This is a simple water level indicator circuit or water level sensor circuit. The circuit is very easy to build and contains only three PNP transistors and some other components. This is a very useful circuit to detect the level of water in the tank.
The circuit is using three colors LEDs which will indicate low, medium and full level of water in the tank. The three probes (Low, Medium, Full) are shown in the circuit to attach on desired levels in the tank. The ground probe should be attached at the bottom of the water tank.
3 – Transistor A1015
6 – Resistor 470 ohm
3 – LEDs (Red, Yellow, Green)
1 – 9volt Battery