In this tutorial, we are making a project on an automatic water pump controller (transistor-based). This circuit is a low-cost version of an automatic water pump controller, it is only using some transistors, a relay, transformer, a BT139 TRIAC, and a few other discreet components. Since all these components are common and inexpensive that’s why the whole project costs low. The purpose of this circuit is to control any liquid or water pump according to the desired upper and lower level of the container or tank. This circuit is completely automatic.
There are three sensor points specified for each level marked as A, B, and C as shown in the circuit diagram, they will be placed at different levels in the water tank. The sensor C is for the bottom level of the tank. Sensor B is placed where you want the pump to start filling water in the sensor and sensor A is placed at the top level where you want the pump to stop filling as the tank is filled at this level.
Hardware Components
The following components are required to make the Automatic Water Pump Controller Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Step-down transformer | 230V to 9/12V, 100mA-200mA | 1 |
| 2. | Resistor | 1KΩ | 1 |
| 3. | Diode | 1N4148 | 6 |
| 4. | Transistor | 2N4401 | 4 |
| 5. | Relay | 12V | 1 |
| 6. | LED | Green | 1 |
| 7. | Pump motor | – | 1 |
| 8. | TRIAC | BT139 | 1 |
2N4401 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N4401
Automatic Water Pump Controller Circuit
Working Explanation
A transformer will step down the mains voltage 230V to 9 or 12V to the circuit. This voltage will be converted into DC voltage through a bridge rectifier and then filtered through an electrolytic capacitor. Now the input signal is ready for the circuit and will activate the transistors. This will activate the relay and the LED. There is a Pump motor connected so when the water will be at the sensor B level this circuit will turn on the motor.
You can also operate this voltage at a 5-6V supply or transformer. The relay should have the same value as the operating voltage.
