We found this circuit in a 1980s American documentation. The operational amplifiers of the integrated circuit used can be common types in an experimental setup.
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...