In the water level sensor schematic, the common probes connecting the underground tank and the overhead tank to +9V supply are marked ‘C’. The other probe in underground tank, which is slightly above ...

It will switch off only after the water drops below level A. Figure 2 illustrates the complete circuit. Using a rail-to-rail op amp for U2 allows for the application of a single 5-V power supply.

The professional sensors use a float with a direction sensor inside. When the float hangs down, it is open. When the water lifts the float up, it turns over and the circuit is closed.

This simple water level indicator will activate an active buzzer (e.g. BeStar BPT-23CX ) in order to make a noise when a certain level of water is being reached. Because the water sensor and the ...