Water detector



Rain water is collected in a 1000 liter tank  on the main floor.

This water is pumped to another water tank upstairs. This second tank hasn´t got any system to stop the pumping system. When the maximum level is reached the water leaks out.

To sort out this situation a water sensor has been developed.

The technology used is based in the BJT Transistor.

The target of the project has been to solve the problem using the minimum number of electronic  elements. Furthermore, The circuit used, unique amplification, one transistor or double amplification, 2 transistor, can be easy  be re-designed to mend a different task.


- Rigid  Wire (plastic coat)

1,5 Kohm resistor

2 Kohm Resistor

-500ohm resistor

-1N4007 diode

- LED diode

-BC549 BJT transistor

-2222A BJT transistor

- Relay 3V/250v

-220v/12 transformer

-220v source


-PVC plastic







The sensor has 4 open circuits along its height. These open circuits  are open  while the air is among them, when the water  reach them  the circuit will be  close.( very low electric current, water is bad conductor ).Then, the circuit should amplify this small current and active a 3v/250v relay. This relay separated the Command Circuit( BJT circuit) and de Power Circuit ( light and Pump). When the water tank is full the device  will switch on a warning light and switch off the main pump at the same time.





Project start: 
June, 2016