Found in a 1969 EEE, this circuit is based on an operational amplifier of the time and on old type MOSFETs. The components support modern equivalents.
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...