BALLAST CIRCUIT FOR DISCHARGE LAMP

A high frequency ballast circuit for a discharge lamp particularly of the so-called energy saving type adapted to fit into conventional incandescent lamp sockets. The circuit comprises an inductive choke and a transistor switching device connected in series with the lamp and a rectified source of AC supply. The transistor is switched with a high frequency, preferably asymmetrically square, waveform and a diode having a direction of conduction opposite to that of the transistor is connected in shunt across the series-connected choke and lamp. The circuit enables lightweight air core coils to be used for the inductive choke facilitating integral combination of the circuit and discharge lamp into a lamp unit having the same general configuration as a conventional incandescent lamp.