Make Robot Glow with Alliance Colors Automatically

[Jon Stratis]

It's also possible to do this with a single Spike relay instead of two... Simply wire the LED's backwards of each other - for example, red gets its + wire to M+, and its - wire to M-, while blue gets its + wire to M-, and its - wire to M+. Put the spike in forward, one will light up. Put it in reverse and the other will light up. For the default/invalid state, turn it off.

This works because LED's are, above all else, a diode - they only conduct electricity (well, in an ideal world... in the real world there is some leakage) in one direction, and not the other. Thus, when powered "backwards", an LED won't light up!