# Using Apogee PAR Sensor and mVMeter



## 691175002 (Apr 28, 2009)

Try testing the mV meter alone to narrow down the possible problem. If you can link its part number or datasheet it might be easier to help.


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## mistergreen (Dec 9, 2006)

I'm look at the spec and it has 3 wires.

Green: Positive (signal from sensor)
White: Input power
Clear: Ground (for sensor signal and input power)

So you need to create a circuit for the signal to be read I assume.

White go to positive of the 9V, clear to negative of 9V. Positive lead of meter to green and ground lead of meter to negative of 9V.


I have the SQ-120 I use with a volt meter.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> I'm look at the spec and it has 3 wires.
> 
> Green: Positive (signal from sensor)
> White: Input power
> ...


Yes, that's how it is hooked up, but the meter has 4 leads, red for battery +, black for battery -, green for signal +, and blue for signal -. I have the blue and black connected to the sensor ground (transparent), and the green to the sensor green.

I used my multimeter to try to measure the voltage across the green and blue wires, and got zero voltage. The 200 mV meter is: https://www.amazon.com/gp/product/B008M0CIHS/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1


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## mistergreen (Dec 9, 2006)

Can you draw out a quick diagram of how you have things hook up or a photo?

Try testing on a simple photo diode you have laying around. No need to supply the diode with power. It'll generate voltage when light strikes it.


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## Hoppy (Dec 24, 2005)

Testing the mV meter with a simple diode is a very good idea. I will do so shortly.


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## jeffkrol (Jun 5, 2013)

AFAICT the output signal of the Apogee is 0-2.5V..
your box is 0- 200mV...
you can't measure (peg the circuit ) at more than 200PAR 
1mV = 1PAR
https://www.google.com/url?sa=t&rct...xDPiDw5sg&sig2=TMobrLqbLcRn9ysx_HrV-g&cad=rja
All you need is a standard VOM w/ one probe on neg.. the other on signal..
At least that is how I see it..
OR a simple voltmeter gauge

Point of the powered sensor is the low level signal is amplified..

better...
https://www.amazon.com/bayite-wires...100729&sr=1-2&keywords=digital+voltmeter+0-30



> Wiring:
> Red wire: Power supply +
> Black wireower supply -, Measured Voltage -
> White wire: Measured Voltage +












Link for meter PDF:
https://www.google.com/url?sa=t&rct...4pYFo12Hg&sig2=DrqC-85ZCgRQkuSDQCsiMA&cad=rja

red/black power to the meter 
green/blue what you want to measure..

My guess is you would need 2 power supplies..


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## jeffkrol (Jun 5, 2013)

mistergreen said:


> Can you draw out a quick diagram of how you have things hook up or a photo?
> 
> Try testing on a simple photo diode you have laying around. No need to supply the diode with power. It'll generate voltage when light strikes it.


Still need to power the meter .. just connect the 9v to red/black..
diode goes blue/green


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## Hoppy (Dec 24, 2005)

jeffkrol said:


> Still need to power the meter .. just connect the 9v to red/black..
> diode goes blue/green


Why wouldn't a single battery work? I have the diode in parallel with the meter power leads. That should be exactly the same as two separate batteries. The "ground" is not connected to any real ground, so it is just a common negative terminal. I realize I'm missing something, but what?

I haven't tried the simple diode yet, but may get to it tonight.


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## mistergreen (Dec 9, 2006)

You should be able to use one power supply. The apogee meter only has one power supply. It powers the meter and powers the sensor.


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## jeffkrol (Jun 5, 2013)

mistergreen said:


> You should be able to use one power supply. The apogee meter only has one power supply. It powers the meter and powers the sensor.
> 
> 
> Sent from my iPad using Tapatalk HD


Different sensor...not amplified.. passive..well depending.. and who knows how the meter internal wiring works.. 

Bump:


Hoppy said:


> Why wouldn't a single battery work? I have the diode in parallel with the meter power leads. That should be exactly the same as two separate batteries. The "ground" is not connected to any real ground, so it is just a common negative terminal. I realize I'm missing something, but what?
> 
> I haven't tried the simple diode yet, but may get to it tonight.


From the spec sheet of the 4 wire device..
No no power supply needed for a diode.. it is self powered..so technically you have 2 power supplies..

If you stick the photodiode on blue/green and 9v on red/black it will work..or should if the signal is strong enough
As to your other sensor.. Different animal.. built in circuitry (amp) which needs power..
You meter looks to be "isolated" so to speak and again NOT enough range for over 200PAR..

Happy to be proven wrong.. but don't see it..

Depends on the sensor..









FIND what is wrong w/ the above vs the below:











(tired..)


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## Hoppy (Dec 24, 2005)

I hooked up a simple photodiode to the meter, and it worked fine. So, the problem is in how I'm using the powered sensor, but as far as I can understand, I am using it as it is designed to be used. Tomorrow I think I will disassemble all of my connections and do them again from scratch. I'm tired too!


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## mistergreen (Dec 9, 2006)

Are you using a bread board? Using a multimeter to check the circuit is helpful too.


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## jeffkrol (Jun 5, 2013)

never mind


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## Hoppy (Dec 24, 2005)

It is a very simple circuit, so breadboard isn't needed. Here is the circuit:










And, I think I found my wiring mistake! As I recall, I had the two green wires connected. That wouldn't work at all. So, I will follow my plan and take it apart and rewire it.

It is back together again, and I'm 99% sure the connections are correct, but it now indicates -0.8 PAR at all times, no matter how much light it is sensing. Perhaps a solder joint isn't good, but I will wait awhile before checking it again.


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## mistergreen (Dec 9, 2006)

Oh! I just thought of something. If it's still not working for you, you might need a drop down or up resistor on your signal lead. 

I have a thermo sensor that needs a drop down on the signal. Without it, it'll be full voltage/signal all the time. Try a 5-10K resistor. Pull out the breadboard


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## jeffkrol (Jun 5, 2013)

What we have here is a failure to communicate..........










On a side note your unit should be range adjustable by moving the decimal place..


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## mistergreen (Dec 9, 2006)

Hoppy's meter will read a max of 200 PAR since that's the limit. 2.5V is basically 2500 PAR. 2000 PAR is mid day summer sun. He's not measuring the sun.

I just saw the pictures, try a pull down or up resistor depending on the sensor setup.


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## jeffkrol (Jun 5, 2013)

mistergreen said:


> Hoppy's meter will read a max of 200 PAR since that's the limit. 2.5V is basically 2500 PAR. 2000 PAR is mid day summer sun. He's not measuring the sun.
> 
> I just saw the pictures, try a pull down resistor.


Why limit the sensor so...........Current LED's can exceed 200PAR at almost any depth..









seems ridiculous since you could have a much larger range w/ "apparently" much less hassle hooking an analog voltmeter to it..

and these "module" apparently has 3 ranges possible

0-200mV , 0-20V and 0-200V 

At 200PAR it is really easy to "peg" the meter..


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## mistergreen (Dec 9, 2006)

jeffkrol said:


> Why limit the sensor so...........Current LED's can exceed 200PAR at almost any depth..
> 
> 
> 
> ...


yes but I think he wants a cheap and portable solution. Also I don't think a voltmeter can send out 9V to the sensor, maybe 1V for circuit testing?


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## Hoppy (Dec 24, 2005)

The sensor does not have anything on it to allow you to change the calibration, so it is factory adjusted to yield 1 mV per PAR unit. I am a planted tank hobbyist. I will never in my remaining lifetime use more than 100 PAR lighting, so I have zero interest in any readings above 200 PAR. The 200 mV digital volt meter also has nothing that is user adjustable, without also destroying the factory set calibration. My goal is a 0-200 micromoles per square meter per second PAR meter.

Nothing in either Apogee's information sheet, or the Chinese manufacturer of the voltmeter's information sheet says a word about using a resistor in the signal lead. Wouldn't that change the calibration in an unknown way?

When I looked at all of my soldered connections all I found was a very poorly soldered connection to the switch on one terminal. I fixed that, but of course it had no effect at all. I think the sensor may be damaged. The voltage reading doesn't change between moderate shade outdoors and complete blackout. When I tried this with a multimeter measuring the sensor output it did show sensitivity to changes in light, which suggests that the voltmeter is where the problem is.

I got the sensor from a fellow member here, who preferred not to be named, because he had bought it a few years ago, hoping to do what I'm trying to do, but never got around to it, and, like me, realized that there is a time when you have to accept that some of your plans just aren't going to happen. So, he offered it to me. But, during the time it was sitting around waiting to be used it is possible that something damaged it. I have no way to test it in any definitive way so I may have to just accept that my project, which looks absolutely great, may never actually be usable. Only if someone can find an alternative way to connect it to the voltmeter that is theoretically sound will I have any chance to make it work. I'm not even close to being an expert on this.


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## mistergreen (Dec 9, 2006)

Hey,
try getting a reading from the sensor leads without powering it. You should get some voltage from light just like your generic photodiode. If you're not getting anything then it's possible broken. You can send it to me to play with if you have a feeling it's not broken.

I don't think a drop down interferes with the signal. The drop down/up could be in the apogee meter. I don't think they would tell you. I would try it anyway just to see if you get ANY signal. The only thing for sure are the self powered ones like SQ-110,120 etc...


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## jeffkrol (Jun 5, 2013)

> I have no way to test it in any definitive way


Huh? A 9v battery Upon (further review, see below, VOM and a light source will test it..


> I have no way to test it in any definitive way so I may have to just accept that my project, which looks absolutely great, may never actually be usable.


Unless someone put more than 24V though it it should be fine.
Send it to me.. I'll pay shipping..










you guys are making this way too complicated.. It is apparently a passive sensor w/ a built in amplifier..
See highlighted above..



> These sensors have been designed to have all the circuitry inside the head, the same as our non-amplified sensors. This means they are rugged and there is no worry about water damage to the circuit board. The circuitry is a basic non-inverting configuration of an operational amplifier (op-amp). The op-amp has been specifically chosen to have a low voltage offset and be physically small enough to fit inside of our current sensor body head. The op-amp has a max voltage specified at 5 V which is why the maximum output of our amplified sensors is 5 V. Included in the circuitry is a Zener diode that will short to ground if a voltage higher than 6 V is applied. This keeps the main circuitry from getting destroyed if the sensor is wired incorrectly


http://www.apogeeinstruments.com/amplified-sensors-explained/

More "anomolies"..








One sheet says ps 5-24V this says 5 go figure..
Use a phone charger as a power supply..


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## Hoppy (Dec 24, 2005)

The Apogee PAR meters, like the ones we are familiar with, don't use a sensor that is adjusted to give 1 mV per PAR unit. The electronics that drive the digital readout module are in the readout module, not the sensor. This sensor, which I didn't realize even existed, is designed to be used with any mV meter and the meter reading will be the PAR value. It is designed to operate with any DC supply between 5 and 24 VDC. It gives a readout of 0 to 2500 mV (0 to 2500 PAR). On the surface it is perfect for DIYers like me, or at least DIYers who have more knowledge of digital circuits than I have.

My gut feeling is that I have made a simple mistake that people with more experience wouldn't even know they were avoiding.

If this ends up just frustrating me I will probably do a RAOK in that forum, or, sell it for the $20 it would cost to pay my parts cost and the shipping cost. Hobbies are supposed to be fun, not sources of frustration!


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## jeffkrol (Jun 5, 2013)

there are dozens of digital voltmeters. Some w 3 wires. Why did youpick that one.
btw there is an amp buyable that would allow the new 
apogee to work w/ any digital vom.
https://blueacro.com/?gclid=CKfxk5n6u9ECFQiMaQoddncB6w
the much better sensor to go with it is only $100 more and $30 for the amp just add vom. 
also calibrated.


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## mistergreen (Dec 9, 2006)

You can also use an arduino to get the par values.


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## mistergreen (Dec 9, 2006)

jeffkrol said:


> https://blueacro.com/?gclid=CKfxk5n6u9ECFQiMaQoddncB6w
> the much better sensor to go with it is only $100 more and $30 for the amp just add vom.
> also calibrated.


Neat component but it looks like it only works with self powered sensors like the sq-500.


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## jeffkrol (Jun 5, 2013)

To be exact it ONLY works w/ the 500...
New sensor has a very low output..

Small point being it is "only" $100 more than any other Apogee powered sensor, has increased sensitivity in the red,blue region.

so for DIY-ers on a higher budget $320 and a VOM...
ADDENDUM.. Aduino and powered sensor..SQ225
https://bitknitting.wordpress.com/2016/06/19/making-a-par-and-dli-meter-using-an-arduino/


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## jeffkrol (Jun 5, 2013)

Any progress???

Still annoyingly contradicting

www.qualiteitems.com/images/Apogee_SQ212.pdf


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## mistergreen (Dec 9, 2006)

hmm, quite. Try to limit the input voltage to 2.5 or 5V with a regulator or otherwise. Maybe 9V was too much.


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## mistergreen (Dec 9, 2006)

jeffkrol said:


> Any progress???
> 
> Still annoyingly contradicting
> 
> www.qualiteitems.com/images/Apogee_SQ212.pdf


Oh, those are specs for sq212 not 222 which hoppy has but it couldn't hurt to see if 5v works.


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## Mathman (Apr 5, 2009)

What's a better meter/sensor

Apogee MQ500 or MQ510 


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## mistergreen (Dec 9, 2006)

Mathman said:


> What's a better meter/sensor
> 
> Apogee MQ500 or MQ510
> 
> ...


It looks like the MQ510 comes with a meter and MQ500 doesn't.
I personally wouldn't buy one. GO the cheaper SQ 120 or MQ210. Sure it might be a bit less accurate but why spend all that money for something you'll use a few times. It might be worth it for a club where members can share.


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## Mathman (Apr 5, 2009)

mistergreen said:


> It looks like the MQ510 comes with a meter and MQ500 doesn't.
> I personally wouldn't buy one. GO the cheaper SQ 120 or MQ210. Sure it might be a bit less accurate but why spend all that money for something you'll use a few times. It might be worth it for a club where members can share.




I've read that the MQ510 is so much more accurate when reading PAR levels for LED fixtures. Is there a great significance between the two other than the price tag?

I'm sorry for somewhat hijacking the thread.



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## mistergreen (Dec 9, 2006)

Mathman said:


> I've read that the MQ510 is so much more accurate when reading PAR levels for LED fixtures. Is there a great significance between the two other than the price tag?
> 
> I'm sorry for somewhat hijacking the thread.
> 
> ...


as I've mentioned, the price tag difference is the METER. They're basically the same sensor but here's the difference.


> The MQ-510 performs exactly the same underwater as the MQ-500, but the MQ-510 simply multiplies the PAR reading by 1.32 to account for the immersion effect.


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## jeffkrol (Jun 5, 2013)

MQ-510 (meter plus sensor) is actually listed under "aquarium use" (PAR METER, aquarium) and is the same price as the MQ-500.


Sensors only are SQ-XXX Probably would pick the 520...USB attachment to computer..


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## Hoppy (Dec 24, 2005)

jeffkrol said:


> Any progress???
> 
> Still annoyingly contradicting
> 
> www.qualiteitems.com/images/Apogee_SQ212.pdf


No progress because I put it aside to wait until I can work on it without feeling so frustrated. Nothing has come to mind on the lines of a simple, stupid wiring mistake, which doesn't mean I didn't make one. I hope to take another try at it this week.

That reference pdf is for model SQ212, where mine is model SQ222, or at least I hope it is.


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## jeffkrol (Jun 5, 2013)

PDF states "sq 200 series"


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## Hoppy (Dec 24, 2005)

jeffkrol said:


> PDF states "sq 200 series"


Yes, I noticed that, and I assumed that that pdf was published before the SQ222 model was available, then was not updated to include the 222 version. Lots of assumptions!

I may use a voltage divider to get a 5 volt supply from the 9 volt battery, just to see what the effect is. But, I would need to go buy a couple of resistors, and they are sold in packages of 10 each (?), so that does discourage me.


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## jeffkrol (Jun 5, 2013)

no cell phone chargers laying around?.. eAsy 5V .. also USB ports..


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## Hoppy (Dec 24, 2005)

I finally admitted to myself that I wasn't able to make this work, but one of our most prolific DIYers with digital devices is mistergreen, who generously offered to try to make it work and send it back if it does work, so I sent it to him. Today he told me he got it to work by correctly connecting it to the voltmeter!! I'm still totally in the dark about what dumb mistake I was making, but I'm also thrilled that I will finally have a very good PAR meter, that can be reliably used under water. As I have known for some time, this forum is a really amazing resource! I would say drinks on the house, but it's not my house, and I'm not a bartender, and ........

Since I got the sensor as a RAOK, and am getting it made to work as a RAOK, I'm going to have to do a lot of RAOKs with plants, etc. to pass this along.:smile2:


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## mistergreen (Dec 9, 2006)

I checked it against my apogee sensor and outputs are pretty much the same.


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## jeffkrol (Jun 5, 2013)

mistergreen said:


> I checked it against my apogee sensor and outputs are pretty much the same.


sooo...how did you wire it?


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## mistergreen (Dec 9, 2006)

From what I remember without reopening it.


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## jeffkrol (Jun 5, 2013)

so to solve the spec sheet problem.. 9V was OK..
And the other one is not to do a common ground since it must be "internal"...


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## mistergreen (Dec 9, 2006)

Yup, 9V is ok. The spec on the SQ-222 is correct.
Yeah, Hoppy just had the ground in the wrong place.


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## mistergreen (Dec 9, 2006)

Hey @Hoppy,
Where did you get the box? It's nice and some other people might want to get it.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> Hey @Hoppy,
> Where did you get the box? It's nice and some other people might want to get it.


I got it at Fry's. It fits very well and has a nice externally accessible battery compartment, but no connector to the battery. I cannibalized a lux meter for that. Since it is ABS plastic it was easy to cut holes the right size for the voltmeter and switch.


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## joebob296 (Sep 30, 2016)

Can some share some pics of the working setup?

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## Hoppy (Dec 24, 2005)

joebob296 said:


> Can some share some pics of the working setup?
> 
> Sent from my SM-G935V using Tapatalk


Yes, when I get it back I plan to take some more pics and post them. Probably early next week.


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## Hoppy (Dec 24, 2005)

Given that this is basically a RAOK project, one I could never afford to do otherwise, and which I was totally stumped by until another RAOK fixed it for me, I am thinking of using this as a loaner so others can borrow it for a week to make it useful to more than just me. Normally this isn't viable, because PAR meters typically cost about $300, and that is just too much to risk by loaning it repeatedly. But, this one only cost me about $50 total.

I'm thinking I could ask for a $40 deposit, with $30 of that refunded when it is returned and still in good condition. Any guess as to whether there would be much demand for this? (The $10 actual cost is because it costs about $10 to mail it by Priority Mail with insurance each way.) What would be the odds that someone would just keep it?


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## vvDO (Oct 18, 2010)

Hoppy said:


> Given that this is basically a RAOK project, one I could never afford to do otherwise, and which I was totally stumped by until another RAOK fixed it for me, I am thinking of using this as a loaner so others can borrow it for a week to make it useful to more than just me. Normally this isn't viable, because PAR meters typically cost about $300, and that is just too much to risk by loaning it repeatedly. But, this one only cost me about $50 total.
> 
> I'm thinking I could ask for a $40 deposit, with $30 of that refunded when it is returned and still in good condition. Any guess as to whether there would be much demand for this? (The $10 actual cost is because it costs about $10 to mail it by Priority Mail with insurance each way.) What would be the odds that someone would just keep it?




I think that's a great idea, but I would recommend making the deposit a bit higher, i.e. What it would cost you to replace it.


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## Hoppy (Dec 24, 2005)

vvDO said:


> I think that's a great idea, but I would recommend making the deposit a bit higher, i.e. What it would cost you to replace it.
> 
> 
> Sent from my iPhone using Tapatalk


If the deposit is too high few people would be able to use it. And, I couldn't replace it because the cost for the sensor is just too much. So, I can only see basing this on how much the project has cost me. I agree that the lower the deposit the more likely someone would just keep it rather than return it.


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## mistergreen (Dec 9, 2006)

When I have time, I'd borrow it again and use the sensor to plug it into an arduino. It could read up to 1023 mV at 5V. I guess that's 1023 PAR. That's a bit more flexible than the 200mV limit now. I think I can play with my SQ-120 with the arduino which I haven't thought of till now since I just use my voltmeter usually.


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## mistergreen (Dec 9, 2006)

I wrote an Arduino script for anybody to use for an SQ-120. Just include an LCD and code to make it mobile.


```
// get PAR for apogee SQ-120
// black & clear go to ground
// red go to A0

void setup() {
     
  Serial.begin(9600);
  //Get 1.1V (instead of 5V) reference for more accurate reading
  analogReference(INTERNAL); //UNO
  //analogReference(INTERNAL1V1) // mega
}

void loop() {
   // read the input on analog pin 0:
  int sensorValue = analogRead(A0);
  // Convert the analog reading (which goes from 0 - 1023) * 1.1V reference for Volt * convert to mV * 5 to get PAR
  float voltage = sensorValue * (1.1 / 1023.0) * 1000 * 5;
  // print out the value you read:
  Serial.println(voltage);
  delay(1000);
}
```


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## joebob296 (Sep 30, 2016)

Hoppy said:


> If the deposit is too high few people would be able to use it. And, I couldn't replace it because the cost for the sensor is just too much. So, I can only see basing this on how much the project has cost me. I agree that the lower the deposit the more likely someone would just keep it rather than return it.


I agree that the deposit needs to be higher. If they want to use it they will pay for it. With priority mail I'm guessing 2 weeks top until they have their money back. If the deposit is only $40 it will probably disappear within the first month.

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## Hoppy (Dec 24, 2005)

joebob296 said:


> I agree that the deposit needs to be higher. If they want to use it they will pay for it. With priority mail I'm guessing 2 weeks top until they have their money back. If the deposit is only $40 it will probably disappear within the first month.
> 
> Sent from my SM-G935V using Tapatalk


What do you think would be high enough to discourage keeping it, but not discourage borrowing it? I really don't have a good feel for it. If I do this and someone keeps it I would give them a very bad rating, possibly preventing them from using the for sale forums here. Would that be a deterrent?

I have seen several posts where people say they plan to rent theirs out, but I don't recall anyone actually doing it, so I'm guessing that this dilemma has been faced often.


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## joebob296 (Sep 30, 2016)

I would charge the cost of the sensor, $200. Firstly, the fact that it is a lot of money is the exact reason why you would be getting it back. Anything less then that and the chances of getting it returned are very low. If the deposit is lower then the cost of the sensor, what is to stop someone form getting it and just selling it online elsewhere and making a profit? You are on the honor system for renting it out to people for lower then the cost of a replacement. Secondly, it is a deposit for a reason, they would be getting it back minus whatever cost you decide. It is not a sale, in the time span of less then 2 weeks, it can be shipped used and returned. It is on the person who rented it as to when they want their money back. It could take them a week or a month.

This next point is a catch 22 for newer members including myself, knowing the PAR is very beneficial especially when starting out. I would put in some time requirements as to being active on the site I.E been a member for X months. This so you don't have people create a new account, rent the sensor without any intention of sending it back. Knowing the PAR of your lights would eliminate the vast majority of light questions. With that being said, people with mature successful tanks can still benefit from it. 



Hoppy said:


> If I do this and someone keeps it I would give them a very bad rating, possibly preventing them from using the for sale forums here. Would that be a deterrent?


Honestly, I don't think that would do anything. Getting a very bad rating while being able to keep a $200 sensor....is a steal. Anyone can make a second account, rent the sensor, keep it and continue on with their main account. Even if they used a real account and were banned from specific ares of the forum. They could just create a new account and start selling from there.

The only way that renting it out to people successfully is to make the deposit the cost of a replacement.

Thoughts?


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## mistergreen (Dec 9, 2006)

Keep the deposit high. There are strange users you haven't seen before pop up to get roak, and freebies.

I wouldn't trust them.

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## Hoppy (Dec 24, 2005)

Bad news! mistergreen tested it with his arduino and it worked ok, but when I hooked it back up to the battery it didn't work. In fact the battery burned out - twice - because the on/off switch was across the battery terminals. I put the switch back where it turns on the power, and it still doesn't work right, giving a constant 180 reading - approximately. The odd thing was, it gave a few normal readings with the battery shorted out before it quit working right??????? Here is how it is now hooked up? Where is that incorrect?


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## mistergreen (Dec 9, 2006)

Ouch. Check for shorts. The wiring might have loosened during shipping. It worked for me before I shipped. Some wires are touching that aren't suppose to touch probably, usually a ground touching +. Touch any components to see if it's hot too.


Use a voltmeter to see if the 'polarity' is correct too. Red should be + and Black should be ground.


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## jeffkrol (Jun 5, 2013)

Short probably damaged the battery holder (long shot)..Try wiring it direct w/ switch..

Need to correct this image..


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## Hoppy (Dec 24, 2005)

I did check the polarity several times, and stopped when I noticed that the battery was hot. By then the battery voltage was down to 5.1 volts. So, I found a good battery and checked it to be sure my multimeter was correct - 9+ volts. Only then did I carefully trace out the circuit, ending with the power circuit, and noticed that the battery was wired so the switch shorts out the battery. What really stumps me is how it worked so well for the first couple of minutes. One possibility is that it dropped the voltage to about 5 volts, with the big current draw, which was what it perhaps should be. "Shortly" after that it just read 0.1, when I assume the battery was dead. With the nearly new battery I found the hot battery, etc. Should I get a couple of resistors and do a voltage divider to get it to run on 5 volts instead of 9 volts?


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## mistergreen (Dec 9, 2006)

Jeff is right. The switch is causing the short. If you connect the wires directly to the battery, it'll work. I should have checked the heat in the battery.


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## mistergreen (Dec 9, 2006)

Sorry about that. This should be correct.

I think you can put the switch on the ground wire if it's easier.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> Sorry about that. This should be correct.
> 
> I think you can put the switch on the ground wire if it's easier.


It is hooked up exactly as shown in that diagram. When the cap is on the sensor it reads about 130, when it is off it reads about 150, while it is in a pretty bright fluorescent light. It does this repeatedly. It seems to be measuring the light intensity + about 130. When I put the uncovered sensor much closer to the light it goes to above 180 then goes into the overdrive mode, registering 1 as the reading.

The voltmeter should work fine with 9 volts driving it, but the sensor maybe should have 5 volts? Add a small 10K pot wired as a voltage divider to reduce the voltage to the sensor to 5 volts?


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## mistergreen (Dec 9, 2006)

When there's no light, it reads 150?
THat's definitely not right.

Be aware that your meter is limited to 200mv. So when it goes over, you'll see the 1.

Yeah, try the resistor and see.

Oh, is the Blue wire on the meter Positive or ground?


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## Hoppy (Dec 24, 2005)

The blue wire on the VM is negative - a ground. Now, I need to see if Frys has a 10K pot that isn't packaged with 9 others.


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## mistergreen (Dec 9, 2006)

Is there a RadioShack by you? I know they closed down a bunch of stores but they are handy. I have one by me.


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## Hoppy (Dec 24, 2005)

I thought all Radio Shack stores closed! I see there is still one near me, so I will be there tomorrow morning. They have exactly what I need - cheap!


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## mistergreen (Dec 9, 2006)

I think I figured out why the old wiring worked for me. Your battery was down to 5V when I got it and when the switch is on the off state, the meter and sensor worked. It would short if the switch was on the on state.


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## jeffkrol (Jun 5, 2013)

mistergreen said:


> I think I figured out why the old wiring worked for me. Your battery was down to 5V when I got it and when the switch is on the off state, the meter and sensor worked. It would short if the switch was on the on state.


So we are back to 9V doesn't work??????


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## mistergreen (Dec 9, 2006)

jeffkrol said:


> So we are back to 9V doesn't work??????


probably. With no light, it's outputting 150mv.


btw. Radioshack sells a 5V regulator. It's better than using pots and resistors I think. You might need to solder the back of it to some sort of heat sink though.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> Oh, those are specs for sq212 not 222 which hoppy has but it couldn't hurt to see if 5v works.





jeffkrol said:


> So we are back to 9V doesn't work??????





mistergreen said:


> probably. With no light, it's outputting 150mv.
> 
> 
> btw. Radioshack sells a 5V regulator. It's better than using pots and resistors I think. You might need to solder the back of it to some sort of heat sink though.


This project is at the "panic" stage! It seem obvious that 9V doesn't work, so what's left is to try 5V. Using a $2 trim pot is the cheapest, easiest way to do this. A voltage regulator just introduces a new device that could be miswired by me, and at a higher cost, plus it isn't adjustable like a potentiometer is.

If this doesn't work I will have to look for a "Plan B".


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## jeffkrol (Jun 5, 2013)

I know I once bought a "5V battery pack" (batteries not included but takes AA) for a cell phone "backup" from a Dollar Store..for $1.. Outputs on a usb cable and must have a boost/regulator circuit.. (2 AA's is not 5V)
Like this:
https://www.fasttech.com/product/1286307-2aa-battery-powered-usb-emergency-charger-with-fla

would need to strip a USB cable..


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## mistergreen (Dec 9, 2006)

yeah, to test, you can just use a 5V source. That'll power the meter too.


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## Hoppy (Dec 24, 2005)

I picked up a trim pot from Radio Shack, https://www.radioshack.com/products/radioshack-10k-ohm-15-turn-cermet-potentiometer-trimmer then measured the resistance the slider connection gives - it was roughly 50% of full resistance, so I hooked it up as shown in










I used a new 9 volt battery, and measured the voltage at the sensor - 5 volts! So, I tried it out..........................................*IT WORKS*!!

It gives a zero (actually a 0.1) reading with the cap on the sensor, and with the sensor about a foot from my little reading light, it shows about 20 PAR, which is what I would expect.

My conclusion is that this sensor, which is at least a couple of years old, was made to be used with 5 volts powering it, but later versions were improved so they can use 5-10, or whatever it is, volts.

Now, I need to try it in my tank to see how close it reads to what I am 90% sure is my PAR at the substrate. And, I will take some photos of it, inside and out, to post later.


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## mistergreen (Dec 9, 2006)

Good to hear. I knew it would work.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> Good to hear. I knew it would work.


You had a lot more confidence than I did:grin2:


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## mistergreen (Dec 9, 2006)

The down side to using a resistor vs a v regulator is you'll have to use a fresh batter every so often. Say the battery goes down to 8V. The sensor would get less than 5V because of the pot. I'm not sure that would affect the PAR reading or not, but probably will.

I reread the sensor spec, it should stay operational at 2.5V-5V.


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## vvDO (Oct 18, 2010)

mistergreen said:


> The down side to using a resistor vs a v regulator is you'll have to use a fresh batter every so often. Say the battery goes down to 8V. The sensor would get less than 5V because of the pot. I'm not sure that would affect the PAR reading or not, but probably will.
> 
> I reread the sensor spec, it should stay operational at 2.5V-5V.




If it can work at 2.5-5V then 2-3 AA batteries should work, right?



Sent from my iPhone using Tapatalk


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## mistergreen (Dec 9, 2006)

vvDO said:


> If it can work at 2.5-5V then 2-3 AA batteries should work, right?
> 
> 
> 
> Sent from my iPhone using Tapatalk


Yeah, but the 9v is convenient. You only need 1 battery instead of multiple and you need to share power with the meter.


Sent from my iPad using Tapatalk HD


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## jeffkrol (Jun 5, 2013)

mistergreen said:


> Yeah, but the 9v is convenient. You only need 1 battery instead of multiple and you need to share power with the meter.
> 
> 
> Sent from my iPad using Tapatalk HD


both the meter and sensor will run off 3V-5V (30V for the meter)..
One rechargeable Lithium battery will power both..
IMR type have plenty of power and "start" at about 4V..


> 1. Brand: Efest
> 
> 2. Model:Efest 26650
> 
> ...


 What exactly does "IMR" mean?


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## 691175002 (Apr 28, 2009)

Is there no part number on the sensor itself, or did they just randomly change SQ-222s specifications without altering the part number?


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## jeffkrol (Jun 5, 2013)

They have "errors" on various spec sheets (one lists mA as mV) .. There is no guarantee there are 2 "models" even AFAICT..
Sloppy is all I can say


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## Hoppy (Dec 24, 2005)

More good news. It works fine in a water filled aquarium, and the readings I got are very consistent with what I had a year ago, using a standard Apogee Quantum PAR meter (the original sensor type). I now have a acrylic pad attached to it to make it easy to use in an aquarium without your arm obstructing or reflecting light to introduce errors.

Now, I am figuring out details for making this available on loan to other members here. The really nice case I have for it won't fit into a small flat rate box or even a small flat rate padded envelope. So, I ordered a soft case from Amazon. That will fit the small flat rate box. Look for me to list this in the RAOK forum in a few days.

As usual with PAR meters once I made my measurements I may not want to use this for another 3 months, but it feels good to have one.


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## mistergreen (Dec 9, 2006)

You should let people know that the meter won't read anything above 200PAR so they don't freak out thinking they broke it


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## Hoppy (Dec 24, 2005)

mistergreen said:


> You should let people know that the meter won't read anything above 200PAR so they don't freak out thinking they broke it


Good point! I will do that. This limitation has a good point too - it reduces it to being useful for planted tanks and nothing else, reducing the temptation to swipe it.


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## mistergreen (Dec 9, 2006)

One more.
When shipping, disconnect the battery. When I got your package, the meter was turned on, I guess from the rough and tumble of transit.

That's how the battery was drained to 5V I think.


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## Hoppy (Dec 24, 2005)

mistergreen said:


> One more.
> When shipping, disconnect the battery. When I got your package, the meter was turned on, I guess from the rough and tumble of transit.
> 
> That's how the battery was drained to 5V I think.


I have been thinking about this. That switch is very easy to turn on. One possibility would be a "cap" over the switch to protect it. Disconnecting the battery is the most reliable possibility, but can easily lead to a damaged battery connection. A piece of tape across the "off" end of the switch would work, but would quickly lead to a gummy, dirty area around the switch. Are there other options???

Incidentally, if the battery had not drained down I would still be stumped as to what the problem was.


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## jeffkrol (Jun 5, 2013)

Even after "someone" mentioning try 5V a few times...................... 
(Sorry couldn't resist)


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## mistergreen (Dec 9, 2006)

I think the battery connection will be fine unless people yank on it constantly.

Manufacturers don't package their products with batteries for this reason unless the device is wireless/buttonless.


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## joebob296 (Sep 30, 2016)

Anybody know when Hoppy will be back? He has some equipment I would like to "purchase" then "return" from him.


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## Nlewis (Dec 1, 2015)

joebob296 said:


> Anybody know when Hoppy will be back? He has some equipment I would like to "purchase" then "return" from him.


It be best to send him a pm.


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## joebob296 (Sep 30, 2016)

Nlewis said:


> It be best to send him a pm.


I tried that with no response, maybe he didn't get it, I'll try again. However, once I get in contact with him I can open a different channel of communication outside of this forum.

Sent from my SM-G935V using Tapatalk


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## oly99 (Mar 5, 2018)

has anyone connected one of these to a esp32 or other esp such as a sonoff ? im looking toi add the readouts to a node red dashboard


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## labboy (Apr 2, 2020)

I am sorry to revive this old thread, but I was wondering if one could provide a diagram how to use the passive version sq120 with raspberry pi. I have the MCP3008 analog to digital converter, but when i hook it up using the 3.3V I get the maximum voltage (3.3) as readout even in the dark. Obviously I should not power it from raspberry cause its passive? But still i cant make it work...Any ideas?
thank you !!
Stay Healthy!!


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## jeffkrol (Jun 5, 2013)

labboy said:


> I am sorry to revive this old thread, but I was wondering if one could provide a diagram how to use the passive version sq120 with raspberry pi. I have the MCP3008 analog to digital converter, but when i hook it up using the 3.3V I get the maximum voltage (3.3) as readout even in the dark. Obviously I should not power it from raspberry cause its passive? But still i cant make it work...Any ideas?
> thank you !!
> Stay Healthy!!


SQ-120 is self powered..


> Connect the sensor to a measurement device (meter, datalogger, controller) capable of measuring and displaying or recording a millivolt signal (an input measurement range of approximately 0-500 mV is required to cover the entire range of PPFDfrom the sun). In order to maximize measurement resolution and signal-to-noise ratio, the input range of the measurement device should closely match the output range of the quantum sensor. DO NOT connect the sensor to a power source. The sensor is self-powered and applying voltage will damage the sensor


https://electronicshobbyists.com/raspberry-pi-analog-sensing-mcp3008-raspberry-pi-interfacing/
https://pimylifeup.com/raspberry-pi-adc/


I can only "point " you but the Apogee outputs mA signal not voltage ..



not sure how you digitize 0-800mA...


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## labboy (Apr 2, 2020)

Thanks Jeffkrol. I am aware that is self powered thats why i would like to know the diagram. All the sensors that they describe in the links (others as well) are with sensors that need external power source, or? This TMP36 for example, you counnect the VCC to the 3.3V of the raspberry. Do i miss something?


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## jeffkrol (Jun 5, 2013)

labboy said:


> Thanks Jeffkrol. I am aware that is self powered thats why i would like to know the diagram. All the sensors that they describe in the links (others as well) are with sensors that need external power source, or? This TMP36 for example, you counnect the VCC to the 3.3V of the raspberry. Do i miss something?





first you need to convert the mA to a voltage.. then go from there with the ADC converter (technically the easiest? though ??)

since raspberry pi has on analog input...
AFAICT..
https://forum.arduino.cc/index.php?topic=589808.0


https://www.rototron.info/raspberry-pi-analog-water-sensor-tutorial/


Waaay too many error points for my liking..

"As I understand it" you just need to find a suitable resistor across the 2 output wires of the sensor.
That's fed to the ADC to go to the Pi..

https://www.industrologic.com/aninput.htm

You'll have to calibrate the output to the orig specs i.e mA X 5 = y volts.
pg 11
https://www.apogeeinstruments.com/content/SQ-100-300-manual.pdf

Don't forget the immersion effect..


> The SQ-100 and SQ-300 series sensors have an immersion effect correction factor of 1.08. This correction factor should be multiplied to measurements made underwater.


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## labboy (Apr 2, 2020)

But I thought that the output of the sq120 is volt in the range 0-500mV.
If what you say is correct, using a 250 ohm resistor between the the two outputs of the sensor will give me a range of 0-5 Volts (according to your link), which is within the range and i can use the 3.3V of raspberry, right? Are you sure about this calibration? The outcome should be that the ADC should read now volt values in this region and then i have to calibrate mV*5=PPFD (manual pdf page 12, it doesnt say ampere, rather mV).
As you can see, its all new to me. Thanks again for your time!

I was unaware of this 4-20mA thingy...


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## jeffkrol (Jun 5, 2013)

labboy said:


> But I thought that the output of the sq120 is volt in the range 0-500mV.
> If what you say is correct, using a 250 ohm resistor between the the two outputs of the sensor will give me a range of 0-5 Volts (according to your link), which is within the range and i can use the 3.3V of raspberry, right? Are you sure about this calibration? The outcome should be that the ADC should read now volt values in this region and then i have to calibrate mV*5=PPFD (manual pdf page 12, it doesnt say ampere, rather mV).
> As you can see, its all new to me. Thanks again for your time!
> 
> I was unaware of this 4-20mA thingy...



DANG, not sure where I made the wrong turn but yea..





> *Apogee SQ-100 and SQ-300 series quantum sensors are self-powered devices and output a voltage signal proportional to incident PPFD*



Sorry, been a bit stressed out lately...
Technically the sensor part does output a mA or micro amp output but it's "converted" on the sensor head itself here..
It's best to use the mA output for a number of reasons BUT that is also a long story and not applicable here.


So* IGNORE* most of my prev. posts..and I have to see where I got lost..


you need to go sorting through this..
https://www.reef2reef.com/threads/r...troller-based-on-raspberry-pi.289256/page-279

Only difference between a pH probe and your sensor is calibrating output to ppfd.. instead pf pH..oh and no need to power the sensor (apogee) and you never have negative voltages..

https://raspberrypi.stackexchange.c...ion-and-adc-using-mcp3008-pcf8591-and-ads1115

Attach a BNC end to the 2 wires of the Apogee.. 
Then use this board..or one like it.. 
https://www.reef2reef.com/threads/reef-pi-ph-orp-adapter.478158/
https://github.com/reef-pi/pH-Board
SADLY unavailable..
https://www.tindie.com/products/ranthalion/isolated-ph-probe-interface-for-reef-pi/
Nuts and bolts using pH probe as an example.
https://www.atlas-scientific.com/_files/_datasheets/_oem/pH_oem_datasheet.pdf

*THIS also should be helpful..*
https://www.abelectronics.co.uk/p/69/adc-pi-raspberry-pi-analogue-to-digital-converter
https://www.abelectronics.co.uk/kb/article/27/analogue-to-digital-converter-buyers-guide


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