Bidirectional motor control circuit

Claim 1

A CONTROL CIRCUIT COMPRISING: A LOAD IMPEDANCE ELEMENT; A PAIR OF SEMICONDUCTOR DEVICES OF OPPOSITE CONDUCTIVITY TYPES AND HAVING THEIR RESPECTIVE EMITTER ELECTRODES AND COLLECTOR ELECTRODES COMMONLY CONNECTED; AN ALTERNATING CURRENT ENERGIZING POTENTIAL SOURCE CONNECTED IN SERIES WITH SAID LOAD IMPEDANCE ELEMENT BETWEEN SAID COMMONLY CONNECTED EMITTER ELECTRODES AND SAID COMMONLY CONNECTED COLLECTOR ELECTRODES; A FIRST DIRECT CURRENT CONDUCTIVE PATH CONNECTED BETWEEN THE BASE AND EMITTER ELECTRODES OF ONE OF SAID PAIR OF DEVICES, A NORMALLY CUT-OFF FIRST SEMICONDUCTOR DEVICE OF A TYPE OPPOSITE OF THAT OF SAID ONE OF SAID PAIR OF DEVICES HAVING ITS EMITTER AND COLLECTOR ELECTRODES IN SAID FIRST PATH FOR PREVENTING THE DEVELOPMENT OF A FORWARD BIAS ACROSS THE BASE-EMITTER ELECTRODES OF SAID ONE OF SAID PAIR OF DEVICES; A SECOND DIRECT CURRENT CONDUCTIVE PATH CONNECTED BETWEEN THE BASE AND EMITTER ELECTRODES OF THE OTHER OF SAID PAIR OF DEVICES, A NORMALLY CUT-OFF SECOND SEMICONDUCTOR DEVICE OF A TYPE OPPOSITE TO THAT OF SAID OTHER ONE OF SAID PAIR OF DEVICES HAVING ITS EMITTER AND COLLECTOR ELECTRODES IN SAID SECOND PATH FOR PREVENTING THE DEVELOPMENT OF A FORWARD BIAS ACROSS THE BASE-EMITTER ELECTRODES OF SAID OTHER ONE OF SAID PAIR OF DEVICES; MEANS FOR APPLYING CONTROL SIGNALS ACROSS THE BASE AND EMITTER ELECTRODES OF SAID FIRST AND SECOND SEMICONDUCTOR DEVICES, SAID FIRST DEVICE BEING RENDERED CONDUCTIVE IN RESPONSE TO A CONTROL SIGNAL OF ONE POLARITY TO DEVELOP A FORWARD BIAS ACROSS THE BASE-EMITTER ELECTRODES OF SAID ONE OF SAID PAIR OF DEVICES THEREBY ENABLING THE PASSAGE OF CURRENT THROUGH THE EMITTERCOLLECTOR ELECTRODES OF SAID ONE OF SAID PAIR OF DEVICES IN SAID ONE DIRECTION, SAID SECOND DEVICE BEING RENDERED CONDUCTIVE IN RESPONSE TO A CONTROL SIGNAL OF THE OPPOSITE POLARITY TO DEVELOP A FORWARD BIAS ACROSS THE BASE-EMITTER ELECTRODES OF SAID OTHER ONE OF SAID PAIR OF DEVICES THEREBY ENABLING THE PASSAGE OF CURRENT THROUGH THE EMITTER-COLLECTOR ELECTRODES OF SAID OTHER ONE OF SAID PAIR OF DEVICES IN THE OPPOSITE DIRECTION; FEEDBACK CIRCUIT MEANS COUPLED TO THE EMITTER-COLLECTOR CURRENT PATHS OF SAID PAIR OF TRANSISTORS FOR DEVELOPING A FEEDBACK VOLTAGE, AND MEANS FOR APPLYING SAID FEEDBACK VOLTAGE BETWEEN THE BASE AND EMITTER ELECTRODES OF SAID FIRST AND SECOND SEMICONDUCTOR DEVICES, SAID FEEDBACK VOLTAGE BEING OF A POLARITY TO DRIVE A CONDUCTIVE ONE OF SAID PAIR OF SEMICONDUCTOR DEVICES IN THE MORE CONDUCTIVE DIRECTION AND TO DRIVE A NONCONDUCTIVE ONE OF SAID PAIR OF SEMICONDUCTOR DEVICES IN THE LESS CONDUCTIVE DIRECTION.