The theremin, originally known as the ætherphone/etherphone, thereminophone or termenvox/thereminvox, is an early electronic musical instrument controlled without physical contact by the thereminist (performer). According to Wikipedia, the instrument is named after the westernized name of its Russian inventor, Léon Theremin, who patented the device in 1928.
Inspired by the musical instrument, the Adafruit crew went ahead and designed a pseudo-theremin built around an Atmel-powered Arduino Uno (ATmega328) – combining the board with a light-sensitive cadmium sulfide (CdS) photocell to make a light responsive music machine.
“Changes in light intensity on the photocell will change the pitch of a note on the piezo speaker as you wave your hand in front of the cell,” Barela explained. “While not a true theremin (which uses changes in a circuit’s reactance), this project is much simpler to build.”
As previously discussed on Bits & Pieces, the Gemma is a tiny wearable platform board packed in a 1″ diameter package. The device – powered by Atmel’s versatile Attiny85 – is easily programmable with an Arduino IDE over USB. Similarly, Adafruit’s Trinket, a tiny microcontroller board, is also built around Atmel’s ATtiny85.