Ultrasonic pair HR-S04; 1 KΩ resistor; Arduino Uno; USB Interfacing cable; Connecting wires; LED of choice; THEORY. Ultrasonic waves are basically sound waves which is beyond the human audibility ie., ...

The HC-SR04 ultrasonic sensor uses SONAR to determine the distance of an object just like the bats do. It offers excellent non-contact range detection with high accuracy and stable readings in an easy ...