The basic full-wave Triac phase control circuit shown in Figure AN1003.9 requires only four components. Adjustable resistor R1 and C1 are a single-element phaseshift network. When the voltage across C1 reaches breakover voltage (VBO) of the DIAC, C1 is partially discharged by the DIAC into the Triac gate. The Triac is then triggered into the conduction mode for the remainder of