GB628505A - Improvements relating to electronic time switching apparatus - Google Patents

Abstract

628,505. Switching systems for consuming devices. HIRST ELECTRONIC DEVELOPMENT, Ltd., and BRAMSON, S. M. April 23, 1947, No. 10856. [Class 38 (iv)] A load is connected across an A.C. supply for a period of not more than half a cycle by time switching apparatus comprising an igniter controlled mercury pool rectifier in series with the load and a cold-cathode tube arranged to control the discharge of a condenser through the igniter gap to cause the rectifier to operate for the remainder of the half cycle. Peaked triggering impulses are applied to the cold cathode tube from a circuit comprising a gas-discharge diode in series with a condenser and resistor. As shown, the cold cathode tube F fires on the first or second impulse following the closing of contacts S<SP>1</SP> and causes tube E to fire allowing condenser D previously charged from a battery or rectifier T to discharge through the two tubes and the gap of rectifier C, whereupon a pulse of current passes through transformer B and load A, the rectifier becoming non-conducting at the end of the positive half cycle. Closing of contacts S1 by relay S also opened contacts S2 so that the condenser is disconnected from source T, hence the rectifier ignites only once for each relay operation. The duration of the load energization is altered by varying the phase relationship between the triggering of tube F and the supply to the rectifier by means of condenser M<SP>1</SP> and resistor M<SP>2</SP>, while the phase of the triggering signals may be shifted by a bridge circuit, including resistors N<SP>1</SP>, N<SP>2</SP> and condenser N<SP>3</SP>, N‹ connected to a transformer P, as shown and a peaking circuit including a diode or neon tube Q, condenser Ql and resistor Q<SP>2</SP>.