ELECTRICAL CONDUCTIVITY MEASUREMENT CIRCUIT

摘要

A conductivity measurement circuit (4) is formed by a resistance dependent oscillator in which the frequency-controlling resistance is that presented by a liquid (3) whose conductivity is to be measured. The circuit (4) is formed essentially of four stages. A supply splitter (10) provides an accurate reference voltage to an integrator (11), which integrates a signal output from a driver (13). The output of the integrator (11) provides input to a Schmitt trigger (12). A level adjustment circuit (14) is connected between the Schmitt trigger (12) and the driver (13). The circuit (4) drives the liquid (3) with a symmetric, amplitude-controlled voltage signal.