Elektronisches Schaltnetzteil

摘要

A switched electronic supply unit for supplying an accumulator (61) and aswitchable electric consumer (62) has a self-heterodyning blocking oscillator with a transformer (50), a switching transistor (1) with an emitter resistor (22), a feedback circuit (11, 27) and a driving circuit (St) influenced by the accumulator voltage (U). A switching-off unit (AS) permanently blocks the switching transistor (a) when the ratio of the duration of the oscillation pauses to the duration of the oscillation packets exceeds a determined value in the oscillating mode of operation of the supply unit.