Abstract: A power supply for providing an output voltage amplitude modulated by a command signal, includes a rectifier for rectifying the command signal, a comparator network for comparing the instantaneous rectified level of the command signal with a plurality of predetermined reference voltages, for producing a plurality of phasing signals, respectively, for operating a switching network to (1) alternately and successively connect positive and negative polarity DC voltages to the one ends of a primary windings of a plurality of transformers, and to (2) connect either the positive or the negative DC voltage to the other ends of the primary windings in different combinations, over each half-cycle of a clock signal, for producing in a common secondary winding for the transformers the amplitude modulated output voltage. Another rectifier may be provided for rectifying the AC output voltage, for producing a DC output voltage amplitude modulated by the command signal.