This 1968 circuit makes use of MOSFETs of the time. The circuit can be mounted based on modern common FETs. Observe the high supply voltage.
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...