Motor drive circuits

Claim 1

IN A CAPSTAN TAPE DRIVE SYSTEM, A SYSTEM FOR BIDIRECTIONALLY DRIVING THE TAPE COMPRISING A CAPSTAN IN CONSTANT CONTACT WITH THE TAPE SURFACE, A MOTOR COUPLED TO DRIVE THE CAPSTAN AND PROVIDING AN OUTPUT TORQUE PROPORTIONAL TO THE MAGNITUDE OF THE APPLIED CURRENT, MEANS FOR SENSING THE ACTUAL SPEED AND DIRECTION OF THE MOTOR, MEANS FOR PROVIDING AN INPUT SIGNAL INDICATIVE OF THE DESIRED MOTOR SPEED AND DIRECTION, MEANS RESPONSIVE TO THE SENSING MEANS AND THE INPUT SIGNAL MEANS FOR DELIVERING A CONSTANT LEVEL CURRENT TO THE MOTOR HAVING A POLARITY DEPENDENT UPON THE DESIRED ROTATIONAL DIRECTION IN RESPONSE TO INPUT SIGNALS GRETER THAN A PREDETERMINED MAGNITUDE AND FOR DELIVERING A CURRENT PROPORTIONAL TO THE DIFFERENCE BETWEEN THE DESIRED SPEED AND THE ACTUAL SPEED IN RESPONSE TO INPUT SIGNALS LESS THAN SAID PREDETERMINED MAGNITUDE, AD THRESHOLD SETTING MEANS FOR ADJUSTING THE MINIMUM AMPLITUDE OF SIGNAL TO THE CURRENT DELIVERING MEANS.