GB641229A - Improvements relating to devices employing spark discharge gaps to produce illuminating flashes for photographic purposes - Google Patents

Abstract

641,229. Pulse generating circuit. BRITISH THOMSON-HOUSTON CO., Ltd. Jan. 2, 1947, No. 150. Convention date, Jan. 4, 1946. [Class 40 (vi)] In a circuit for producing spark discharges a capacitor 1 is charged through a limiting resistor 4 to a potential which is greater than, but not more than twice, the individual breakdown voltage of two similar spark-gaps 9 and 10 connected in series across the capacitor, resistors 5 and 6 ensuring equal voltage distribution. Discharge of the capacitor through the gaps is effected by firing a thyratron 12, connected in series with a limiting resistor 13 across gap 10, causing gap 9 to be subjected to the whole capacitor voltage so that it breaks down, whereupon gap 9 breaks down as it in turn is subjected to the full capacitor voltage, the capacitor then discharges through the two gaps. The thyratron is fired by closing switch 16 which reduces its positive cathode potential until capacitor 15 has charged through resistor 5 and 6, the purpose of this capacitor being to prevent the thyratron from firing again until the switch has been re-opened, thus allowing the capacitor 15 to discharge through resistor 17. The spark-gap electrodes 9a and 10b may be attached to the terminals of capacitor 1, while electrodes 9b and 10a may be attached to an inverted U-shaped member mounted above the capacitor terminals. Specification 582,850 is referred to.