I created an instrument similar to a theremin using an Arduino uno, ultrasonic rangefinder and a potentiometer. The ultrasonic rangefinder uses the distance between your hand and itself to play a note. The ultrasonic range finder determines the distance by sending out a sound and measuring how long it takes for the sound to return. The potentiometer changes the duration of each note. The picture on top shows the finished box. The picture on the bottom shows the wiring. The code is displayed in this link here: code. If the code has an error please send me the error on the home page.
arduinodesigns 