GB1058160A - Improved voltage stabilizer circuit arrangements - Google Patents

Abstract

1,058,160. Automatic voltage control. RANK-BUSH-MURPHY Ltd. Dec.1 1965 [Sept. 15, 1964], No. 37609/64. Heading G3R. A voltage stabilizer comprises an input source 1 to 9 of rectified A.C., a reservoir capacitor 11, a series transistor 12, an amplifier 14 for controlling transistor 12 in dependence upon variations in output voltage at terminals 13, 16, and a thyristor 15 associated with a pulse generator circuit responsive to the potential between the collector and emitter of the transistor 12. In operation, if the said potential increases because of the adjustment to a low value of the output voltage or because of an increase in the input voltage, the thyristor 15 is triggered at a later point in the half cycle of the applied A.C., whereby the potential across capacitor 11 is reduced and the voltage drop across the transistor 12 minimized; conversely, the triggering of thyristor 15 is advanced when the said emitter/collector potential decreases, whereby this potential is held nearly constant so that it is not necessary for the transistor 12 to be of the high-dissipation type. The pulse generator circuit includes an auxiliary voltage source +, - capacitors 17, 18 connected across the input source and a transistor 19 which is responsive to the emitter/collector potential of transistor 12 and which produces pulses having a width proportional to this potential; these pulses are applied to the control electrode of thyristor 15 by way of a differentiating circuit 24, 25, a transistor 26 and a capacitor 28.