| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an electric conductivity measuring instrument of simple structure with measurement precision hardly affected by a ground potential. <P>SOLUTION: This electric conductivity measuring instrument is provided with an oscillation circuit 10 having: a computation amplifier Q1 with a feedback capacitor C1 charged by a current flowing between electrodes 1a, 1b immersed into a measuring object; and a comparator Q2 for inputting an output from the computation amplifier Q1 into an inversion input (-), and for comparing the input with a voltage having 2/3 of output voltage from the own inversion input. A voltage having 1/3 of output voltage from the comparator Q2 is impressed in a non-inversion input (+) of the computation amplifier Q1. A computation circuit 20 computes the electric conductivity, based on an output frequency from the oscillation circuit 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
