In this charger the current is limited by the incandescent lamp. Lamps from 40 to 100 W can be used and even connected in parallel, depending on the load.
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...