This power supply uses two VN400A 400 Volts MOSFETs in a half-bridge power switch configuration. Each output consists of +5V at 20 A and 15 V at 1 A . Three-terminal regulators are used for the low-currents outputs , either 12 Volts or 15 Volts can be made available with a simple change in the transformer secondary windings. Schematic diagram below :
IC TL494 switching regulator IC provides pulse-with modulation control and drive signals for the power supply , The upper MOSFET , Q7 , in the power switch stage is driven by a simple transformer drive circuit. The lower MOSFET , Q6 , since it ground referenced , is directly driven from the control IC.