This circuit was found in the July 1978 issue of Radio Electronics magazine. The circuit uses a common digital voltmeter as the indicator. The sensors are integrated circuits of the time.
This circuit was found in a 1975 documentation. The SCR can be of any type and in this case, we...
This fuzz circuit is more elaborate with the previous ones, as it has a selection switch that...
The XR2206 is not a common component today, but if you have one you can build this function...