Electronic motor control

Claim 1

IN A MOTOR CONTROL CIRCUIT INCLUDING AN ARMATURE HAVING FIRST AND SECOND TERMINALS, VARIABLE IMPEDANCE MEANS, AND CONTROLLABLE IMPEDANCE MEANS CONNECTED IN SERIES BETWEEN TERMINALS ADAPTED TO RECEIVE A SOURCE OF VOLTAGE, THE IMPROVEMENT COMPRISING SAID VARIABLE IMPEDANCE MEANS HAVING AN IMPEDANCE VALUE EQUAL TO THE IMPEDANCE PRESENTED BY SAID ARMATURE, INCLUDING THE WINDING AND BRUSH IMPEDANCE THEREOF, A COMMON TERMINAL CONNECTED BETWEEN SAID VARIABLE IMPEDANCE MEANS AND SAID CONTROLLABLE IMPEDANCE, TERMINALS FOR RECEIVING A SOURCE OF REFERENCE VOLTAGE, A VOLTAGE DIVIDER, MEANS CONNECTING SAID TERMINALS FOR RECEIVING A SOURCE OF REFERENCE VOLTAGE TO SAID VOLTAGE DIVIDER, MEANS CONNECTING A FIRST TERMINAL OF SAID ARMATURE TO SAID VOLTAGE DIVIDER, COMBINING MEANS HAVING TWO INPUT TERMINALS, A COMMON TERMINAL AND AN OUTPUT TERMINAL FOR DIFFERENTIALLY AMPLIFYING SIGNALS APPLIED TO THE INPUT TERMINALS THEREOF AND PROVIDING AN OUTPUT SIGNAL ON SAID OUTPUT TERMINAL, MEANS CONNECTING SAID DIVIDING MEANS TO A FIRST OF THE INPUT TERMINALS OF SAID COMBINING MEANS, MEANS CONNECTING A SECOND OF THE TERMINALS OF SAID ARMATURE TO THE SECOND INPUT TERMINAL OF SAID COMBINING MEANS, AND MEANS CONNECTING THE OUTPUT TERMINAL OF SAID COMBINING MEANS TO SAID CONTROLLABLE IMPEDANCE TO CONTROL THE IMPEDANCE THEREOF, WHEREBY SAID COMBINING MEANS PROVIDES AN OUTPUT SIGNAL DIRECTLY PROPORTIONAL TO THE COUNTER E.M.F. PRODUCED BY SAID ARMATURE AND CONTROLS SAID CONTROLLABLE IMPEDANCE IN RESPONSE THERETO.