Self-balancing potentiometer systems for use

Claim 1

IN AUTOMATIC WEIGHING APPARATUS OF THE TYPE HAVING BRIDGE CIRCUIT MEANS FOR APPLYING AN ENERGIZING VOLTAGE OF FIXED MAGNITUDE TO A FIRST PAIR OF OPPOSITE TERMINALS OF SAID BRIDGE, A SELF-BALANCING POTENTIOMETER IN ONE PAIR OF LEGS OF SAID BRIDGE AND A VARIABLE RESISTANCE CIRCUIT IN AN OTHER PAIR OF LEGS OF SAID BRIDGE ADAPTED TO BE ADJUSTED TO CAUSE BALANCE OF SAID BRIDGE CIRCUIT WITH A SELECTED COMBINED WEIGHMENT OF TWO INGREDIENTS; MEANS INSERTING AUXILIARY IMPEDANCE IN SAID BRIDGE CIRCUIT FOR APPLYING A REDUCED VOLTAGE ACROSS SAID POTENTIOMETER DURING THE WEIGHING OPERATION OF THE FIRST INGREDIENT TO THEREBY CAUSE THE POTENTIOMETER TO SET UP A BALANCED CONDITION AT AN INDICATED WEIGHMENT CORRESPONDING TO THE PROPORTION OF THE FIRST INGREDIENT TO THE TOTAL WEIGHMENT, AND A CIRCUIT INCLUDING SWITCHING MEANS REMOVING SAID AUXILIARY IMPEDANCE FOR APPLYING FULL VOLTAGE ACROSS SAID POTENTIOMETER WHILE PRESENTING NO CHANGE IN IMPEDANCE TO SAID OPPOSITE TERMINALS DURING THE WEIGHING OPERATION OF THE SECOND INGREDIENT TO THEREBY CAUSE THE POTENTIOMETER TO INDICATE A BALANCED CONDITION AT THE SELECTED COMBINED WEIGHMENT.