As the top sensor goes low (water above level C), the CLR signal is activated and the output of the flipflop is low. This allows Q1 to turn on and activate a triac or relay for the pump.

Check out the new water level sensor circuit. The simple water level indicator circuit presented here makes this system automatic, i.e. it switches on the pump when the water level in the overhead ...

What he ended up with was a water ... sensor module. The water acts as a sort of switch that closes the circuit. When the water gets too low, the circuit opens and [Bob] knows that the water level ...