Automatic Water Pump Controller Project

The Automatic Water Pump Controller circuit operates as a closed-loop feedback system designed to monitor and regulate liquid levels within a storage reservoir using discrete analog and digital logic components. Powered by a stable 12V DC power supply, the system utilizes conductive probes placed at different heights inside the tank to detect the presence or absence of water. These water-level sensing probes interface with a network of BC547 transistors configured to translate subtle changes in electrical conductivity into distinct logic-level voltage signals. The core decision-making unit of the circuit is the CD4011 IC, which contains quad 2-input NAND gates. By configuring these NAND gates in a set-reset or latching logic arrangement, the circuit remembers the current state of the water tank, preventing rapid and erratic switching when water ripples near the sensor thresholds. When the water level drops below the lower limit probe, the logic state changes to drive the transistors, which in turn energize the relay designated as RL1 or RL2. These electromechanical relays act as heavy-duty switches capable of safely handling the electrical load required to turn the water pump motor on. Conversely, once the water reaches the upper limit probe, the circuit inverts its output state, de-energizing the relay and shutting off the water pump motor to prevent overflowing. Through this continuous combination of probe sensing, transistor signal conditioning, NAND gate logic processing, and relay actuation, the system autonomously maintains optimal water levels without requiring manual intervention.