Found in Motorola documentation from the 1970s, the circuit presented uses a component from the era that is not common today. The characteristics of the coils are given next to the diagram.
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...