Inside the base of the generator there is a simple electric motor. The motor is attached to a plastic pulley inserted inside the lower end of a rubber belt. This belt runs up through a tube to the metal dome.
There are no electric circuit boards or high voltage generators. The only thing the power switch and knob do is control the motor.
In fact, the only strange object is a copper comb. The back of the comb is connected by a wire to electrical ground. The teeth are set so that they almost touch the bottom of the rubber belt.