Abstract: For energizing remote lamp loads subjected to indeterminate transmission losses, a current regulating power supply is described which delivers a regulated current to the load using for example, a full wave rectifier supplying an unfiltered pulsating voltage to a switching regulator controlled by a feedback loop incorporating a current sensing resistor and pulse width modulator. The supply has a substantially unity power factor, a self-quenching characteristic in the presence of circuit interruptions, and can deliver regulated current to a variety of lamp types.

Abstract: A power converter for converting 60 Hertz line power to 20 kilohertz power for driving a low voltage incandescent lamp (42). A field effect transistor power switch section (12) is connected through bridge rectifiers (10, 32) for charging a capacitor filter (34) with the AC input power. A 20 kHz oscillator (38) drives a half-bridge inverter (36) for coupling the capactitor voltage to the lamp (42) as high frequency power. The conduction of the FET power switch (12) is controlled by a phase locked loop (16) for synchronizing the conduction with the zero crossing points of the AC cycle. A ramp generator (18) and a summing network (20) are responsive to a lamp intensity control (22) for changing the conduction duty cycle of the FET power switch (12) such that a desired lamp intensity is maintained.