This circuit with junction field effect transistors was found in documentation from the 1980s. The transistors can be MPF102 or BF245 and details of the coils are not given in the original.
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...