Simple Water Level Detector

This simple water detector circuit uses alternative voltage in order to prevent the corrosion of the electrodes. It is easy to build and uses N1 as a trigger Schmitt gate which generate the AC. If between the electrodes is a electricity conductor, for example an aqueous solution, then because of the rectification action of D1 and D2, the C4 capacitor is charging.

Simple water detector circuit diagram:

When the capacitor voltage reaches switching threshold of the N2 trigger Schmitt, the relay will trigger and connect, for example a drain pump. The pump will be disconnected as soon as the electrodes won’t touch the liquid.

Components List:

R1 = 470K

R2 = 10M ? 22M

C1 ? C4 = 2.2nF

N1, N2 = 1/2 4093

D1 ? D3 = 1N4148

T1 = pnp transistor (BC557)