Summary

Just a simple Theremin (first project post!) using a distance sensor and a buzzer. To make it, simply connect an ultrasonic distance sensor (I used the SR04, because it came with the starter kit I got) and a passive buzzer (not an active, passives are much better) to your board. In the picture I used a prototype shield, but that is not necessary.

Wiring

Distance:

• GND to GND
• VCC to +5V
• Echo to PWM12
• Trig to PWM11

Buzzer:

EXPANDED TECHNICAL DETAILS

Non-Contact Musical Synthesis

Inspired by the classic electronic instrument, this Theremin uses sound waves to generate music based on hand position.

• Proximity Detection: Uses an HC-SR04 Ultrasonic sensor. The Arduino calculates the distance from the hand to the sensor in real-time.
• Pitch Mapping: The distance value (e.g., 5cm to 50cm) is mapped to a frequency range (e.g., 100Hz to 2000Hz).

Sound Generation

• Tone Function: The Arduino uses the tone() function to output a square wave to a speaker.
• Interactivity: By moving one hand near the sensor, the user can play melodies like a futuristic instrument. Advanced versions use a second sensor for volume control, creating a fully non-contact 2-axis expressive musical interface.