Mains power unit esp. for cordless telecommunication equipment - supplies battery-recharging DC from bridge rectifier via pre-regulating series thyristor circuit and output voltage stabiliser

摘要

The mains transformer (130) supplies AC to the bridge rectifier (131) from which the DC output (UGL) is fed to a voltage stabiliser (132) whose output terminals (110,111) provide the current for recharging the battery of the cordless handset. The unstabilised DC voltage (UE) is pre-regulated by an intermediate circuit (140) in which the thyristor (141) is gated (G) by the output from a control circuit (143) comprising two limiting resistances (1430,1431) and a Zener diode (1432). The cathode current is smoothed by a filtering capacitor (142). ADVANTAGE - Losses due to difference between input and output DC voltages of stabilising circuit are avoided by pre-regulation between bridge rectifier and stabiliser.