Abstract: A regulated chopped DC power supply comprising an alternator with a stator and a rotor, the alternator having a three-phase winding for providing a high voltage output (1, 2, 3) and a star-connected three-phase winding for providing a low voltage output. Also included is a control circuit (14) for controlling a rectifier (12) which is connected to the high voltage output (1, 2, 3) of the alternator to produce a regulated chopped dc output (52) for powering electrical appliances. The control circuit (14) periodically interrupts the rectifier (12) at a frequency to interrupt substantially simultaneously all of the phases of the high voltage output.