Electrical control system

Claim 1

A control system for controlling the conductivity of solid state alternating current switch means connected in an alternating current circuit having a load and a source of supply voltage, said switching means having control means responsive to voltage pulses to control the conductivity of a said switching means, said control system comprising an oscillator circuit including an input circuit, means including switch means and low voltage supply means for supplying an input voltage having a magnitude substantially lower than that of said supply voltage to said input circuit, a pair of transistors each having base, collector and emitter electrodes, a saturable core transformer including a saturable core, a pair of main windings, a pair of feedback windings, and an output winding, all of said windings being disposed on said core, one of said main windings being coupled in series with the emitter and collector of one of said transistors and to said input circuit, the other of said main windings being coupled in series with the emitter and collector of the other of said transistors and to said input circuit, said feedback windings being coupled respectively to the base electrodes of said transistors for supplying bias current for said transistors in response to induced voltages in said feedback windings, whereby output of said transistors is utilized to turn off successively and alternately one or the other of said transistors, and means coupling said output winding to said control means, said main windings and said feedback windings being related to effect alternate conduction of said transistors to produce a signal pulse in said output winding on both half cycles of said supply voltage to thereby effect conduction of said switching means on both half cycles of said supply voltage when said input voltage is supplied to said input circuit.