the great article!!!


----------



## All your base

Skimmed the thread and I have a few questions. Some you guys are probably sick of answering but I guess I missed em so forgive me. 

The parts list in the first post claims to be updated 9-25-12, is that the most current information? I see a 27k resistor on the low side of the jack, I'm assuming that's the resistance that's being discussed recently as far as calibration (someone mentioned a 15k resistor and 15k pot, I think?)

What light source are you all calibrating to?

Are you all just using a pair of wires for the cable to the sensor? Has anyone had interference or noise issues and switched to shielded cable?

Ironic that you're using 2447 as the diffuser. That's what my overflow box and ATS scaffolds and a bunch of other nicknacks on my tanks are built from, and I have lots of it around the shop.


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## mistergreen

genocdex said:


> edit:
> i saw you offered to calibrate another member's par meter, is that an open offer? when i build mine would you be willing to do the same for me?


Sorry, I'm busy with other projects and won't have time to calibrate your meter. Set the resistor to 24.7K and hope for the best.



All your base said:


> What light source are you all calibrating to?


A regular white spiral bulb.

And use the smallest guage wire you can find. I'm using an ethernet cable. There are lots of variables if you use different materials so that's why having a PAR meter to calibrate against is good.

I'm getting PMs from science people who aren't even in planted tanks wanting to measure sunlight for their tomato plants  I think it works even better for sunlight since light bulbs are so varied and low in output compared to the sun.


----------



## Hoppy

mistergreen said:


> Sorry, I'm busy with other projects and won't have time to calibrate your meter. Set the resistor to 24.7K and hope for the best.
> 
> 
> A regular white spiral bulb.
> 
> And use the smallest guage wire you can find. I'm using an ethernet cable. There are lots of variables if you use different materials so that's why having a PAR meter to calibrate against is good.
> 
> I'm getting PMs from science people who aren't even in planted tanks wanting to measure sunlight for their tomato plants  I think it works even better for sunlight since light bulbs are so varied and low in output compared to the sun.


I stumbled onto this a few days ago: http://www.apogeeinstruments.com/apogee-instruments-quantum-sensor-technical-information/ The Quantum PAR meter isn't perfect either. Unless a PAR meter is made with multiple photodiodes, each measuring a portion of the spectrum, the meter will have various errors when measuring light from different sources. For the Quantum meter, it is pretty accurate with typical fluorescent aquarium lighting, but not that accurate with sunlight.


----------



## mistergreen

Hoppy said:


> I stumbled onto this a few days ago: http://www.apogeeinstruments.com/apogee-instruments-quantum-sensor-technical-information/ The Quantum PAR meter isn't perfect either. Unless a PAR meter is made with multiple photodiodes, each measuring a portion of the spectrum, the meter will have various errors when measuring light from different sources. For the Quantum meter, it is pretty accurate with typical fluorescent aquarium lighting, but not that accurate with sunlight.


yup, you have to ask apogee to calibrate your sensor for indoor or outdoor light. There's a 10% difference.


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## genocdex

i was wondering why you used a photodiode vs a phototransistor? i was looking threw products and it looks like this one:
http://www.alliedelec.com/search/productdetail.aspx?SKU=70019988#tab=specs
has an very similar responce to wavelengths as the graph in your first post, its a bit cheaper too...


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## mistergreen

genocdex said:


> i was wondering why you used a photodiode vs a phototransistor? i was looking threw products and it looks like this one:
> http://www.alliedelec.com/search/productdetail.aspx?SKU=70019988#tab=specs
> has an very similar responce to wavelengths as the graph in your first post, its a bit cheaper too...



Phototransistor output is usually too small in term of resolution to have it be meaningful. The spectral response for the transistor you showed is similar but not quite.


Sent from my iPad using Tapatalk HD


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## AlanLe

Hi you guys still selling these? I would love to buy one. Thanks


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## mistergreen

AlanLe said:


> Hi you guys still selling these? I would love to buy one. Thanks


Yeah, will be making some this weekend.


Sent from my iPad using Tapatalk HD


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## xmas_one

Are you calibrating these prior to shipment? Looking at similar data from others, mine seems to be reading at least double sometimes triple what would be expected. Any ideas?


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## mistergreen

xmas_one said:


> Are you calibrating these prior to shipment? Looking at similar data from others, mine seems to be reading at least double sometimes triple what would be expected. Any ideas?


It is matched to an apogee sensor. If you feel the readings are too high, you can adjust it by fiddling with the pot (blue thingy), counter clockwise to bring down the reading.


Sent from my iPad using Tapatalk HD


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## xmas_one

mistergreen said:


> It is matched to an apogee sensor. If you feel the readings are too high, you can adjust it by fiddling with the pot (blue thingy), counter clockwise to bring down the reading.
> 
> 
> Sent from my iPad using Tapatalk HD


Can you walk me through your calibration process? There is another guy in my local club that bought one too and is having similar issues. It almost seems like you calibrated to a low data value and the error just gets larger the farther we go towards the high end. I also noticed that outside it is invariably reading 1391 no matter what. Please advise.


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## mistergreen

I match reading again a spiral cf ranging from 160 - 50 par by varying distance.

Your 1300 par reading sounds right. The par is calibrated for indoor light. It's the beginning of spring. You should get 1800-2000 at noon around July, remember the earth is on an axis.


I'll try a different light source next round just to make sure. I have a feeling it's slightly high but x2 or x3 is too much. Again, if you feel it's too much, change the pot to your liking.

Sent from my iPad using Tapatalk HD


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## shrimpNewbie

Used one of your DIY par meters I'm impressed, I hope I used it correctly, flat end towards the light right? Put my light at about 116-130 par at 40"


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## xmas_one

mistergreen said:


> I match reading again a spiral cf ranging from 160 - 50 par by varying distance.
> 
> Your 1300 par reading sounds right. The par is calibrated for indoor light. It's the beginning of spring. You should get 1800-2000 at noon around July, remember the earth is on an axis.
> 
> 
> I'll try a different light source next round just to make sure. I have a feeling it's slightly high but x2 or x3 is too much. Again, if you feel it's too much, change the pot to your liking.
> 
> Sent from my iPad using Tapatalk HD


This meter pegs out at 1391 no matter how bright it is outside. Readings are two to three times greater than what a real par meter is showing me. Buyer beware, this meter is not legit. Sorry bro, I gave you a chance to come correct and you failed.


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## mistergreen

xmas_one said:


> This meter pegs out at 1391 no matter how bright it is outside. Readings are two to three times greater than what a real par meter is showing me. Buyer beware, this meter is not legit. Sorry bro, I gave you a chance to come correct and you failed.


Sure, people should get all the info before they buy. I'll make some today and see if your problem is showing up.

What par meter are You using btw and how old is it?
What is the reading from the par meter to sunlight?

Sent from my iPad using Tapatalk HD


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## mistergreen

Just did a quick apogee par sensor reading

At 4/21/13 - 11:30am, sunny slight cloud
1415 par
Sound right huh. I'll let the numbers speak for themselves.

I seem to misplaced my photodiodes.. Hope I didn't throw away $50 worth of photodiodes.... I did find one
I can use to test.

*** I might have used up all of the photodiodes last time... Buying more.

Sent from my iPad using Tapatalk HD


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## mistergreen

ok, I made one, 
and here are the numbers

spiral cf
at 6"
PAR- 57.5 CEP - 50

t5-ho
at 9"
PAR - 167.5 CEP - 176

My numbers check out.

Oh, I just realized the max output for this is 1391 my bad so this won't work effectively for outdoor readings. The analog input range for the arduino or ATMega is 0-1023.


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## Nothingman

Hi mistergreen, have you measured any bulbs that is designed especially for plants ? I played with photodiode that you are using for your project. Thought about ways to calibrate this thing and stumbled across Sylvania FAQ in which they write about PAR to lux conversion factors for different bulbs (including their own bulbs):
http://assets.sylvania.com/assets/documents/FAQ0017-0605.ed512ef3-36b1-47cb-b052-0f9ca74348ca.pdf
In that FAQ document they state, that Cool White factor is 0.013 and GRO (Sylvania Gro-Lux) is 0.030 . So i bought Grolux and found out that actual value that gives photodiode illuminated with Grolux is almost the same as the value that Cool White bulb emits at same lux value. But in FAQ Sylvania say that Grolux should emit ~2.3 times more umol/m-2/s-1 at same amount of lux (0.030/0.013 = 2.3). I don't have real PAR meter and was willing to calibrate my sensor using several bulbs with known lux factors, such as Grolux. But now I am confused why there is no marginal difference between daylight bulb and bulb for plants, maybe the photodiode for emphasized blue and red spectrum bulbs is not that great after all, or maybe Grolux is just a marketing trick and actually does not give so much advantage in PAR ? That is why I would like to know if you tried comparing values between household bulbs and special bulbs.
Sorry for my english, i hope you understood what i mean


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## mistergreen

Ok, I'm rewriting the 'firmware' for this meter, correcting it so the max value would be 2000par.

While I'm at it do you guys want some indoor and outdoor functionality? Like if PAR is less then 500, it'll be for indoor (fluorescence) , and above, it'll adjust mathematically for Sun light. We know that it should be 10% more in output since my apogee sensor is calibrated for indoor.


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## O2surplus

mistergreen said:


> Ok, I'm rewriting the 'firmware' for this meter, correcting it so the max value would be 2000par.
> 
> While I'm at it do you guys want some indoor and outdoor functionality? Like if PAR is less then 500, it'll be for indoor (fluorescence) , and above, it'll adjust mathematically for Sun light. We know that it should be 10% more in output since my apogee sensor is calibrated for indoor.


I think that modding the firmware to include a mode for outdoor use is a good idea. Since there's still plenty of space on the 16 x 2 display, could you include a few characters to distinguish between indoor & outdoor reading modes? Like maybe "indoor mode" & "outdoor mode"? LOL I can see instances where knowing what mode the CEP was in, could save some confusion for the end user. 
500 PAR may be a little low, how about an even 1000 before switching modes? ( You gotta "idiot proof" this thing for use by people.......... people like me Lol)


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## mistergreen

O2surplus said:


> I think that modding the firmware to include a mode for outdoor use is a good idea. Since there's still plenty of space on the 16 x 2 display, could you include a few characters to distinguish between indoor & outdoor reading modes? Like maybe "indoor mode" & "outdoor mode"? LOL I can see instances where knowing what mode the CEP was in, could save some confusion for the end user.
> 500 PAR may be a little low, how about an even 1000 before switching modes? ( You gotta "idiot proof" this thing for use by people.......... people like me Lol)


heh, We should have built a switch just to tell the processor indoor or outdoor.
I think I'll just have an indoor firmware and an outdoor firmware version. The user will have to tell me which and I'll upload it when needed.


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## xmas_one

I messed with the pot indoor and outdoor. Your meter always reads 2 to 3 times too high. Just because you calibrated it to a cfl doesn't mean that it is going to give correct numbers for other readings. You seem to miss the point on this. Maybe I can send it back to you and you can send me a new one once you figure things out. Don't sell us your beta junk.


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## jarvitron

Wow. What a jerk.


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## mistergreen

xmas_one said:


> I messed with the pot indoor and outdoor. Your meter always reads 2 to 3 times too high. Just because you calibrated it to a cfl doesn't mean that it is going to give correct numbers for other readings. You seem to miss the point on this. Maybe I can send it back to you and you can send me a new one once you figure things out. Don't sell us your beta junk.


Well, if you want a refund, just send it back (undamaged)! There are other people who gladly would want one and thanks for being a stand up guy and posting your complaint in public rather than pming me.

ps. your statements doesn't help me at all. I'll ask again. What lights are you reading? WHat is your reference? What PAR meter are you using and how old is it? Old PAR meters need to be calibrated. This DIY meter will need to be re-calibrated over time too.


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## mistergreen

ok, with the ugliness out of the way.

I took O2Surplus' advice and added both indoor and outdoor onto the same LCD screen. It looks good and easy to read. The serial output will be ('indoor,outdoor') e.g. (100,103). You'll have to parse out the value by the delimiter ','.


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## 2wheelsx2

That's cool.

I just wanted to add my 2c that I got one and am very happy with it. For those who want to get and Apogee and pay the price just go and get that. Why complain about a DIY that someone else did for you at no profit? Sheesh...


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## audioaficionado

I got one of the first run units. I'm ecstatic that I got it. Don't need the outdoor reading function, but it's awesome that these guys are going to include it from now on. Why the hate?


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## mistergreen

Yeah, aquarists won't need an outdoor function. I've been getting PMs from people wanting to keep track of tomato plants and such.

I don't mind the confusion, it's part of dealing with people.


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## O2surplus

Hey that's cool MISTERGREEN. So it shows both indoor and outdoor at the same time- I like it.
I'm going to bite my tongue, and hold in my words concerning the *&^%$*# clown that was giving you a hard time. Some people just like to complain- even if you're the one doing them the favor. Unfortunately,there's always a few like him on every online Forum.


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## mistergreen

O2surplus said:


> Hey that's cool MISTERGREEN. So it shows both indoor and outdoor at the same time- I like it.
> I'm going to bite my tongue, and hold in my words concerning the *&^%$*# clown that was giving you a hard time. Some people just like to complain- even if you're the one doing them the favor. Unfortunately,there's always a few like him on every online Forum.


Thanks. The funny thing is I was going to suggest him sending it back to me to see what the issue is but now, I'd just give him his money back and be done with him. I'm not doing this for the money, lol. I could care less.

I'll just let people read his posts and make up their own minds about him.


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## xmas_one

Sorry if my last post was a little gruff, but I was pretty upset at the time. OK, so here's the deal. After testing the meter against known Finnex values on two different lights, I'm seeing the values are still 2 to 3 times as high as Finnex's published data. I purchased another DIY meter from a different builder here on TPT. Testing against the Finnex values the new meter was accurate to +/- 5%, I'd call that good enough. Now that I had something to calibrate to I decided to "fiddle with the pot" to my surprise to pot was already turned down as low as it could go. I'll give you credit in that it was reading 55 at 6" from the CFL, but as soon as you use a different source, the numbers begin to rapidly increase from reality. I called around and found a hydroponics shop that had an Apogee MQ200 that they said I could use in the store. We ran all three meters together with MH, T5HO, and CFL sources. Again your meter only gave decent readings with the CFL, but with the other lighting sources and your meter was again reading two to three times higher than both the "other DIY" meter and the Apogee. I guess I can't really be too upset if you intended this meter to be specifically used on that particular CFL configuration. I know now for a fact after my last posting that I am not the only one having this issue with the meter. I would like to encourage others who have the meter to compare it with a legit PAR meter and see what the results are. The thing that kinda burned me was that since the pot was turned all the way down, you either did not test the unit, or you tried to trim it down so that the high readings would not be as glaringly obvious. Again, I apologize for the derail and my prior rudeness. If you would please PM me your address I will send the meter back.


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## mistergreen

Ok, send me back the meter and I'll refund you. Something is wrong electronically. The photodiode might be blown. It happens. I'm getting normal readings here against t5-ho bulbs. I'll pm you.

Ps. I just checked reading on my DIY led. Readings are dead on. Let me give everybody a tip, on any light sensor, when you're measuring up close to a light source like a bulb, they are wildly variable. You can have one measurement and move the sensor closer to the light by an inch! You can get double the reading. The angle of the sensor can vary the reading as well. Published readings from light manufacturers can be off as well. Take the tip for what it's worth.

For aquarists, the only reading that really matters is the reading on the substrate. That'll give you an idea how much you have and it's physically fixed. You don't need to eyeball the distance to the light.

Sent from my iPad using Tapatalk HD


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## jccaclimber

Could something like this be used with a little calibration:
http://publiclaboratory.org/tool/spectrometer


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## mistergreen

jccaclimber said:


> Could something like this be used with a little calibration:
> http://publiclaboratory.org/tool/spectrometer


nice find. I think you can if the software can output some value (number) based on the light, not just a graph but I don't see that capacity from my quick overview.


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## Cardinal's Keeper

Mr. Mistgreen, if you recall I PM'd directly after receiving the par meter I ordered from you telling you it was reading too high as well. I bought in the same run as Xmas_one. We exchanged PM's but once I sent you pictures you somewhat passed off the issue as I had good growth. Maybe this was a bad batch, I don't know. 

I would like the same offer as Xmas_one to send your meter back please. I still have the PM's from you if you do not recall.

Thank you


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## bhazard451

Are any more available to purchase?


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## mistergreen

I will make a few this weekend to sell. I checked up on the complaints on the returned meter. It is indeed a calibration problem. The readings are a bit high about (10 - 20 par ) but not 2x, 3x.
It turned out it's more accurate if I calibrate it against a high light rather than a low light value.


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## mistergreen

New firmware with new outdoor function. The new total resistance is ~15.9K ohm instead of the previous 21K-27K.



Code:


// CLOSE ENOUGH PAR Written in Arduino 23 By MISTERGREEN
// for sunlight and indoor light
#include <math.h>
#include <LiquidCrystal.h> // modified by O2surplus to include correct LCD pinout for "CLOSE ENOUGH PAR Meter" V1.0
                           //  Code also includes provision for seial output of PAR values to a PC.
float average = 0;
float output_indoor = 0;
float output_outdoor = 0;
float factor = 0;
unsigned long time; 
int counter = 0;
// create the LCD
LiquidCrystal lcd(8, 7, 5, 4, 16, 2);
// set up backlight
int bkl = 6; // backlight pin

void setup() {
  time = millis();
  // set up the LCD's number of rows and columns: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Indoor   Outdoor");
  pinMode(bkl, OUTPUT);
  digitalWrite(bkl, HIGH);
  // initialize the serial communication:
  Serial.begin(115200); // Max for Arduino Uno
}

void loop() {

  int sensorValue = analogRead(0);
  average += sensorValue;
  counter++;

  //every second or 1000 millis
  if(millis() > time+1000) {
    //corrections to fit par
    average = average/counter;

    if(average <= 560) {
      factor = 2.077;
    } 
    else {
      factor = 1.934;
    }
    float tempout = average * factor;
    //indoor fluorensence
    output_indoor = tempout;
    
    //add 10% to output for sunlight
    output_outdoor = tempout + (tempout * .10);

    // set the cursor to column 0, line 1
    // (note: line 1 is the second row, since counting begins with 0):
    lcd.setCursor(0, 1);
    // print the number of seconds since reset:
    lcd.print(round(output_indoor));
    lcd.print("   ");
    
    lcd.setCursor(9, 1);
    lcd.print(round(output_outdoor));
    lcd.print("   ");
    
    // send PAR data to the Serial output.
    
    Serial.print(output_indoor);
    Serial.print(",");
    Serial.println(output_outdoor);
    
    //reset timer & counter to get ready for the next second.
   time = millis();
   counter = 0;
   average = 0;
    
  }
  
  delay(5);

}


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## O2surplus

Oooooh! New firmware. I'm going to re-flash mine and give it a try. Just as soon as I can pry it away from "ShrimpNewbie" Lol.


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## genocdex

thanks for all the hard work on these meters. i just wanted to add in that i found a cheaper source for the 2447 plexi. estreetplastics i ended up with a 6x12x1/8" peice for 7.15 shipped. im not sure if the larger peices would save you anything but for the person building one of these (myself) it would save 4$ or so.


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## widebody

*Pm*

Pm u


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## saiko

Hi Mistgreen, its a very long interesting thread and great effort, I read a few posts in starting, few at end few in middle.... and I wish to make one of these. Few questions before I plunge.

1. Is the acrlyic filter necessary for the cup?
2. Can I used it for mix of WW,NW,CW,Red,Rolay blue LEDs, without any concern?
3. Is a PAR meter compulsory if one is building, or do you have any ready made feed in values?


Thanks for your time.


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## mistergreen

1. yes the filter is necessary. The data curve would be steep and won't fit the par data curve.
2. Any full spectrum (warm or cool) white light should work great. I would worry with one color light especially yellow and green light.
3. It's best if you can get your hands on a PAR meter to callibrate this against. All sensors will drift after long use anyways. But if you don't have a PAR meter, use the materials and firmware outlined and set the main resistance to ~15.9K.


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## saiko

Thanks for the reply mistgreen.
I ll take a call once I am able to figure out the 1 and 3.

Cheers!


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## mistergreen

saiko said:


> Thanks for the reply mistgreen.
> I ll take a call once I am able to figure out the 1 and 3.
> 
> Cheers!


PM me, I can mail you a piece of the acrylic. I have plenty.


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## mistergreen

Just out of curiosity and some questions from reefers, 
I wanted to measure color bulbs too.
I had a green bulb around so I included in the measurement.

The bulbs.

Untitled by professorminh, on Flickr

Untitled by professorminh, on Flickr

The light

Untitled by professorminh, on Flickr

Untitled by professorminh, on Flickr

*The measurements*
control, 14w spiral CF white light
PAR sensor: 3" - 118.5, 6" - 44
CEP sensor: 3" - 121, 6" - 36

Blue bulb
PAR sensor: 3" - 40, 6" - 12.5
CEP sensor: 3" - 32, 6" - 7

Green bulb
PAR sensor: 3" - 29, 6" - 9.5
CEP sensor: 3" - 25, 6" - 5

Conclusion:
The cep reading isn't perfect for color lights but it's in the same ball park.


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## dzega

ive done this by taping photodiode to standard 5$ multimeter voltage measure pins. with opams amplifier inbetween. it was ment for measuring light bulb startup times

but i dont see how you can measure photosynthesis intensity with that. in my understanding, you need an optical light filter with photosynthesis pattern


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## mistergreen

For those using this meter to measure the Rapid LED Onyx, take the value and multiply by 5.5 to get a approximate PAR value. The Onyx has a distinct blue wavelength spike at 450nm and not much else.


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## opcode1300

Anyway to get just a sensor? I have the rest of the parts.
Thanks!


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## jeffkrol

Just an FYI on PAR sensor construction.. 









Seems the filters are the "expense bits" ... and small volume.. and the construction BUT.. I'm thinking on a workaround.. Photographic plastic "colored filters" are relatively cheap.. and easily cut.


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## mistergreen

I'll send you a 1"x1" piece of the acrylic for free. Just pm me. It'll only cost me a stamp through snail mail.

your photo is broken btw.


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## jeffkrol

mistergreen said:


> I'll send you a 1"x1" piece of the acrylic for free. Just pm me. It'll only cost me a stamp through snail mail.
> 
> your photo is broken btw.


my photo??
anyways interesting article on correction factors..
http://www.licor.com/env/pdf/light/TechNote126.pdf

and I'm a bit confused.. the PAR sensors are flat through the whole vis. spectrum..w sharp cutoffs at both ends (IR and UV) w/ apparently more sensitivity in the red region than normal GaAs sensors.. hmm odd.. I was really expecting more of a peak and dip type sensor.. Seems to oversample green to me.. must be missing something.



> Although the
> photosynthetic efficiency of an absorbed quantum of blue
> light is somewhat less than an absorbed quantum of red
> light, scientists have agreed that the ideal sensor will be
> equally responsive to all photons across the 400 to 700 nm
> wavelength range so the response will be flat across the
> spectrum. Since almost all photosynthetic activity is driven
> by photons in the 400 to 700 nm wavelength range, it has
> become universally accepted that the ideal sensor should
> have clear cutoffs to light below 400 nm and above 700 nm


a simple "purple" gel filter (different densities of blue and red "gel" filters) would fix a lot of the problems in the vis light spectrum.. for those using 660nm red LEDs' .. you will still underestimate PAR quite a bit..

ne thing it does tell me is GaAsP sensors are not "that bad" in general.. but do need tweaking and understanding of their limitations..


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## mistergreen

Nice quote! So green light is important too. I think that's why you're seeing the green oversample?

This DIY meter is a close enough PAR meter. It comes close to the apogee sensor that I base this off. The more technical/precise stuff I don't think we can achieve in an affordable way.


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## jeffkrol

mistergreen said:


> Nice quote! So green light is important too. I think that's why you're seeing the green oversample?
> 
> This DIY meter is a close enough PAR meter. It comes close to the apogee sensor that I base this off. The more technical/precise stuff I don't think we can achieve in an affordable way.


I have a scientific issue in "green light being as important as other wavelengths".. but that is a arguable scientific issue..  As to improving a violet filter would cost zero to a few dollars and would "cut" the green a bit to improve efficiency of the normal "light meter" sensors.. 
As to the Apogee, are you referring to the actual PAR one???


> i have an extra Apogee PAR meter SENSOR (SQ-120). It's new, never used. It is just the sensor w lead. Instead of buying the pricey meter and sensor, you can just use the sensor and attach it to a multimeter and multiply the reading by 5 to get the PAR readings. I use the same setup! More affordable way to measure PAR!
> 
> Just want to get rid of it for what I paid for it. $139.


I'm sticking w/ my green bashing.. based on this.. Those "conventional" PAR meters, as much as they are used in "research" are not ideal in a sense... A real sensor should model the curve below AFAICT: 









If you are my "thinking" does not apply...


----------



## jeffkrol

Then again there is this..
http://www.apogeeinstruments.com/content/GreenhouseBusinessMay1997.pdf
W/ a completely different chart... 

On a more personal (and nit picky) point I am more worried about the poor response in the really important red area than the green vs blue areas..

Fun FYI:
$10 light meter... 
http://bigbro.biophys.cornell.edu/~...on/Light_Meter/Build_Your_Own_Light_Meter.pdf

And an interesting photodiode.. w no idea of the cost..
http://www.ophiropt.com/laser/pdf/PD300_PD300-1W_PD300-TP.pdf

And a really fun toy:
http://www.vetco.net/catalog/product_info.php?products_id=13580&gclid=COy97qva5rgCFYWe4AodDSoAFQ



> In the TCS3200, the light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have
> blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear
> with no filters.




Please forgive the diversion.............


----------



## mistergreen

Yes, I have the apogee PAR sensor calibrated for indoor light. It's the only way I can see what I'm building is close enough.

Check out Hoppy's thread on his PAR sensor. He uses the same photodiode as me but also use a violet filter. It isn't expensive. I proposed the filter use at first but not sure how big a difference it'll make.


----------



## jeffkrol

mistergreen said:


> Yes, I have the apogee PAR sensor calibrated for indoor light. It's the only way I can see what I'm building is close enough.
> 
> Check out Hoppy's thread on his PAR sensor. He uses the same photodiode as me but also use a violet filter. It isn't expensive. I proposed the filter use at first but not sure how big a difference it'll make.


That sensor is, itself $140... My point was, knowing some of the specifics, it puts it into the "cheap stuff" sensor range..

The filter will make a difference but not as much as having a cutoff @ 600nm-ish will to real "par"..

more info:
http://www.advancedaquarist.com/2013/2/equipment


----------



## mistergreen

opcode1300 said:


> Anyway to get just a sensor? I have the rest of the parts.
> Thanks!


Oh, I missed this, yeah, just Pm me.


Sent from my iPad using Tapatalk HD


----------



## jeffkrol

Guess I may have to stop my green bashing.. based on this.. go figure..
http://pcp.oxfordjournals.org/content/50/4/684.full



> Absorbance spectra of chlorophylls or pigments extracted from green leaves show that green light is absorbed only weakly. Action spectra of photosynthesis for thin algal solutions, transparent thalli of ordinary green algae, and leaves of aquatic angiosperms also show that green light is less effective than red light. As has been pointed out by Nishio (2000), these facts are often confused, and it is frequently argued that green light is inefficient for photosynthesis in green leaves. However, many spectra of absorptance (the absolute value of light absorption) measured with integrating spheres have shown clearly that ordinary, green leaves of land plants absorb a substantial fraction of green light


well sort of...........


> However, light sources with a higher fraction of green photons (> 50 % of total PPF) resulted in the reduced plant growth. Among the levels of green photons tested, the addition of 24 % green light (500 – 600) to red and blue LEDs enhanced plant growth..NASA


.


and actually fits w/ the first link because they were referring to green in the presence of high white light.. 
Blink and the world changes.............. 
Anyways in re: to PAR meters.. so much for filtering out the "green"....


----------



## mr.bigglesworth

So Confused........



ENGLISH PLEASE!
(Kidding. No but seriously, I lost you after firmware..... :| )


----------



## mistergreen

mr.bigglesworth said:


> So Confused........
> 
> 
> 
> ENGLISH PLEASE!
> (Kidding. No but seriously, I lost you after firmware..... :| )


Heh, firmware is software that runs the hardware.


Sent from my iPad using Tapatalk HD


----------



## seran

Hi Mistergreen,

I want to build myself one of these 'good enough par' meters.

But I am having a bit of trouble getting the PAR value. I used main resistance 15.9K(one 15k ohm and three 300 ohm resistance)and connected the VTB8441BH to arduino like your diagram on the breadboard. but the PAR value is like 1357.00 ~ 1400.00 (using serial monitor) and it didn't change when the brightness was changed. 
I think that something is wrong. 

Do you know what is the problem? and Would you show me the lastest diagram?


----------



## Jeff52478

seran said:


> Hi Mistergreen,
> 
> I want to build myself one of these 'good enough par' meters.
> 
> But I am having a bit of trouble getting the PAR value. I used main resistance 15.9K(one 15k ohm and three 300 ohm resistance)and connected the VTB8441BH to arduino like your diagram on the breadboard. but the PAR value is like 1357.00 ~ 1400.00 (using serial monitor) and it didn't change when the brightness was changed.
> I think that something is wrong.
> 
> Do you know what is the problem? and Would you show me the lastest diagram?


Check the polarity on the photo diode, if it is in backwards you will read max par on the display ( uasually around 1300-1400)


----------



## mistergreen

+1


Sent from my iPad using Tapatalk HD


----------



## seran

Jeff52478 said:


> Check the polarity on the photo diode, if it is in backwards you will read max par on the display ( uasually around 1300-1400)


I checked the polarity on the photo diode and still get the value like 1300 ~ 1400. 

I connected the photo diode to Arduino mega like this picture.










yellow jumper wire --> analog pin a0
red jumper wire --> VCC(5V) 
green jumper wire --> GND

Could you look at this picture?
How should I connect the jumper wire correctly?


----------



## mistergreen

What's your code? It might be the software.


----------



## seran

mistergreen said:


> What's your code? It might be the software.


This code is what I used. Is there any something wrong? 



> <CODE>
> 
> // CLOSE ENOUGH PAR Written in Arduino 23 By MISTERGREEN
> // for sunlight and indoor light
> #include <math.h>
> float average = 0;
> float output_indoor = 0;
> float output_outdoor = 0;
> float factor = 0;
> unsigned long time;
> int counter = 0;
> 
> void setup() {
> time = millis();
> // set up the LCD's number of rows and columns:
> Serial.begin(115200); // Max for Arduino Uno
> }
> 
> void loop() {
> 
> int sensorValue = analogRead(0);
> average += sensorValue;
> counter++;
> 
> //every second or 1000 millis
> if(millis() > time+1000) {
> //corrections to fit par
> average = average/counter;
> 
> if(average <= 560) {
> factor = 2.077;
> }
> else {
> factor = 1.934;
> }
> float tempout = average * factor;
> //indoor fluorensence
> output_indoor = tempout;
> 
> //add 10% to output for sunlight
> output_outdoor = tempout + (tempout * .10);
> 
> Serial.print(output_indoor);
> Serial.print(",");
> Serial.println(output_outdoor);
> 
> //reset timer & counter to get ready for the next second.
> time = millis();
> counter = 0;
> average = 0;
> 
> }
> 
> delay(5);
> 
> }


----------



## mistergreen

something weird. Check for shorts.
try this simplified code. It simply reads analog 0.



Code:


void setup() {
Serial.begin(115200); // Max for Arduino Uno
}

void loop() {
  int sensorValue = analogRead(0);
  Serial.println(sensorValue);
}

The values are not par but should change in different lighting situations. If it doesn't, something is wrong with the hardware.


----------



## Tom in Cincy

Hi. New here but love Arduino projects. Looking to buy a scrap of 2447 and a sensor if anyone has any extra.


----------



## thor79

I do believe I'm going to dive into this...though I'm going to convert it to use a Netduino. It should work exactly the same hardware-wise but .Net is the framework I work in and C# is the code (web developer at a .Net shop is my day job). Already have all the tools I need to do it as I've already done some work with a previous Netduino mini and a toy Tron Identity Disc 

edit: parts ordered


----------



## ucrdave

Are these still being sold?


----------



## mistergreen

I have a few I can sell. 

Btw. I've updated this using light filters on the photo diode to make it a bit more sensitive to PAR waves. I'll post picts soon.


----------



## ucrdave

Cant wait to see the updates. Thank you for the prompt email and known availability. Ill make sure to stash away funds till next month =) Ive already spent too much on getting my two 5 gal nano tanks going. pssst (still need to purchase a paintball tank for my azoo regulator)


----------



## mistergreen

Here are the updates
http://aquatictechtank.net/viewtopic.php?f=11&t=150&p=508#p508


----------



## thor79

Mistergreen...I may be interested in picking up one of those meters you still have to sell.

The thread turned from a pure DIY project to a bit more of a community developed full blown product. Because of that, it seems the DIY-ness of the thread went by the way side, and there are some details lacking from the original post. It's a little difficult to pick up on all the details in a thread 39 pages long. I still want to build my own just to do it (and possibly add some features)....as I already have most of the parts for it, but I figure picking up one of your prepared meters to calibrate against would be good to get a Netduino based version going.

After developing that I think I may put together a more comprehensive guide on building this from scratch (crediting you completely for all the work involved developing the fantastic meter built from this thread, of course)...for the true DIYer's out there.


----------



## ucrdave

thor79 said:


> Mistergreen...I may be interested in picking up one of those meters you still have to sell.
> 
> The thread turned from a pure DIY project to a bit more of a community developed full blown product. Because of that, it seems the DIY-ness of the thread went by the way side, and there are some details lacking from the original post. It's a little difficult to pick up on all the details in a thread 39 pages long. I still want to build my own just to do it (and possibly add some features)....as I already have most of the parts for it, but I figure picking up one of your prepared meters to calibrate against would be good to get a Netduino based version going.
> 
> After developing that I think I may put together a more comprehensive guide on building this from scratch (crediting you completely for all the work involved developing the fantastic meter built from this thread, of course)...for the true DIYer's out there.


This sounds like a great idea. I would hope you start this soon. He does sell the PAR meters, just contact him directly on his page or email.


----------



## thor79

ucrdave said:


> This sounds like a great idea. I would hope you start this soon. He does sell the PAR meters, just contact him directly on his page or email.


Yep, that's what I did. One of the meters should be on the way to me soon. That will help quite a bit to finishing off my Netduino-based Meter. It's close, but there are some details I need to work out.

I will start working on the guide after I get my meter working and calibrated.


----------



## mistergreen

Ok, I've sold off the last meter. I won't make anymore new ones.


----------



## O2surplus

mistergreen said:


> Ok, I've sold off the last meter. I won't make anymore new ones.



Wow- Talk about "having the patience of Job"! It's been 4 years since you started this thread! Consign this project to the history books!:bounce:


----------



## mistergreen

Well, it was kind of fun. I think the last iteration with the light filters researched by hoppy is the best. It also has readings for sun light base on apogee's known 10% discrepancy.

So, I'm out of O2surplus' atmega boards and calling it a day


----------



## RootedMind

I just read this entire thing and am amazed at the dedication and cooperation, polite constructive criticism given and received. Awesome work.


----------



## Quizcat

*PAR Meter for Dummies Tutorial Needed...*

I just read through the thread from beginning to end, and I concur that seeing this project through from beginning to end is a monumental achievement indeed! 

I would love to build one of these for my tanks as well. Where I become confused is over the Arduino, especially how to program the Arduino. I have never worked with Arduinos before, and not sure what that entails. I have the electronics experience to deal with building the project...just never played with Arduino before. Does anybody know of a good, concise tutorial on how to program the Arduino, something for newbies, and even more specifically, how to program this project's recommended Arduino? 

I realize that publishing a step by step tutorial on how to build one of these, after the design has been finalized, would probably be a monumental task, especially after having seen this project through to this stage of development. But, that sure would help those of us who are not as competent as those of you that participated in the development process with respect to the technicalities, and what they all mean. 

This project has had such a lengthy development process, that it's kind of difficult to know what was settled on in the end, and ALL the parts we should purchase to build one, such as where to get the small jar that's sealed for immersion in the tank, the cord, the plug(s), etc...Some of the links within the thread that recommend certain parts are no longer functioning, and it would be nice to actually have the technical specs of all the components, once the protype had been finalized, so that the links that no longer work within the thread don't limit our ability to find the parts elsewhere. 

If we had the technical specs of each of the components, then we could possibly find them from other sources when the links go bad. There is a parts list, and good documentation for connecting the Arduino, which was updated in the very first post after the main parts for the finished project had been settled on, so you don't have to search through the whole thread to know some of the main parts to obtain. But, not every detail or part that was settled on is included in the first post. In order to determine ALL of the other parts that were settled on, it seems you have to read through the entire thread to find that information. And, then, because the thread is so long, you're never quite sure that what was finally settled on with respect to a particular part, is what the designers intended in the final prototype... in other words, due to the length of the thread, it's easy to miss something. 

Too much to ask? Yeah, probably...But, I would love to see a concise tutorial all in one place none the less. I would love to build it, drop the sensor in the water, read off the numbers on the display, and know that what I am reading is the PAR value at the sensor, in that position within the tank, or at least be able to interpret data displayed on the LCD to be converted to PAR if conversion of a number on the display was determined in the end to be necessary. Knowing the technicalities is interesting, and the knowledge, expertise, and dedication of those that participated in the development is astounding. But, some of us still need a "Build a PAR Meter for Dummies" kind of tutorial so that the wonderful contributions to this project can be usable by the "masses." :hihi:


----------



## Okedokey

mistergreen said:


> Ok, I've sold off the last meter. I won't make anymore new ones.


Reconsider?? Lol


----------



## mattinmd

Quizcat said:


> I just read through the thread from beginning to end, and I concur that seeing this project through from beginning to end is a monumental achievement indeed!
> 
> I would love to build one of these for my tanks as well. Where I become confused is over the Arduino, especially how to program the Arduino. I have never worked with Arduinos before, and not sure what that entails. I have the electronics experience to deal with building the project, soldering, etc...just never played with Arduino before.
> 
> Does anybody know of a good, concise tutorial on how to program the Arduino for newbies, more specifically, this project's recommended Arduino?


Do you have any experience in C (or C++) programming? If you do, the arduino tutorials provided by arduinio.cc with the IDE should be sufficient.

Something a little more step-by step would be something like this:

http://www.linuxjournal.com/content/learning-program-arduino

But that still assumes you know C.

Technically Arduino is in C++, but there's not a lot of advanced object-oriented C++ going on that you need to deal with. Most of the libraries are done as C++ classes, but if you know C, you could get away with thinking of classes as structs that also contain functions and have some self-initializing capabilities. Instantiating a class object can take parameters that get passed to the self-initializer (constructor in C++ parlance), so from a C world that looks really strange.

So don't balk when you see things that look like this:

someClassType foo(6);

instead of:

someStructType foo;

The C++ version is just creating an instance named foo, same as the struct, and passing 6 to the constructor for initialization.


----------



## Quizcat

"C" is the third letter of the aphabet :tongue: Well, I am relatively knowledgeable with respect to computers, but not when you get into the actual written code aspects...

The article you linked to says "One excellent way to get started with Arduino is the Arduino starter kit from Sparkfun..."

Do you recommend the Sparkfun starter kit to possibly give me the base knowledge to move forward with Arduino programming for the PAR meter project, or should I plunge right in, and get the Arduino for the PAR meter project instead, using it's manual, and/or along with an open source "C" tutorial for a generic Arduino, and apply that knowledge to experiment with programming the specific Arduino for the PAR meter project? 



mattinmd said:


> Do you have any experience in C (or C++) programming? If you do, the arduino tutorials provided by arduinio.cc with the IDE should be sufficient.
> 
> Something a little more step-by step would be something like this:
> 
> http://www.linuxjournal.com/content/learning-program-arduino
> 
> But that still assumes you know C.
> 
> Technically Arduino is in C++, but there's not a lot of advanced object-oriented C++ going on that you need to deal with. Most of the libraries are done as C++ classes, but if you know C, you could get away with thinking of classes as structs that also contain functions and have some self-initializing capabilities. Instantiating a class object can take parameters that get passed to the self-initializer (constructor in C++ parlance), so from a C world that looks really strange.
> 
> So don't balk when you see things that look like this:
> 
> someClassType foo(6);
> 
> instead of:
> 
> someStructType foo;
> 
> The C++ version is just creating an instance named foo, same as the struct, and passing 6 to the constructor for initialization.


----------



## mattinmd

There's a dozen different "starter kits", and technically I believe sparkfun calls theirs an "inventors kit". 

I don't have that particular kit, so I don't really know how easy their guidebook is to work with... I have the Sunfounder kit, but it just comes as a box of parts and assumes you know what you are doing (fine for me).


----------



## mistergreen

Arduino is c++ but doesn't include a lot of the functions because it takes up too much memory for a little micro controller so C code is used to compensate. So it's a blend of both.

If you can a very basic tutorial on programming check out this article in my little forum.
http://aquatictechtank.net/viewtopic.php?f=37&t=8

That PAR meter would be a perfect project to jump into because it's very simple. On my forum, I keep a more condense step by step so it's easier to follow.
http://aquatictechtank.net/viewtopic.php?f=11&t=150

ps. Sparkfun is having a 30% off sale on Arduino products starting tonight at midnight. You can also get a cheap Chinese clone of the arduino too. They work pretty well.


----------



## mistergreen

Okedokey said:


> Reconsider?? Lol


I've moved on to an arduino web controller.


----------



## Quizcat

Oh, thanks, maybe I missed it in the lengthy thread, but I had no idea you had a forum page with everything boiled down to the bottom line. I just reviewed it very quickly, and that looks like something I can deal with. 

I will check out the Arduino Inventor's Kit...I always wanted to learn Arduino, and just never took the plunge. Thanks very much!



mistergreen said:


> I've moved on to an arduino web controller.


----------



## Quizcat

I've been educating myself on the Arduinos...

I think I am going to order one of the Chinese clones soon. As I understand the E-B-A-Y advertisement, I have a choice of either the UNO R3 with ATMEGA328P or ATMEGA16U2. 
Which of these is the better choice for the PAR Meter project, assuming one or the other is better, and why? I want to use the Arduino to build the PAR meter, and also to generally learn more about Arduinos. 

I did already download the Arduino IDE program, but I don't have an Arduino hooked up to the computer, so there's nothing to play with yet. I am just getting the following text in the window, which I assume is the norm when there is no Arduino present:

void setup() {
// put your setup code here, to run once:

}

void loop() {
// put your main code here, to run repeatedly:

}

But, it appears that it's something that's pretty straight forward with respect to uploading the code to the Arduino device using the Arduino IDE program. Can I just simply take what you've posted with respect to the strings of code within your forum, simply cut and past it verbatum into the Arduino's programming window, and send it to the Arduino device once I have the Arduino connected? 

If so, it looks like you've done most of the work, and that this is going to be a little easier than I might have originally thought. It doesn't seem that building the device is going to be difficult in and of itself. All the important development work has already been completed...roud: 

I just have to say once again...All of you that participated in the development of this project are truly amazing with respect your technical expertise and persistence!



mistergreen said:


> Arduino is c++ but doesn't include a lot of the functions because it takes up too much memory for a little micro controller so C code is used to compensate. So it's a blend of both.
> 
> If you can a very basic tutorial on programming check out this article in my little forum.
> http://aquatictechtank.net/viewtopic.php?f=37&t=8
> 
> That PAR meter would be a perfect project to jump into because it's very simple. On my forum, I keep a more condense step by step so it's easier to follow.
> http://aquatictechtank.net/viewtopic.php?f=11&t=150
> 
> ps. Sparkfun is having a 30% off sale on Arduino products starting tonight at midnight. You can also get a cheap Chinese clone of the arduino too. They work pretty well.


----------



## mattinmd

328 has twice the flash and 4x the sram. Ie: more space to work in. The 16u2 has an on chip usb port, but I doubt you need it. (328 should have an off-chip one for programming and print debugging.


----------



## Quizcat

Under what circumstance would I need an on-chip USB port? Just curious...




mattinmd said:


> 328 has twice the flash and 4x the sram. Ie: more space to work in. The 16u2 has an on chip usb port, but I doubt you need it. (328 should have an off-chip one for programming and print debugging.


----------



## mattinmd

Wait.. it's early... 

The board should have *both* processors on it.

The 16U2 is used by arduino uno and higher as a USB converter for programming and printing.... the 328 is the processor that you are programming.

Earlier boards used an FTDI chip, but they most all use the 16u2 for programming now.


----------



## mistergreen

Yeah, get the ATMEGA328P Uno. It comes with the 16u2 or the newer boards should.

The hardest part is the hardware. You should get a beginner items like breadboard, connecting wires, and variety of resistors, a few 10K potentiometer, a soldering iron & some solder and tinning ; an 2x16 LCD too. You can get it online or go to your nearest radioshack before they close for business. 

A breadboard is used for prototyping where you don't solder things and can move components around easily. Heck some people don't bother soldering and just use the breadboard


----------



## Quizcat

The description from the ad says:

"UNO R3 ATMEGA328P ATMEGA16U2 2012 New Version Board + USB Cable For Arduino" via E.B.A.Y. 

I originally thought I would have to choose between the two, but it looks like the new board must have both.



mattinmd said:


> The board should have *both* processors on it.


----------



## Quizcat

Would it be best to do a price comparison between what's offered in the Chinese Kits, versus my purchasing the important things alacarte?

For example, I figured that I might want more connecting wires, a bigger breadboard, etc...than what is offered in the kits, perhaps a little more diversity of selection with respect to certain components than what's offered in the kits. But, I'll see how the prices shake out between the kits versus alacarte. 

When considering a breadboard size, what size do you recommend I start out with? Any optimum size for all-around projects? I figured that there may be a size breadboard that is not too small, but also not too big to be cumbersome with respect to most projects. 

I actually already have a good professional level soldering station, Hakko brand, various sizes of solder, extra solder tips of varying sizes, etc...so, I am good to go there. 

I actually have some experience with electronics, but old school, primarily before the advent of the "computer age," before IC. So, this should be a fun departure from my previous experience. I've kept up with some technological advances with respect to being quite comforable with computers, basic electronics, etc...but some of what was discussed as you developed the PAR meter was definitely over my head, more akin to electrical engineering, computer code, etc...whereas my knowledge is primarily hands-on basic electronics, and I consider myself just slightly above average in my competancy level with respect to windows based computer usage. 



mistergreen said:


> Yeah, get the ATMEGA328P Uno. It comes with the 16u2 or the newer boards should.
> 
> The hardest part is the hardware. You should get a beginner items like breadboard, connecting wires, and variety of resistors, a few 10K potentiometer, a soldering iron & some solder and tinning ; an 2x16 LCD too. You can get it online or go to your nearest radioshack before they close for business.
> 
> A breadboard is used for prototyping where you don't solder things and can move components around easily. Heck some people don't bother soldering and just use the breadboard


----------



## mistergreen

I'd go for the big breadboard, 2"x6.5".

You're half way there with a soldering station.

Get some LEDs while you're at it. Nothing more fun than see something light up.


----------



## mattinmd

Yep, a few things to add to really have more-or-less the same setup I use:

1) liquid flux. This is really important for good soldering IMO. Yes, the solder has some, but joints just flow a lot better (better wetting, more even heat transfer) if you put a drop on first... 

I use this stuff, mostly because it is cheap. Kester would be better, but hard to get in small quantities.
http://www.amazon.com/gp/product/B005DNR01Q/
And a dispenser bottle:
http://www.amazon.com/gp/product/B00CIB9UHS/


2) something to hold your work. I use a panavise, but those alligator-clip ones work fine for most light stuff. (I use the panavise for small woodworking projects too). In the past I used a locking curved forceps and just set it on a bench, but that only holds it a half inch up or so. You can't hold wires in one hand and solder one-handed 

3) Reading glasses, magnifying visor or bench magnifier... Even if your eyes are very good, this stuff is small and inspecting joints is best done under magnification.


Unless you can see good enough to tell differences like the ones shown here:
https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems


----------



## O2surplus

*GERBER Files for the DIP version of the CEP meter*

A few people have been asking for the build files needed to make their own CEP Meters. I've attached the GERBER files below. I recommend using SeeedStudios in China for production. I use them all the time. They're fast, cheap, and crank out quality work.

Here's a link to SeeedStudios- http://www.seeedstudio.com/service/index.php?r=pcb

Upload the GERBER files

Select the 5cm X 10cm size option to order the boards. All of the other options can be left at their default state for no additional costs. 

Choose a shipping option and you're done.


----------



## Quizcat

O2Surplus,

Thanks very much for that information...









So, once you access Seed Studios website, they have an app that you can download the Gerber File to them, and you will immediately receive an illustration of what the finished board will look like, along with a price.

O2Surplus, reference my PM to you inquiring about a finished board, it appears to me after visiting their site that the finished board is what they do, correct, and not just the PCB with tracings? Except, it appears that they will also do that as an option, if that's what you want. I noticed that they had an option that you could order just the PCB only, no components apparently. But, then you would have to obtain the parts, solder them in place, etc...

I recall that the cost of just the board alone, with just the tracings and the parts illustrations, was around $9.00+ for (10) boards(?), not sure if they mean each, or for ten boards. 

Well, if I am reading their site correctly, the option for a completed board with all components mounted is also available. If so, then the cost of the completed board should be $18.90 for (10) pcs., plus shipping, or they have a price option of (5) pcs for $15.90, plus shipping. 

Just to confirm, that is (5) complete boards with components mounted for $15.90, plus shipping? Is that right, or do they mean to say (5) complete boards with components mounted x $15.90 each, (10) complete boards with components mounted for $18.90 each? Since they're in China, I wondered if I'm misinterpreting the price for (5) or (10) complete boards with components mounted.

Their ship date was pretty good. If I order them today, they will ship by April 1st. Of course, the actual delivery time might be a few weeks depending on the option you choose for shipping.




O2surplus said:


> A few people have been asking for the build files needed to make their own CEP Meters. I've attached the GERBER files below. I recommend using SeeedStudios in China for production. I use them all the time. They're fast, cheap, and crank out quality work.
> Here's a link to SeeedStudios- http://www.seeedstudio.com/service/index.php?r=pcb
> 
> Upload the GERBER files
> 
> Select the 5cm X 10cm size option to order the boards. All of the other options can be left at their default state for no additional costs.
> 
> Choose a shipping option and you're done.


----------



## mistergreen

Once you have the IC board, you'll need to burn the bootloader and then the arduino sketch onto the Atmega328 chip. I usually go through the Arduino ISP process here
http://arduino.cc/en/Tutorial/ArduinoToBreadboard

Maybe O2Surplus can recommend something easier.

You can upload the Arduino sketch straight to the CEP IC board once your have the bootloader. You need a USB to UART cable. Make sure the black wire is the ground or you'll kill the Atmega chip.


----------



## O2surplus

Quizcat said:


> O2Surplus,
> 
> Thanks very much for that information...
> 
> View attachment 452545
> 
> 
> So, once you access Seed Studios website, they have an app that you can download the Gerber File to them, and you will immediately receive an illustration of what the finished board will look like, along with a price.
> 
> O2Surplus, reference my PM to you inquiring about a finished board, it appears to me after visiting their site that the finished board is what they do, correct, and not just the PCB with tracings? Except, it appears that they will also do that as an option, if that's what you want. I noticed that they had an option that you could order just the PCB only, no components apparently. But, then you would have to obtain the parts, solder them in place, etc...
> 
> I recall that the cost of just the board alone, with just the tracings and the parts illustrations, was around $9.00+ for (10) boards(?), not sure if they mean each, or for ten boards.
> 
> Well, if I am reading their site correctly, the option for a completed board with all components mounted is also available. If so, then the cost of the completed board should be $18.90 for (10) pcs., plus shipping, or they have a price option of (5) pcs for $15.90, plus shipping.
> 
> Just to confirm, that is (5) complete boards with components mounted for $15.90, plus shipping? Is that right, or do they mean to say (5) complete boards with components mounted x $15.90 each, (10) complete boards with components mounted for $18.90 each? Since they're in China, I wondered if I'm misinterpreting the price for (5) or (10) complete boards with components mounted.
> 
> Their ship date was pretty good. If I order them today, they will ship by April 1st. Of course, the actual delivery time might be a few weeks depending on the option you choose for shipping.





mistergreen said:


> Maybe O2Surplus can recommend something easier.


You're getting 10 *BARE *PcB's for $18.90. The Chinese work cheap, but not that cheap. LOL You'll still need to source and solder on all the parts yourself. *OR *after you receive the PcB's just send me one and I'll put it together for you :hihi:. ( I have everything needed, except the bare PcB's) I'll even program it, but calibrating it will be up to you.


----------



## rottison

02 didn't know you had a par meter? how well does it work?


----------



## Quizcat

Yeah, still, that is cheap! But, really cheap with all the stuff mounted! Too bad! :tongue:

But, yes, I appreciate your offer to help me out very, very much. So, I'll get them on order, and PM you when I get them in. That's very nice of you, and I can't thank you enough for the help. I would like to send one of them to you, so I know that it's done right, then maybe try my hand at it myself once I determine the parts that'll be needed, and have more hands on experience with it. 

I am quite sure I can source the parts if I have a detailed list. The soldering isn't a problem for me at all. But, I would probably need some kind of hobbiest "schematic for dummies," something to go by so that the proper positioning of the components is observed, etc...Don't want to put anything in bass-ackwards. 

Did you say that the layout is etched or printed on the boards when I get them back from "Seeedsstudio," or not? If so, then all I would probably need are the tolerances of the components in order to source the proper ones.

I was hoping it was going to be as easy as ordering the PCBs with the stuff already mounted and soldered. But, even then, were I to be so fortunate, I wondered exactly where and how I was supposed to connect the PAR sensor once it is built, whether there was polarity to be observed, etc...again another case of bass-ackwards potential.

As far as calibration, I remember Mistergreen mentioning the calibration values somewhere within this thread, and if I remember correctly, it may have been that the calibration value changed once or twice over time. So, I need to make sure I find the most recent calibration values for the potentiometer. And, I'm not even sure how to actually go about adjusting for calibration. So, I may need to read over the thread once again so that more will sink in before going that far. Is there a calibration procedure posted somewhere within the thread...is it something you read on a VOM meter, connected where, etc...? 

I still have an interest in the Arduino as well, and I may build one of the PAR meters using the breadboard, LCD Display, and the Arduino, just to gain some more knowledge about the Arduinos. 

Fascinating stuff...Looking forward to it very much!





O2surplus said:


> You're getting 10 *BARE *PcB's for $18.90. The Chinese work cheap, but not that cheap. LOL You'll still need to source and solder on all the parts yourself. *OR *after you receive the PcB's just send me one and I'll put it together for you :hihi:. ( I have everything needed, except the bare PcB's) I'll even program it, but calibrating it will be up to you.


----------



## Quizcat

O2 gave me much easier option...send it to him :hihi:

But, I am very interested in learning, so I'll be sure to review the link you sent. I brieflly reviewed it, and it looks relatively simple and concise. This is where my also messing with the Arduino to gain additional expertise will go hand in hand with burning the bootloader/sketch to the chip.

Thanks for the handholding...I am learning a lot. 



mistergreen said:


> Once you have the IC board, you'll need to burn the bootloader and then the arduino sketch onto the Atmega328 chip. I usually go through the Arduino ISP process here
> http://arduino.cc/en/Tutorial/ArduinoToBreadboard
> 
> Maybe O2Surplus can recommend something easier.
> 
> You can upload the Arduino sketch straight to the CEP IC board once your have the bootloader. You need a USB to UART cable. Make sure the black wire is the ground or you'll kill the Atmega chip.


----------



## robsworld78

Hey Quizcat, don't be to scared about the programming, if you've done anything with code like a simple website or whatever you'll catch on. Here's a link to the language reference, this page has helped me so many times. Lots of good examples if you need to know how to use something.

http://arduino.cc/en/Reference/HomePage


----------



## mistergreen

If you buy an Arduino, no need for burning the bootloader. You can start programming out of the box. It comes with a bootloader.

When you build something that you'd like to mass produce, you can buy those Atmega chips for $3 and build your applications. So as you can see, it's much cheaper than an Arduino.


----------



## robsworld78

mistergreen said:


> If you buy an Arduino, no need for burning the bootloader. You can start programming out of the box. It comes with a bootloader.
> 
> When you build something that you'd like to mass produce, you can buy those Atmega chips for $3 and build your applications. So as you can see, it's much cheaper than an Arduino.


I'm going to attempt that when I'm completely finished.


----------



## Quizcat

Thanks very much for the link. I have actually taken a several courses on programming, not with respect to the Arduino, but other computer oriented projects. One thing I learned is that actually writing the code is very different than just entering the code. I never really mastered what I learned with respect to writing or programming code because I didn't practice it on a daily basis. But, I have had some exposure to it. I just don't have proficiency at it. But, I do know enough about it that I realize that there are many things I don't know. 



robsworld78 said:


> Hey Quizcat, don't be to scared about the programming, if you've done anything with code like a simple website or whatever you'll catch on. Here's a link to the language reference, this page has helped me so many times. Lots of good examples if you need to know how to use something.
> 
> http://arduino.cc/en/Reference/HomePage


----------



## Quizcat

Does the photo diode connect at D1, and is there a particular polarity to be observed?


----------



## mistergreen

D1 is a regular diode.
The photodiode goes at 5v out (+) & in (-)


Sent from my iPad using Tapatalk HD


----------



## Quizcat

Ok, thank you very much! Is the Anode(+) and Cathode(-) marked on the Photodiode? 

With regard to the PAR meter input, are you talking about the two holes above and to the left of where it says "5 Volts Out/Par Signal In", the holes that are to the left of the capacitor marking entitled "C3" "22pf"?

Also, is the FTDI1 on the board used for powering the device via the USB on your computer only, or are there programming requirements that make the FTDI1 necessary? If not, then you could operate the board off of a battery pack at 9Vdc. As little time as is necessary to take readings, it would lessen the cost of the project if the FTDI1 was omitted, if that's even practical.



mistergreen said:


> D1 is a regular diode.
> The photodiode goes at 5v out (+) & in (-)
> 
> 
> Sent from my iPad using Tapatalk HD


Seeedstudio has a service where they will solder the parts to the boards for an upcharge. They have quoted me $84.90/10 PCBs, plus parts cost. Most of the parts on the board are cheap, .15 cents here, .15 cents there, etc...with the exception of the cost of the chip, power regulator, etc...I suspect that total cost for parts is probably under $10.00.

The limitation may be that the parts must come from their list of in-house parts. So, it is possible that you could receive a complete board from them, or at least one with most items already soldered, and for a relatively nominal additional parts cost. But, anything they don't have in their standard parts offering would have to be purchased and soldered yourself. 

Anybody have a Bill of Materials? I can have them quote it, and let everyone know how far they can go with the PAR Meter PCB manufactured complete. Then, you would only have to make the Photodiode part of the project. And, of course, you would have to learn to burn the bootloader to the chip, and find some way of calibrating the par meter. 

They have my order for (5) PCBs, but are interested in quoting the project complete. I'm planning to send one of my PCBs to O2Surplus to be soldered up. However, I'll have five other PCBs to get rid of. I was wondering if anybody might be interested in having them manufacture a complete board, at least one that has as many parts already on it as are available from their parts offering. If so, I could have four of the boards manufactured with the parts already mounted and soldered. But, I don't have a bill of materials to submit to them. I could guess at it based on the basics that are printed on the board, but don't want to risk actually having them manufactured complete without being sure of the actual bill of materials. So, if someone has an actual bill of materials for the project, I'll be happy to submit it to them in order to get an accurate cost, and to know how many of the parts they can provide.


----------



## O2surplus

Partlist

Exported from PAR MeterDIP .brd at 3/28/2015 12:02:37 PM

EAGLE Version 6.4.0 Copyright (c) 1988-2013 CadSoft

Assembly variant: 

Part Value Package description 

5VREG UA7805 TO263-3 Texas Instruments LDO regulator 
C1 0.1uF C1206 ceramic capacitor 
C2 0.1uF C1206 ceramic capacitor 
C3 22pf C1206 ceramic capacitor 
C4 22pf C1206 ceramic capacitor 
C6 10uF C1206 ceramiccapacitor 
D1 BAS15 DO34-7 through hole diode 
FTDI1 1X06 .1"pin header 
Q1 16MHz SM49 SMD crystal 
R1 5kOhm TRIM_POT_SIDE potentiometer 
R2 10k M1206 SMD chip resistor 
R4 15K M1206 SMD chip resistor 
U1 LCD-16X2 LCD-16X2 SparkFun-Displays 
U2 ATMEGA328-PU DIL28-3 atmel(purchase w/ arduino bootloader installed) 
VR1 10k TRIM_POT_SIDE potentiometer 

Also needed: 9v battery wire harness
10mm plastic standoffs to mount 16x2 liquid crystal display.
.1"X 16 pin header


----------



## Quizcat

Hey, thanks O2,

I have submitted it to SeeedStudio...I suspect they are off duty in China right now, but they're very responsive, and I suspect I'll get a response by about 3am our time. So, lets see what they come back with. I suspect there are some things they won't have in their standard parts inventory, but if they have 90% of it, then it would make the complete board pretty easy to obtain, all be it probably in quantities of at least (10) pcs minimum...although, I haven't asked them if they'll do them in lesser quantities yet. 

I wonder if they can build the sensor?



O2surplus said:


> Partlist


I wasn't aware you could purchase the ATMEGA328 with the bootloader installed. I assume you would not need the Arduino to program the PAR meter. Is it done via the Arduino software through the USB on the PAR Meter board? 



O2surplus said:


> U2 ATMEGA328-PU DIL28-3 atmel(purchase w/ arduino bootloader installed)


----------



## mistergreen

Quizcat said:


> I wasn't aware you could purchase the ATMEGA328 with the bootloader installed. Do you still need the Arduino to program the PAR meter, or is that done via the Arduino software through the USB on the PAR Meter board?


You upload the arduin sketch through the IDE (software)... You'll need a USB to UART cable or if you have an Uno, you can pop out the Atmega, upload the sketch, and then pop it back to the CEP board.


----------



## Quizcat

Anyone have the part number for a chip receptical to hold the ATMEGA328-PU DIL28-3 atmel chip, or does it customarily come with the chip? 

I could add a chip receptical to the bill of materials, and fire it off to SeeedStudios, so the chip can be popped out for programming via the Arduino. 

Otherwise, I assume the Chinese will solder the chip directly to the PCB. Might as well have them quote it with a receptical for the chip soldered in place, provided there will still be clearance above the chip/receptical for the LCD. 



mistergreen said:


> You upload the arduin sketch through the IDE (software)... You'll need a USB to UART cable or if you have an Uno, you can pop out the Atmega, upload the sketch, and then pop it back to the CEP board.


----------



## mistergreen

Look for 28 pin DIP socket. I'm not sure if seeed has it come with the chip.


----------



## O2surplus

Quizcat said:


> I wasn't aware you could purchase the ATMEGA328 with the bootloader installed. I assume you would not need the Arduino to program the PAR meter. Is it done via the Arduino software through the USB on the PAR Meter board?


You'll need a USB/FTDI adapter to connect to the chip. The CEP has a six pin header that's used for programming the chip using the Arduino IDE.

Here's a link to the chip if you need it-http://www.digikey.com/product-search/en?KeyWords=atmega328p-pu&WT.z_header=search_go

They're also available for sale on FleaBay. Many with the bootloader already installed. I've got ten of them if you need some. I burned the optiboot bootloader to them myself, so they're ready for use.

The chip holder-http://www.digikey.com/product-detail/en/ED281DT/ED3050-5-ND/4147600


----------



## Quizcat

Thanks very much O2 and Mistergreen! 

I'll send SeeedStudios the links for both the chip and the holder, O2, so they'll know what I'm referring to with respect to the one already with the bootloader, as well as the pin socket, and they can add them to the Bill of Materials to quote some of these to be soldered. 

I don't know how much of the bill of materials they'll have in stock, but they have an abundance of parts available in that part of the world, so I assume the parts would be easy to obtain, if they're so inclined. Just depends if they want to do it with parts they don't already have.

With respect to the parts you have 02, I am going to send a couple of the PCBs your way, unsoldered, and we can use up some of your parts. Just as soon as I receive the boards, I'll PM you for a mailing address. That way, we can use up some of the spare parts you have in the process so you aren't stuck with them. 

SeedStudios had already apparently finished my PCBs (unsoldered) before they were able to stop the process. I was kind of hoping they would delay the order so that some of my (5) pc. PCB order could be soldered. But, at least this way, if we know what the total cost of the boards will be, soldered, then other forum members can order some if they want to build a PAR meter using the PCBs instead of the Arduino. And, I haven't given up on the Arduino yet either. I am eager to learn... 




O2surplus said:


> You'll need a USB/FTDI adapter to connect to the chip. The CEP has a six pin header that's used for programming the chip using the Arduino IDE.
> 
> Here's a link to the chip if you need it-http://www.digikey.com/product-search/en?KeyWords=atmega328p-pu&WT.z_header=search_go
> 
> They're also available for sale on FleaBay. Many with the bootloader already installed. I've got ten of them if you need some. I burned the optiboot bootloader to them myself, so they're ready for use.
> 
> The chip holder-http://www.digikey.com/product-detail/en/ED281DT/ED3050-5-ND/4147600


----------



## Quizcat

Just to clarify,

Do you have a link that depicts the USB/FTDI adapter? You are referring to just the cord that plugs into the board for access to the chip via the Arduino, but different than the pin header for same, correct? 








Looks like this?

http://www.mouser.com/ProductDetail...id=251223089&gclid=CI_VwfyN08QCFYQvgQodzxgAWQ

The part that we want soldered to the board is the receptical for the USB/FTDI cord, FTDI1 1X06 .1" pin header, soldered in the area where the PCB is labeled FTDI1, right?



O2surplus said:


> You'll need a USB/FTDI adapter to connect to the chip. The CEP has a six pin header that's used for programming the chip using the Arduino IDE.


----------



## mistergreen

That's the cable. That plugs into your computer and the FTDI part plugs into the header on the CEP board. You can upload your Arduino sketch with this just like a normal Arduino. Make sure the black wire goes to ground.

Or you can pop out the Atmega chip like I mentioned earlier. $20 for a cable is steep while you can buy an Uno.


----------



## mistergreen

Hey so I got an email from instructable wanting my projects I listed on Youtube on their site and they'd set me up with a free pro account. I had no idea they had a pro account. Why do people want to pay them to post?


----------



## mattinmd

Pro lets you do a few things like have private instructables that are only visible to those you send a link to. Useful for draft/review (later made public) or club materials (not made public), etc.


----------



## Quizcat

Yes, very good point Mistergreen...In fact, I am in contact via PM with O2Surplus about that very subject. So, I am hoping there's an Uno in my future pretty soon. 



mistergreen said:


> $20 for a cable is steep while you can buy an Uno.


----------



## Quizcat

SeeedStudio doesn't have all of the parts in their inventory to complete the project. So, they declined to quote the PCBs with the parts soldered-up.
If anyone on the forum wants one of my extra PCBs to solder-up themselves, then send me a private message.


----------



## mistergreen

Well, you can save money and build it from scratch with an Uno. It won't look as nice but it'll be cheaper, maybe build yourself an Uno shield using wires instead of a PCB.


----------



## Quizcat

Yeah, that's true...actually, I hope to have O2Surplus solder one of the PCBs up too, maybe all five of them. He has the parts to complete five of them. So, if I do that, then the CEP will have a smaller footprint, etc...

I have access to a Nano, which means I should end up with two of them in the end, some from the PCB design, and one via a Nano. 

What's the difference between the Nano and the Uno. Should I get an Uno if I get a Nano? What limitations are placed on me by only having the Nano...don't want to miss out on any of the potential other projects I might be able to mess with, and I really wouldn't be opposed to also getting an Uno if it has a lot more capability. 

Sorry, but what's an Uno "Shield?"




mistergreen said:


> Well, you can save money and build it from scratch with an Uno. It won't look as nice but it'll be cheaper, maybe build yourself an Uno shield using wires instead of a PCB.


----------



## mistergreen

A shield is any board that fits directly over an arduino usually via male header pins. Something like these https://www.sparkfun.com/categories/240?page=all

So you can mount the lcd and all other components ( not as much as on the cep) on the shield; a small foot print.

A nano should work. It's a 5v logic like the uno.


Sent from my iPad using Tapatalk HD


----------



## Quizcat

I visited the link, and I can see that the Shields expand the various options, making it a nice neat little package. 

So, the shield at the following link includes the screen, and plugs directly into the Uno, correct?

https://www.sparkfun.com/products/11851









So, do you purchase the pinned header to adapt the shields to the Uno separately, or does the Uno already have the male header pins in the pacakage, and all you have to do is purchase the shield itself for whichever of the shield functions you desire?

Do you know if the Nano version acommodates the shields also?



mistergreen said:


> A shield is any board that fits directly over an arduino usually via male header pins. Something like these https://www.sparkfun.com/categories/240?page=all
> 
> So you can mount the lcd and all other components ( not as much as on the cep) on the shield; a small foot print.
> 
> A nano should work. It's a 5v logic like the uno.
> 
> 
> Sent from my iPad using Tapatalk HD


----------



## jeffkrol

Quizcat said:


> I visited the link, and I can see that the Shields expand the various options, making it a nice neat little package.
> 
> So, the shield at the following link includes the screen, and plugs directly into the Uno, correct?
> 
> https://www.sparkfun.com/products/11851
> 
> View attachment 455482
> 
> 
> So, do you purchase the pinned header to adapt the shields to the Uno separately, or does the Uno already have the male header pins in the pacakage, and all you have to do is purchase the shield itself for whichever of the shield functions you desire?
> 
> Do you know if the Nano version acommodates the shields also?


buy one of these, a I/O board and reprogram to your hearts content..
PWM/ LCD/ RTC all included.. 
http://shop.stevesleds.com/Typhon-Typhoon-LED-Controller-8794102479.htm
http://www.gearbest.com/development...currency=USD&gclid=CPWVoMfZ18QCFZRgfgodgRkAIA

Yes it is more expensive..


----------



## Quizcat

Yeah, I need something...I realized over the last few weeks, that when my RGBW(WARM)+W(Cool) LED strips come back on after being off at night, they don't stay on the color that was on when the lights went off the night before. And, they come back on at a lower intensity than they were set at the night before as well. So, something like the LED Controller you linked to would be pretty cool, and probably be much more consistent. I'm curious to see what the PAR is of these LED strips, and then I'll do something about a controller, assuming PAR is sufficient. If not, then I have to go back to the drawing board, which may require a completely different driver/controller or series of drivers/controllers. 



jeffkrol said:


> buy one of these, a I/O board and reprogram to your hearts content..
> PWM/ LCD/ RTC all included..
> http://shop.stevesleds.com/Typhon-Typhoon-LED-Controller-8794102479.htm
> http://www.gearbest.com/development...currency=USD&gclid=CPWVoMfZ18QCFZRgfgodgRkAIA
> 
> Yes it is more expensive..


----------



## Quizcat

*PCB Update...*

Well, I think the PCBs are on the way...I got an email today from SeedStudios that said the order is now "traceable," which I suppose means they are en-route.


----------



## Quizcat

Is the area circled in yellow (below) where the two wires from the photodiode/sensor attach? 

The photodiode is extremely small. I can see a small triangle within the photodiode screen pointed toward the center of the photo diode screen, and I assume that differentiates between the Cathode and the Anode sides, but not sure which hole the triangle side connects to on the PCB, assuming the area circled in yellow is the connection point. I have always been told you can reverse polarity for short periods of time with respect to standard diodes, and not suffer any negative consequences, and just reverse the connection to get the proper function if you connected it improperly in reverse. But, I am not sure that applies to photodiodes, so I want to make sure I connect it properly so I don't blow it out. 

Is it recommended to solder a small jack in place to plug the photodiode/sensor wire into, or is it best to solder the wires from the sensor directly to the PCB? 









Also, there is a POT labeled "LCD" right above where the two holes are circled in yellow. Is this POT labeled "LED" an intensity adjustment for the LCD screen?


----------



## mistergreen

I tried soldered the sensor line directly to that port but they tend to snap off so I used this










You can use a barrel jack if you want. It would be nice. V out is (+) , signal in is (-)

Yes, the LCD pot is to adjust the LCD.


----------



## Quizcat

So, do you know if the leg of the photodiode that has the triangle in the window of the diode itself connects at the "Signal IN" side or visa versa? There are no other markings that I can see on the photodiode using a magnifying glass to know which leg goes to "Signal IN" and which leg goes to "Signal Out." Just for my own knowledge, if I were to accidentally reverse the connection, will it harm the circuit or the photodiode?

I like the barrel jack idea too...But, I've looked at a few barrel jacks online, and the PCB style are all three legs, and they're oriented differently so that it might be difficult to line it up with the holes in the PCB so that the jack opening is accessible from the side. So, your connection block might be the only viable option. Do you recall where you obtained your connection block? 





mistergreen said:


> I tried soldered the sensor line directly to that port but they tend to snap off so I used this
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> You can use a barrel jack if you want. It would be nice. V out is (+) , signal in is (-)
> 
> Yes, the LCD pot is to adjust the LCD.


----------



## mistergreen

screw terminals here
https://www.sparkfun.com/products/10571
You might be able to find it cheaper elsewhere.

On the photodiode (top side), there is a dot. That's the (+) side.


----------



## Quizcat

Ah, ok, thanks with respect to the "DOT" !

The LCD just unplugs from the PCB, once I release the little stand-offs on the corners, right? 

Appreciate the link to the screw terminal block too!




mistergreen said:


> screw terminals here
> https://www.sparkfun.com/products/10571
> You might be able to find it cheaper elsewhere.
> 
> On the photodiode (top side), there is a dot. That's the (+) side.


----------



## mistergreen

yup, the LCD unplugs. I got your meter in the mail today. I was wondering how to pull off the LCD without ruining the plastic stands. I didn't have to deal with that before.


----------



## rottison

Mistergreen how well do the DIY light meters work specially under water? I haven't read this whole thing yet


----------



## mistergreen

rottison said:


> Mistergreen how well do the DIY light meters work specially under water? I haven't read this whole thing yet


It works fine. I didn't run into the same issue as hoppy. The only issue is possible leaks . It's held together with silicone. I didn't want to drive up time & expense building a solid housing.
Other people have rebuilt the housing like this


----------



## rottison

very nice looking might have to look in to buying an extra board from some one


----------



## Quizcat

On other electronic boards that have stand-offs that I've worked with, I usually use a very small needle nose pliers to pinch the split plastic pin together where it fits through the hole, then pop them out of their respective holes, usually only one corner at a time. They will usually pop back together without any issues, one hole at a time. The trick is lining everthing up with the pin connector first when they go back together. I haven't taken the LCD screen off of one of the boards yet, but that's how I had envisioned doing it were I going to use a connector block for the sensor wire. 

O2Surplus supplied them with the stand-offs. He might have a suggestion how to remove them without damaging them. 

If not, if you have an extra sensor for sale, and you wanted to go ahead and solder a sensor in place, I would be glad to buy one from you. I don't suppose you have any of those green little connector blocks in your stash, do you? That would be nice too...

Or, if you don't want to take it that far, you could solder the wire in place and splice it to your sensor temporarily by just twisting the leads together according to polarity in order to complete the calibration. Either way, the wire could probably be soldered in place without removing the LCD, and that would be fine with me too. 

The other option is that I could obtain the green connector block, solder it in place on one of my other boards, then send you a board with the green connector block. You could return the both of the boards once you have the one with the green connector board calibrated. I want to make it as easy on you as possible. I appreciate the help!



mistergreen said:


> yup, the LCD unplugs. I got your meter in the mail today. I was wondering how to pull off the LCD without ruining the plastic stands. I didn't have to deal with that before.


I have a couple extra boards available. Just send me a PM and we can go from there. 



rottison said:


> very nice looking might have to look in to buying an extra board from some one


----------



## O2surplus

Quizcat said:


> On other electronic boards that have stand-offs that I've worked with, I usually use a very small needle nose pliers to pinch the split plastic pin together where it fits through the hole, then pop them out of their respective holes, usually only one corner at a time.



I've use "reversible" snap ring pliers to pop the plastic standoffs loose. As long as you're careful not to let the pliers pry against any electronic components on the PcB, there shouldn't be any damage done. Just pop them loose one at a time... and you'll be fine.


----------



## rottison

man 50 pages to read to catch up on this


----------



## Quizcat

Does anyone know the origin of this particular sensor housing, and whether there is a tutorial on how to build it, sourcing of the parts, etc...?









Also, did anyone ever pass final judgement on how this sensor housing design worked using heat shrink, especially with respect to sealing it to make it waterproof?












mistergreen said:


> It works fine. I didn't run into the same issue as hoppy. The only issue is possible leaks . It's held together with silicone. I didn't want to drive up time & expense building a solid housing.
> Other people have rebuilt the housing like this


----------



## mistergreen

That first housing is made by ichristos. I don't see him around much. He posted here http://www.aquatictechtank.net/viewtopic.php?f=11&t=150&start=20#p525

That shrink tube should work. It would simplify a lot of things. If you rather me make a shrink tube version for you, I can do it.


Sent from my iPad using Tapatalk HD


----------



## Quizcat

Yes, please go ahead and make me one of the shrink tube type sensors. I might as well test one of them out. I have several extra photodiodes if it happens to get wet. I would like to build a couple of the heat shrink sensors myself too. So, if you can sell me some of your extra parts so I can experiment, I would appreciate it. Or, please send me the links, and I can obtain the parts I'll need, whichever is easiest. 

I think the advantage of the shrink tube type is that I could put a guide onto the cable that would bend the shrink tube sensor cable up at right angles, in a hooked configuration, which would be much easier to manuever inside the tank with respect to where the lighting is located, and allow it to be positioned under plants, into shaded areas, etc...

Does the heat shrink seem to seal tight just from the shrink process? If not, I was thinking that once I get the sensor, I might be able to dip it in something that dries quickly, and will seal it without changing the function of the diffuser. Do you think that by doing that I would be changing the ability of the diffuser to do it's job properly by dipping it a sealer (ie:distorting the light through the diffuser)? 

Anybody have any suggestions as to what kind of liquid sealer would work well to seal any openings from the heat shrink by just dipping the end of the sensor, something that will also preserve the heat shrink so it doesn't change shape? Polyurethane (clear), acylic sealer (clear)?

I think that I will probably not expose the sensor you send to any experiments, and maintain it's original design, so that my experiements don't alter the calibration of the original. I can experiment with making new sensors on my own, so I can compare the performance of those subsequent sensors to your calibrated original version. So, just make the heat shrinked version as you envisioned it originally in the thread, and I'll further contemplate other sealing methods to be applied to subsequent sensors I'll make on my own. 

I would still also like to build one of the paint bottle types, but I don't know if you still have the parts to send along with the shrink tube sensor. If so, I'll buy some of your paint bottle parts too, the bottle, the cable connector, the diffuser, filter material, etc...and/or whatever else I need to experiment with building several sensors. Or, if you can help me source some of that stuff I'll need in order to build one of the paint bottle types by providing me with links to those parts, then I can obtain that stuff on my own. 

I checked out ichristos post via the link you sent, and that appears to be his one and only post there. If I were to contact him about his methodology, I'm not sure he checks the site, and would know to respond. It has been a while since he took an interest. But, I'll give it a try contacting him...

Thanks!




mistergreen said:


> That first housing is made by ichristos. I don't see him around much. He posted here http://www.aquatictechtank.net/viewtopic.php?f=11&t=150&start=20#p525
> 
> That shrink tube should work. It would simplify a lot of things. If you rather me make a shrink tube version for you, I can do it.
> 
> 
> Sent from my iPad using Tapatalk HD


----------



## mistergreen

ichristos is on this forum too somewhere.

No need to seal the shrink wrap. I'm curious too if this leaks or not. 

I'll send you the paint bottle parts too.

I still can't get the standoff off.... Will try to look for a smaller plier to see if that works.


----------



## Quizcat

Worse case scenario, if you had to cut them off, I assume that 02Surplus can probably get some more, or point me in the right direction where I can acquire some more to re-mount the LCD. 

You know, they make a black sealer we use for sealing wiring connections that have to be buried under ground. The stuff is called liquid tape, and that's the cheapest stuff. They also make even better formulations, but I've forgotten the name of them. I might apply some of that to the shrink wrap where it meets the cable, and where the shrink wrap contacts the filter material, ever so daintily of course. That stuff works very well, all-be-it ugly as sin. It's cheap, but good. I know of connections that have been buried in the ground for twenty years and are still dry as a bone. As long as I don't get it where it will obstruct the light to the photo diode, it might be a good precaution before I plunge it under the surface of the water. 









I dawns on me that perhaps I could mask the filter material prior to applying the shrink wrap, then spray the end, peal the mask back, and SHAZAM, sealed.



mistergreen said:


> ichristos is on this forum too somewhere.
> 
> No need to seal the shrink wrap. I'm curious too if this leaks or not.
> 
> I'll send you the paint bottle parts too.
> 
> I still can't get the standoff off.... Will try to look for a smaller plier to see if that works.


----------



## mistergreen

Yeah, I'm going to cut the standoff off. You can replace it. I'll fill the inside with silicone before I shrink wrap so the there won't be any shorts from wire contacts.


----------



## Quizcat

Yeah, good idea, silicone the connection...That would be much more attractive. And, if the shrink wrap buckles over time, or whatever, you just replace it.



mistergreen said:


> Yeah, I'm going to cut the standoff off. You can replace it. I'll fill the inside with silicone before I shrink wrap so the there won't be any shorts from wire contacts.


----------



## mistergreen

I just cut off the tips and was able to pull off the LCD. The main part of the standoff is still there.


----------



## Quizcat

That's fine...They should be easy to replace. Besides, when I put a terminal block on there, I would have needed to remove the LCD anyway to get to it. 



mistergreen said:


> I just cut off the tips and was able to pull off the LCD. The main part of the standoff is still there.


----------



## mistergreen

So I made the heat shrink version









I went to calibrate it but if it wasn't getting enough light compared to the bigger paint container version. My conclusion is the size of of diffuser plays a role, more area for photons to hit, I guess. 

I can make the heat shrink version work but I'd have to change the calibration code. It's water proof btw. 

I'll stick with the 1" diameter diffuser.


----------



## Quizcat

Ok, sure, stick with the larger diffuser...Well, it was a nice idea, small footprint, and it is nice to know that it's waterproof. But, if changing the code to compensate would make it less accurate, or more difficult to make work with what has already been developed with respect to the PCBs, etc..., then it's wisest to stick with the paint jar sensor. 

Do you remember if the gap between the photodiode and the diffuser were the same in both versions? I was thinking that maybe it may not be the larger diameter of the diffuser, but it could be that there is a larger gap between the photodiode and the surface of the diffuser within the paint jar, versus the photodiode directly contacting the surface of the diffuser within the smaller version sensor. 




mistergreen said:


> So I made the heat shrink version
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I went to calibrate it but if it wasn't getting enough light compared to the bigger paint container version. My conclusion is the size of of diffuser plays a role, more area for photons to hit, I guess.
> 
> I can make the heat shrink version work but I'd have to change the calibration code. It's water proof btw.
> 
> I'll stick with the 1" diameter diffuser.


----------



## mistergreen

Quizcat said:


> Do you remember if the gap between the photodiode and the diffuser were the same in both versions?


no gap on both.


----------



## Quizcat

*The CEP is finished...*

I wanted to make a very inexpensive case and cover for the CEP in order to protect it from sustaining damage to the PCB and LCD, and make it more convenient to use. It's ugly, but functional, and more importantly, it's cheap! 

I put the CEP in an inexpensive double gang box from Lowes, cut out some acrylic sheet with a dremel tool for a cover, and fitted it to the top of the double gang box. The CEP board is afixed to the back wall of the double gang box using some 1/4" thick double-stick tape. It really works well, solid as a rock! I installed (2) 2.1mm power jacks in the side wall of the box for plugging-in the power and the sensor cable. 

I cut out some round shapes of the Roscolux Filters, to the size of the acrylic diffuser, positioned them in back of the acrylic diffuser in the bottom of the jar, and hot glued them in just a couple of places along the inside bottom corner of the side walls of the jar, to hold the Roscolux filters in place against the surface of the acrylic diffuser. The photo diode is positioned as close to center of the acrylic diffuser as possible, and right up against the Acrylic Diffuser/Roscolux Sandwich. The Roscolux Filters are firmly held in place, and they cover the entire diameter of the acyrlic diffuser. There are three Roscolux Filters, and they can be put into the jar in any order, one on top of the other. I sealed the jar and sensor wire with several applications of "Loctite Crystal Clear" caulking, to seal everything up so the sensor can be plunged into water and the photo diode will not get wet inside the jar. I also masked off the receptor end of the sensor, then painted the side walls of the jar and cable connector, up to where the cable enters the jar. I used a piece of 4-conductor 22 gauge, solid wire, as a sensor cable (only uses two of the four wires). I temporarily attached the sensor cable to a wire clothes hanger with some black electrical tape...I'll probably improve upon this with some velcro or something. The nice metal clothes hanger is not too easy to find these days, but luckily I had one that is actually vinyl coated that I found tucked away in my stash, just perfect for this kind of application. The sensor can now be oriented at the bottom of the tank in various locations within the tank, always facing upward toward the light source. The only disadvantage is that the length of the sensor housing and cable connector orient the surface of the photo diode about 2" off the substrate, 2" closer to the light source than in optimal...unless you push the sensor/hanger into the substrate. So, being 2" closer to the light source, due to the length of the sensor housing, PAR readings are actually about 2 PAR more than were the sensor flush with the substrate. This slight discrepency should be accounted for in determining a final PAR number. 

I drilled a couple of holes in the double gang box so that they are adjacent to the POT for the screen contrast, and for the calibration POT, so you can easily make adjustments if need be without taking the acrylic top off the box. But, once calibrated to an actual commerically produced PAR meter, and once you've adjusted the screen contrast to your liking, because the CEP is in the enclosure and protected, these kinds of adjustments should not really be necessary...but you can if you need to.

In addition, I purchased a 9v battery holder ($2.50), and bolted it to the side of the double gang box using some 2mm RC Airplane bolts I happened to have in my stash of junk, using blue thread locker on the bolt threads, just to make sure the bolts don't wiggle loose inside the enclosure. In addition, I also hot glued the 9v battery holder in place on the outside of the box, under the 9v battery holder housing, just to be safe with respect to bumping the 9v battery housing. I also tacked the power lead to a recessed area on the box, just to give the power lead some added support so that it can't be jerked out of the battery holder. 

Photos:





































I still want to have the CEP officially calibrated because I made these changes, and need to make sure that it's on PAR according to Mistergreen's commercially produced PAR meter. But, I wanted to get all the changes made before sending it back to him for calibration. 

But, just to get it in the ball park, I took a sensor reading outside on a sunny day at 12:00 noon, and adjusted the CEP to an outside reading of 1950, which should be right in the middle of an average "Outside" PAR number of 1900-2000 PAR at noon on a sunny day here in the Midwest. 

I've taken PAR readings in the tanks where the sensor is positioned about 2" off the substrate. The PAR readings in the 20H tank, from the LED light strip fixtures that I made are rather dismal I'm afraid, one of them around 12-15 PAR (8 rows of SMD5050 RGBW(Warm)+W(Cool) LEDs), and the other homemade fixture (4-rows of Cool White SMD2835 LEDs) is closer to 18-20 PAR. I can add 3-4 more rows of SMD2835 Cool White LEDs to the one fixture, and I theorize that PAR will come up exponentially. The light fixture gutter housing with the 8-rows of SMD5050, RGBW+W (with Warm White and Cool White) is at capacity with respect to the number of strips in the fixture. So, I doubt it can be improved. 

Were these homemade fixtures moved to the 10 gallon tank, they would undoubtedly return better PAR readings. I will experiment with that next. Here is the link on the LED light strip fixtures I made, http://www.plantedtank.net/forums/showthread.php?t=822521. Post #80 within the homemade light fixture thread will better illustrate the two homemade light fixtures I refer to herein. I was hoping that these comparatively inexpensive light strips would deliver sufficient light for plants that require low to medium levels of light. It seems that within a 10 gallon tank both homemade fixtures might be sufficient, but in the 20H tank, the fixture that is filled to capacity with strips, the SMD5050 RGBW+W LEDs, is lacking. With regard to the other homemade light fixture that uses SMD2835 Cool White LEDs, it is possible that strips can probably be added to it, and performance would probably be sufficient for plants requiring low to medium levels of light in a 20H tank. 

The 10 gallon tank that has (1) 23 Watt and (1) 5 watt CFL retrofitted to an old Perfecto brand florescent light housing, the light housing that came with the original tank cover, returned a PAR reading that was better, around 43-65 PAR depending on where the sensor was positioned in the tank. If I used (2) 23 Watt CFLs in the light housing, instead of (1) 23 watt CFL and (1) 5 watt CFL in the housing, this PAR number would certainly increase accordingly. 

But, the CEP still needs to be officiallly calibrated, so maybe these readings in my tanks, which are based on my own outside PAR calibration only, aren't really accurate. I won't know for sure how my homemade LED strip lights are performing until the CEP can be calibrated using a commerically produced PAR meter.


----------



## mistergreen

nice. You can probably put the battery in the electrical box to make it cleaner.


----------



## Quizcat

Yep, thanks! I thought about that too, but figured that by having the 9v battery holder on the outside, I wouldn't have to take the acrylic lid off the box to change the battery, plus I was running out of room on the inside. Plus, with there being no on/off switch, I figured that taking the lid off everytime to turn it on/off would be a pain. Installing an on/off switch might be a nice addition to this prototype though. 

I also thought about just using a 9v power supply, then a battery wouldn't even be necessary. But, I wasn't sure what kind of specs would be tolerated by the CEP with respect to a 9v power supply (ie:current rating?). But, I kind of like the portability of the battery anyway.

I'll get with you in the next few weeks to have you calibrate this beast once again. Will you need me to send you my sensor with it, or will you be able to use yours to calibrate it? Can we be pretty confident that different sensors used on the CEP will calibrate the same? If not, then I'll be sure to send you mine with the CEP.

Question, just curious about your opinion...do you think I'm close to calibrated based on the outside calibration I did by reading the noon day sun? How far off percentage wise do you suspect it is by calibrating it to the noon day sun? That might be an interesting experiment to see how far off I am when you calibrate it to your PAR meter.

Thanks for all the help!



mistergreen said:


> nice. You can probably put the battery in the electrical box to make it cleaner.


----------



## mattinmd

You could always measure the current draw, but given that you are able to run off a 9v battery your current draw is likely very low, at least compared to what even the smallest power bricks can handle.. 

You're probably under 20ma, and even the smallest power bricks can deal with 100ma.

Also, assuming you're using the correct power input to the arduino (the power jack, instead of feeding 5v pin directly), you should be able to get away with a pretty wide range of voltages too... There's a regulator on the arduino to bring it all down to 5v, although the higher the input, the hotter the regulator will run. Regardless you're probably safe from 7v to 12v.

If you were feeding the 5v pin directly, you'd probably have blown your board with the 9v battery already.


----------



## Quizcat

Well, I'm not sure how this compares to the Arduino. This is the version that's the stand-alone PCB/LCD designed by 02Surplus, similiar to the Arduino I suppose, but I don't have the technical expertise to know whether in the process of making this a stand alone PCB, Arduino-less, there was a circuit change that would effect the power supply aspects. But, you're right, the current draw has got to be really small compared to most bricks out there. That was my concern, that I could potentially burn it up if I exceeded the current capacity of the PCB using a power supply instead of a 9v battery, not to mention the heat factor. 



mattinmd said:


> You could always measure the current draw, but given that you are able to run off a 9v battery your current draw is likely very low, at least compared to what even the smallest power bricks can handle..
> 
> You're probably under 20ma, and even the smallest power bricks can deal with 100ma.
> 
> Also, assuming you're using the correct power input to the arduino (the power jack, instead of feeding 5v pin directly), you should be able to get away with a pretty wide range of voltages too... There's a regulator on the arduino to bring it all down to 5v, although the higher the input, the hotter the regulator will run. Regardless you're probably safe from 7v to 12v.
> 
> If you were feeding the 5v pin directly, you'd probably have blown your board with the 9v battery already.


----------



## mistergreen

The onboard regulator is there for a 9v.


----------



## mattinmd

> Well, I'm not sure how this compares to the Arduino. This is the version that's the stand-alone PCB/LCD designed by 02Surplus, similiar to the Arduino I suppose, but I don't have the technical expertise to know whether in the process of making this a stand alone PCB, Arduino-less, there was a circuit change that would effect the power supply aspect


Fair enough...

I was digging through the thread and it looked like early stuff was using an Arduino, but that's obviously changed... Regardless, is there a schematic around for the o2 surplus board? I couldn't find one. Being battery powered it almost certainly has a regulator because batteries don't have stable output voltage..



> But, you're right, the current draw has got to be really small compared to most bricks out there. That was my concern, burning it up.


As for burning up, which part were you concerned about burning up? The power brick or the CEP? 

With the low current draw the brick should be fine.

It is also safe to use a brick rated for higher current draw with your device... Power bricks are constant voltage devices. Thus, a 9v, 1 amp power brick will provide 9v, but won't force 1 amp into your device (it would have to raise the voltage to do that). The current rating on a power brick is just an upper limit before the power brick will fail in some fashion. 

Constant current power supplies exist, but are inherently variable voltage. They also tend to have issues if there's nothing connected to them as a load, thus they aren't really usable as power bricks. Can you picture how well people would react to a power brick that self destructed if you accidentally disconnected it from the device it was powering while it was still plugged in to the wall?


----------



## Quizcat

I was mostly concerned about the PCB circuitry, and how it was designed, whether introducing too much current might burn it up. 



mattinmd said:


> As for burning up, which part were you concerned about burning up? The power brick or the CEP?
> 
> Yeah, the thread is so long, and the design effort took such a long period of time, around 4 years I think, that it's hard to keep track of how things progressed. But, the Arduino design is still just as viable an option. It's just that the PCBs are a smaller footprint. For me, it was just more concise with respect to getting a working CEP. I had some of the PCBs made in Asia based on 02Surplus' PCB design, which is posted somewhere within the thread, around a third of the way through the thread I think. If you go to the very first post in the thread, it may be there too. I still have a few of the PCBs left. You would have to obtain the parts and solder them to the PCB, get the LCD and plug it in, etc...If your interested in a clean PCB send me a PM.
> 
> 
> 
> mattinmd said:
> 
> 
> 
> I was digging through the thread and it looked like early stuff was using an Arduino, but that's obviously changed...
Click to expand...


----------



## mattinmd

Quizcat said:


> I was mostly concerned about the PCB circuitry, and how it was designed, whether introducing too much current might burn it up.


Yeah, you don't have to worry about introducing too much current into the board as long as your voltage is right. 

Your US wall sockets can deliver 15-20 amps (varies with how your house is wired), but your 60w desk lamp only runs at 1/2 and amp because that's all it will allow at 120v.


----------



## O2surplus

Quizcat-

Don't worry about burning up your CEP due to over-voltage. The regulator that it uses is good for 30V/1amp. I use that regulator all the time in applications where it's fed with 24V, and I've never had a failure. The Reg has built in protection circuits that will prevent it from being damaged, so feel free to feed it with any voltage between 7 & 24V.


----------



## rottison

after reading that the shrink wrap didn't work out is due to just not enough surface space at the end for the diode to read from I was planning on putting mine in the bottom of a glass rod about the size of a pencil 12mm with the small piece of white diffuser in front of the diode. does the surface area need to be bigger as in the 1 inch small paint jars ?


----------



## mistergreen

rottison said:


> after reading that the shrink wrap didn't work out is due to just not enough surface space at the end for the diode to read from I was planning on putting mine in the bottom of a glass rod about the size of a pencil 12mm with the small piece of white diffuser in front of the diode. does the surface area need to be bigger as in the 1 inch small paint jars ?


Not sure but It definitely needs to be bigger than the photodiode.


----------



## rottison

the glass tube is about half as big again as the photodiode. So there is not a lot of extra room. has anyone put a handle on this? I can't reach the bottom of my tank with out standing on a foot stool


----------



## mistergreen

You'd have to provode pictures. Not sure what you mean.
I have an algae scrapper with a long handle and prongs. I use that to get anything to the bottom of my 75G if I don't feel like getting my arm wet.


----------



## rottison

I can get pics tomorrow but just think of the glass tube being the same size as your pointer finger with the photodiode siting on top.


----------



## mistergreen

rottison said:


> I can get pics tomorrow but just think of the glass tube being the same size as your pointer finger with the photodiode siting on top.


And it's long? I'd worry it would break.


----------



## Quizcat

Great idea engineering that kind of voltage latitude into the design. It's nice to know we can use a power supply (ie: brick) to power the CEP if we want to, and not be particularly concerned about burning it up. 

Just curious, do you have any estimate of how long the CEP will last on 9v battery power? 



O2surplus said:


> Quizcat-
> 
> Don't worry about burning up your CEP due to over-voltage. The regulator that it uses is good for 30V/1amp. I use that regulator all the time in applications where it's fed with 24V, and I've never had a failure. The Reg has built in protection circuits that will prevent it from being damaged, so feel free to feed it with any voltage between 7 & 24V.


I had an idea for a wand...but haven't built it yet. I was thinking of using a 1/2" piece of PVC pipe, in whatever length is convenient for the tank in question, then installing some bends using 45 or 90 degree PVC fittings on the end, then feeding the cable through the pipe so that the sensor is pointed up. Conceptually, I was thinking that there may even be a way of permenently connecting the jar, via the cable connector, to a PVC fitting opening at the end of the wand, to give it more rigidity and permanence, but I haven't checked at the hardward store to see what kind of fittings might be available for that part of it. That cable bushing is about 1/2" diameter after all, and it might be adaptable to fit right into a PVC fitting opening at the end of the wand, oriented the sensor at a right angle to the light source...possibly using an adhesive or caulk of some kind to permanently join the cable bushing to the end of the PVC. That would make the entire thing water proof too, versus the metal coat hanger idea. My only reservation is the height off of the substrate that a PVC wand might require, could be several inches, which would require you to allow for several inches of descrepency in relation to not being at the substrate when reading the PAR meter. 



rottison said:


> I can get pics tomorrow but just think of the glass tube being the same size as your pointer finger with the photodiode siting on top.


----------



## mistergreen

A 9V battery will last you years. You won't be using the meter all that much. At first, you'll be measuring everything but then it'll go in the drawer


----------



## Quizcat

That's what I figured too...You wouldn't probably need to use it very often, maybe once every four to six months to make sure everything is still on PAR, and if not, time to buy new bulb(s). 

Where I can see using it more frequently at first is in designing a fixture for a tank. I've been working on several fixtures over the last several months, some good, some not so good. Without a PAR meter it has all been guess work. You know, little algae blooms here or there, some plants not responding like you had hoped, etc... I'll still have to guess at it when building another fixture, but the PAR meter will sure help in determining if I'm on the right track. 




mistergreen said:


> A 9V battery will last you years. You won't be using the meter all that much. At first, you'll be measuring everything but then it'll go in the drawer


----------



## Quizcat

For those of you intending to build one of the CEPs...There are a couple of important things I learned when building the sensor that you might find helpful. 

I had done what I thought was a really nice job of encapsulating the entire bottom part of the photo diode, from the side rim of the photo diode, all the way down to where the cable begins, making absolutely certain not to get any caulk on the face of the photo diode, so as to not obscure in any way the area where the light is collected through the photo diode surface. 

I thought this would seal everything up really well, but the caulk must have acted as a conductor, causing the leads to short, and readings to be way off on the meter. So, I pulled the caulk loose, and cleaned everything up (once the caulk was dry). Readings came back to normal, and the meter starting working perfectly again. Maybe it's the brand of caulk I used...who knows? I used a caulk made by Locktite that comes out white and dries clear. Perhaps another brand, such as GE Silicone, would not have caused this problem...not sure. If you do caulk the leads, make sure you allow several days for it to dry. Perhaps that would have avoided the issue of the leads shorting. But, after waiting at least two days for the caulk to dry, I still experienced the issue with the short, and the meter returning bogus readings. I also tried caulking where the jar lid meets the jar, on the inside. But, drying time was so lengthy, that I abandoned that idea, and cleaned all the caulk up that was on the inside rim of the jar rim and lid. 

I finally decided just to caulk the outside surfaces of the jar rim where it meets the lid, also caulking around where the cable meets the cable connector. I also completely caulked the cable connector where it meets the outside top portion of the jar lid where the cable enters the jar. Actually, I made two applications of caulk, allowing the first application to completely dry before moving on to the second application. It seems to have sealed very well. 

So, caulking the leads of the photo diode doesn't really seem to be necessary. But, if you do it, I would recommend caulking each lead separately, and trying not to get any between the leads, allowing it to dry a long time, thereby avoiding potential for a short between the two leads of the photo diode, assuming mine wasn't sufficiently dry after two days. When I soldered the leads, I also used heat shrink on each lead, which I thought would sufficiently insulate the leads from a short by the caulk. But, I suppose that enough caulk migrated from one pin entry point into the diode to the other pin entry point, and created a short. 

Also, if you want to layer the Rosco Filters the full diameter of the acrylic diffuser, like I did, this may be of interest. I requested some sample sheets from Rosco Filter Company, requesting a sample of each of the specific types that are outlined earlier in the thread. I requested them in the size 6" x 10", so I would have plenty to work with, since I have several PCBs, and figured I might want to build more at a later date. I never received an answer from them after making my request with their customer service department via email. But, low and behold, a sample of each showed up in the mail today, in the size I requested, 6" x 10", and free of charge. 

Also, just so you are aware, the face of the photo diode is pushed all the way flush with the Acrylic Diffuser/Rosco Filter Sandwich on the inside of the jar. I then painted the jar because I figured that mine looked better that way, and I figured it would also limit light entering the jar from the sides/lid of the jar, thereby directing light only through the surface of the diffuser. I doubt that it's functionally necessary to paint the side walls/outside lid of the jar, but it can't hurt.


----------



## Quizcat

Mistergreen,

Can you advise where you obtained the jars/lids? I recall from reading early in the thread that you had some difficulty at first finding a jar that did not have an obstructed bottom area where there was an embossed area, printed matter, or an uneven surface area, which would distort the light coming through the bottom of the jar, and that it needed to be perfectly flat to achieve the best results.

Also, can you advise your source, and/or the specifications for, the acrylic diffuser material. Some have PM'd me requesting this information so they can build a sensor to the proper specification. I didn't want to advise them to obtain just any acrylic from Lowes or Home Depot, not knowing if there is a particular scientific standard or charactertistic to the acrylic you used.


----------



## mistergreen

I found the paint container at Hobby Lobby I think. It might be easier to buy off their online store because you never know what they have in stock at the stores. I'm sure you guys can find another way to build the housing though.

As for the diffuser, it's 1/8" thick 2447 white acrylic. I've only found them online. I've posted the links on the first post.


----------



## Quizcat

Do you think that a white opaque acrylic sheet from someplace like Lowes or Home Depot would suffice, something they sell as a flat sheet shade material for flourescent light fixtures for example. Those are probably about 1/16" thick. 

Would you consider that to be the wrong type of material, and/or too thin?



mistergreen said:


> I found the paint container at Hobby Lobby I think. It might be easier to buy off their online store because you never know what they have in stock at the stores. I'm sure you guys can find another way to build the housing though.
> 
> As for the diffuser, it's 1/8" thick 2447 white acrylic. I've only found them online. I've posted the links on the first post.


----------



## mistergreen

You will have to ask Lowes & home depot what the specs on those acrylic sheets. They vary.

The code on the CEP is specifically for 1/8" 2447. You're welcome to change the code but you'll need a PAR sensor, or a calibrate CEP to calibrate.


----------



## Quizcat

No, I wouldn't change a thing. I was just curious for those that might find it cheaper to obtain the sheets from a local source, rather than pay the shipping costs, which are often as expensive as the product itself. Besides, it sounds like changing the code would be more of a hassle than it's worth.



mistergreen said:


> You will have to ask Lowes & home depot what the specs on those acrylic sheets. They vary.
> 
> The code on the CEP is specifically for 1/8" 2447. You're welcome to change the code but you'll need a PAR sensor, or a calibrate CEP to calibrate.


----------



## mistergreen

I found this interesting, a micro spectrometer component.

http://www.hamamatsu.com/us/en/product/category/5001/4016/C12666MA/index.html#1328467071301
sensitivity from 380nm - 780nm

You'd have to inquire what the cost is. You can plug it into an arduino, which is cool.


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## mattinmd

mistergreen said:


> I found this interesting, a micro spectrometer component.
> 
> http://www.hamamatsu.com/us/en/product/category/5001/4016/C12666MA/index.html#1328467071301
> sensitivity from 380nm - 780nm
> 
> You'd have to inquire what the cost is. You can plug it into an arduino, which is cool.


You can get it as an arduino board.. they claim the sensor alone is $250...

https://www.tindie.com/products/PureEngineering/arduino-c12666ma-micro-spectrometer-/


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## mistergreen

mattinmd said:


> You can get it as an arduino board.. they claim the sensor alone is $250...
> 
> https://www.tindie.com/products/PureEngineering/arduino-c12666ma-micro-spectrometer-/


Yeah, I saw their all in one device
https://youtu.be/vzMV6IBzmjs

ouch $250.


----------



## mattinmd

To be honest, if you really want to do a spectrophotometer, you're better off with a diffraction grating and a cheap digital camera, webcam, or old smartphone...


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## Quizcat

You would use the mini spectrometer from Hamamatsu to measure the actual color range claimed for a particular LED, or other kind of light emitter, for example? 

Uhm, many different uses with respect to the Tindi Spectrometer... 

Sample Applications
Fruit ripening detector
Sunscreen pre-warning detection (Solar UV radiation levels)
Astronomical spectroscopy
Plant/Leaf Health levels
Color Calibration and matching
CFL and LED performance measurements
Basic Spectroscopy (molecule fingerprinting)
Mineral and Chemical Detection and classification
Diamond/Gemstones verification
Fluorescence spectroscopy (organic compound analysis) biochemical research.
Oil spill verification 

Seems like you'd have to be using it professionally to justify the cost. But, other devices in this category are supposedly over $1,000.00. Interesting...



mistergreen said:


> I found this interesting, a micro spectrometer component.
> 
> http://www.hamamatsu.com/us/en/product/category/5001/4016/C12666MA/index.html#1328467071301
> sensitivity from 380nm - 780nm
> 
> You'd have to inquire what the cost is. You can plug it into an arduino, which is cool.


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## mattinmd

I think that checking the light intensity as a function of frequency was the intent...

That said, if all you're looking to do is make relative comparisons of spectral intensity, the diffraction grating suggestion I made earlier is all you need to do things like this: (Finnex Planted+ 660nm LED vs 7000k white LED)



In theory you could post-process an image like that into an intensity graph.

That said, with a spectrum-aware probe, you could use some software and actually create a PUR meter instead of a PAR meter... a bit tricky calibration wise, but doable...


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## Quizcat

*New Thread relating the CEP...*

In case anyone is interested in following an important thread that relates to the CEP. Hoppy is testing CFLs with a commercially produced PAR meter to establish whether CFLs are consistent enough within the same model to rely on them as a bench mark in order to be able to calibrate your CEP to a particular model CFL. 

http://www.plantedtank.net/forums/sh...d.php?t=875977

Once several different bulbs are tested, and the data is gathered and recorded, CFLs may be able to be used to calibrate your CEP yourself, without having to obtain a commercially produced PAR meter to calibrate to, or having to send your CEP to someone with a commercially produced PAR meter for calibration.


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## Quizcat

They have a 2nd iteration of the Hamamatsu Product, Model #C12666MA, which costs $234...They also offer an evaluation kit. If you're interested, send me a PM, and I'll give you their contact information. They're in Bridgewater, New Jersey. 



mistergreen said:


> I found this interesting, a micro spectrometer component.
> 
> http://www.hamamatsu.com/us/en/product/category/5001/4016/C12666MA/index.html#1328467071301
> sensitivity from 380nm - 780nm
> 
> You'd have to inquire what the cost is. You can plug it into an arduino, which is cool.


----------



## mistergreen

Quizcat said:


> They have a 2nd iteration of the Hamamatsu Product, Model #C12666MA, which costs $234...They also offer an evaluation kit. If you're interested, send me a PM, and I'll give you their contact information. They're in Bridgewater, New Jersey.


I've talked to them before. Their prices are not so friendly for hobbyists. They want corp accounts


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## jeffkrol

mistergreen said:


> I've talked to them before. Their prices are not so friendly for hobbyists. They want corp accounts


FYI................
https://hackaday.io/project/4141-c12666ma-micro-spectrometer


> Why did you make it?
> 
> There is currently no other simple breakout board for the Hamamatsu C12666MA spectrometer. Additionally the sensor itself is difficult to buy. We will provide both.





> *Supply?*A limited run of the breakout boards have been completed and are in stock, they are working well. Still waiting for a larger supply of sensors to arrive. Note that most of the costs of this product is for the C12666MA sensor itself @ $250. If you are interested in the sensor itself join this GroupGet Buy for a better price.
> Breakout boards will be sold on Tindie with the sensor.
> Breakout boards without a sensor are currently sold here


http://www.pureengineering.com/store









https://www.tindie.com/products/PureEngineering/arduino-c12666ma-micro-spectrometer-/

Breakout board and sensor.. $298.......


----------



## Quizcat

Yeah, I got that same impression myself...



mistergreen said:


> I've talked to them before. Their prices are not so friendly for hobbyists. They want corp accounts


----------



## Quizcat

I wanted to bring this discussion back to the CEP thread, so as not to hijack Hoppy's CFL testing endeavors. 

I took some readings off of the PAR meter that Mistergreen calibrated to his commerically manufactured PAR meter, and the CEP is calibrated according to the readings on the POT as follows:

By the way, the 15K resistor on the calibrated CEP reads exactly the same as my other uncalibrated CEPs, 11.94K, not 15K.

CEP #1 (Calibrated by Mistergreen):

POT 1st Pin = 11.94K
POT 2nd Pin = 15.56K
POT 3rd Pin = 15.56K

Actual Calibration = 27.5K

I took readings as Mistergreen recommended, one probe on the top pad of the 15K resistor, and the other probe taking individual readings from Pin #1, #2, and #3 of the 10K POT. Just to make sure I took accurate readings, I took them numerous times, and the readings repeated each time. 

I adjusted the other two CEPs that haven't been calibrated as follows, mimmicking as closely as possible the readings I took off of the CEP that Mistergreen calibrated using his PAR meter. However, the POTs are very touchy, so I got as close to the POT readings from the calibrated CEP as possible. 

CEP #2: 
POT 1st Pin = 11.94K
POT 2nd Pin = 15.52K
POT 3rd Pin = 15.52K
Calibration = 27.46K (Adding together the values from the 1st and 3rd Pins of the POT).

CEP #3:
POT 1st Pin = 11.94K
POT 2nd Pin = 15.56K
POT 3rd Pin = 15.56K

Calibration = 27.5K (Adding together the values from the 1st and third pins of the POT)

The center pins on all the CEPs always read the same as the 3rd pin of each of the POTs, even on the one calibrated by Mistergreen. I was very careful not to touch the POT on the calibrated CEP, other than to take readings off the pins, in order to make sure to preserve the calibration done by Mistergreen via his commercially manufactured PAR meter.

Now, with regard to the discrepency between mathematical calibration of 22.53K, versus the 27.5K reading taken off the calibrated CEP, I suspect that it may be because the 15K resistor isn't really 15K. But, even at that, the resistor is only off by 3.06K, not 4.97K, which is the actual discrepency between what should be the mathematical calibration (22.53K) versus the actual calibration (27.5K) based on Mistergreen's PAR meter calibration. So, I'm not really sure how to interpret these findings as to why there is this discrepancy between the mathematically calculated calibration number of 22.53K versus the actual number calibrated by Mistergreen of 27.5K. 

My next step will be to compare how the other two CEP meters perform based on setting them according to the calibrated CEP, by taking actual light readings from each of the CEPs to see what numbers they return, to see if they all correlate. 

I want to use the same sensor from CEP #1 that Mistergreen had in his possession when he calibrated CEP #1 if possible, rather than build a new sensor to test CEP #2 and #3. But, the sensor from CEP #1 has a 2.5mm plug on it, and rather than mess with that, I plan to use a 2.5mm jack to plug that sensor into, which can then be connected to CEP #2 and #3 with a wire extension off the jack. 

The problem is, my local Radio Shack, as well as all the Radio Shacks in St. Louis, have closed down, effective last week, and there is only one remaining in the area, and it's about 50 miles away. Our Industrial Electronics Distributors in the area are also 50 miles away. So, until the 2.5mm jacks that I have on order with China arrive, there may be some delay in making the comparison between CEP #1 (calibrated via PAR meter) and CEP #2 and #3 (mimmicked calibration).


----------



## Quizcat

That does seem like the better way to go for what appears to be a very reasonable up charge. Frankly, I had to be persuasive in order to get them to answer me with respect to specifics, like price. 



jeffkrol said:


> Breakout board and sensor.. $298.......


----------



## jeffkrol

Quizcat said:


> That does seem like the better way to go for what appears to be a very reasonable up charge. Frankly, I had to be persuasive in order to get them to answer me with respect to specifics, like price.


Unit price $180.......... 
https://groupgets.com/campaigns/61-hamamatsu-c12666ma-mems-u-spectrometer-round-2

sensor response is somewhat sketchy...
https://d3s5r33r268y59.cloudfront.net/datasheets/4240/2015-01-28-07-00-32/c12666ma_kacc1216e.pdf

They have others:
Maybe get a closeout... 
http://www.hamamatsu.com/resources/pdf/ssd/c11007ma_etc_kacc1157e.pdf
I've checked spec's on 'ham"'s analog sensors.. were not impressive on the blue end response...


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## mistergreen

Hey quizcat, can you measure the pot pin 1&2. That should give the resistance of the pot setting.

http://www.instructables.com/id/How...a-Potentiometer/step7/Varying-the-resistance/


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## Quizcat

In order to reach that position, because it's in the enclosure and those pins are face down, and the POT is all the way against the surface of the PCB, I'm working kind of blind, and having some difficulty reaching with a probe underneath the board and being sure that the probes are in the right position. I can take more time to attempt to confirm it later today if this number doesn't make sense. 

It looks like .896K, or could be 8.96K. I didn't stop to verify if the meter was on the proper decimal setting. This is on the CEP that you calibrated to the PAR meter. 

Let me know if you want me to make a more definitive attempt at it, and I'll be happy to get it to you later this evening.



mistergreen said:


> Hey quizcat, can you measure the pot pin 1&2. That should give the resistance of the pot setting.
> 
> http://www.instructables.com/id/How...a-Potentiometer/step7/Varying-the-resistance/


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## mistergreen

oh, you can't take the CEP out the case easily?


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## Quizcat

No, the PCB is stuck to the base of the cabinet with double stick tape and I can't remove the PCB to access the bottom of it. It's stuck like concrete. But, I can try to take another reading tonight and get back to you.



mistergreen said:


> oh, you can't take the CEP out the case easily?


----------



## Quizcat

Now, on the other two CEPs, I have total access. I can play with pins 1 and 2 on those, and see what I can achieve with respect to 22.53K. But, I'll try to access the pins on the one you calibrated, but it might take me a while to feel confident that the numbers I give you are valid, since I have to snake around under there with a wire probe attached to the Ohm Meter probes in order to gain access to the pins. But, I'll do it...you have me curious!



mistergreen said:


> oh, you can't take the CEP out the case easily?


----------



## Quizcat

I assume that the pins are numbered as follows:
1 = left, 2= center, and 3= right, per the PCB photo below. 

The reason I ask is there are actually two 3s indicated on the PCB. I just wanted to point that out, not knowing if perhaps there is something specific to these kinds of POTs that differentiate them from the standard larger POTs with stem adjustment. 









I'll try to measure pins 1 and 2 as soon as I can. I'm opening the pool tonight, and it might go late. 





mistergreen said:


> Hey quizcat, can you measure the pot pin 1&2. That should give the resistance of the pot setting.
> 
> http://www.instructables.com/id/How...a-Potentiometer/step7/Varying-the-resistance/


----------



## Quizcat

OK, Mistergreen, I was able to take a reading of 3.62K ohms between Pin #1 and #2 below. I checked it numerous times, and I am absolutely confident that I was on the right pads. The polarity of the probes from the ohm meter was as depicted in the image below. And, by the way, the reading between Pin #1 and Pin #3 was the same, 3.62K ohms. 









I was able to push the POT back ever so slightly on the board to gain access to the pins that were directly underneath the POT from the front, rather than having to search blindly for the solder blobs underneath the PCB. I took the readings you requested between pins 1 & 2, verified them several times, and also checked to make sure there was not a change in the readings I had previously taken between the resistor and the POT, after having pushed the POT back slightly. I made some thin solid wire extensions, attached them to the probes so that I could reach into the cabinet to take the readings. 

The readings on the meter changed very slightly compared to what I reported before, but not enough to matter, only about .001 Ohms, and they fluctuated in that manner before as well. So, I don't think that pushing lightly on the POT to gain access to the pins, or attaching the wire extensions to the probes, made any difference in the calibration setting of the POT, as the readings on the POT fluctuated the same amount (.001K) before I pushed on the POT to gain access, and attached the wire extensions to the probes. 

So, to reinterate, between the back pad on the resistor, and the following pins, the readings are as follows:

Pin #1: 11.95K
Pin #2: 15.58K
Pin #3 15.58K




mistergreen said:


> Hey quizcat, can you measure the pot pin 1&2. That should give the resistance of the pot setting.
> 
> http://www.instructables.com/id/How...a-Potentiometer/step7/Varying-the-resistance/


----------



## mistergreen

very odd. We can't use final resistance for calibration then. I guess it varies from batch to batch; a PAR meter or calibrated CEP is the only way.


----------



## Quizcat

Too bad...Well, maybe by measuring the resistance of the one that was calibrated to the PAR meter, and plugging in those same numbers into the POTs of the uncalibrated ones, or as closely as possible, we'll find that the other ones will calibrate pretty closely based on those same settings of the resistance showing on the PAR meter calibrated CEP. 

I'll experiment, and compare the readings I get from light sources using the one calibrated via the PAR meter, against what PAR readings I get off the ones that were calibrated using the same resistance settings as the one calibrated to the PAR meter, and see what I get. 

But, if not, then I at least I have the one calibrated via the PAR meter, and can set the other two to the PAR levels returned off the one calibrated to the PAR meter. 



mistergreen said:


> very odd. We can't use final resistance for calibration then. I guess it varies from batch to batch; a PAR meter or calibrated CEP is the only way.


----------



## O2surplus

I've got an idea that should make calibrating the new meters against the known calibrated unit really easy. You can use the voltage signal on A0 and the PAR number output to the Lcd to calibrate the units. It's a simple matter of turning the sensor circuit into a voltage divider by using a resistor instead of the photo diode.

1.) Start by disconnecting the photo diode from the known good calibrated unit.

2.) Install a 10K resistor across the photo diode connection points at the CEP PcB.

3.) Power up the CEP and take note of the PAR number displayed on the Lcd. This PAR number will be your reference.
4.) Reinstall the photo diode and set this CEP meter aside.

5.) Grab one of the new units and install the same resistor across the photo diode connections.

6.) Power up the unit and adjust the pot until the Par reading is the same as the original calibrated unit.

7.) Perform the same steps above on any remaining uncalibrated units.

Following these steps should set up all your CEP's to be identically calibrated. The only variable left will be slight electrical variations between the photo diodes.:hihi:


----------



## mistergreen

heh, crazy enough to work!

ok, I just did the 10K trick. I'm reading 4357 for indoor. See if you get that quizcat.


----------



## O2surplus

mistergreen said:


> heh, crazy enough to work!



LOL- I knew there had to be a dirt simple solution......Just had to stare at the circuit for awhile to see it.:hihi:


----------



## rottison

so if quizcat gets that can I plug that into mine and call it calibrated


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## mistergreen

rottison said:


> so if quizcat gets that can I plug that into mine and call it calibrated


theoretically, yes.


----------



## Quizcat

I'll try this as soon as I can. Because I live in a rural area, it may take a few days to come up with a 10K resistor. They just closed our Radio Shack for good. I'll check my stash to see if I have one, but if not, then I'll have to order one from Mouser. So, it may be a few days before I can get back to you guys. But, if it works, it's a wonderful stroke of genious!

Now, one question, regarding my calibrated CEP, the PCB is permanently stuck to the back wall of a plastic cabinet via double stick tape, and can not be removed, it's like concrete. The photo diode is connected to the PCB via a power jack/plug via wire extensions between the jack and the input for the sensor at the PCB. See the white wire on the left? The sensor connects to the PCB through the jack. Power, is the Red/Black wire on the right, connected to power on the PCB through a power plug/jack. 

Can I just unplug the sensor, unplug power, and put the 10K resistor across the center pin and ground at the sensor's jack terminals, and be good to go, or will having the jack in the mix throw things off with respect to the jack and wire extenstions to the PCB adding resistance? And, if accessing the sensor terminals through the jack is a problem, technically speaking, then it just makes it a little more difficult to access the sensor terminals inside the cabinet to make the connections, due to the confined space inside the cabinet, and because the CEP can't be removed. It can be done, no problem, but it would make it easier and quicker to connect at the jack if it won't throw everything off.









What are the anticipated electrical varitions (ie:tolerances) between the photo diodes with respect to photo diode specs? Anybody know the percentages? 



O2surplus said:


> I've got an idea that should make calibrating the new meters against the known calibrated unit really easy. You can use the voltage signal on A0 and the PAR number output to the Lcd to calibrate the units. It's a simple matter of turning the sensor circuit into a voltage divider by using a resistor instead of the photo diode.
> 
> 1.) Start by disconnecting the photo diode from the known good calibrated unit.
> 
> 2.) Install a 10K resistor across the photo diode connection points at the CEP PcB.
> 
> 3.) Power up the CEP and take note of the PAR number displayed on the Lcd. This PAR number will be your reference.
> 4.) Reinstall the photo diode and set this CEP meter aside.
> 
> 5.) Grab one of the new units and install the same resistor across the photo diode connections.
> 
> 6.) Power up the unit and adjust the pot until the Par reading is the same as the original calibrated unit.
> 
> 7.) Perform the same steps above on any remaining uncalibrated units.
> 
> Following these steps should set up all your CEP's to be identically calibrated. The only variable left will be slight electrical variations between the photo diodes.:hihi:


----------



## Quizcat

*Here are the results...*

I was very fortunate, in that I had an Electronics Rainbow kit for my grandson that I was able to find a 10K ohm resistor. 

So, I wrapped black electrical tape around the leads of the resistor so that my holding it did not change the resistance. 

First, I tested the CEP that had been calibrated to Mistergreen's commercially produced PAR meter, we will call it CEP #1, and got the following result on the LDC screen of the CEP:

Indoor = 3813
Outdoor = 3458
(Note Mistergreen's reading was 4357, an almost identical reversal of the 1st two numbers above on my Outdoor reading)

I tested several ways, from the soldered pins of the jack, and also from the two terminals of the green block where the Sensor wires connect, holding the resistor with my fingers, making sure to only hold the resistor through the black electrical tape I applied to the resistor. I also took readings holding the resistor with a set of tweezers grasping the black tape area. But, I don't have a set of plastic tweezers, which would have been preferable to perform this test. So, I hope that the black electrical tape did the job to isolate the resistor from any effects from my touching it. The readings were taken multiple times, and the results were always consistent. 

I also tested the two CEPs that have only been calibrated by me using the resistance method, and not through a light emitter via a commercially produced PAR meter. These CEPs were calibrated by putting a probe on the top pad of the 15K ohm resistor, and touching the other probe to pin #1 and #2 on the 10K POT. You may recal that CEP #2 calibrated 
to 27.46 ohms, and CEP #3 calibrated to 27.5K ohms using this method, and were calibrated to closely match the results using this method from CEP #1, which had been calibrated using a PAR meter by Mistergreen. 

When using the 10K ohm resistor touched to the input of the sensor terminals, the CEPs returned the following values on the LCD screen:

CEP #2 previously calibrated to 27.46K using the resistance method between the 15K resistor and terminals 1 & 2 at the POT:
LCD Reading =
Indoor = 3813 using 10K resistor at the input terminals of the sensor
Outdoor = 3458 using 10K resistor at the input terminals of the sensor

CEP #3 calibrated to 27.5K using the resistance method between the 15K resistor and terminals 1 & 2 at the POT:
LCD Reading =
Indoor = 3819 using 10K resistor at the input terminals of the sensor
Outdoor = 3463 using 10K resistor at the input terminals of the sensor

CEO #2 and CEP #3 are consistent with the results returned from CEP #1, the one calibrated to Mistergreen's PAR meter, but slightly off from one another because the POT is pretty touchy, and it's hard to get that fine of an exact adjustment using a screw driver. 

I did not change the POT adjustments of CEP 2 & 3 because they appeared to mimmick the adjustment I made via the top resistor pad and the POT terminals previously made, versus the 10K resistor method, so I left them alone, right where they were. 

I don't know why the values I obtained versus the values obtained by Mistergreen on his CEP using the 10K resistor at the sensor terminals are so far off from one another. 

Could it have anything to do with my 15K resistor value being measured at 11.94K versus 15K? If so, then perhaps a reading of the 15K resistor would be in order before calibrating using the 10K resistor method, and some kind of conversion factor could be applied to acheive actual calibration based on the actual 15K resistor value of any random CEP.


----------



## Quizcat

I think that O2Surplus envisioned that any calibrated CEP, once calibrated to a PAR meter, and the values known, will calibrate exactly the same way each time via the 10K resistor method, the 10K resistor eliminating the variability of the sensor itself. Then, because of the standardization of the sensor input to 10K, only one calibrated CEP would be necessary for anyone to calibrate their individual CEP using the 10K resistor method. 

But, having taken some readings from my own CEP, the theory does not seem to correlate to readings Mistergreen obtained from his calibrated CEP. 

I confirmed the value of my 10K ohm resistor that was put across the sensor terminals, and it is 9.97K ohms. Close enough, tolerance of about 3%, but it occurs to me that there may be variabilites in all the components within the circuits of individual CEPs to make universal calibration through a mathematical formula almost impossible as these variabilities add up...unless there is some kind of conversion factor that can be used to acount for the actual values of components used in individual CEPs. Take my 15K ohm resistor for example. Mine reads 11.94K, and not 15K.


----------



## mistergreen

hmm, interesting. The only thing I can think of is the variance on the voltage regulator and resistors in that chain to the atmega that would give us different results. So it would vary from batch to batch.

The regulator is outputting to 4.99V (middle & right pin)and the resistor by the atmega is 10.05K. 

Yeah, there might be too many variance to get an exact number. I guess the only way to calibrate is to use another calibrated CEP with light sensor or a PAR sensor.


----------



## rottison

mistergreen does it matter what filter or disk goes to the bottom of the jar fist or in what order


----------



## mistergreen

The order of the light filters doesn't matter but I would put the diffuser on top.


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## rottison

so in the morning I will make it more permanent but I have 3 colored ronco disk cut to fit the jar and just dropped in then I will glue the photo optic to the diffuser and drop that in and dab a bit of silicon on the edges to hold it in place few hours drying time I should be almost done.


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## Quizcat

I believe that the diffuser goes into the bottom of the jar first, then you put the filters between the acrylic diffuser and the photo diode, so that light passes first through the diffuser, then through the filters, where it hits the screen of the photo diode. Correct me if I'm wrong Mistergreen. 



rottison said:


> so in the morning I will make it more permanent but I have 3 colored ronco disk cut to fit the jar and just dropped in then I will glue the photo optic to the diffuser and drop that in and dab a bit of silicon on the edges to hold it in place few hours drying time I should be almost done.


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## rottison

that is how I thought it went also just wanted to make sure before it was glued down


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## rottison

mistergreen now that I have my par meter built I need to calibrate it my local club has a apogee meter I can use. Do you do any thing special to calibrate? And how do you calibrate the par meter normaly?


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## rubenhak

mistergreen said:


> *Edit *5-10-13*
> NOTICE - Firmware has been updated for outdoor lighting.
> 
> Final product list:
> 
> Photodiode: VTB8441BH
> price: $4.660
> Excelitas Technologies Sensors - VTB8441BH - SILICON PHOTODIODES - Allied Electronics
> 
> Cosine diffuser: 1/8" thickness, 2447 white plexiglass
> price: varies, get the sample or buy a big sheet of it.
> Plexiglass White & Black acrylic sheets
> Acrylic 1/8" Tinted & Colored Sheeting | U.S. Plastic Corp.
> 
> Basic 16x2 Character LCD - Black on Green 5V
> price: $14 but you can get it cheaper on e b a y
> http://www.sparkfun.com/products/255
> 
> Arduino Uno
> price: $30
> http://www.sparkfun.com/products/10356
> http://www.sparkfun.com/products/11021 (newer model)
> 
> 
> Diagram


Dear Mr. Green,
I see you've been through a long journey of building a PAR sensor. May I ask if you have complete instructions on hand? If yes I'd really appreciate if you could share them.

If not, could you give me few pointers. I have few questions here. What is the purpose of Cosine diffuser and how do you use it? Is the Photodiode VTB8441BH submersible? I was thinking to put the sensor into the aquarium for constant monitoring. Will this work with Miniature Solar Cell - BPW34? I'd prefer to use the latter one since it is much smaller.

Also, what is the algorithm to calculate the PAR value from the sensor reading?

Thanks a lot,
Ruben


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## mistergreen

rubenhak said:


> Dear Mr. Green,
> I see you've been through a long journey of building a PAR sensor. May I ask if you have complete instructions on hand? If yes I'd really appreciate if you could share them.
> 
> If not, could you give me few pointers. I have few questions here. What is the purpose of Cosine diffuser and how do you use it? Is the Photodiode VTB8441BH submersible? I was thinking to put the sensor into the aquarium for constant monitoring. Will this work with Miniature Solar Cell - BPW34? I'd prefer to use the latter one since it is much smaller.
> 
> Also, what is the algorithm to calculate the PAR value from the sensor reading?
> 
> Thanks a lot,
> Ruben


Hi, It's best to build a water proof housing of the vtb8441bh.
I've also added spectral light filters to the diode to further help with PAR calculations. You can find it here

AquaticTechTank.net ? View topic - DIY PAR meter


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## Killavolt

This has been a long thread, hopefully it can still garner some activity.

What would need to be done to make this code work with an Arduino Mega 2560 and a ITDB02 or Nextion TFT screen?

I'm wanting to building my own LED lighting controller and I think having a PAR meter built in would be a great feature. This way it could display the PAR value during the different light cycles like sunrise/sunset etc.


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## mistergreen

It should work. You would need a different library for your display.


Sent from my iPad using Tapatalk HD


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## diverjoe

This is common for small manufacturing companies. Assumed that you would order larger quantities and would want 30 days like most other purchaser. The $50 min pays for that and setting you up an account on their system etc, etc, etc


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## paronaram

I have some parts for this project if you like ...
Including PCB


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## mistergreen

paronaram said:


> I have some parts for this project if you like ...
> Including PCB


I found another use for the pcb by adding on a apogee par sensor.
http://www.plantedtank.net/forums/showthread.php?t=1122714

Paronaram can sell anybody who wants one.


Sent from my iPad using Tapatalk HD


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## Brian Rodgers

Fantastic project, glad you are sharing.


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## svoicum

Hello all!

Sorry to revive this old thread, but I want to build 4 PAR sensors in order to measure the light dispersion over a small tray of an aquaponic system. Is there any schematic available? I can build one here and by the end of the week, I will also have a PAR meter for calibration.
I already have the diodes from the first post (the VTB8441BH).

Thank you!


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## jeffkrol

svoicum said:


> Hello all!
> 
> Sorry to revive this old thread, but I want to build 4 PAR sensors in order to measure the light dispersion over a small tray of an aquaponic system. Is there any schematic available? I can build one here and by the end of the week, I will also have a PAR meter for calibration.
> I already have the diodes from the first post (the VTB8441BH).
> 
> Thank you!


http://www.plantedtank.net/forums/10-lighting/443073-par-meters-what-takes-make-one.html
http://www.plantedtank.net/forums/20-diy/443185-assembling-diy-par-meter.html












another in a nutshell..The Teflon diffuser is an upgrade over acrylic









https://hackaday.io/project/12125/logs

If using w/ strictly standard LED diodes adding the UV/IR cut filter would be unnecessary for the most part since there are little emissions >700 or < than 400nm.
Still need to enhance the blue response a bit.. or not..

PTFE is easy to find..
https://www.zoro.com/value-brand-ro...MIhr2i4ZHz1wIVluNkCh3K9AcDEAkYAiABEgJ3bPD_BwE


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## paronaram

svoicum said:


> Hello all!
> 
> Sorry to revive this old thread, but I want to build 4 PAR sensors in order to measure the light dispersion over a small tray of an aquaponic system. Is there any schematic available? I can build one here and by the end of the week, I will also have a PAR meter for calibration.
> I already have the diodes from the first post (the VTB8441BH).
> 
> Thank you!


Hi Svoicum
PM me I have PCB and some parts for this project if you are interested, and will let you start in no time 
Some soldering will require ...

Thanks.


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## henrybri

mistergreen said:


> Oh, I'm just looking into the Hamamatsu diode... Haven't bought it yet until I played around with the cheaper diode.
> 
> photo sensitivity is a electrical engineering term referring to photodiodes:
> http://en.wikipedia.org/wiki/Photosensitivity#Interpretation_in_electronic_engineering
> 
> And spectral sensitive is another term for photo sensitivity ( another unit of measurement like inches & centimeters ).. I assume they measure the same thing.


Photo sensitivity is a general term. Adding the "spectral" prefix means photo sensitivity for a series of light wavelengths, as those shown on mistergreen charts above


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