Automatic Wash Basin Tap Using Arduino

The Automatic Wash Basin Tap project operates by combining distance sensing logic with electromechanical fluid control, coordinated through an Arduino Uno microcontroller. At the core of the sensing mechanism is the HC-SR04 ultrasonic sensor, which is mounted near the wash basin. This sensor emits high-frequency sound waves and measures the time it takes for the echo to return after bouncing off an object, such as a user's hands. The Arduino Uno continuously processes these distance calculations. When a user places their hands within a pre-programmed threshold range, the Arduino detects that the measured distance is shorter than the baseline value. Upon recognizing this proximity event, the microcontroller changes the digital output state of its control pin. Because the Arduino's digital output cannot directly drive high-power loads, this signal typically interfaces with a switching transistor or relay circuit to safely control the 12V normally closed solenoid valve. A 12V power supply provides the necessary electrical energy to actuate the valve. When triggered, the solenoid coil energizes, creating a magnetic field that lifts the internal plunger and opens the valve, allowing water to flow freely through the tap. Once the user removes their hands, the ultrasonic sensor registers an open space or a distance exceeding the threshold. The Arduino immediately drops the control signal, causing the solenoid valve to de-energize and return to its normally closed mechanical state, halting the water flow. This automated loop ensures water is dispensed only when actively needed, integrating microcontroller programming with basic power electronics and sensor integration.