GB1116111A - Electric-discharge apparatus - Google Patents

Abstract

1,116,111. Control systems for discharge lamps. GENERAL RADIO CO. 19 Jan., 1966 [28 Jan., 1965], No. 2508/66. Heading H2H. A control system for intermittently energizing a discharge tube FT so as to produce flashes of light comprises a capacitor C which is charged from a D.C. source E which capacitor is then discharged through the tube FT when a triggering pulse is applied thereto by the trigger 2. Simultaneously with the pulse to the tube FT the trigger 2 applies a signal to a pulser 4 which then applies a pulse to the base of a transistor S to render it conductive whereupon current flows in the primary winding Lp of a transformer T which current increases in a linear manner. The voltage induced in the secondary winding Ls of the transformer does not cause charging of the capacitor C due to the presence of a diode D. Termination of the pulse from the pulser 4 renders the transistor S non- conductive, the collapse of flux in the core of the transformer T then producing a voltage which charges the capacitor. The following pulses from the trigger 2, and hence the pulser 4, cause a flash of light from the tube FT by the discharge of the capacitor C therethrough and a build-up once more of current in the primary winding Lp. The duration of the pulses applied to the base of the transistor must be longer than the de-ionization time of the tube FT. The frequency of flashing of the tube may be varied by changes in the value of the capacitor. In a further embodiment the pulses applied to the base of the transistor S are supplied by a monostable vibrator, the capacitor then being charged in an incremental manner and the voltage to which the capacitor is charged is determined by a Zener diode which controls the monostable vibrator by way of a bi-stable circuit and a gating device. The time during which the capacitor is charged is determined by a delay circuit.