Triac and Diac Tutorial

The triac conducts in both directions and provides full wave control of power.

Variable phase trigger pulse are provided by the pulse generator and are positive with respect b1.

The diac is high resistance below a certain voltage, say 30 volts, but when the applied voltage exceeds this value, it goes low resistance and conducts, applying a pulse to the gate.

It gives more reliable triggering of the triac.