First-generation LED project2009/08/01
I first built LED lighting hardware around 3 years ago, after first reading about the BAM technique from Artistic License. I ended up building a kit from scratch consisting of a controller and 8 fixtures. The controller has 2 boards with ATmega8515’s each driving 16x 2N2222’s grouped in 4’s, with RJ-45 connectors. The fixtures are 4x4x2″ enclosures with PCBs holding a total of 96 LEDs each, 24 each of red, green, blue, and white, again with RJ-45’s. The first round of 4 fixtures were strictly resistive-ballast, while the second round used LM317’s in constant-current mode. This coupled with a slightly higher drive voltage allows the fixtures to be strung on anywhere from 3ft to 100ft of standard Ethernet cable.
Last Christmas I decided to go a little overboard on the first tree of my own… 4 of the fixtures are embedded in the tree, while 4 more are behind the curtains as uplights. Control is via DMX-512 driven by an ENTTEC Open-DMX USB bridge, with a cable running to my computer running custom color-changing code written in Python.