This current boosting circuit uses an op-amp and 3 transistors. The current depends on Q1. The circuit is from the 1995 Encyclopedia of Electronic Circuits Volume 5.
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...