Abstract: A programmable alternating current switch for connecting an A.C. supply to a load for a controlled fraction of each cycle to thereby control the average power to loads, such as lamps, heaters, motors, etc. A Programmable Unijunction Transistor (PUT) is employed to control the phase angle of the A.C. wave at which a Triac is fired, the Triac continuing to conduct and deliver load current for the remainder of that half-cycle. Coupled between the PUT and the Triac is a Light Activated Silicon Controlled Rectifier (LASCR) and a diode bridge which provides full-wave operation.