Abstract: A D.C. to D.C. voltage converter for producing a regulated, adjustable D.C. output voltage from an unregulated D.C. input voltage. An inverter produces alternating rectangular output pulses from the unregulated D.C. input, which are rectified to produce the regulated D.C. output voltage, with the timing and duration of the inverter output pulses being determined by alternating rectangular control pulses produced by a control pulse generator.The control pulse generator includes an operational amplifier having an inverting input connected to a positive D.C. reference voltage, and a non-inverting input connected to the slide connection of a potentiometer connected between the regulated positive D.C. output voltage and ground. A diode is connected between the amplifier output and ground to block current flow to ground, thus assuring that the amplifier output error signal is essentially always positive, and is only generated when the non-inverting input voltage exceeds the referenced voltage.