Automatic Water Pump Controller Using 555 Timer IC

A simple but very reliable and effective water level controller circuit diagram is shown here. The circuit uses 6 transistors, 1 NE555 timer IC, a relay and few passive components. The circuit is completely automatic which starts the pump motor when the water level in the over head tank goes below a preset level and switches OFF the pump when the water level in the over head tank goes above the full level.

Automatic Water Pump Controller Circuit Using 555 Timer IC

Description:

This circuit will automatically switch on the water pump or motor when the level of water reaches below from the required level and then automatically switches off the pump when the tank is filled. It can be used for various purposes and not only to control the water level but also other kinds of liquids. The main component of this circuit is a 555 timer IC.

There are three probes in this circuit, they will detect the high and low levels of water. The probe which is marked as the upper-level probe will detect the upper level of water when the tank gets full. So you should position this probe at the level where you want the pump to switch off. The other two probes marked as bottom level probes will detect the bottom level of the tank so you should position them where you want the pump to switch on.

Components: 

1. Input Supply DC 9-12V

2. Probes 3 pcs.

3. Resistor 390K 2 Pcs

4. Resistor 1K 1 Pcs

5. Capacitor 100nF 1 Pcs

5. IC NE555 1Pcs

6. Relay 1 Pcs

7. Diode 1N4007 1 Pcs

8. Transistor 2N3904 1 Pcs

Circuit Diagram:

Circuit Diagram of Automatic Water Pump Controller

Working Principle:

The operating voltage of this circuit is 9 to 12 volts DC. This circuit is built around the timer IC NE555. When the water will be below the bottom level probes the IC will be activated and turns the relay on, which will turn on the pump. When the tank gets full it will reach the upper-level probe and the IC will give a low signal at its output which will turn off the tank. The sensitivity of the circuit is controlled by increasing or decreasing the value of the two 39K resistors. You can operate it with low voltages but make sure to use the relay with the same voltage.

Power supply for this circuit:

A classic 12V regulated DC supply based on 7812 is shown above. A power ON indicator LED is also added in the circuit. Resistor R13 limits the LED current. A small aluminium heatsink can be fitted to the 7812 for better saftey. Small Al heatsinks for TO-220 package are readily available in the market.

A 9-12V Power Supply Circuit for this Project