We found this circuit in the April 1993 Electronics Now magazine. Almost any general-purpose JFET can be used. Power is supplied by a battery (2 x 9V).
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...