Parts so far
- 10 watt RGB LED (ebay)
- 3x LED Drivers, one for each color (sureelectronics.net)
- Wire (sparkfun)
- 3x 10k Rheostats (sparkfun)
- Heatsink (savaged from spare parts bin)
- TIM, thermal interface material (spare parts)
- 12v powersupply (using spare atx pc power supply)
- Arduino Mega
- Character LCD 2x16
Sureelectronics had the cheapest led driver I could find for high power leds($4each) but they were out of stock the 350ma ones I needed, but they had plenty of the higher capacity 700ma ones. I looked at the spec sheet and found the only difference was the 700ma one had two addtional resisters on it that I could easily remove. The chip on driver determines what the output amperage by reading what the resistance is between to of its pins.
So the first thing i did was remove the two resisters to change the output amperage to 350ma. A little work with my soldering iron and they were off. Next, I soldered the drivers into the adapter boards that have the nice screw terminals.
Next I soldered leads to the LED which I then used to connect the LED to the drivers. Then drivers I the wired together to the 12volt powersupply. The white wire takes 5v PWM from the arduino to control the brightness of the led.
I mounted the LED on a heatsink to exhaust the heat it generates. The led needs to be in perfect contact with the heatsink so I put some TIM on the bottom of the led to fill any gaps between it and the heatsink. Then I tacked the led down with a bunch of Hot glue.
I got the rest of the arduino wired up with three rheostats, one for each color-, red, green, and blue athing them to the analog inputs 0-2.
A little debugging to get the get values right (the lcd is perfect for this)
and voila! I can turn the knobs to create any color I want! The LED is blindingly bright so until I have time to fabricate a shade for it, a rolled up piece of trace paper works.