each key pressed would switch two different tapped inductors into the circuit to produce the dual-tone audio signal. Other switches controlled power to the oscillator circuit as well as attenuatin ...

I try to keep the piezo signal as an acoustic baseline using perhaps a pre-amp and some compression to bolster the tone, and maybe a Boss OC-5 Octave in Poly mode for some bass in the bottom end.

Known as the dual-tone multifrequency (DTMF) system, the signal is a combination of the row and column frequencies of the digit key. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other ...