Speed control system

Claim 1

A SPEED CONTROL SYSTEM FOR CONTROLLING THE OUTPUT SPEED OF AN ELECTROMAGNETIC INDUCTION COUPLING DEVICE, COMPRISING A TACHOMETER GENERATOR DRIVEN FROM THE OUTPUT SHAFT OF THE COUPLING DEVICE AND PRODUCING A VOLTAGE PROPORTIONAL TO THE SPEED OF SAID OUTPUT SHAFT, A FULL WAVE RECTIFIER CIRCUIT PRODUCING THE EXCITATION CURRENT FED TO THE EXCITATION COIL OF SAID ELECTROMAGNETIC COUPLING DEVICE AND COMPRISING A PAIR OF SILICON CONTROLLED RECTIFIERS, A PULSE GENERATOR CIRCUIT FOR PRODUCING PULSES FOR CONTROLLING THE FIRING ANGLE OF THE SILICON CONTROLLED RECTIFIERS, SAID PULSE GENERATOR CIRCUIT INCLUDING A CAPACITOR, A FIRST TRANSISTOR WHOSE CONDUCTANCE IS CONTROLLED BY THE CHARGE ON SAID CAPACITOR, A SECOND TRANSISTOR CONNECTED TO THE FIRST TRANSISTOR AND WHOSE CONDUCTANCE IS CONTROLLED BY THE FIRST TRANSISTOR, AN OUTPUT LOAD FOR SAID SECOND TRANSISTOR ACROSS WHICH IS DEVELOPED THE FIRING PULSES FOR THE SILICON CONTROLLED RECTIFIERS, A THIRD TRANSISTOR WHOSE CONDUCTANCE CONTROLS THE CHARGING OF SAID CAPACITOR, A FEEDBACK RESISTOR CONTROLLING THE CONDUCTANCE OF SAID THIRD TRANSISTOR, MEANS FOR APPLYING THE OUTPUT VOLTAGE FROM THE TACHOMETER GENERATOR AND A REFERENCE VOLTAGE REPRESENTING THE DESIRED RUNNING SPEED FOR SAID COUPLING IN OPPOSITE ACROSS SAID FEEDBACK RESISTOR, TO CONTROL THE CONDUCTANCE OF SAID THIRD TRANSISTOR AND HENCE THE CHARGING RATE OF SAID CAPACITOR WHICH IN TURN DETERMINES THE CONDUCTANCE STATE OF SAID FIRST AND SECOND TRANSISTORS AND THE DURATION OF THE FIRING PULSES PRODUCED ACROSS THE OUTPUT LOAD OF SAID SECOND TRANSITOR, WHEREBY THE CONDUCTANCE OF SAID RECTIFIERS CONTROLS THE EXCITATION CURRENT FED TO THE COUPLING AND HENCE ITS SPEED AS A FUNCTION OF THE REFERENCE VOLTAGE.