Automatic Water Tank Filling System

The Automatic Water Tank Filling System operates through a coordinated network of sensing elements, processing hardware, and power-switching components designed to automate fluid management. At the heart of the system is an Arduino Nano, which continuously monitors fluid levels via a set of electrodes submerged in the water tank. These electrodes detect changes in electrical conductivity as water rises or falls, providing real-time digital feedback to the microcontroller's input pins. To bridge the voltage gap between the delicate low-voltage logic signals and the higher power requirements of the system's actuators, the circuit employs three BC548 NPN bipolar junction transistors. These transistors act as solid-state switches to drive two IRF530 power MOSFETs and a mechanical relay. Depending on the logic state determined by the water level readings, the Arduino triggers the relay and power MOSFETs to intelligently route power to the connected water pump and solenoid valve. This enables the system to dynamically select between a municipal supply line and an underground storage reservoir, ensuring the tank is replenished efficiently without overflowing. Simultaneously, a 16x2 LCD panel connected via an I2C interface provides a continuous visual readout of the current system status and fluid levels, keeping operators fully informed of the automated filling cycle.