Arduino Touchless Trash Can (HC-SR04 + SG90 Servo + LED)

Wave your hand and the lid opens by itself! When the **HC-SR04 ultrasonic sensor** sees your hand closer than 15 cm, an **SG90 servo** lifts the lid in half a second and an **LED** lights up. Once the hand is gone, the lid waits 3 s and closes slowly. If the sensor detects a hand while the lid is closing, it reopens; contact is still possible because of measurement delays or an undetected hand. A school project favourite that is genuinely useful at home.