Triac voltage controlled trigger cct. - has series connecting of resistor and charge capacitor coupled to mains control voltage and trigger diode

摘要

The direct voltage controlled triggering circuit for triacs has a series combination of a resistor and a charge capacitor connected the mains control voltage, while a triggering diode serves for teh supply of the capacitor voltage to the triac gate. A series combination of a second charge capacitor and the drain-source channel of a field-effect transistor is in parallel to the first charge capacitor, the field-effect transistor gate being regulated by the control voltage. Preferably the control voltage terminal is connected to the triac anode. For the purpose of a symmetrical feed at least part of the drain A.C. voltage may be superposed onto the control direct voltage.