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post #1 of 14 (permalink) Old 03-21-2011, 04:05 AM Thread Starter
Algae Grower
 
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ArcLED

Well, thanks to DealExtreme I can at last afford my very own aquaria LED grow light. I've been keen on this idea for about a year now and first encountered them on Nanoreef.

Here is my design:



I have three of these, each heatsink is 8.4 X 8 in. and holds (9) Cree XR-E 3W LEDs on a 3" grid, and (14) 5mm RGB LEDs for looks. I had to use some empty 20mm stars for mock up and drilling because I ordered the LEDs from DealExtreme and their shipping takes forever. But...the order came in over spring break and I'm going to pick it up from usps tomorrow.

I am hoping this will work as a modular system that can be used on any of my tanks. I was thinking that two over a 10 gallon, three over the 20 long, or three raised and spead a bit over my 3' tanks (46BF and 30L) would work nicely. I'm planning on the Crees needing to be dimmed over the 10 and 20L, so maybe full power over the 46 would work?

It's going to be controlled with an Arduino UNO. I should be able to dim the Crees of each heatsink individually, but the RBGs will be controlled in unison across each heatsink (there's only 7 PWM channels on the UNO).

Parts list so far:
(27) Cree XR-E WD LEDs==$73.65 (Deal Extreme)
(3) 1000mA 30W Drivers==$33.63 (Deal Extreme)
(3) 8.4" X 8" Aluminum extrusions==$54 (heatsinkusa)
(50) 5mm RGB LEDs==$3.99 (ebay: 2008topshop)
(100) 5mm LED holders==$0.6 (ebay: citychainch)

Total: $165.87

Still need power supply for RGBs, some nice ribbon wire for RGBs, an enclosure, hardware, mounting system, other.

thats all for now folks
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post #2 of 14 (permalink) Old 03-21-2011, 05:09 AM
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This sounds very interesting. I'll be watching to see how it goes. How are you mounting the heatsinks above the tank, and are you using a fan?

Hoppy
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post #3 of 14 (permalink) Old 03-21-2011, 05:33 AM Thread Starter
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Thanks, I'll enjoy your input. No fans on the heatsinks, I think they'll do fine on their own. I want to try to get the surface polished tho. I may look at a fan for the enclosure.

I haven't figured out mounting yet. I'd like something with a fair bit of vertcal travel for maitenance. Here is a sketch of my first shot at a design, I don't know if I'll be able to get the dimensions right for the amount of travel I'm looking for.


Arm for desktop aquarium.
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post #4 of 14 (permalink) Old 03-21-2011, 10:39 AM
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You can polish the aluminum quite well with jeweler's rouge, or red tripoli compound---- you just need a $5 cotton/flannel buffing wheel and a drill press or lathe.

One step will be plenty...... but you can take it to another level by using a second wheel loaded up with white diamond compound, will come off basically mirror slick.
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post #5 of 14 (permalink) Old 03-21-2011, 03:27 PM Thread Starter
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Thanks, can you think of somewhere local I might be able to find those items? I was thinking of using an auto buffing compound.
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post #6 of 14 (permalink) Old 03-21-2011, 03:32 PM
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Nice! Thanks for sharing all the details. Good to see that prices are getting more and more reasonable if you do DIY. Sooner or later some manufacturers will follow suit (and somehow avoid getting sued ).


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post #7 of 14 (permalink) Old 03-21-2011, 04:11 PM
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A mirror finish is nice to look at, but not that important for cooling the LEDs. Flatness is the major concern, so the surface of the LED star has good contact with the heatsink. I did mine with just 3 grades of sandpaper, and was very pleased with how flat it was. I used hard sanding blocks of course.

Be careful with the flat head screws to mount the LEDs. I shorted a couple of LEDs to the heatsink that way, and ended up having to remove all of them and used adhesive to hold the LEDs in place. Nylon screws would be ideal if they are strong enough not to break as you screw them in.

Hoppy
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post #8 of 14 (permalink) Old 03-21-2011, 04:33 PM Thread Starter
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Thanks for looking and posting Wasserpest!

The finish on the sink in the first pic is 1200 grit from 800 I believe. I wet sanded it by hand, feel like I was pretty consistant and I got the highspots from machining cut down, but I'll probably redo it with a block now that you mention it...thanks. Miror finish is cool in my book, if it's not too much work.

I was worried about the screw heads too from my research, but I found some regular #4 sheetmetal screws with tapered bottoms at ACE that work. Only broke one bit and two screw heads during drilling and tapping, it sucked.

Last edited by Arctangent; 03-21-2011 at 08:18 PM.
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post #9 of 14 (permalink) Old 03-27-2011, 10:30 PM Thread Starter
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Update:

I've got all of the heatsinks re-sanded with a block and tried my hand at polishing with buffing compounds. It could have been much better with more time and work on the sanding prep side, but the compounds were interesting to learn about and did give me a semi reflective surface. I used a brown tripoli compound followed by a white tripoli each on a stitched cotton wheel.

I also got the Crees mounted, wired and tested. The wire goes trough the heatsink and runs along the backside. The wire came from a 5' length of thremostat wire my Dad gave me, it has 10 conductors in it, I used one per heatsink.



At 1.06A.



The RGBs are going to be more complicated than I had originally planned. Their 4-pin, common positive layout means that they can't be physically wired on respective strings in sreies. They will have to be wired in parallel. The only way to safely wire LEDs in parallel is to assign a current limiting resistor to each LED, otherwise the failure of one LED would damage the rest. That could mean a bunch of extra wires, but I've geen trying to keep this thing extra clean. So my plan is to use 1/8 watt resistors soldered directly to the leads of the RGBs and tucked away inside the holder in the heatsink, then fill the holder with silicon. Then I only have to run four wires on the sink itself and they would all still be in parallel.

One positive note about wiring in parallel is that it makes it easier to control LEDs individually, if I use a controller with more channels or try some type of multiplexing.

Another problem is that each color cone is offest from the others by a couple degrees, and each cone is only 25 degrees total so it spotlights a little. I think I can save the project idea by scuffing up the lense of the RGBs with a little sandpaper to diffuse and mix the colors a little better.

I also got some polycarbonate cut and drilled for splash shields, but I'm still looking for some spacers.

Last edited by Arctangent; 03-28-2011 at 02:18 PM. Reason: spelling
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post #10 of 14 (permalink) Old 03-27-2011, 11:10 PM
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Sorry about not seeing your response earlier. You can usually find the jeweler's rouge at Harbor Freight if you have one locally. That or "tripoli" compound. I suspect they are the same, and they give the exact same result for me when I buff aluminum, silver, or gold with it (wedding bands).

But like Hoppy said, it's not critical. Neat, but not crucial. Looks like you have it running well anyhow
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post #11 of 14 (permalink) Old 03-28-2011, 01:13 PM Thread Starter
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It's cool, I wound up getting the compound from harbor freight.
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post #12 of 14 (permalink) Old 03-28-2011, 02:16 PM
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It's hard to beat HF for those one-offs that you don't know where to get anywhere else, and I have a good handful of HF tools that are actually well made and well used. And. Some that got returned immediately after opening the box lol.
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post #13 of 14 (permalink) Old 03-28-2011, 08:49 PM Thread Starter
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True that, they have a storefront just down the road from me. Being from a small town, it's what refer to as: extra luxurious. The heli shop down the road is also extra luxurious.
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post #14 of 14 (permalink) Old 05-21-2011, 02:22 PM Thread Starter
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Testing

It's been a while. School's out and I finally had enough time to solder all the resistors to the legs of the RBGs (well, for one heatsink). I still havn't got the controller up and running, but I've started breadboarding it...just need to make sure I can use PWM off of these static 1A drivers without flyback problems. So the pics below are under full power.


Power supply box


RBG Red Only.


RBG Blue Only


RBG Green Only


Crees plus Reds


Back side

I am happy with the RBG power and spectrum under pure colors. I am also happy with the installation, it came out very clean considering the the RBGs are all in parallel. Also happy with the spread and mixing of light intensity...no spotlighting (but I designed it that way ). The RBG intensity is respectable when the crees are on, they give the crees just a hint of color. This will probably be more pronounced once I am able to dim the crees.

I am a little disapointed in color the mixing capabilities. The RBGs were cheap chinese models and the quality shows when you try mixing. The elements in the LEDs must not be placed consistantly. When mixing red and greens for example, some RBGs come out orange but others favor a little more red or green. It's no big deal, it'll still look good...maybe even more natural? I would buy quality RBGs if I did it again.

Thanks for looking. I'll updated my parts list and cost when I get back to my records.


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