Abstract: A method and a ballast circuit are disclosed for operating a metal halide lamp particularly suited for horizontal applications that provides signals capable of being varied so as to control the power applied to the metal halide lamp while still providing a uniform arc. The ballast circuit has a filter which passes a selected band of frequencies for the operating signals of the metal halide lamp.

Abstract: An improved tapped-inductor boost converter for operating a gas discharge lamp is disclosed. The converter includes a pair of input terminals connected to a power source supplying an input voltage, a pair of output terminals for providing an output voltage greater than or equal to the input voltage to the lamp, or other load, a tapped-inductor having first and second windings, an active switch for controlling current flow through the first winding for variably controlling the output voltage, a passive switch for controlling current flow through the second winding, and a first capacitor. The converter further includes an arrangement for varying the clamping voltage at the active switch in response to variations in the output voltage and also includes a clamping capacitor for transferring energy stored in the leakage inductance of the tapped-inductor to the load for improved efficiency.

Abstract: A control circuit for supplying power to a piezoceramic coupler includes a controllable oscillator for supplying an output signal having the resonance frequency of the piezoceramic coupler and an amplitude control circuit to control the amplitude of the output signal of the piezoceramic coupler. Switching devices are also included to control interruption of the application of the drive signal to the piezoceramic coupler.