An electronic power supply (100) receives power from an AC source (10) and supplies power to a load (20) that is referenced to earth ground (30). Power supply (100) comprises a power converter (200) and a voltage regulator (400). Power converter (200) draws a ground leakage current from AC source (10) and is capable of providing a steady-state output current having an average value that is greater than that of the ground leakage current. Voltage regulator (400) limits the output voltage of the power converter (200) to a predetermined level. In a preferred embodiments power converter (200) is implemented as a self-oscillating converters and power supply (100) draws a ground leakage current that is sufficiently small to meet regulatory limits and to avoid tripping of conventional ground-fault interrupters.
A controllable electrical switch having a power system and switching device for connecting a source voltage to a load. The power system includes a switching regulator to extract energy directly off the non filtered full wave rectified input voltage to minimize the average magnitude of the current when the switching device is in the off-state. For on-state power the controllable electrical switch may include a transformer connected in series with the switching device. The controllable electrical switch and power system may be used to replace a standard two- wire or three-wire wall switch, and may be used over a wide voltage and load power range in a low cost, small package with low power dissipation.
