Power is provided by an internal spring-driven generator.
The BayGen Freeplay radio incorporates the wind-up generator invented by Trevor Baylis. The user cranks a fold-out handle on the side of the radio to wind up a carbon steel spring. The clockwork spring then drives a DC generator though a transmission and the generator provides an output of about three volts to power the radio's electronics. A full winding of the spring is accomplished with about 60 turns of the crank which takes about 20 seconds and the mechanical advantage provided by the handle makes winding the generator easy, although the radio needs to be steadied with the other hand. Once fully wound, the generator will power the radio for about 30 minutes.