Electrical measuring instrument with digital indication

Claim 1

AN ELECTRICAL MEASURING INSTRUMENT PROVIDING ANALOG-TO-DIGITAL CONVERSION AND DIGITAL INDICATION OF THE MEASURED VARIABLE COMPRISING A POTENTIOMETER NETWORK INCLUDING A REFERENCE VOLTAGE SOURCE CONNECTED ACROSS A PLURALITY OF BANKS OF SERIES-CONNECTED UNIFORM RESISTORS; ADJUSTABLE CONTACTS IN EACH RESISTANCE BANK WITH THE ADJUSTABLE CONTACTS IN EACH RESISTANCE BANK WITH THE ADJUSTABLE CONTACTS AND RESISTOR BANKS CONNECTED TO PROVIDE A POTENTIOMETER BALANCING RESISTANCE COMPRISING PORTIONS OF THE RESISTANCE BANKS ACROSS WHICH SAID VOLTAGE SOURCE MAINTAINS A REFERENCE ELECTOMOTIVE FORCE IN OPPOSITION TO AN ELECTROMOTIVE FORCE TO BE MEASURED; ELECTRICAL MEANS RESPONSIVE TO UNBALANCE BETWEEN SAID ELECTROMOTIVE FORCES SUBSTANTIALLY INDEPENDENTLY OF THE MAGNITUDE OF UNBALANCE TO ENERGIZE ONE OR THE OTHER OF A PAIR OF CONTROL CIRCUITS DEPENDENT ON THE POLARITY OF UNBALANCE; A PLURALITY OF RELAY MECHANISM EACH CONNECTED TO ONE OF SAID ADJUSTABLE CONTACTS AND OPERABLE WHEN ACTUATED TO SELECTIVELY ADJUST THE POSITION THEREOF; SWITCH MECHANISM IN SAID CONTROL CIRCUITS INCLUDING MEANS SELECTIVELY CONNECTING SAID RELAY MECHANISMS INTO SAID CONTROL CIRCUITS IN PREDETERMINED SEQUENCE TO BE ACTUATED THEREBY IF THEN ENERGIZED AND TO SEQUENTIALLY ADJUST SAID ADJUSTABLE CONTACTS TO POSITIONS SUCH THAT THE POTENTIOMETER NETWORK BECOMES SUBSTANTIALLY REBALANCED, AND MEANS INDICATING THE REBALANCE POSITIONS OF SAID ADJUSTABLE CONTACTS TO THUS PROVIDE A DIGITAL INDICATION OF THE MAGNITUDE OF THE ELECTROMOTIVE FORCE MEASURED.