Patent ID: 7034469

Claim:
A phase-control power controller that converts a line voltage to an RMS load voltage, the controller comprising: an analog load voltage sensor that includes a first light emitter that provides an optical output related to an RMS load voltage; and a phase-control circuit that has a comparison circuit that varies a resistance in said phase-control circuit responsive to the optical output, said comparison circuit comprising a first optically coupled transistor that senses the optical output from said first light emitter, a first load sensitive resistor connected to said first optically coupled transistor and that emits an amount of thermal energy corresponding to an amount of optical energy sensed by said first optically coupled transistor, and two resistors connected in series, one of said two resistors having a resistance that corresponds to the amount of thermal energy emitted by said first load sensitive resistor and that varies the resistance in said phase-controlled dimming circuit.