The integrated circuit used in this application is uncommon, but equivalent operational ones can be used. The circuit is from the Signetics integrated circuits manual from 1972.
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...