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.
The difference between this circuit and the previous one is that it uses PNP transistors. The...
Found in Radio Electronics from the 80's, this circuit can also be controlled by a microcontroller acting...
This circuit was found in a 1976 documentation. We can assemble it with equivalent transistors, for...