A phase-control power controller that converts a line voltage to an RMS load voltage includes a fixed phase forward/reverse hybrid phase-control clipping circuit that performs phase-control clipping of a load voltage to provide an RMS load voltage. A conduction angle of the phase-control clipping circuit is defined by a time-based pulse source that triggers conduction in the phase-control clipping circuit independently of line voltage magnitude during time periods that span polarity changes of the load voltage and that are separated by intervals when conduction is not triggered. The phase-control clipping circuit includes a transistor switch whose gate receives positive polarity signals from the time-based pulse source to trigger conduction of the phase-control clipping circuit. The power controller may be in a voltage conversion circuit that converts a line voltage at a lamp terminal to the RMS load voltage usable by a light emitting element of the lamp.