There are two ways to interface the unidirectional logic pulse to control a Triac. Figure AN1003.19 illustrates one easy way if load current is approximately 5 A or less. The sensitive gate Triac serves as a direct power switch controlled by HTL, TTL, CMOS, or integrated circuit operational amplifier. A timed pulse from the system’s logic can activate the Triac anywhere in the AC sinewave producing a phase-controlled load.