DIODE_MATCHING_CIRCUIT_I

Published:2009/7/16 20:41:00 Author:Jessie | From:SeekIC

A 2N2222 transistor is connected in an emitter-follower circuit that is powered by a 12-Vdc source. Potentiometer R4 sets the voltage feeding the diodes under test. Two 1000-0,1percent resistors, RI and R2, make up two legs of a four-element bridge circuit. The diodes you want to test make up the other two legs. Potentiometer R3 is a fine-balance control. Meter M1is a 100-0-100-μA, center-zero unit. Connect jumpers in place of the test diodes, set RC to midposition, and set R4 to its maximum-voltage position (minimum resistance).Apply power and adjust R3 for a zero meter reading. Disconnect the power, set R4 to its minimum-voltage position (maximum resistance), and connect two diodes in the test positions. Slowly in-crease the bridge voltage with R4 and watch the meter for any change. The diodes are perfectly matched if the meter remains at zero as the voltage is increased.



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