A BEAM “head” robot is a robot that can “look around” for the brightest source of light. This usually means mounting everthing on top of a gear motor, and then fixing the spindle of the motor to the base.
This is a bare-bones photo head which uses a 74AC240 IC, and two photodiodes as light detectors. It’s based on this schematic, which uses a Miller solar engine. You can see the free-formed solar engine overhanging the front of the capacitor; the IC is hidden under the solar panel.
The motor is an Omron gear motor obtained from a Mac floppy drive (it’s the motor that gives the Mac floppy drives their distinguishing feature—software eject). The base is made from parts of a hard drive motor.
This little guy chatters every second or so in the sun. It was my first well-functioning head, and I like the way it turned out.