We found this circuit for musical instruments in the March 1992 Radio Electronics magazine. The circuit has outputs according to the desired scale from a crystal oscillator at the indicated frequency.
This circuit was adapted from an Italian publication that no longer exists. This is “Onda Quadra”...
This circuit was obtained in an Electronic Engineering of the 90s. The operational amplifiers and...
The basic component of this circuit is a general-purpose SCR. The voltage is according to the...