HIGH_GAIN_D_C_PREAMP_FOR_VTVM

Published:2009/7/24 1:49:00 Author:Jessie | From:SeekIC

Use of current source as load resistor of Q2 minmizes battery supply effect on zero selling. Additional current source Q5-R3-D3-D4 serves in place of common-emitter resistance for Q1-Q2 to reduce sensitivity to negative supply voltage excursions and boost open-circuit gab above 300. Preamp will extend 1.5-v range down to 500, 150, and 50 my full-scale for voltage measurements in semiconductor circuits without damaging transistors.-A. K. Scidmore, Low-Cost Emitter-Follower Extends Voltmeter's Range, Electronics, 39;3, p 87.



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