This fuzz effect for guitars was found in an American 1980s documentation. The transistors may be the BC549 and should be battery powered for noise sensitivity. Diodes are commonly used.
This configuration was found in an old technical documentation from the 70s, but it can be...
In the figure we have a converter that generates a negative voltage from a positive voltage...
This circuit was found in a 1976 magazine. The circuit emits a sound when a balance sensor placed on...