GB1227489A - - Google Patents

Abstract

1,227,489. Supply circuits for discharge lamps. DR.-ING. h.c.F. PORSCHE K.G. 30 July, 1969 [23 Oct., 1968], No. 38183/69. Heading H2H. A supply circuit for a high pressure discharge lamp, particularly a h.p.m.v. lamp has a circuit 4 for operating the lamp 14 and an ignition circuit 19 energized as a function of the operating circuit voltage. A blocking oscillator comprising transformer windings 8, 9 and transistor 11 charge through a diode 12 a capacitor 13, which at a determined voltage energizes a relay coil 18 on break down of a Zener diode 17. The oscillator is disconnected through relay contacts 5, 26 and contacts 25, 26 complete the discharge circuit of a capacitor 23, previously charged through a further winding 10 and diode 24, through a transformer primary winding 21, the voltage across the secondary 22 breaking down a spark gap 27 which should ignite the lamp 14 and hence partially discharge capacitor 13, the drop in voltage across which de-energizes the relay which recloses contacts 5, 26 to restart the oscillator. Failure of the lamp to start causes the above sequence to be repeated. A plurality of oscillators may be connected in parallel to a common output capacitor. The oscillator frequency may be several k.c./sec.