(Experiment, tuned to A4=440Hz)
This is an A Major chord, comprised of the musical notes A4, C#5, and E5.
Sine waves at these frequencies produce something close to a sine wave of 440Hz with amplitude modulation at a rate of 55Hz. As frequency halves, the note is transposed down one octave. Therefore, the amplitude of the signal is modulated by the frequency of the root note minus two octaves. My hypothesis here is that as more (fitting) notes are added to the chord, the AM signal will gradually become a 55Hz sine wave with an amplitude of 3V.
