Motor control circuit

Claim 1

A MOTOR SPEED CONTROL CIRCUIT INCLUDING IN COMBINATION, A PLURALITY OF SEMICONDUCTOR SWITCHING DEVICES CONNECTED IN A BRIDGE CIRCUIT, MEANS CONNECTING ONE PAIR OF OPPOSITE CORNERS OF SAID BRIDGE CIRCUIT ACROSS A FIXED D.C. POTENTIAL, MEANS CONNECTING THE OTHER PAIR OF OPPOSITE CORNERS, OF SAID BRIDGE CIRCUIT TO A SYNCHRONOUS MOTOR FOR SUPPLYING CURRENT PULSES OF ALTERNATELY OPPSOITE POLARITY IN RESONSE TO CONTROL PULSES SUPPLIED TO SAID SWITCHING DEVICES, AN INPUT TRIGGERING TERMINAL, AND CONTROL CIRCUIT MEANS INCLUDING BISTABLE CIRCUIT MEANS AND MONOSTABLE CIRCUIT MEANS COUPLED TO SAID INPUT TRIGGERING TERMINAL AND ACTUATED BY TRIGGERING PULSES APPLIED THERETO, SAID CONTROL CIRCUIT INCLUDING MEANS APPLYING CONTROL PULSES TO SAID SWITCHING DEVICES IN RESPONSE TO OPERATION OF SAID BISTABLE CIRCUIT MANS AND SAID MONOSTABLE CIRCUIT MEANS TO PROVIDE CONSTANT DURATION CURRENT PULSES HAVING A DUTY CYCLE WHICH VARIES IN PROPORTION TO THE REPETITION RATE OF TRIGGERING PULSES APPLIED TO SAID INPUT TRIGGERING TERMINAL, WHEREBY SUBSTANTIALLY CONSTANT AVERAGE CURRENT IS SUPPLIED TO SAID MOTOR OVER A RANGE OF MOTOR SPEEDS.