Triac switching cct. - triac in series with load lamp controlled from bistable flip-flop supplied from rectifier diode

摘要

The triac switching circuit has its triac coupled in series with the load lamp across the a.c. supply. The triac's gate is connected to the output of a bistable flip-flop whose state is determined by a switching signal coming via an amplifier from a touch-plate. The flip-flop and amplifier receive their d.c. supplies from a rectifying diode and resistor coupled into the a.c. supply line. With this diode forward biased, the resistor forms a voltage divider with one or the other of the flip-flop's two collector resistors. Since the circuit acts as a 'zero voltage' switch, no HF blocking filters are necessary to avoid noise.