# DIY LED Pendant Light



## xmas_one (Feb 5, 2010)

Looks promising, which leds are you planning on using?


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## The Big Buddha (Jul 30, 2012)

As usual, another very interesting post Hoppy. Can't wait to see the outcome. I have a radion on my 40B and find the corners are a little too dark, I was thinking maybe some pendant lights. Keep up the good work!


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## Hoppy (Dec 24, 2005)

xmas_one said:


> Looks promising, which leds are you planning on using?


I purchased the LEDs on Ebay, so they are generic ones, two 10 watt cool white, and 2 each blue and red. They are cheap enough that if they don't perform as I want, I can afford to replace them with better ones. 

I also got the LED drivers on Ebay, two 10 watt ones and two 1 to 3-1 watt ones with the latter only costing me $2.53 total. I will run the red and blue LEDs in series. They have different forward voltages so I can't easily run them in parallel. The polished insides of the aluminum "cans" should act to diffuse the red, blue and white colors together enough to avoid colored shadows on the substrate.


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## 0live (Jun 8, 2013)

Interesting Build!


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## Sake (Mar 30, 2012)

Subbed, looking good Hoppy. How much par do you think this will be putting out? I know you can't predict but what are you shooting for high med or low?


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## Hoppy (Dec 24, 2005)

Sake said:


> Subbed, looking good Hoppy. How much par do you think this will be putting out? I know you can't predict but what are you shooting for high med or low?


I'm wishing for low intensity, with the lights about 12-18 inches above the top of the tank. But, I really have no way to guess what I will actually get. If I'm off too far I may try 20 watt LEDs, or 3 Cree LEDs, or who knows what else. My gut feeling is that I will be ok with the configuration I started with.


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## Sake (Mar 30, 2012)

I'll take your gut feeling over anyone else, you are the parmaster ya know. Please continue with the updates, if you do get low par I may try this build myself.


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## daffyfish (Jan 5, 2011)

Looking forward to seeing how this looks.
Thank you for posting.


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## Edub (Mar 23, 2011)

Are you planning on using dimmable drivers or are you just gonna run the leds at full blast and adjust height as necessary?

Also, I see no mention of lenses. Are you running the leds without? Is this to help blend colors, even out PAR, or something else? I have 60 degree lenses on my DIY leds and I kind of hate it. A wider spread would work better for me, but I dont want to lose too much power. 

I'm very interested to see how this works for you. The "cans" seem like a great idea to both blend light as well as hide glare. The next led project I build will be a pendant, I think they look very clean and modern and I've been thinking of ideas to hide the glare.


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## redman88 (Dec 12, 2008)

with the configuration he is showing there won't be room for lenses


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## Hoppy (Dec 24, 2005)

Edub said:


> Are you planning on using dimmable drivers or are you just gonna run the leds at full blast and adjust height as necessary?
> 
> Also, I see no mention of lenses. Are you running the leds without? Is this to help blend colors, even out PAR, or something else? I have 60 degree lenses on my DIY leds and I kind of hate it. A wider spread would work better for me, but I dont want to lose too much power.
> 
> I'm very interested to see how this works for you. The "cans" seem like a great idea to both blend light as well as hide glare. The next led project I build will be a pendant, I think they look very clean and modern and I've been thinking of ideas to hide the glare.


For cost savings I gave up on using dimmable drivers, but being able to adjust the intensity by raising or lowering the lights entered into that also.

The basic reason for the cans is to shield the glare, but they also substitute for lenses, in that they confine the light out put to a fairly narrow cone, granted with some stray light from multiply reflected rays. A side effect is the increased blending of the colored LED light with the white light, although that may not be necessary due to keeping the 3 LEDs so close together. And, the last effect is to act as chimneys, to improve air flow past the finned heatsinks. I picked the .085" wall thickness tubing over thin wall sheet aluminum ducts to make assembly design easier and much more rugged, as well as to increase the weight of each pendant so it will be easier to make it hang at a true vertical - otherwise each pendant would be likely to always hang off vertical due to the wire unbalancing it. All of this is just theoretical at this point.

I plan to paint the "cans" today, using flat white spray can paint. My room wall is white, so this should make the lights tend to blend in with the wall. It was a hard choice between white and flat black.

A chronic problem I always have when I DIY something is price creep! I keep having to buy odds and ends at the hardware store or Home Depot, and those little costs really add up eventually.


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## xmas_one (Feb 5, 2010)

That's a pretty slick idea to use the cans for color mixing, I never would have thought of that. I have a par38 "full spectrum" bulb for reefs, the "disco ball" effect off of it is downright nauseating (maybe I could remove the optics and mount in a can as well). Eager to see how this build turns out!


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## skanderson (Jul 25, 2010)

dam this thread is going to make my led pendants on my 300 look derivative. i would love to see the par numbers you get and the color that the pendants produce. my pendants are for a bigger tank and i plan on using 5 of them. im going to use 20 watt bxra at 4k from bridgelux for light and then balance out the color with various 3 watters using a6 inch makers heatsink and a diy reflector that im working on this week. please keep us informed im interested alot in the round reflector with parallel sides. i was planning on a square reflector with a slight outward angle and a 6 to 8 inch depth. thanks again for the post.


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## Hoppy (Dec 24, 2005)

My two 10 watt LEDs just arrived. Here is how it fits on the heatsink assembly:


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## McShrimp (Oct 7, 2013)

Hoppy,
Would you you please PM me the links for components? I am just starting to play with LEDs and I like the idea you have here. I would like to light one part of a long tank to a higher level than the rest.


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## Hoppy (Dec 24, 2005)

McShrimp said:


> Hoppy,
> Would you you please PM me the links for components? I am just starting to play with LEDs and I like the idea you have here. I would like to light one part of a long tank to a higher level than the rest.


PM sent


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## Hoppy (Dec 24, 2005)

Now this is weird! (Wired and weird!) I temporarily connected one of my 10 watt LEDs, mounted on its heatsink, to the 10 watt driver for it. Plugged in the power, and it came on. Made an appropriately bright circle of light on the floor, with a well defined boundary, as it should be. So, I lugged everything to my dining area where I set it up to measure PAR and take some photos. Plugged it in and nothing happened. So, I reversed the plug in the wall socket - nothing happened. So, I used an extension cord, with a neon light in the plug telling me the power is there, plugged the LED driver into the extension cord - nothing happened. So, I got my multimeter, and measured the DC voltage at the output of the driver - got a 0 to fluctuating reading. Repeated it a few times - mostly got zero. Unplugged the driver. Just for fun, measured the output voltage for the presumably dead driver - got a few volts, which dropped to zero. What the heck is going on??

I checked the polarity of my connections to the LED several times, and it was correct, for sure. I'm thinking of repeating this with the other driver, but I wish I knew what was going on before I try that.


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## Hoppy (Dec 24, 2005)

I figured out what the problem was. The LED was not in good enough contact with the heatsink, so it worked only until it overheated and failed. Today I tried the other LED, removing the aluminum bar extension on the heatsink and mounting the LED to the heatsink using 4 screws instead of two. It worked fine this way, with repeated starts and several minutes of trial running.

So, I set it up to measure the PAR vs distance. I used a steel pipe across the backs of two dining chairs, with the electric cable as the support for the light, with everything taped so it couldn't slip or fall. The results are encouraging and disappointing, both.









At a LED to PAR meter distance of 20 inches I got 21PAR, which is too little, but the light is well contained by the "can" so it gives very little spillover outside the main beam. The intensity within that circle of light drops off about 33% from the center to the edge of the circle - also very good. At other distances:

















I got 13 PAR at 25 inches, and about 8 PAR at 33 inches, which is about the distance I want to use it at.

I think my next step will be using more efficient LEDs, probably 2 or 3 whites in each can, possibly without the supplemental colored LEDs. I'm still thinking about that step.


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## shift (Jan 7, 2013)

Nice work. They look good


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## Hoppy (Dec 24, 2005)

I found some 20-30 watt LED rated heatsinks on Ebay, which are the same diameter, but heavier, so I just order a couple of those. Now, I need to decide what LEDs to get - probably 20 watt ones. Depending on the dimensions of the heatsinks I may still be able to include the red and blue low wattage LEDs.

There are some 100 watt, 200 watt, and higher LEDs now available. I suppose those are for welding tungsten pieces together??


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## redman88 (Dec 12, 2008)

Get some thermal paste won't need to screw it in and the heat transfer will be better


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## redman88 (Dec 12, 2008)

Reef central has some led builds with this type if led


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## Hoppy (Dec 24, 2005)

redman88 said:


> Get some thermal paste won't need to screw it in and the heat transfer will be better


I used thermal paste between the LED and the heatsink extension and between that extension and the heatsink. But, one of the tiny screws holding the LED on went in cross threaded and slightly deformed the edge of the LED so it wasn't in good contact in the middle. From now on I will be using 4 screws if I use that type of LED, which I probably will.

It looks like the 20 watt LEDs might have about the right lumen rating to make this work. I'm still debating that with myself though. I would prefer a 30 watt version, but haven't seen one like that on Ebay.


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## Hoppy (Dec 24, 2005)

I found several 30 watt LEDs on Ebay and other internet sites. I don't know why I didn't see them before. So, I ordered a couple of them, plus compatible drivers. It now looks like the heatsinks will handle 30 watts only with a fan attached, and it isn't clear from the Ebay listing whether the fan is included or not, although it does say in one place that it is. This project is going to take several weeks, possibly until next year, to be completed. (And, that is if everything goes ok.)


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## Haagenize (Sep 30, 2008)

If you modify a nice 100mm case fan (it might be a tight fit since your OD is 4" probably) right above the LED's. You probably will have to settle on a 80mm with a pretty hefy width that has a higher CFM rating. 

Nice project though, would go wonderful with a smaller cube


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## saiko (Mar 30, 2007)

Hi Hoppy,

How about using a box shape insted of cylinder? That way you could get a rectangular beam on the floor, and better suited for our aquariums?

And do you plan to spray paint inside of the can as well?

Thanks and regards.


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## benjaf (Mar 27, 2012)

I like the idea of using the can to blend the colors!
Been using a combination of Cold White and Warm White 10W ebay diodes for a while now. Man do they put out a lot of heat! Had to add more cooling fins to my fixture that I originally planned. I don't even want to imagine the output of the 30W.

The waterproof drivers they sometimes come with mostly react nicely to PWM switching, but some do not!
For the people considering these LEDs with the 44mm lenses sold for them on ebay: The resulting cone of light is fairly narrow with a spread of roughly 22 degrees when using the lens + reflector on a 10W diode.


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## Hoppy (Dec 24, 2005)

saiko said:


> Hi Hoppy,
> 
> How about using a box shape insted of cylinder? That way you could get a rectangular beam on the floor, and better suited for our aquariums?
> 
> ...


The reason for using a round aluminum tube for the housing is the great reflectivity of aluminum, even when not polished. The inside is fairly rough, compared to a mirror, but I have been sanding it off and on, getting it smoother and closer to being polished. No, I won't paint it. A square aluminum tube would work also, but would require some attention to how it is hung, so the square beam of light stays aligned with the sides of the tank. The round one is much easier to work with, for that reason.

I did a lot of surfing looking for suitable fans, and found a Titan "TFD9525H12ZP Kukri" http://www.newegg.com/Product/Product.aspx?Item=N82E16835192023 which looks very promising. It has a 90 mm fan, and minimal structure outside so it is largely a round cylinder requiring very little trimming to make it fit the 4" tube. I'm still thinking about how to attach it and be able to easily and neatly hang the assembly. Until I get the heatsinks I won't decide on this.

Haagenize, thanks for the idea!


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## McShrimp (Oct 7, 2013)

Have you considered making the can longer above the heatsink?
The chimney effect can often move a great deal of air.
Efficiency being an important consideration, fans can eat up some real power.


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## Hoppy (Dec 24, 2005)

McShrimp said:


> Have you considered making the can longer above the heatsink?
> The chimney effect can often move a great deal of air.
> Efficiency being an important consideration, fans can eat up some real power.


If I was starting over I would make the cans about 2 inches longer, but I don't want to spend that much more money on this, so I will make what I have work. There is no guarantee that this will end up working well enough to be useful, but in theory a 30 watt LED will give a bit more light than I need, and the heatsink is rated for up to 30 watts, with a fan, so I like my chances of success.

The red and blue LEDs and their drivers arrived yesterday, but I won't start doing anything with them until I have a working light with just the white LED. If I add the red and blue ones it does block some of the air circulation, which may be critical.

Now, I on the hardest part of a project - waiting for parts to arrive.


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## Tom S (Mar 5, 2013)

Watching your build closely - I have a 40 breeder to build lights for and hopefully can piggy-back off your work here. I'm thinking about using the Cree MP-L Easywhite LEDs, which are rated at 20W @ 250mA. How would I simulate a pendant light in your calculator?


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## Hoppy (Dec 24, 2005)

Tom S said:


> Watching your build closely - I have a 40 breeder to build lights for and hopefully can piggy-back off your work here. I'm thinking about using the Cree MP-L Easywhite LEDs, which are rated at 20W @ 250mA. How would I simulate a pendant light in your calculator?


I have no idea how to simulate a pendant light in that calculator, so I haven't been using it for this. I took PAR readings with a 10 watt LED, then scaled up the claimed lumens for that LED to what should give the PAR I desire, which led me to the 25-30 watt LEDs. If I can get one of the 30 watt ones to work with the design I'm using, I will have data for two of the multiple emitter LEDs, and from that it might be possible to figure out a way to use that for a general calculator for pendant lights.

While I wait for my parts to arrive I have been thinking and reading more. Since it looks like adding the red and blue LEDs to the heatsink will block enough air flow to possibly "derate" the heatsink too much, I am thinking of just adding the red LED to the white one. It looks like the cool white LEDs have plenty of blue light in their spectrum, but may be short of red light only.


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## Tom S (Mar 5, 2013)

Hoppy said:


> While I wait for my parts to arrive I have been thinking and reading more. Since it looks like adding the red and blue LEDs to the heatsink will block enough air flow to possibly "derate" the heatsink too much, I am thinking of just adding the red LED to the white one. It looks like the cool white LEDs have plenty of blue light in their spectrum, but may be short of red light only.


In my experience upgrading store fixtures to LED lights, cool white LEDs always have plenty of blue. It's the reds and greens that are lacking - it becomes pretty apparent when you look at meat or veggies under a cool white LED.


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## accordztech (Dec 6, 2004)

So im curious. Depending on the light angle output of those LED's I wonder if the output is better or different than when its not in the aluminum tube. Similar to a light tube for a sealing has a high reflectivity rate, does the aluminum tube help at all?


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## Hoppy (Dec 24, 2005)

accordztech said:


> So im curious. Depending on the light angle output of those LED's I wonder if the output is better or different than when its not in the aluminum tube. Similar to a light tube for a sealing has a high reflectivity rate, does the aluminum tube help at all?


The tube definitely does help. It semi-collimates the light, giving me a circle of light with a well defined border, almost no light outside that circle, and relatively uniform light in the circle. I had planned to do the measurements without the tube just to verify that, but it was very difficult to do - the heatsink comes back out of the tube only reluctantly. The light "cone" is supposed to be 140 degrees, as I recall, so a lot of the light output of the LED ends up being reflected off the inside of the tube. There is no lens on the LED.


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## skanderson (Jul 25, 2010)

do you have the name of the emitters you will be using? and the efficiency. seems odd to go through a build without getting very efficient emitters. also do you have the color temp of the emitters. i am hoping to get at least one of my cannons up and running tomorrow. i will have one 30 watt bxra bridgelux 4k , 2 cree xml 7k, 2 different reds, 2 royal blues, 2 cool blues, and one violet and green. the 3 watters will all be run on different drivers so i can see what they do to the appearance of the light. using just the 4k 30 watt emmiter it gave 34 parr 36 inches below the light using a 60 degree optic. i also need to trim and bend and rivet my reflectors which i will be repurposing the pieces i had cut out of light tube aluminum to make diy MH reflectors. i will be trying for a 10 degree out angle on all 4 sides and making it square. sorry for the hijack but following with great interest.


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## Hoppy (Dec 24, 2005)

You can get loads of information on LEDs, when you use Cree LEDs, and a lot of information for other name brands, but the really cheap ones on Ebay come with a color temperature and lumen rating, and that's about all. The ones I ordered have these specs:
LED Emitter: 30W
Color: Cool White
Output Lumens: 2500-3500LM
DC Forward Voltage (VF): DC 33-35V
DC Forward Currect (IF): 1050MA
Color Temp: 2850-3050K(Cool White)
Beam Angle: 140 degrees
LifeSpan Time: > 50,000 hours

I suspect the color temperature isn't correct, but I won't know until I see them lit up. The driver, which comes with the LED, has these specs:
Driving power: 30w
Model: 10series 3 in parallel
Input Voltage: 85V~265V
Output Voltage: 33-35V
Current:1050mA
Efficiency > 88%
Power Factor >0.98
Operating Temperature: -20~80
Size (L * W * H): 85mm * 26mm * 21mm

The major spec. that attracted me for this combination of LED and driver is:
$5.72 with free shipping

Theoretically I don't need that high a lumen output, so I am thinking of using a parallel resistor to "waste" some of the 1050 mA current, running the LED at a lower current so the heat from it is much less. I would probably shoot for about 700-800 mAmps. At 800 mAmp, I would need a 140 ohm resistor, able to dissipate about 10 watts, in order to bypass about 250 mAmps of the 1050 mAmps driver output. I could get a 25 watt 300 ohm pot from Ebay for about $10, and that would work as a dimmer by bypassing current. If the LED failed the pot would be subjected to 1050 mAmp, about 100 watts until the LED driver failed - a very short time. (Needs more thought!)


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## prototyp3 (Dec 5, 2007)

Sweet project, can't wait to see the final product. I'm a fan of the pendants look over tanks.

I totally hear you on the cost creep while taking the DIY route, it can be troubling. But at least you know what's all going into your project, both in materials and attention to detail.


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## Deano85 (Nov 14, 2011)

Are you sure of that price? That seems like just the led price to me. 

Why not just use a 20w led and driver instead of limiting a 30w to 20 ish watts?


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## Matsnork (Jun 3, 2013)

I like this projekt. Good job.

Some spontanious thoughts: 

* Why not incorporate the thick aluminium tubing in the heatsink solution? Thats a lot of cooling potential just sitting there so close to the led. 

* As you have discovered, 10w "cheap led" is way to weak for anything but nano.


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## skanderson (Jul 25, 2010)

wow excellent price. if the color is decent and they are correct on the lumen rating i may have to get a set of these for a friends new 210 build.


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## mache62 (Aug 10, 2008)

…..so wait, are you using any optics with these LEDs or are you trying to use the can as the optic?


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## Sgtreef (Jun 6, 2004)

Hoppy said:


> PM sent



Could you send to me too Hoppy. thanks

Jefff


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## Hoppy (Dec 24, 2005)

Deano85 said:


> Are you sure of that price? That seems like just the led price to me.
> 
> Why not just use a 20w led and driver instead of limiting a 30w to 20 ish watts?


I sent you a PM with the Ebay item I bought. It is definitely listed as both LED and driver.
Theoretically a 20 watt LED will not provide the PAR I want at the distance I want the light to be. If I do this right I will be able to dim the 30 watt LED a little, and be able to dial it in to the PAR I want. Obviously I need to do some more thinking before using the idea of bypassing some of the current through a potentiometer. There is a way to do this safely, but I haven't thought it through yet.



Matsnork said:


> I like this projekt. Good job.
> 
> Some spontanious thoughts:
> 
> ...


I originally planned for the aluminum can to be part of the heatsink, but I wasn't able to find a circular heatsink that I could easily modify so it would make good thermal contact with the can. Those that are a big enough diameter require a lathe to machine the OD down to match the ID of the can. And, smaller ones have a too small OD to match any available tubing size. That's when I decided to just rely on the can to act as a chimney to enhance the air flow through the heatsink.


mache62 said:


> …..so wait, are you using any optics with these LEDs or are you trying to use the can as the optic?


The can is the optic. It collimates the wide beam of light from the LED into a much narrower beam.


Sgtreef said:


> Could you send to me too Hoppy. thanks
> 
> Jefff


Now that I am switching to a higher wattage LED/driver my parts list is changed. I will wait until I find out if this will work at all, and until I have made any other changes that are needed, before I send out another list of parts.


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## Hoppy (Dec 24, 2005)

This should work, unless it constantly blows fuses on start-up, or unless the surge when a LED fails damages the parts before the fuse blows. It isn't as cheap as I expected though. I will look at dimmable drivers again.

Note: the 550 mA current through the resistors and fuse is when the LED is dimmed the most, down to 500 mA current.


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## Hoppy (Dec 24, 2005)

Re-thinking a bypass current dimmer design, I don't need continuous adjustment of the LED current, just an option to reduce the current a bit to ease the cooling requirement. So, here is my next idea:









The possible problem I see is the total power required, which is 36 watts and the driver is a 30 watt driver.


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## Hoppy (Dec 24, 2005)

I managed to measure the PAR from my 10 watt LED without the can. Here is the photo, from before, with the LED 20 inches from the PAR meter:








and the photo I just took, without the can, with the LED 20 inches from the PAR meter:









You can see the PAR dropped from 21 to 13 at that distance, so the can increased the PAR by 62%. Without the can the PAR drops from 13 to 10 outside of a 12 inch circle.


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## Deano85 (Nov 14, 2011)

Is it possible to remove a resistor like this guy did to get a lower current you`re after.

You can fast forward to 6 minutes. https://www.youtube.com/watch?v=_gTWBo_sUOA&feature=c4-overview&list=UUmHvGf00GDuPYG9DZqQKd9A


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## saiko (Mar 30, 2007)

Hi Hoppy,
I got two ideas for you
(a) Heatsink- if you use a box shape, you can easily attach the heatsink to the side of box. For circular beam, just allow a circular(or even hexagonal) opening at end.

(b) For dimming- why dont you use the light filters you used for your PAR meter? may be have a dial like thing that you can over lap with two half filtered discs, and dial these discs like volume tuner to arrange intensity. Just felt resistor stuff a bit complicated. And this ll look bit special too.

Cheers!


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## prototyp3 (Dec 5, 2007)

At first I was like ... The can increased PAR to 120?!?  ... Then I noticed the display was rotated.


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## Hoppy (Dec 24, 2005)

Deano85 said:


> Is it possible to remove a resistor like this guy did to get a lower current you`re after.
> 
> You can fast forward to 6 minutes. https://www.youtube.com/watch?v=_gTWBo_sUOA&feature=c4-overview&list=UUmHvGf00GDuPYG9DZqQKd9A


It certainly looks like it can be done, but I haven't received the LED or driver yet, so I can't tell if it is made the same way. It probably is, except this driver is already equipped with the DC supply set for 33-36 volts output.


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## Hoppy (Dec 24, 2005)

saiko said:


> Hi Hoppy,
> I got two ideas for you
> (a) Heatsink- if you use a box shape, you can easily attach the heatsink to the side of box. For circular beam, just allow a circular(or even hexagonal) opening at end.
> 
> ...


As I noted before, I don't have a box shaped aluminum tube, but I do have the circular one, so that's what I have to work with for now.

I don't want to dim the output, just reduce the power, to reduce the heat output to the heatsink. And, that may not even be necessary. I'm sort of zeroing in on how to mount a fan on this, without it looking bad or not being effective. It is still a work in progress.

I have thought a lot about adjusting the color temperature using the light filters, but that always involves losing a lot of light too. It would work, but require a higher wattage LED.


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## accordztech (Dec 6, 2004)

Hoppy said:


> I managed to measure the PAR from my 10 watt LED without the can. Here is the photo, from before, with the LED 20 inches from the PAR meter:
> 
> 
> 
> ...


Excellent! This is very interesting. Thanks for sharing!


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## lochaber (Jan 23, 2012)

Someone else who didn't pay attention to detail and thought that aluminum tube was giving you a 10x increase in PAR 

but, neat project, and the pic (021/120 par ...) with the pendant looks pretty nice. simple design, clean, effective, just overall looks good.


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## accordztech (Dec 6, 2004)

If you wanted a fan, you can drop the heatsink down an inch or so. Then secure it with screws or dowels inside. Then put the fan on top (doesn't even have to be a fast flowing fan). Then to mount the light create a cross that will fit within the can and hang it from there on top of the fan.

Doing it this way will hide everything.


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## Hoppy (Dec 24, 2005)

This is how I plan to assemble the new, thicker heatsink, the fan, and the can. The can has the stop "hoop" in the top. The heatsink will have the mounting ears trimmed back so it just fits in the can. The top half of the heatsink will have the fins trimmed back so that part extends above the top of the can, with the bottom part hitting the stop in the can. The fan will sit on top of the heatsink, with the mounting lugs at the top held to the stubs of the mounting lugs on the heatsink with twisted wire in 4 places. The assembly to be hung from a loop of the same wire from a pair of the mounting lugs of the fan. The electric wires will snake into the can through the fins on the heatsink. For now I will omit the red LED - until I see how hot the heatsink gets from just the 30 watt LED. The LED will be screwed to a piece of 1/4" thick aluminum plate which will be held with one countersunk screw to the hub of the heatsink which is only an inch in diameter. (With use of heat conducting grease, of course)

The reason the heatsink will be partly above the top of the fan is to get more area for air flow through the heatsink fins, and to raise the LED to the location where I had the 10 watt one. It won't look as good as it did, but I think I can make it look ok - probably paint the fan housing white to match the aluminum tube can.

The fans I have ordered from Ebay at $10 apiece - $$$ keep adding up!


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## accordztech (Dec 6, 2004)

lol my exact idea...


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## The Big Buddha (Jul 30, 2012)

Great thread. When will these go into mass production?


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## Hoppy (Dec 24, 2005)

The Big Buddha said:


> Great thread. When will these go into mass production?


I will mass produce them when bananas grow in Antarctica.:icon_mrgr

I received the 30 watt LEDs and drivers yesterday. The LEDs are huge, compared to 3 watt star mounted LEDs - about 2 inches square with the mounts. The Drivers are just a DC voltage supply with a voltage regulator set up as a current regulator. I can't identify which of the tiny resistors soldered on the bottom of the circuit board are the current setting resistors, nor can I tell what resistance they have. And, this requires a magnifying glass for me to even pick them out. I doubt that I will try to remove a resistor to drop the current - I do think there are 3 parallel resistors that do that job.








The voltage regulator terminals are the 3 closely spaced solder dots on the top left side of the photo. But, I can't trace the connections well enough to identify the current setting resistors.


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## O2surplus (Jan 31, 2010)

Hoppy-

Can you see a part # on U1? That may be the driver IC and more could be learned if the chip is identifiable?


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## Hoppy (Dec 24, 2005)

O2surplus said:


> Hoppy-
> 
> Can you see a part # on U1? That may be the driver IC and more could be learned if the chip is identifiable?


The numbers on that part are:
BP3309
135568
039

(I'm a vacuum tube man!)


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## Sake (Mar 30, 2012)

> I will mass produce them when bananas grow in Antarctica.


 Lol Hoppy with global warming that may be sooner than ya think!


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## O2surplus (Jan 31, 2010)

Hoppy said:


> The numbers on that part are:
> BP3309
> 135568
> 039
> ...


I found it! That little IC is an Led driver. Here's a link to it-http://www.bpsemi.com/BP3309.asp
From the diagram, it looks like the current sensing resistor is attached to pin #1 (CS). Just locate the #1 pin identifier "dot" and and follow the trace to the first resistor.


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## Hoppy (Dec 24, 2005)

O2surplus said:


> I found it! That little IC is an Led driver. Here's a link to it-http://www.bpsemi.com/BP3309.asp
> From the diagram, it looks like the current sensing resistor is attached to pin #1 (CS). Just locate the #1 pin identifier "dot" and and follow the trace to the first resistor.


Very interesting! Here is some more information.









Assuming I could remove/replace a resistor on this, which one and what would I replace it with? (That is a much bigger assumption than you might think.)


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## Deano85 (Nov 14, 2011)

Can you see any values on the resistors ?


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## O2surplus (Jan 31, 2010)

Hoppy-

The two resistors marked 1R20 should be the current sense resistors that your looking for. They appear to be made in the metric "1206" package and should ohm out at 1.2 ohms each. If they happen to be wired in parallel with each other, I'd say de-solder one of them and try out the driver again.Removing one resistor should essentially cut the current reaching the CS pin in half and reduce the driver's output considerably.


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## Hoppy (Dec 24, 2005)

I will try the drivers as they are first, and if they are usable that way I won't bother with trying to reduce the current. I'm pretty sure it is beyond my ability to desolder one of those resisters, or re-solder it back. Maybe I could have done that 20 years ago, but not now.


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## skanderson (Jul 25, 2010)

can you put a killowatt on this when it is all set up. i am wondering how efficient that driver/led combo is at putting out lumen/watt.


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## Hoppy (Dec 24, 2005)

skanderson said:


> can you put a killowatt on this when it is all set up. i am wondering how efficient that driver/led combo is at putting out lumen/watt.


The efficiency isn't a concern of mine. I will be delighted if it works, provides the PAR I want, and doesn't spill light all over the room. For the best efficiency you would always use LEDs sitting right at the top of the tank, and that isn't the goal here.


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## The Big Buddha (Jul 30, 2012)

Hoppy said:


> I will mass produce them when bananas grow in Antarctica.:icon_mrgr


Careful about making promises like that. :red_mouth


http://www.polarcom.gc.ca/eng/content/did-you-know-they-grow-bananas-iceland

Yeah I know this isn't Antarctica, but similar climate.


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## Tom S (Mar 5, 2013)

Brief diversion from your build to ask a couple questions. 

Do you think you would get the same light dispersion if you were to go with a number of smaller LEDs instead of a single 20-30W LED? I'm bouncing the idea of fabricating a light in much the same way, but using a punched Aluminium plate to hold 7 LEDs mounted on a star pcb's. I'm hoping that by having the aluminium plate make good contact with with the walls of the fixture the whole fixture will form an effective heatsink with a chimney effect to promote airflow. 

Here's a screenshot of what I was thinking:



Ok, back on topic.

How do you plan on mounting the pendant with the fan on top like that?


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## Hoppy (Dec 24, 2005)

Tom S., Theoretically, the more you spread out the LEDs from the center of the "can", the more spillover light or the bigger the circle of light will be, and the more variation in PAR across the circle of light. But, the longer the "can" the smaller those effects will be, and the smaller the circle of light. So, I'm pretty sure your idea of using several lower wattage LEDs, star mounted, will work. Another way to do it would be to have 3 or more LED junctions on one 20 mm star mount, like http://shop.stevesleds.com/3-up-Tristar-Connected-Wiring-AntiDisco-Tristar-AntiDisco.htm This could let you build a similar light, but with 9 LEDs mounted on only 3 star mounts, so they would be clustered in the center close together. I looked at this a long time, but I'm not sure I would get enough oomph for what I want, without using a very much higher cost set of LEDs.

I will hang the can's with a wire from two of the fan mounting holes, with a wire attached to the center of that, to the support above. Until I get the fans I ordered I can't be sure of the details. A last ditch way would be one of the wire grids that are sold to attach to the fans to protect people's fingers, with the hanging wire attached at the center of that.


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## Hoppy (Dec 24, 2005)

I got the fans I ordered yesterday. They are exactly as advertised, with simple cylindrical body and 4 tabs at one end for mounting. I spent a few hours trying to find a way to install it like the sketch I posted before, but the dimensions just wouldn't work for that - not enough room for all of the parts. So, I started over, with the idea of keeping the fan and heatsink totally out of the can. This will work much better, easier, and with less modification of the heatsink, plus better air flow over the fins.










I will use 4 #8-32 pan head screws and make angle end pieces for each end, one to attach the fan/heatsink to the can, on top of it, and the other as a place to tie the support cable on top. I got a 3 foot length of aluminum angle, at Home Depot, with 1/2" and 3/4" legs, 1/16" thick material. That gives me more than enough material to learn to make angle brackets that will fit right. I hope to start working on this again, tomorrow.


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## Hoppy (Dec 24, 2005)

This is where I stand right now. The assembly scheme works. I still need to drill and tap the holes in the can for the 6-32 screws to hold the can to the heatsink/fan assembly.


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## 93MSB (Dec 5, 2013)

did you switch to a pvc tube?


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## Hoppy (Dec 24, 2005)

93MSB said:


> did you switch to a pvc tube?


No, it is the same aluminum tube, just painted flat white on the outside. 

I just finished adding a 1/8" thick aluminum plate on the LED mounting surface of the heatsink, to enlarge the surface to accomodate the big 30 watt LED and 2 small 1 watt red LEDs. I flattened and polished the mating surfaces, drilled and threaded a hole in the middle of the heatsink, used thermal compound between the two pieces.









Now I need to drill and tap the LED mounting holes in the plate.

I'm also rethinking the method for hanging the light. Since I will have a 6 conductor cable going from the two LED drivers and the fan DC power supply, I might as well use that cable to hang the light. I'm not sure yet how to make that look good.


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## Hoppy (Dec 24, 2005)

This is how it looks externally. The electric cable, with 6 conductors, 2 each for the fan, the 1 watt red LEDs, and the 30 watt white LED, will be separated into two bundles of 3 conductors each. Each of those will be held together with shrink tube insulation, and those will go down through the extra mounting holes in the fan, then through the extra mounting slots in the heatsink, and into the can. That cable will also be the hanger wire for the light.

My 12 VDC power supply (wall wart), for the fans, will arrive next week sometime - $3.40 on Ebay. Then I can complete the assembly and test it. (Fingers crossed).


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## Hoppy (Dec 24, 2005)

LED's on heatsink. The big one is held by 4 #4-40 screws, with heat conducting compound, and the small ones will be cemented on. Tomorrow I will go shopping for the 6 conductor cable, and maybe do the hook-up.


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## xmas_one (Feb 5, 2010)

Very nice!!! Can't wait to see the numbers on this one.


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## Hoppy (Dec 24, 2005)

The wiring at the light is complete. The hanging "bridle" isn't perfect, but from the normal distance it looks pretty good. Next will be mounting the drivers, etc. on a board, to be installed under the tank, with some kind of water protection, and connecting the cable to the power.

Soldering was very difficult because of the heatsink cooling the LEDs so effectively. This was much harder than the other LED light soldering I did.


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## skanderson (Jul 25, 2010)

looking good really like to see the final numbers and what it looks like. i just finished soldering and testing all my leds this afternoon. i need to drill and rivet my reflectors and then i will post my pendants on my tank build thread. very nice looking product hope it works well.


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## Hoppy (Dec 24, 2005)

skanderson said:


> looking good really like to see the final numbers and what it looks like. i just finished soldering and testing all my leds this afternoon. i need to drill and rivet my reflectors and then i will post my pendants on my tank build thread. very nice looking product hope it works well.


I can't turn it on until I have the 12VDC power supply for the fan. I'm getting pretty anxious too.:icon_sad:


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## Deano85 (Nov 14, 2011)

I know its too late, but you could of gone for a real factory look with these.


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## Hoppy (Dec 24, 2005)

Deano85 said:


> I know its too late, but you could of gone for a real factory look with these.


Darn! I missed the boat.:frown:


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## accordztech (Dec 6, 2004)

Looks good bud!


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## Hoppy (Dec 24, 2005)

I finally received my 12VDC power supply. It is a 12 Volt, 2 Amp "Switching power supply". Please don't tell me that means it is a constant current supply?


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## vladguan (Dec 19, 2013)

Hoppy, it is a constant voltage supply. I use them for my lights. I run 4 12V 0.75a LED lights off of one 12V 5a switching supply. The switching bit, from memory just means it can switch betwen different AC supply voltages. Merry Xmas.


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## yashmack (May 20, 2013)

Hoppy said:


> I finally received my 12VDC power supply. It is a 12 Volt, 2 Amp "Switching power supply". Please don't tell me that means it is a constant current supply?


Switching does not mean constant current
if it were constant current the specs would be something like 10 - 15 Volts at 2A constant
Switching power supplies are not constant current normally and are more like the power supplies you find in a PC
You will probably need a constant current driver to get the best use out of your LED

http://en.wikipedia.org/wiki/Switched-mode_power_supply


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## m00se (Jan 8, 2011)

Well, not quite. The switching PS uses high frequency switching transistors that are not in a state or condition that passes maximum current constantly but only when called for. These are much more efficient than constant current PS's and also cost a lot less to make. No need for a huge chunk of copper. They also need to be designed to minimize RF noise created by their HF switching. If not they can wreak havoc on your other electronics. They're also sensitive to the types of loads they see. But they're definitely not variable current unless designed that way.


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## yashmack (May 20, 2013)

m00se said:


> Well, not quite. The switching PS uses high frequency switching transistors that are not in a state or condition that passes maximum current constantly but only when called for. These are much more efficient than constant current PS's and also cost a lot less to make. No need for a huge chunk of copper. They also need to be designed to minimize RF noise created by their HF switching. If not they can wreak havoc on your other electronics. They're also sensitive to the types of loads they see. But they're definitely not variable current unless designed that way.


Im pretty sure with most generic switching power supplies you get that they only supply as much current as the load demands...
if you have a 12v 1 amp fan on the 2 amp power supply it will only supply 1 amp and not the full 2 amps, which means that the load is variable and therefore not constant current

we would need a manufacturer and model to tell you for sure though


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## m00se (Jan 8, 2011)

Of course, but the CC supply would have that full 2a available at all times unlike the SS.


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## yashmack (May 20, 2013)

m00se said:


> Of course, but the CC supply would have that full 2a available at all times unlike the SS.


which is why i said he would need a constant current driver for the switching power supply


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## Hoppy (Dec 24, 2005)

This switching power supply is just for the cooling fans, so it should work fine. Now, I just have to see what it does to my TV reception - at $3.40 it may be electrically noisy. If I hadn't made a snap judgment in buying this on Ebay I should probably have just looked for a used battery charger at my local electrical salvage store. But, who could resist an auction where a $3.40 bid would buy such a wonderful product?? Ebay is not for those with poor impulse control:hihi:


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## benjaf (Mar 27, 2012)

AFAIK the biggest difference a switched power supply brings you (aside from potential noise) is, that it actually keeps a constant voltage. A lot of the cheap wall adapters you get with various electronics will supply a much higher voltage than it is supposed to if the load is smaller than the rated current. For instance, one of the wall adapters I have 'salvaged' from old electronics is rated 9v 500mA. If drawing very little current (like an arduino) it can go as high as 14v, but used to it's limit it will be right around 9v as expected. This should not happen with a switched supply.


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## vladguan (Dec 19, 2013)

I totally concur with benjaf. I had some spare 12v adapters and tested them with multimetres. multimetres don't draw much current so the voltage reading was 19v. One other thing, as m00se said, switching ones will weigh a lot less than the old non-switching ones (chunk of coper) and are definitely constant voltage and provide as much current as needed, upto its max. Thus my four 12v/0.75a LEDs hooked up to a 12v/5a switching adapter in parallel each daws 12v/0.75a which means it has a reserve of 2a. And as mentioned already, switching or switch-mode are designed to handle an input voltage/frequency range via transistors and provide regulated constant voltage and current on demand upto their max.


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## Hoppy (Dec 24, 2005)

I feel very much better about my "bargain" 12VDC supply now! Of course, being the holiday season, I haven't had the time to work on this to find out how it all works together. I think by tomorrow, Friday, I will have the time again. If not, as they say, wait until next year.

EDIT: I just spent a few minutes connecting the power to one of the lights. It works! The only disappointment, and one I expected, is that the red light doesn't mix at the edges with the white light, because the red LEDs are not centered, but on each side of the white. That puts a red area to each side of the white. I just heard that we are about ready to leave for one more visit - 4th of the week - so I can't do any PAR measurements today. Something to look forward to for tomorrow.


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## Hoppy (Dec 24, 2005)

Disappointing results! I got 27 PAR at a distance of 27 inches, 16 PAR at 33", and 8 PAR at 45 inches. That's about 2/3 of what I wanted, and even less than I expected. It works fine other than that. And, it will be usable on my tank, but not at the height I wanted above the top of the tank. Here is the Rube Goldberg set-up I calibrated it with:


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## Deano85 (Nov 14, 2011)

Can you measure the par just with the white led. Wondering how much the red and blue actually does.


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## Hoppy (Dec 24, 2005)

Deano85 said:


> Can you measure the par just with the white led. Wondering how much the red and blue actually does.


No blue LEDs involved. I am using two red 1 watt LEDs, one on each side of the cool white 30 watt LED. The red ones add an insignificant amount of PAR, without even testing. At most it would add 3/30 of the PAR, or around 1 PAR, which isn't detectable by the PAR meter. Their only value is to help pep up the red colors in the fish and/or plants.


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## vladguan (Dec 19, 2013)

Hi Hoppy, I suggest replacing the reds with warm white ones to add warmth to the colour. I have read that a few people have done that when they weren't happy with the blend.


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## Hoppy (Dec 24, 2005)

vladguan said:


> Hi Hoppy, I suggest replacing the reds with warm white ones to add warmth to the colour. I have read that a few people have done that when they weren't happy with the blend.


I could do that, but the only reason for the red ones is to help show the red colors on the plants and fish. Warm white 1 watt LEDs would add very, very little in either PAR or color enhancement.

Here is the data I have, plotted in order to see what it would take to make this do what I want it to do:









I would need to use at least 40 watt LEDs, and I haven't seen a heatsink this size for that high a power. One factor I hadn't looked at is that the little LED drivers that match the 30 watt LEDs don't drive them at full current, so I am probably not getting the rated lumen output on them. I wouldn't gain enough to do much good even if I could increase the current. I'm not sure if I will finish this now.


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## skanderson (Jul 25, 2010)

I will take the par readings under my new pendants with 30 watt leds to see what the difference the bridgelux make. should be interesting. there will be some difference due to the reflectors being different as well. but it should still be interesting. thanks for posting numbers, I hate it when people only show things that work great.


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## Hoppy (Dec 24, 2005)

My next move will be what Vlad suggested:  replace the red 1 watt LEDs with warm white 3 watt LEDs. That will increase the power, and lumens by about 20%, and should get me very close to the PAR I want. I just ordered them and their drivers from the LED capital of the world - China.


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## vladguan (Dec 19, 2013)

Get the warmest you can to add as much red as possible.


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## yashmack (May 20, 2013)

what power supply are you using for the LEDs?


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## Hoppy (Dec 24, 2005)

yashmack said:


> what power supply are you using for the LEDs?


I'm not using a power supply. I'm using a 30 watt LED driver for the 30 watt LED and a driver for 1 to 3 one watt LEDs for the 2 one watt LEDs. They are fed with standard 120 VAC power, and produce a constant current at the appropriate voltage for the LEDs. In both cases they drive the LEDs at a bit less than full rated current. I am thinking about installing a 1 ohm resistor in the wire to the LEDs to measure the current, but, since I can't easily change that current I may not bother.


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## Hoppy (Dec 24, 2005)

I bought a couple of LED drivers on Ebay for the 3 watt warm white LEDs I now have. Both have no markings to identify which wires on them are output, + and -, and which are input AC voltage. Is there an easy way to tell which is which?


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## Deano85 (Nov 14, 2011)

My guess is the white pair because they are closer to the transformer.


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## Rooster (Apr 3, 2006)

the two whites will be ac.... 

Sent using Tapatalk from my ZX81


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## Hoppy (Dec 24, 2005)

I think the two whites are AC, and I suspect the pink one is DC+. Does that seem reasonable? The other one has a yellow wire instead of a pink one.


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## vladguan (Dec 19, 2013)

Yes, the two white ones will be AC as polarity does not really matter. You can check DC polarity via a multimeter or a DC fan. See the way it is spinning to determine polarity.


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## Hoppy (Dec 24, 2005)

This is the light, with 2 x 3 watt warm white LEDs, plus the 30 watt LED, at 36 inches above the PAR meter. Only 15 PAR! I'm disappointed I think. My plan was to get 20-25 PAR at that distance. More testing to follow.










25 PAR at 29 inches. This isn't any better than it was with the 2 x 1 watt red LEDs. I think this would work fine with a 40B tank, but it isn't likely to work at all well with my 65 gallon tank. The distances are from the LEDs not from the end of the can. That means the bottom of the can is only about 23 inches from the sensor in this photo. That would be about 1 inch above my 65 gallon tank if I used it there - 2 inches of substrate.


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## Deano85 (Nov 14, 2011)

What about shortening the can and attaching some kind of optic.


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## Hoppy (Dec 24, 2005)

Deano85 said:


> What about shortening the can and attaching some kind of optic.


Of course there are many ways to use LEDs. This project is about using them with a cylindrical "can" as the optical element that concentrates and evens out the PAR. The evening out part worked perfectly. For both of those tests shown above the PAR was very nearly the same over the entire diameter of the main circle of light. None of the optics we can easily buy for LEDs have that feature.

I think the next step is to try to greatly improve the polishing of the inside of the cylinder, to see if that gives me the needed gain in PAR. I haven't figured out a good, non power tool way to achieve that polish, but I'm sure there is a way.


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## DogFish (Jul 16, 2011)

I'll be interested in seeing how you manage to polish inside that little can without resorting to a power tool. 

I did see a Foam Buffing Ball attachment at AutoZone, if you should need take advantage of modern tool technology.


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## Hoppy (Dec 24, 2005)

DogFish said:


> I'll be interested in seeing how you manage to polish inside that little can without resorting to a power tool.
> 
> I did see a Foam Buffing Ball attachment at AutoZone, if you should need take advantage of modern tool technology.


While trying to go to sleep last night it occurred to me that I can just line the can with aluminum foil and find out if it is even worth the work polishing the inside of the can. That will be my next test. I am cautiously optimistic

EDIT: I just tested it with aluminum foil lining the "can", shiny side towards the light, and the foil is a little crinkled. I got 14-15 PAR at 36 1/2 inches. That is the same as without the foil, so I doubt that there is much to gain by polishing the inside of the can any more. Most of the reflectivity of aluminum is due to molecular issues, not extreme polishing - aluminum is inherently a very good reflector. 

The somewhat crinkled surface did result in a less well defined circle of light. The effect isn't a big effect, but it is still there. And, the almost uniform brightness over the circle of light is still there.

DogFish, I was thinking of using a flapper wheel to start the polishing, by getting rid of the ridges and grooves. Then using finer and finer sand paper to finish it. I don't consider a hand drill to be a "power tool".


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## Hoppy (Dec 24, 2005)

I have one more idea for increasing the PAR from this. One thing the "cans" do is concentrate the light into a relative small circle. The longer the "can" the smaller the circle. So, tomorrow I plan to add a 3 inch long extension to the "can", made from aluminum foil, and measure the PAR with and without it. That should tell me what length of "can" is needed to get the PAR I want. If it is a reasonable length I can make new "cans" from cheaper material than the thick wall aluminum pipe - PVC, thin wall aluminum pipe, even cardboard, using aluminum foil for the reflective surface for the non-aluminum materials.


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## Hoppy (Dec 24, 2005)

I made an extension for the can from a big envelope - heavy paper - plus aluminum foil, and extended the can to 12.5 inches long, then 10.5 inches long. 










Plotting the PAR vs the length of the can, with the LEDs always 36 inches from the PAR sensor gave me this:









Making the can longer definitely is a way to get higher PAR, over a smaller circle. It looks like I need to make the can about 10 inches long to get 20-25 PAR at 36 inches.


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## benjaf (Mar 27, 2012)

Hoppy said:


> Making the can longer definitely is a way to get higher PAR, over a smaller circle. It looks like I need to make the can about 10 inches long to get 20-25 PAR at 36 inches.


So.. You will end up with the pendent ending ~4 inches above the surface? That's unfortunate! 

EDIT: Maybe if you lost the 3w LEDs you could use a second narrower can inside the primary one?


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## Hoppy (Dec 24, 2005)

benjaf said:


> So.. You will end up with the pendent ending ~4 inches above the surface? That's unfortunate!
> 
> EDIT: Maybe if you lost the 3w LEDs you could use a second narrower can inside the primary one?


Yes, I would prefer that the can end about 6 inches above the top of the tank, but I can live with 4 inches. At least there will be virtually zero spilled light this way.

I think I will get a 4" aluminum vent pipe for dryers to use for the can. It may be larger in diameter than this one, so I may end up with the can even closer to the water. I picked the 4" diameter to match the heatsink, but I suppose I could use a 3 inch diameter without it looking too weird.


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## Rooster (Apr 3, 2006)

Can't you simply add a lens? 

Sent from my ZX81


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## vladguan (Dec 19, 2013)

My thoughts too but Hoppy wants to mix colours which wont work with a lens.


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## Hoppy (Dec 24, 2005)

A lens tends to give you a very intense light in the middle of a decreasing intensity ring. In other words it doesn't give you anything near uniform lighting. This "can" idea does give a nearly uniform circle of light. And, it also mixes up the colors of any multiple LEDs you use. And, as a bonus, it eliminates virtually all of the glare and spilled light.


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## vladguan (Dec 19, 2013)

How about a 90 deg lens in conjunction with the can?


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## Hoppy (Dec 24, 2005)

I don't think a 90 degree lens would do anything useful. Unless the lens angle is around 40 degrees the light gets semi-collimated anyway. The lens might reduce the size of the circle of light a little, by reducing the outer, lower intensity part, that caused by light single reflected in the can.

I have a 10 1/2 inch long piece of 4 inch dryer vent duct now, ready to mount on the heatsink, which looks fairly easy to do. If I make it overlap the heatsink by about 1/2 inch I will have my 10 inch can length. That's tomorrow's job!

The aluminum dryer vent ducts come not yet rolled up completely, so they are easy to cut, with scissors, and very shiny polished aluminum. Kind of flimsy compared to my nice .085" wall aluminum tube, but adequate and not too bad looking. http://www.acehardware.com/product/index.jsp?productId=1276784 except the store sells them individually for about $4.50 each.


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## benjaf (Mar 27, 2012)

Hoppy said:


> A lens tends to give you a very intense light in the middle of a decreasing intensity ring. In other words it doesn't give you anything near uniform lighting. This "can" idea does give a nearly uniform circle of light. And, it also mixes up the colors of any multiple LEDs you use. And, as a bonus, it eliminates virtually all of the glare and spilled light.


Actually, the ebay lenses + base combined with a 'collar' to eliminate glare gives a pretty even light distribution on my 10W LEDs. Maybe because the light source is relatively large?

But I must admit, I was quite intrigued by the idea of using only a can..


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## Hoppy (Dec 24, 2005)

benjaf said:


> Actually, the ebay lenses + base combined with a 'collar' to eliminate glare gives a pretty even light distribution on my 10W LEDs. Maybe because the light source is relatively large?
> 
> But I must admit, I was quite intrigued by the idea of using only a can..


I started this idea thinking only about eliminating the glare, then noticed that it should help increase the PAR from a 10 watt LED. Now I am determined to see it through as the only "optic" being used to get the PAR and distribution of PAR that I want. So, I'm intrigued too. :biggrin:

Unfortunately, my low cost LED light is now a high cost light, given all of the changes I have made, and parts I have had to discard. It might still be economical if I don't include the cost of the mistakes.


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## benjaf (Mar 27, 2012)

Hoppy said:


> Unfortunately, my low cost LED light is now a high cost light, given all of the changes I have made, and parts I have had to discard. It might still be economical if I don't include the cost of the mistakes.


These kinds of projects have a tendency to do that.. I have spent more money on my 'cheap' 10W (now 30W combined) light than I care to think of. Fried LEDs, drivers reacting badly to PWM switching, just ONE more length of aluminium, the list goes on. But I guess that is the price of learning. And this is not exactly a cheap hobby to begin with! :redface:


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## yashmack (May 20, 2013)

have you tested it without the can? Im just curious as to what the par is without the can on it.


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## Hoppy (Dec 24, 2005)

yashmack said:


> have you tested it without the can? Im just curious as to what the par is without the can on it.


No, I haven't tested the 30 watt + two 3 watt warm white LEDs minus the can. I will do so soon.

I just ran into another interesting thing: I tested this with the dryer vent duct can, which is very shiny polished inside. I got 20 PAR at 36 inches, but not very uniform. The PAR varied from about 15 to 20, with two peaks off center where the warm white added the most light. I'm going to use 400 grit paper to dull the finish inside to see if that gets me back to where I was. I think I'm getting too sharp an "image" of the light now, due to the better polish of the aluminum. (The opposite of what I expected!)


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## benjaf (Mar 27, 2012)

How about a diffuser somewhere below the LEDs? Might be able to get a decent result that way without damaging the duct.


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## Hoppy (Dec 24, 2005)

This is without any can on the light. That's 12 PAR, not 21. And, it is at 36 inches, where I got about 20 with the can, a 67% increase in PAR with the can.










This is after the inner surface of the can has been lightly sanded with 400 grit paper. The PAR dropped from about 20 to 17, still with two "hot spots" off center, apparently in line with the 2 warm white 3 watt LEDs. You can see two dim yellow circles where the warm white LEDs are giving maximum light. But, the light is much better mixed, and the variation in PAR is much less, now dropping to about 15-16 away from the hot spots. Based on this the can gives a 42% increase in PAR. The very bright small circle of light is a direct reflection from the floor of the end of the can.


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## Hoppy (Dec 24, 2005)

I tried to use simple geometry to figure out how the PAR reading should vary with the length of the can, at a fixed distance. I used my last data point, with the lightly sanded can as a starting point. From this I figured that a 12 inch long can should give me a maximum PAR in the lighted circle of 20-25. So, I made a 12 inch long can from the rest of the dryer vent pipe I have, and set it up at 36 inches and measured the PAR again:


















You can see that I did get the 20-24 PAR that I should get. Of course now the circle of full PAR light is only about 12 inches in diameter, a bit small for an 18 inch front to back 65 gallon tank, but workable I think.

The chart of PAR vs can length, with the red data points the two can lengths I used, and the red line is what I calculate should be the variation with can length, is:









Now, I need to decide whether it is worth it to finish the project. This seems to be a good lighting arrangement for a 40B tank, only 17 inches high, but very questionable for a 65 gallon tank, 24 inches high.


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## Hoppy (Dec 24, 2005)

I don't think I will go any farther with this project. It clearly won't be adequate for a 65 gallon tank, and, in fact would only work for a tank 12 inches front to back and 24 inches long. The circle of light is only about 12 inches in diameter at a PAR of 20-25, which is about as low as I would ever want to use. I think the 30 watt LED is just not going to work for a larger tank.

However, if I wanted to spend a lot more money, like $120, I could substitute an array of Cree XM-L high efficiency, high power LEDs and probably make it work. Here is how they would fit in:









Seven of those LEDs would produce about 5600 lumens, about twice what the 30 watt LED is supposed to produce. And, they would be close enough together to produce reasonably uniform light, using the same 4" diameter cans. I think this is still a pretty good approach, but not with the Ebay 30 watt LEDs.


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## skanderson (Jul 25, 2010)

im pretty sure you would get to an acceptable lvl of par is you changed the led to a 30 watt bridgelux bxra. my set up gave 137 par at 37 inches below my 5 pendants. it was directly below the center light but the others were about 18 inches off center. even if you assume max light from 5 leds that is over 30 par per emitter at 36 inches. once I install my dimmer I will light only the center light and remeasure the par although the reading will be through around 24 inches of unclear water. the emitter and bxra together cost less than 15 bucks. you would still need a power supply but that would allow you to run many ldd drivers.


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## yashmack (May 20, 2013)

are you using the same par meter you posted about building in this section?
Im very interested in the data youve provided as ive wanted to see par values for these off brand LEDs lights
Im wondering what kind of PAR values the 10W LEDs will give

I really appreciate the readings with the can off, it is very interesting to see how the can will increase the par value

I want to get some 10w leds and check the PAR on those and possibly with some of the lenses to focus the light a bit more

Im using four 10w LEDs in a 55 gallon but have no idea what the PAR values for them would be


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## Hoppy (Dec 24, 2005)

The PAR meter I am using is one I made several months ago. It reads the same as the Apogee Quantum meter, but about 2% low, from repeated calibrations. It is as good as the Apogee meter as long as it is used for typical aquarium lighting.

I agree that there are other, more expensive LEDs I could use so this would work OK, but I don't want to spend that much more money on it. Maybe I will go back to this some other time. Working with LEDs is very interesting, largely because there are so many ways to set them up, and so many variables to consider when doing so. It is almost a hobby in itself.


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## Hoppy (Dec 24, 2005)

Using the data I have for this design, here is a way to approximate how much PAR you will get, knowing the total lumen output of the LEDs you use, the can height, and the height of the LEDs above the PAR sensor:

I = .05P(L/H)^2 where I equals the PAR, P equals the total lumens, L equals the height of the can, and H equals the distance between the LEDs and the PAR sensor.

This won't give an exact value, but it should let you figure out about what PAR you would get. All of this with a 4 inch diameter can. I don't have any data to be able to figure out the effect of changing the can diameter.

So, if I want 30 PAR at 36 inches, with a 10 inch long can, I will need about 7800 lumens from the LEDs. I only had about 3700 lumens, so it is easy to see that this couldn't work the way I hoped.


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## yashmack (May 20, 2013)

thanks for the data
Ive got a baseline of sorts now for when I start working on my LED set up
I just need to make myself a par meter 
Ive got a cheap lux meter i need to find and see if i can modify


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## saiko (Mar 30, 2007)

Hi Hoppy,
I have been following this regularly, and many thanks for your numbers.
If I wanted to attempt your 7 -XML rig, will it be for running at 2A ?
Also will same heatsink do?


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## saltykisses (Dec 30, 2013)

Why don't you look into making a triangular shape using mirror glass/ or something highly reflective .. To increase the par variance ...


Sent from my iPhone using Tapatalk

So your bending the light at r angles instead of curving the light..

Or maybe a funnel shape ..

Or you could try small mirror tiles to increase the reflectivity of your lampshade..


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## saltykisses (Dec 30, 2013)

Or even bicycle reflectors...


Sent from my iPhone using Tapatalk


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## skanderson (Jul 25, 2010)

an easy but not cheap way of making a better reflector is to buy the light tunnel extension kits from a home improvement store. it is very reflective I think around 96 percent and will hold up well to the moisture. you could either just roll it into a tube or fold it into a square shape for a better distribution of light in a rectangular tank. it definitely isn't cheap though I think they run about 45 bucks for a 14 x20 inch piece.


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## Hoppy (Dec 24, 2005)

saiko said:


> Hi Hoppy,
> I have been following this regularly, and many thanks for your numbers.
> If I wanted to attempt your 7 -XML rig, will it be for running at 2A ?
> Also will same heatsink do?


I think I used 2.5 amps as the current when I was evaluating those Cree LEDs for this. The heatsink didn't get at all warm with the 30 watt plus two 3 watt LEDs, so I think it can keep the Cree LEDs adequately cool. Remember, the Cree LEDs are more efficient, so they have less heat loss to dissipate than the 30 watt LED, per watt of power. You would have to test it to be sure, of course, and don't forget that the fan is essential.



saltykisses said:


> Why don't you look into making a triangular shape using mirror glass/ or something highly reflective .. To increase the par variance ...
> 
> 
> Sent from my iPhone using Tapatalk
> ...


Mirrors are not highly reflective, they just reflect an accurate image. Aluminum is a much better reflector than anything with the possible exception of gold and silver.
You can't "curve" the light. It always reflects, not at right angles, but at an angle equal to that at which it strikes the reflector.



saltykisses said:


> Or even bicycle reflectors...
> 
> 
> Sent from my iPhone using Tapatalk


Again, aluminum is a far better reflector than bicycle reflectors.



skanderson said:


> an easy but not cheap way of making a better reflector is to buy the light tunnel extension kits from a home improvement store. it is very reflective I think around 96 percent and will hold up well to the moisture. you could either just roll it into a tube or fold it into a square shape for a better distribution of light in a rectangular tank. it definitely isn't cheap though I think they run about 45 bucks for a 14 x20 inch piece.


Those skylight tubes are made of either aluminum or aluminized mylar. The aluminized mylar varies greatly in reflectivity, depending on the thickness of the aluminum coating. the skylight tube I installed a few years ago allowed a lot of light to pass through, lighting my attic as well as the room it was supposed to light. But, those are the same idea as this is - a light pipe.


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## saltykisses (Dec 30, 2013)

Is that a fact?! Can you be sure.. That they're is not a better way of concentrating the light


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## Rooster (Apr 3, 2006)

Mirrors are not highly reflective? 
you should point this out to the world's observatories! 

Sent using Tapatalk from my ZX81


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## saltykisses (Dec 30, 2013)

Mirrors are made with different metals though .. So I do understand where hoppy is coming from.. But I think they're must be another way putting the light through a crystal/lense or something.. There has to be something your missing..


Sent from my iPhone using Tapatalk


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## benjaf (Mar 27, 2012)

Sure you could use a lens (that is after all what they are for) but the point of this exercise was to use a reflective can to both mix the light of different color diodes and replace traditional optics. And it sort of worked too, but the cheap LEDs simply aren't efficient enough to light a tank that size.

EDIT: And about (bicycle) reflectors and the like - they are specifically designed to reflect a decent amount of light directly back at the source, which is not exactly a desired property in this case..


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## Hoppy (Dec 24, 2005)

Rooster said:


> Mirrors are not highly reflective?
> you should point this out to the world's observatories!
> 
> Sent using Tapatalk from my ZX81


Not all mirrors are alike. Mirrors made to be used on telescopes are just aluminum reflectors, with a glass backing to shape them properly. The light does not pass through any glass. Ordinary mirrors, made for looking at your pimples, are very poor reflectors. They reflect a relatively small part of the light back to you. Telescope mirrors, and reflectors we want for our lights, have in common the need to reflect as close to 100% of the light as is possible. A household mirror may reflect 80% of the light. That is not highly reflective. Some front surface mirrors, like telescope mirrors are, may let an appreciable amount of light pass on through, due to having a very thin coating of aluminum.


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## Rooster (Apr 3, 2006)

but you didn't WANT good reflector, did you? 
also, if a normal mirror only reflects 80%...where's the other 20 get to? 

Sent using Tapatalk from my ZX81


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## Hoppy (Dec 24, 2005)

Rooster said:


> but you didn't WANT good reflector, did you?
> also, if a normal mirror only reflects 80%...where's the other 20 get to?
> 
> Sent using Tapatalk from my ZX81


Why do you think I didn't want a good reflector? Light that strikes a surface is reflected, absorbed (by the dark substances in the path) or transmitted (through the reflector). I assume you think that my lightly sanding the surface of the aluminum meant I didn't want good reflection. That isn't the case. What I wanted was a bit more diffuse reflection instead of specular reflection.


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## yashmack (May 20, 2013)

I wonder how well a 100W LED would work...
theyre rated at 7500 to 8000 lumens and theyre around 15 dollars on fleabay  edit: found one for 8 bucks!!
Im pretty sure the heatsink you have should work with up to a 100w, might need to get a faster fan though


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## vladguan (Dec 19, 2013)

that is pretty inefficient at 75 to 80 lumens per wat. My 4 LED flood lights are 4000 lumens at 36W/3Amps. Jaycar in Oz has 4WD led spot and flood lights that are very bright. 36W/4000+ lumens spot/flood which are equivalent to 300W halogen spots/flood lights. The flood ones can be used for aquarium which is what I plan to use when I upgrade to a larger tank with open top.


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## yashmack (May 20, 2013)

that is one problem with LEDs right now, as you get into higher power levels and brighter output your efficiency starts to drop


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## skanderson (Jul 25, 2010)

the bridelux ones are a bit north of 100 lumens per watt for a lot of the color temps in the 20 and 30 watt version.


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## skanderson (Jul 25, 2010)

and the lighttube material I used lets no light through the wall and is listed at 96 percent reflective.


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## Hoppy (Dec 24, 2005)

An LED floodlight might work well with one of these "light pipes" on it, and it would be easier to make because no cooling fan would be needed. I don't think a spotlight would work because not enough of the light would be reflected off the pipe walls, leaving you with very uneven light.

Any aluminized mylar would work, but one with no light leaking through the coating would be best. 96% reflectance would be very good. I still wonder if a less specular reflector wouldn't be a better choice.


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## DarkCobra (Jun 22, 2004)

Assume you have a perfect, mirrored reflector material. You make a 6" tube of it, and put an LED with 125° viewing angle in the top. The mirrored finish bounces light back and forth, but angles are preserved, so light that exits the can still spreads out at 125°. _No real collimation occurs_. The effect of the can would essentially be the same as moving the LED 6" closer to the surface.



Hoppy said:


> Why do you think I didn't want a good reflector?


Because you want collimation, and a _good_ tubular reflector doesn't provide that, as described above.



Hoppy said:


> EDIT: I just tested it with aluminum foil lining the "can", shiny side towards the light, and the foil is a little crinkled. I got 14-15 PAR at 36 1/2 inches. That is the same as without the foil, so I doubt that there is much to gain by polishing the inside of the can any more. Most of the reflectivity of aluminum is due to molecular issues, not extreme polishing - aluminum is inherently a very good reflector.


I think you're underestimating the importance of polishing. Seems like you're counting on aluminum to reflect light at _reasonably_ close to the angle at which light strikes it. Which would be true if the surface were _reasonably_ flat.

An image is worth a thousand words, so this is the shiny side of Reynolds heavy duty aluminum foil, magnified 50X:










No matter how good a reflector aluminum is on a molecular level, this ragged surface will reflect at all sorts of wild angles. Including some where light has to reflect multiple times just to escape valleys on the surface, part of the reason this material is only 88% reflective. Worse than "see-through" mylar. Or some good quality chrome paints.

And then it won't all be going downwards, or at sufficient angle where it can escape the can fast enough without reflecting off the aluminum many more times; each time wasting light. Even common household mirrors would be more efficient at this point - despite their poor reflectivity of 80% or so, at least they'd keep light going _downwards_, so that they escape the can faster. In practice even white paper or flat white paint typically outperforms aluminum foil.

Regardless, at least you've achieved your desired spotlight effect.

And some reflected light does end up escaping the can. Some even ends up going in the intended direction, as evidenced by your canless vs. can test going from 13 PAR to 21 at the center.

But not _all_ of what escapes the can is going in the intended direction. You can see a dimmer, but still clearly visible larger circle outside your main spot, which is coming from the reflected light:










So why is the main spot so bright and distinct by comparison to the larger spot of reflected light? Quite simply, the reflector is inefficient. So inefficient that the majority of the light that isn't traveling in the right direction from the LED at the very start - without being reflected at all - is lost.

It should therefore not be a surprise you obtained poor efficiency. It was completely predictable. Can't collimate _and_ have good efficiency, unless you use more complex shapes than tubes. More complex still if you want color blending and uniformity too. It is not a trivial problem, and you'll see commercial manufacturers trying a variety of methods, with varying degrees of success. But you will _never_ any of them using tubes alone. 

And it only made it worse that no-name LEDs were also used, with dubious efficiency and specs.

So it's with some dismay that I see you've abandoned this project in favor of one using _no-name strip LEDs_. This is a step downwards. It's not uncommon to find 50-75% loss of lumens after a year, _even when affixed to a heatsink_, unless also underdriven at a voltage less than 12V.

If you want a diffuse light source with excellent uniformity and color blending, with reasonable efficiency and price, and are willing to experiment (but really no more experimental than what you're already doing), the best bet is Intermatix remote phosphor. Available inexpensively at Future Electronics in many shapes and sizes. There's some good Youtube videos demonstrating how remote phosphors work. It will be driven primarily by royal blue LEDs, which gets converted to white as in a traditional white LED; put some red (and maybe aqua) in there as needed for spectral balance and they get diffused right in, unconverted. And because of the way it blends and produces light from a larger area, you can use fewer LEDs, making the use of high-quality LEDs more economical as well.


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## Hoppy (Dec 24, 2005)

It is true that real collimation doesn't occur with that big a cylinder, but if I had wanted to use a few hundred small diameter aluminum tubes, bundled into a 4 inch diameter, and with very thin walls, like aluminum foil, I would have achieved a big degree of collimation. I was more interested in the mixing of the color LEDs with the white LED, and with evening out the distribution of the light over the whole beam, than with true collimation.

I have tested simple reflectors made with aluminum foil, with aluminized mylar, with white paint, and with aluminum flashing material. The best performer, as determined by PAR measurements, was the aluminum, whether foil or flashing. Next best was the white paint. And, almost as good as the white paint was the mylar. Highly polished aluminum foil is the best reflector if you want accurate reflections, for reflection telescopes or reflectors in single lens reflex cameras. But, the total amount of light reflected is about the same with not nearly as good polished aluminum. The telescope reflectors can focus a very accurate image, while the not nearly as good polished aluminum can't be focused at all accurately and don't give much of any image. But, an image wasn't my goal.


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## vladguan (Dec 19, 2013)

Hoppy said:


> It is true that real collimation doesn't occur with that big a cylinder, but if I had wanted to use a few hundred small diameter aluminum tubes, bundled into a 4 inch diameter, and with very thin walls, like aluminum foil, I would have achieved a big degree of collimation. I was more interested in the mixing of the color LEDs with the white LED, and with evening out the distribution of the light over the whole beam, than with true collimation.
> 
> I have tested simple reflectors made with aluminum foil, with aluminized mylar, with white paint, and with aluminum flashing material. The best performer, as determined by PAR measurements, was the aluminum, whether foil or flashing. Next best was the white paint. And, almost as good as the white paint was the mylar. Highly polished aluminum foil is the best reflector if you want accurate reflections, for reflection telescopes or reflectors in single lens reflex cameras. But, the total amount of light reflected is about the same with not nearly as good polished aluminum. The telescope reflectors can focus a very accurate image, while the not nearly as good polished aluminum can't be focused at all accurately and don't give much of any image. But, an image wasn't my goal.


Hi Hoppy, Any updates on this?
Cheers,
Vlad


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## jeffkrol (Jun 5, 2013)

DarkCobra said:


> It's not uncommon to find 50-75% loss of lumens after a year, _even when affixed to a heatsink_, unless also underdriven at a voltage less than 12V.


Excellent writeup but I have a nit to pick. At least to my current understanding..
first voltage has no real place here.. It is the amps and heat that effects this the most. There is some photon decay of phosphors as well. and I suppose some plastic "fogging'.. 
Bottom line.. it is mostly heat.......


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## Hoppy (Dec 24, 2005)

vladguan said:


> Hi Hoppy, Any updates on this?
> Cheers,
> Vlad


No update because this idea didn't work out. I dropped the idea and moved on to a different idea entirely - using SMD LEDs.


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## vladguan (Dec 19, 2013)

Hoppy said:


> No update because this idea didn't work out. I dropped the idea and moved on to a different idea entirely - using SMD LEDs.


Any photos?
Cheers,
Vlad


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## Hoppy (Dec 24, 2005)

vladguan said:


> Any photos?
> Cheers,
> Vlad


http://www.plantedtank.net/forums/showthread.php?t=545113 tells all about how it worked out.


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