An automatic wash basin tap is quite helpful in maintaining hygiene as it does not need to be touched for water flow. It is especially useful in public places like restaurants and hospitals where a large number of people use the wash basins. Since the water stops flowing after use, it also prevents water wastage.
This circuit lets the water flow from the tap automatically when a person comes in front of the wash basin to wash hands. The water stops flowing as soon as the person tries to leave and removes his hands away from the wash basin. The author’s prototype is shown in Fig. 1.
![Author’s prototype on a breadboard](https://www.electronicsforu.com/wp-contents/uploads/2023/03/Fig.-1-Authors-prototype-on-a-breadboard-500x427.jpg)
Watch live DIY Video below
Circuit diagram for the automatic wash basin tap is shown in Fig. 2. The circuit comprises an Arduino board (BOARD1), ultrasonic sensor HC-SR04, 12V normally closed solenoid valve, and a few other components. The wash basin’s solenoid valve (to let water flow from the tap to which it is connected) opens automatically when a user’s hands are detected just 3 to 5cm away by the ultrasonic sensor HC-SR04.
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