MATCHING_OPAMPS

Published:2009/7/11 1:43:00 Author:May | From:SeekIC

Simple circuit checks condition of quad Norton opamps (Nationai LM3900 or Motorola MC3401). Can also be used to match or select devices for similar DC characteristics in critical applications. Amplifier under test is plugged into socket connected as shown. Good unit makes all four LEDs glow with about same brightness, and all four testpoint voltages will agree within about 2 mV. If one section of amplifier is damaged, associated LED will glow very brightly or not at all. Wide variations between test-point voltages indicate partial damage. For critical applications, select amplifiers by matching average test-point voltages.-R. Tenny, Check Norton Amplifiers Quickly, EDNMagazine, March 5, 1974, p 72.



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