Water Level Sensor with Accurate Measurement

Overview

The project illustrates the design of an accurate water level sensor that is comprised of capacitance probe, analog electronics unit, and digital electronics unit.

Details

Some insulated wire where the insulation comes from the dielectric of a cylinder capacitor with the inner conductor as one plate in order to create the capacitance probe. Since the probe is not conductive enough, it is not suitable for very pure or distilled water. It will work fine with even relatively clean water like the plastic tank’s roof runoff water. High capacitance can be provided by enameled copper wire since the insulation is very thin.

The analog electronics unit is composed of an analog water level meter with commonly available parts used. The output is a voltage that is proportional to the water level. The circuit contains the monostable 555 IC where its width of the pulses is proportional to the water level.

In the digital electronics unit, the capacitance is connected to an ICM7555 that operates in astable mode. Since the timing capacitor is grounded, the 7555 has an advantage as an oscillator for this application. This will instigate the probe to be the timing capacitor.