Current supply cct. from AC mains - uses AC voltage phase control with anti-parallel thyristors in series with load, controlled by flip-flop stage

摘要

The current supply circuit for a load from A.C. mains has an input step-down transformer feeding a bridge rectifier. The rectifier output acts as the D.C. supply for the monostable flip-flop controlling the anti-parallel thyristors and a frequency recognition circuit. The flip-flop output controls a triac that acts as a chopper between the A.C. supply and the lower voltage load. The frequency recognition circuit alters the voltage division ratios between the three resistors, that control the flip-flop reset time. The frequency recognition circuit output transistor switches through a given voltage to the voltage divider. The frequency recognition circuit may be coupled to constant D.C. voltage.