GB684613A - Improvements in and relating to electric discharge producing apparatus - Google Patents

Abstract

684,613. Ignition systems. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Dec. 4, 1950 [Dec. 19, 1949], No. 32540/49. Class 7 (iv) [Also in Group XXXV] Apparatus for initiating discharges in electric discharge devices such as the spark plug of a gas turbine or a gas and/or vapour filled discharge lamp as for photographic "flashing" comprises a main condenser 13 and charging supply connections 11, 12, a trigger condenser 15 serially connected with the primary winding 16 of a H.F. step-up transformer whose secondary winding 17 is connected to the apparatus output connections 18, 19 and a two-electrode spark gap 14 or other voltage operated circuit closing device forming with the primary winding 16 and condenser 15 a local circuit connected to the main condenser 13 whereby when the latter is charged to a given voltage less than that required to initiate the discharge the spark gap 14 breaks down and energisation of the transformer by current flow in the local circuit produces a high voltage across the output connections 18, 19 to initiate a discharge in the device (not shown) which discharge is prolonged by the relatively low voltage charge of the main condenser 13. Numerous embodiments are described of broadly two types, in which, as shown, the trigger condenser 15 is charged at the same time as the main condenser 13, or in which the local circuit is made and the trigger condenser charged only on break-down of the spark gap 14 which is serially connected between the two condensers. The spark gap 14 and the secondary winding 17 may be serially or shunt connected in the main discharge circuit and the transformer may be auto-connected. Where, in the case of discharge lamps, a running supply is needed, this may be connected serially with a choke across the output connections 18, 19, or in the main discharge or transformer secondary winding circuits. Specifications 663,527 and 663,528 are referred to.