Electronic switching power supply

Abstract

An electronic switching power supply for supplying power to an electrical load from a variable voltage level AC or DC voltage source having first and second terminals, the power supply including a transformer having a primary coil and a secondary coil, a first terminal of the secondary coil being connected to the electrical load, a first transistor connected in series with the primary coil, a first diode connected in series with the secondary coil and the electrical load, a first capacitor connected between the base of the first transistor and a second terminal of the secondary coil, a second transistor, the collector-emitter line of which is connected across the voltage source, a first resistor connected between the first terminal of the secondary coil and the collector of the second transistor, a second resistor connected between the first terminal of the secondary coil and the emitter of the first transistor, and a discharge circuit connected between the first capacitor and the electrical load, whereby the first capacitor is electrically charged during a conducting phase of the first transistor, and during a subsequent blocking phase of the first transistor, the electrical load receives the charge built up in the first capacitor during the preceding conducting phase.