Bridge apparatus for determining the input resistance and beta figure for an in-circuit transistor

Claim 1

APPARATUS FOR DETERMINING OPERATING PARAMETERS OF A TRANSISTOR IN ITS ASSOCIATED CIRCUIT, COMPRISING AN IMPEDANCE BRIDGE CIRCUIT HAVING FIRST, SECOND, THIRD AND FOUR IMPDEANCE BRANCHES, SAID THIRD AND FOURTH IMPEDANCE BRANCHES BEING OF EQUAL IMPEDANCE, MEANS FOR CONNECTING THE BASE, EMITTER AND COLLECTOR ELECTRODES OF SAID TRANSISTOR IN A COMMON-EMITTER AMPLIFIER CIRCUIT IN SAID FIRST IMPEDANCE BRANCH OF SAID BRIDGE, POWER SUPPLY MEANS FOR PROVIDING A PREDETERMINED MAGNITUDE OF DIRECT CURRENT TO SAID BRIDGE AND THE TRANSISTOR INPUT CIRCUIT OF SAID ASSOCIATED TRANSISTOR CIRCUIT, SWITCH MEANS FOR SELECTIVELY CONNECTING SAID POWER SUPPLY MEANS IN REVERSE AND FORWARD BIAS RELATION WITH SAID TRANSISTOR EFECTIVE TO SELECIVELY TURN OFF AND TURN ON SAID TRANSISTOR, MEASURING MEANS FOR DETERMINING THE LEAKAGE CURRENT OF SAID TRANSISTOR WHILE IT IS IN SAID OFF CONDITION AND FOR MEASURING THE COLLECTOR CURRENT OF SAID TRANSISTOR WHEN SAID TRANSISTOR IS TURNED ON, THE SECOND BRANCH OF SAID BRIDGE COMPRISING A FIRST IMPEDANCE NETWORK AND A SECOND IMPEDANCE NETWORK CONNECTED IN PARALLEL WITH EACH OTHER, SIGNAL MEANS FOR DELIVERING A TEST SIGNAL TO SAID BRIDGE AND SAID TRANSISTOR, ADJUSTING MEANS FOR ADJUSTING THE VALUE OF IMPEDANCE IN SAID FIRST NETWORK WITH SAID TRANSISTOR TURN OFF AND SAID SECOND NETWORK IN AN OPEN-CIRCUIT CONDITION EFFECTIVE TO BAL-