Here's some action shots of a home-built Arduino DMX light I got working last night. I bought dumb LED modules from Holidaycoro (not the entire lamp kit, so I had to make my own $4 mounting plate) and wired them to an Arduino Duemilanove. The code is a modified version of the example in the DMXSerial library to take it from 4-channel RGBY to 3-channel RGB with an added a textual OLED display for debugging. You can't see them easily in the pictures, but there are three N-channel MOSFETs next to the 10mm LEDs so that the Arduino can drive a 12V strip.
I already had the Arduino and the breadboard, OLED display, and MOSFETs. The lamp housing is from a worklight that was dropped too many times (breaking the ceramic terminals inside), so the only thing I had to buy was the string of LEDs. Fortunately, I already had a Arduino Duemilanove on my experimentation board because it has an FTDI-232RL chip for its serial interface (the newer Uno uses a smaller Atmel MCU instead). There are $20 FTDI cables (for other models of Arduino) out there that should also do the trick.
The lamp is a dual-header and I have 10 more LED modules ready to build a second lamp housing. Holodaycoro specs out the LED modules at ~100mA each (full brightness), so a 2A 12V PSU should be able to handle it.

[Last edited May 14, 2013 19:53:21]