Analog to digital converter

Claim 1

AN ANALOG TO DIGITAL CONVERTER COMPRISING, IN COMBINATION: A COMPARING CIRCUIT FOR RECEIVING AN ANALOG VOLTAGE; A SOURCE OF REFERENCE POTENTIAL CONNECTED TO SAID COMPARING CIRCUIT TO PROVIDE A REFERENCE VOLTAGE MAGNITUDE FOR COMPARISON WITH THE MAGNITUDE OF SAID ANALOG VOLTAGE; A PULSE GENERATOR PROVIDING A SERIES OF PULSES; A STEPPER MOTOR HAVING AN OUTPUT SHAFT CONNECTED TO SAID SOURCE OF REFERENCE POTENTIAL FOR VARYING THE MAGNITUDE OF SAID REFERENCE VOLTAGE IN A GIVEN DIRECTION AND NUMBER OF A GIVEN RANGE DETERMINED BY THE DIRECTION AND NUMBER OF DEGREES OF MOVEMENT OF SAID OUTPUT SHAFT, SAID STEPPER MOTOR INCLUDING A CLOCKWISE ROTATION INPUT AND A COUNTERCLOCKWISE ROTATION INPUT, PULSES RECEIVED AT SAID CLOCKWISE ROTATION INPUT CASING SAID REFERENCE VOLTAGE TO VARY IN ONE DIRECTION AND PULSES RECEIVED AT SAID COUNTERCLOCKWISE ROTATION INPUT CAUSING SAID REFERENCE VOLTAGE TO VARY IN AN OPPOSITE DIRECTION; AND SWITCH MEANS CONNECTING SAID PULSE GENERATOR TO SAID STEPPER MOTOR IN RESPONSE TO THE PRESENCE OF A CONTROL VOLTAGE FROM SAID COMPARING CIRCUIT TO PASS PULSES TO SAID CLOCKWISE ROTATION INPUT WHEN SAID CONTROL VOLTAGE IS OF ONE POLARITY AND TO SAID COUNTERCLOCKWISE ROTATION INPUT WHEN SAID CONTROL VOLTAGE IS OF AN OPPOSITE POLARITY TO ROTATE SAID SHAFT VOLTAGE IS OF TERMINED BY THE POLARITY OF SAID CONTROL VOLTAGE AND THEREBY VARY THE REFERENCE VOLTAGE IN A PROPER DIRECTION TO NULL SAID ANALOG VOLTAGE, SAID SWITCH MEANS OPENING WHEN SAID CONTROL VOLTAGE IS REDUCED TO ZERO WHEREBY THE PULSES PASSED TO SAID STEPPER MOTOR DURING THE TIME INTERVAL REQUIRED TO NULL SAID ANALOG VOLTAGE IS A FUNCTION OF THE MAGNITUDE OF SAID ANALOG VOLTAGE.