A phase-control power controller converts a line voltage to an RMS load voltage and includes a phase-control clipping circuit that clips a load voltage to provide the RMS load voltage. The power controller may be in a base of a lamp and connected to a lamp terminal. The phase-clipping circuit establishes a phase conduction angle that determines the RMS load voltage for the lamp and includes a transistor switch and a microcontroller that operates the transistor switch, where ON/OFF periods of the transistor switch define the phase conduction angle. The microcontroller senses a load voltage at the lamp terminal, compares the sensed load voltage to a reference RMS voltage, and adjusts the ON/OFF periods of the transistor switch in response to the comparison to cause the load voltage to approach the reference RMS voltage. The circuit may be used for reverse, forward, or forward/reverse hybrid phase clipping.