Circuit for producing a spark discharge

Claim 1

A circuit for producing a spark discharge comprising, an ignition capacitor connected so as to be chargeable by a voltage converter from a d.c. source and connected to a discharge circuit through an automatically triggerable electric switch, said voltage converter comprising by a control transistor, a switching transistor, and a converter transformer having a feedback winding, said automatically triggerable electric switch comprising by a thyristor connected to said ignition capacitor and by a pair of trigger diodes and a current-limiting resistor connected in series between the anode and the gate of said thyristor, means for automatically turning off said voltage converter and simultaneously disconnecting said voltage converter from said d.c. source upon said electric switch being triggered, said latter means comprising a field-effect transistor having its collector and emitter connected across said d.c. source, having its collector connected to the base of said control transistor, and having its control input gate connected through a trigger path to a junction between said trigger diodes and said current-limiting resistor of said automatically triggerable electric switch, a capacitor connected to the control input gate of said field-effect transistor, and a zener diode connected in parallel with the capacitor connected to said field-effect transistor.