Water Pump Controller

Here is a circuit that automatically controls the water pump motor. The motor gets automatically switched on when water in the overhead tank (OHT) falls below the lower limit. Similarly, it gets switched off when the tank is filled up. Built around only one NAND gate IC (CD4011), the circuit is simple, compact and economical. It works off a 12V DC power supply and consumes very little power.

http://electronicsforu.com/newelectronics/lab/freecircuitslist.asp?title=Automatic+Water+Pump+Controller&id=1020

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