VARIABLE DUTY CYCLE SWTICHING CIRCUIT

摘要

A magnetically coupled multivibrator is normally prevented from running free due to the presence of a forwardly biased transistor which holds the base electrode of one of the two multivibrator transistors below its level of base-emitter conduction. A variable current source charges a capacitor to a voltage level which cuts off the holding transistor and allows the multivibrator circuit to operate for one cycle, during the latter part of which cycle the capacitor is dumped so that the successive cycles are separated in time by that time necessary to charge the capacitor to the required level and which time is variable according to the charging current. The variable duty cycle thus obtained for the multivibrator circuit controls a voltage or power source whose output is fed back inversely to control the charging current so that a regulated voltage or power output is produced.