What this project does is produce seven different tones (middle C, D, E, F, G, A, and B) with only an Arduino UNO, ultrasonic sensor, force-sensitive resistor (or push button), and piezo buzzer.

This is an Arduino-based Proximity Sensor circuit wired using the popular HC-SR04 Ultrasonic ranging module,used here for non-contact object detection purpose. The HC-SR04 module includes ultrasonic ...