CONDUCTIVITY_METER

Published:2009/7/20 20:57:00 Author:Jessie | From:SeekIC

Circuit using single quad opamp measures relative change in con-centration of salt solution by monitoring its conductance. Use of alternating current through solution eliminates errors caused by electrolysis effect. Wien-bridge oscillator having R4C1 and R4R3 as arms of bridge generates 1-kHz signal for driving amplifier A2 through solution. P1 controls oscillator amplitude, and P2 adjusts gain of A2. A3-A4 form precision rectifier giving output voltage equal to absolute value of input voltage.-M. Ahmon, One-Chip Conductivity Meter Monitors Salt Concentration, Electronics, Sept. 15, 1978, p 132-133.



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