A phase-control power controller that converts a line voltage to an RMS load voltage includes a phase-control circuit with a potentiometer and a capacitor whose resistance and capacitance determine clipping of a load voltage, a load sensing circuit that senses the load voltage and provides a DC signal that is different from but related to the RMS load voltage, and a comparator circuit that compares the DC signal to a reference and adjusts the resistance of the potentiometer to control the RMS load voltage.