This is a simple BEAM robot (BEAM is an acronym for Biology, Electronics, Aesthetics, and Mechanics, and it describes a style of robotics developed by Mark Tilden in the late 90s) that I built a long while back; it was based on a similar design I came across in an old book. In the book, the components were connected directly together, however I mapped the circuit out and used a copper-clad board and acid to make a proper circuit board.
The robot spins, always looking for the brightest source of light in the room. The circuit is really simple: two IR LEDs detect light. As the LEDs detect light, they act as on/off switches, reversing the flow of electricity to the motor.
