GB1509704A - Ignition devices - Google Patents

Abstract

1509704 Control circuit TURNRIGHT CONTROLS Ltd 11 April 1975 [11 April 1974 14 Feb 1975] 16119/74 and 6295/75 Heading F4T An ignition device for a domestic gas burner of the type having spark ignition and a flame detecting circuit which inhibits sparking when the flame is established is adapted to be powered by a battery. In the first embodiment (Fig. 1) transistors T1 and T2 with resistance R1 and linked inductances L1 and L2 constitute a pulse forming circuit. The pulses, transformed through linked inductances L2 and L3, charge up a capacitor C1 until a gas-filled discharge device discharges (~ 220 volts) and the discharge pulse is transformed through transformer T1 to give a spark at electrode E1 and burner nozzle 3. When the flame is established a current flow across the electrodes and through a resistance R4 reduces the potential at the base of a transistor T4 and, as a result, transistors T3 and T4 which are normally non- conducting, start to conduct and bias off transistors T1 and T2 so that sparking is discontinued. If the flame goes out transistors T3 and T4 again become non-conducting and sparking is again started. In a further embodiment (Fig. 2), the charging of a capacitor C11 also causes the charging up of a second capacitor C12 until a neon lamp N11 breaks down and triggers a thyristor D13 which discharges the capacitor C11 through winding T11P to generate a pulse in T11S and a spark at the electrodes. A feedback line from C11 to the base of a transistor T11, normally non-conducting, causes it to conduct when a certain voltage at C11 is reached. This causes the pulses produced by transistor T12 to be reduced in amplitude and thus save battery power. Establishment of a flame short-circuits C12 to prevent it charging and hence discharge of C11. The part of the circuit including the burner nozzle electrode E11, winding T11S, resistor 14, capacitor C12 and neon N11 can be reproduced so that the circuit can control more than one burner.