The commercial item I bought uses a basic brush type motor as the generator, the motor is generally similar size to the deck motor in an old style audio cassette player or a VCR lift motor. Its performance was most unimpressive................
Various magazine projects show using stepper motors salvaged from various equipments. The motors come in all shapes and sizes depending where you get them.
Whatever motor you use; will need some gearing to increase the shaft RPM, robotics and animatronics suppliers are the usual suspects.
