Abstract: A voltage power supply, particularly one which is especially suitable for providing a relatively high DC voltage output of rapidly changing amplitude adapted to drive a cathode ray tube (CRT), is disclosed herein. This voltage supply includes circuitry adapted for connection to a relatively low amplitude (actually magnitude) DC voltage input for first converting this input to an AC voltage output and then converting the AC voltage output to a DC drive voltage having a fixed amplitude substantially higher than the DC voltage input. This higher amplitude DC voltage is applied to voltage varying circuitry, specifically a pullup and pulldown circuit arrangement, for producing at its output an adjustable DC output voltage having an amplitude which does not exceed the amplitude of the drive voltage. A voltage adjusting circuit is connected to this latter circuit arrangement and is also adapted for connection to a coded signal for rapidly changing the amplitude of the adjustable output voltage in response thereto.