Apparatus employing a voltage difference capacitor network for measuring the hold current of negative resistance devices

Claim 1

A CIRCUIT FOR MEASURING THE HOLD CURRENT OF A NEGATIVE RESISTANCE DEVICE, WHICH COMPRISES: (A) A SERIES CIRCUIT INCLUDING A RESISTOR AND A PAIR OF TEST TERMINALS FOR RECEIVING THE DEVICE; (B) A FIRST CAPACITOR CONNECTED IN PARALLEL RELATIONSHIP WITH THE TEST TERMINALS; (C) A SECOND CAPACITOR CONNECTED IN PARALLEL WITH THE SERIES CIRCUIT; (D) MEANS OPERABLE FOR A PREDETERMINED TIME TO CHARGE THE FIRST CAPACITOR TO A VOLTAGE GREATER THAN THE "ON" VOLTAGE OF THE DEVICE, TO CHARGE THE SECOND CAPACITOR TO A VOLTAGE GREATER THAN THAT NECESSARY TO TURN "ON" THE DEVICE, SO THAT THE DEVICE TURNS "ON" DURING THE PREDETERMINED TIME, AND TO ALLOW THE CAPACITORS TO DISCHARGE THROUGH THE DEVICE AFTER THE EXPIRATION OF THE TIME INTERVAL UNTIL THE DEVICE TURNS "OFF," THE VOLTAGE DROP ACROSS THE RESISTOR AT THE TIME THE DEVICE TURNS "OFF" BEING PROPORTIONAL TO THE HOLD CURRENT THEREOF; AND (E) MEANS FOR SUBTRACTING THE VOLTAGE STORED BY THE FIRST CAPACITOR FROM THAT STORED BY THE SECOND TO DETERMINED THE VOLTAGE DROP ACROSS THE RESISTOR AT THE TIME THE DEVICE TURNS "OFF" AND HENCE, TO DETERMINE THE HOLD CURRENT OF THE DEVICE.