Theremin - "Mon Coeur S'ouvre à ta Voix" from "Samson & Delilah" by Saint Saëns late 1920's, and is the only musical instrument played without being touched. Its circuitry includes two radio frequency oscillators; one at a fixed rate, the frequency of the other determined by the thereminist's right hand (acting as the grounded plate of a variable capacitor) as it moves beside the upright antenna; this controls the pitch. The difference between the two frequencies creates audio signals heard via an amplifier. Using a similar principle, the left hand's proximity to the ...From:ThereminstrelViews:0 0ratingsTime:03:19More inMusic