Low-Cost Capacitive Sensor and Interfacing Circuit for Water Level Monitoring Anucha Kaewpoonsuk* and Kriangsak Prompak

Abstract

This paper presents a low-cost capacitive sensor and an interfacing circuit for computer
based water level monitoring. Overall structure consists of a sensor, an interfacing circuit, and a
computer for display. Two varnish-coated copper wires are employed as the sensing parts to produce
capacitance value proportional to water level being measured. Interfacing circuit consists of two subcircuits,
capacitance measurement and signal converter. Experimental results verifying the proposed
equipment performance are closely agreed with the expected values. Maximum error is
approximately equal to 0.7 % of full-scale, for 15 cm water level range.

Keywords: Interfacing circuit, level detection, capacitive sensing, monitoring systems