# Making an LED Pendant



## El Exorcisto (Aug 10, 2006)

So I've got the itch for a little DIY project that's been itchin me for a little over a year, an LED pendant. I ordered 200 20K mcd white LEDs, 40 reds, 40 greens, and 40 yellows to warm up the output a little since from what I have read and seen, white LEDs don't render reds all that well. While the People's Republik gets my LEDs to me, I've assembled a few other parts...

Here's the enclosure it'll all get stuffed into. It's a stainless spackle pan from Lowes:









Here are my two circuit boards, trimmed to size so they sit about 3/4" inside the pan:









Here are my two cooling fans. I don;t know what kind of heat it will generate, but they were cheap and it's always better to be cooler than hotter:









And here is my power supply. It was ripped from a retired HP printer:









I'm planning on using around 160 whites, 40 reds, and probably 20 greens. The greens are more for the visual effect than anything, just to make the green plants pop. I hope 40 reds will warm up the spectrum a bit. If not, I'll add some yellows.

The pan is going over a rimless 10 gallon on top of a homebrew stand. Except the little beater Whisper filter, the entire tank is going to be without "aquarium" grade products. Substrate is MGOC soil capped with Sankrete "Multi-Purpose" sand. I really hope the pendant works as well as it should...


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## davemonkey (Mar 29, 2008)

Very cool prject! I'll being watcing closely to see if I can learn anything about LED's and wiring, as I am very much uneducated on this subject.


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## HX67 (Sep 24, 2009)

Interesting. Thanks for sharing this.


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## El Exorcisto (Aug 10, 2006)

davemonkey, here is the calculator I used to order my resistors:
http://ledz.com/?p=zz.led.resistor.calculator

With 220 ohm resistors I can run 3 white LEDs, 4 green/yellow, or 6 reds per 220 ohm resistor. I'll step-by-step it once everything shows up... DAMN YOU MAILMAN!!!


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## jestep (Nov 14, 2009)

If you want really good heatsinks get pure copper, or aluminum server heatsinks. Many have holes that would allow for easy mounting as well.

Something like this: http://cgi.ebay.com/XEON-HEATSINK-F..._EN_Networking_Components?hash=item439b9b9dbf

Copper is better than aluminum, but is more expensive.

Also, how are you planning the wiring?


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## MoonFish (Feb 12, 2006)

5mm's? I'm unsure why you would deal with them when a couple of crees would put out more?


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## El Exorcisto (Aug 10, 2006)

jestep, I doubt I'll need dedicated heatsinks, I'm sure just blowby cooling will be sufficient since they are low-yield LEDs. Moonfish, I went with the cheap 5mms mainly because, well, they're cheap. All told I'll have $50 into it. If I went with Cree high yield LEDs I'd have more than that just in the LEDs. I also wouldn't be able to tailor my spectrum as readily as I can with this setup.


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