Abstract: Direct current ballasting and starting circuitry for efficiently operating a gaseous discharge lamp on direct current. Series-pass switching means in one of a pair of input lines alternatively switches between on and off states to periodically supply pulses of energy from a source of direct current voltage. During steady-state operation, current sensing means limits the maximum current conductable by said switching means such that the output of the circuitry is current regulated. Starting means, in series connection between the filter means and an output terminal, senses the nonionized state of the lamp and provides a voltage pulse of sufficient magnitude and duration to initiate ionization in the lamp. Various forms of control means or drive means for controlling the conductive state of the switching means are disclosed.An A.C. to D.C.

Abstract: Direct current ballasting and starting circuitry for efficiently operating a gaseous discharge lamp on direct current. A series-pass switching transistor in one of a pair of input lines alternately switches between on and off states to periodically supply pulses of energy from a source of direct current voltage. During steady-state operation, current sensing circuitry limits the maximum current conductable by the transistor such that the output of the circuitry is current regulated. A filter, in series with the transistor, smoothes the pulses of energy delivered by the transistor into direct current with a comparatively small alternating current component. Starting circuitry in series connection between the filter and an output terminal, senses the nonionized state of the lamp and provides a voltage pulse of sufficient magnitude and duration to initiate ionization in the lamp, but permits uninterfered passage of current through the filter to the output.