This circuit for musical instruments was found in a 90’s Elektor. The circuit still applies, as the components used can still be obtained with some ease.
This circuit consists of a test oscillator for medium and high power NPN transistors. For PNP,...
This is a complete version of the previous circuit, with several scales and two transistors, one...
Found in a 1965 Electronic Design, this circuit makes it possible to select signals with an...