Beat-IR
Goal: To simply and cheaply communicate, via IR, to Midi synths, analog synths, CMOS synths, and computer synths.
The absolute simplest circuit schematics for room-wide sharing of a musical tempo. (One could imagine more elaborate musical uses).
This technique was ideated by Sid, at Noisebridge, who suggested blinking a musical tempo to a roomful of analog and digital instruments, by bathing the room in a blinking infrared light. (One could imagine sending more complex musical messages.)
Schematics: