Abstract: A direct current motor which includes a stator for producing a fixed magnetic field and a plurality of armature windings. The motor is caused to rotate by applying current to each winding only while that winding is passing through a zone in a given orientation relative to the stator field. The direction of rotation is changed without changing the direction of the current applied to the windings, by changing the orientation of the zone relative to the stator field, to reverse the direction of the rotational force applied to the armature. Because the current does not reverse through the armature windings, the control circuit can be simple and in a preferred embodiment includes only two gate-turn-off silicon controlled rectifiers, a switch, and a resistor.

Abstract: A lamp is included as a cathode load for a gate-turn-off silicon controlled rectifier (GTO). The conduction path of a transistor is connected between the gate electrode of the GTO and ground. The GTO and lamp are turned off by applying current in the forward direction through the base-emitter junction of the transistor, thereby turning on the transistor and placing the gate electrode of the GTO at ground. The forward current passes through a thermal circuit breaker which periodically opens in response to the heat produced by the current flow, causing the gate electrode of the GTO to become forward biased via the collector load resistance of the transistor and turn on.

Abstract: When a gate-turn-off silicon controlled rectifier (GTO) is turned on, the potential of its gate electrode rises toward the voltage at its anode electrode. This gate voltage is employed to turn on a second GTO to insure that the loads driven by these GTO's are energized in a particular order. Switches in the circuit permit the GTO's to be turned off concurrently or in any order desired. A charge storage circuit may be included for controlling the turn-on delay between the two GTO's.

Abstract: The current through the main conduction path of a gate-turn-off silicon controlled rectifier (GTO) charges a capacitor in the cathode circuit of the rectifier. The GTO is turned off by providing a discharge path for the capacitor via the cathode-to-gate electrode of the GTO. A diode in the charging path of the capacitor becomes back-biased during discharge of the capacitor, thereby preventing the load in the cathode circuit of the rectifier from bypassing any of the discharge current.