A clockwork radio is a radio that is powered by clockwork wind-up mechanism driving an internal electrical generator, rather than batteries, solar cells, thermoelectrics or electricity from the electrical grid. Like other self-powered equipment, it is intended for camping, emergencies and for use in areas of the world where there is no electrical grid and replacement batteries are hard to obtain, such as in developing countries or remote settlements in developed countries. It is also useful when it will not be used on a regular basis, such as at a vacation house or cabin. Clockwork radios sometimes incorporate a flashlight or other useful device. Some models include alternative power sources including conventional supplies such as batteries. The modern clockwork radio is a patented design by Trevor Baylis through a company called Baygen. The key to its design is the use of a constant velocity spring to store the potential energy.
