Abstract: A shaft-mounted electronic sensor with an independent, rotating power supply, and a method for powering shaft-mounted electronic sensors by harnessing the energy present in the residual magnetic fields present in the permanent magnet armature windings of a generator or motor. Windings are placed on the shaft of a rotating machine such as a synchronous motor or generator that uses a permanent magnet generator for supplying exciter field power via a regulator. These windings are placed such that they rotate with the shaft and break the lines of flux produced in the permanent magnet stationary armature windings. Breaking the lines of flux induces a current in the windings of the invention which is used to power an electronic sensor mounted on the shaft.