Method of and switching device for reducing feedback from a consumer periodically connected to an A.C. line

Abstract

A method of polarity-independent reduction of feedback from a complex consumer or consumers periodically connected to an A.C. line is of the type involving disconnection of the consumer or consumers from the line during each half wave of the A.C. line voltage. The consumer or consumers are damped and discharged during each half wave of the A.C. line voltage by a power switching device, the power switching device being rendered operative whenever the connection between the consumer or consumers and the line is interrupted. A power switching device includes the collector-emitter leads of a pair of transistors and a set of rectifiers, preferably in the form of a bridge circuit, supplies voltage at the proper polarity for the consumer or consumers to the transistors. The secondary windings of respective transformers are connected to the base-emitter circuit of the respective transistors. The primary windings of the respective transformers are connected to distinct outputs from a source to supply driving voltage to the transistors. A Darlington transistor is coupled across the consumer or consumers via a further rectifier bridge and a winding of a choke, its input being connected to the secondary winding of a third transformer. The primary winding of the third transformer is connected to a third output from the source.

Dependencies are inferred from the claim text.