My DIY LED light and how it got a bit out of hands

[zaxxon]

Hi all,

Some of you who have been reading the finnish forums might be familiar with my DIY project. It all started with a forum post back in july of 2009 on a forum called Greenpinelane http://www.greenpinelane.com/yaf/default.aspx?g=posts&t=269 and the intention to start a collaborative plant research project. The idea was to develop an affordable, high-quality, no-bullshit modular LED light for horticulture that would enable to conduct this horticultural research project.

I had then studied all this LED stuff for quite a while, and decided to build a prototype to get acquainted with LEDs. The first prototype looked like this:



It was built using Osram GD LEDs (Red, Blue and Neutral White (top bins)), kapton tape, copper tape/track, aluminum heat sink, and two chinese 450mA constant current drivers.

That prototype failed due to mounting the Osram GDs heat slugs to the heat sink using Arctic Silver Epoxy. The epoxy was not as good an insulator as advertised, and I ended up getting an electric shock of 90V from the heat sink. I also managed to fry some LEDs as the thickness of the epoxy was very hard to control.

I then did another similar prototype, that used double sided copper tape for the heat slugs. That worked better (still burning, 55°C heatsink temp). I'm yet to conduct growing experiments with that one.

Throughout this process I've been designing and iterating the original idea for a low-cost DIY light module, and I think it's almost ready now. I expect to have the prototype ready by march. I'll be posting about it here. Meanwhile.. happy sowing! Oh, and one more thing.. A small teaser:

[Trizza]

Looks good!

I found on my lights that I needed to add a small fan running at minimum speed to get the air flowing around the heatsink fins. Without it the light unit (18W of CREE XR-E) got up around 90 degrees. With it running at minimum speed the fixture stays at room temperature.

Keep us posted

[sevenchaos]

Sorry for moving this up but this looks very interesting.
I've been thinking myself too that i should build one of those but haven't ever heard or seen that forum before.
Now im going to start building my own grow led lamp.
I actually have builded one pcb lighter with uv-leds and it worked pretty ok.
I just used turret board and stucked the whole thing inside of an old scanner. It doesn't heat up pretty badly, but max time what it is on is 2-3 minutes.

Turret boards can take a lots of heat. I have been working with hifi and guitar tube amps and they do heat very much.
This would be much cooler since you dont have to play with extremely high voltages.
Tube amps have easily over 500vdc so they are extremely killers at wrong hands.