Raspberry Pi, ultrasonics, and music
My son is a musician and he’s mentioned several times that he’d like to get an instrument called a theremin. If you haven’t encountered this instrument before, it consists of an antenna that the theraminist (yes, that is a real word) waves their hand around. The device responds with a musical tone that’s dependent on how close the theraminist’s hand is to the antenna. How does it actually work? According to Wikipedia: The theremin uses the heterodyne principle to generate an audio signal. The instrument's pitch circuitry includes two radio frequency oscillators set below 500 kHz to minimize radio interference. One oscillator operates at a fixed frequency. The frequency of the other oscillator is almost identical, and is controlled by the performer's distance from the pitch control antenna. / The performer's hand acts as the grounded plate (the performer's body being the connection to ground) of a variable capacitor in an L-C (inductance-capacitance) circuit, which is part of the oscillator and determines its frequency.To read this article in full or to leave a comment, please click here