The channel boxes do the actual "switching", of the 120v supply, to the lights. The boxes contain home made solid-state relays, which consist of resistors, triacs, and opto-couplers. A low voltage (5Vdc) line, supplied by the computer, tells the solid-state relay to turn on and off. You can think of a solid state relay as a regular light switch, except, rather than physically turning the switch on or off, the computer does it. So, essentially, this allows us to control high voltage/current lines with a low voltage signal. Click on the links below to see the details.

2,4, and 8 channel boxes
16 and 24 channel boxes