Auto Water Dispenser For Pets

The Auto Water Dispenser For Pets is an intelligent, microcontroller-based hydration system powered by an Arduino Uno. The entire system relies on a reliable power supply circuit: a 15V AC step-down transformer reduces high-voltage mains power, which is then converted to direct current by a bridge rectifier and smoothed out using filtering capacitors. A 12V voltage regulator IC1 (7812) steps this down further to provide a stable, clean 12V supply for the heavier components like the 12V DC fluid pump P1 and 12V relay RL1, while the Arduino Uno manages the logic. Two primary sensors monitor the environment: an ultrasonic sensor HC-SR04 detects when a pet approaches the dispenser, and a water level sensor SEN18 continuously checks the reservoir to ensure it is adequately filled. When the ultrasonic sensor detects a pet and the water level sensor confirms sufficient water, the Arduino sends a control signal. Because the microcontroller's digital pins cannot supply enough current to drive a mechanical relay directly, a 2N2222 transistor T1 acts as a digital switch, amplifying the signal to energize the 12V relay RL1. Once triggered, the relay activates the 12V DC fluid pump P1 to dispense fresh drinking water into the bowl. Throughout operation, 5mm LEDs (LED1, LED2) provide visual indicators for power and operational status. If the water level drops too low, the system pauses operation to protect the pump from dry running, ensuring safe and automated pet care.