NULL_VOLTMETER

Published:2009/7/15 20:20:00 Author:Jessie | From:SeekIC

Logarithmic voltmeter using Optical Electronics 9818 opamp and 2245C four-decade bipolar logarithmic function can serve as output indicator of Wheatstone bridge, as solid-state galvanometer, or as indicator for differentia[ voltmeter or comparison bridge. Meter scale values are relative; basic sensitivity of circuit corresponds to 1 on scale, representing 100 nV. With this sensitivity, 1 mV gives full-scale reading. Other three positions of range switch give 100 mV, 10 V, and 1000 V for full scale, when using 10-0-10 V meter. Inherent limiting of opamp protects circuit from overvoltage damage.- A Logarithmic Null-Volt-meter Design, Optical Electronics, Tucson, AZ, Application Tip 10084.



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