This is a low-gain amplifier to operate as a booster. We found it in an American documentation from 1947. The circuit uses a coupling transformer at the input.
The transistors for this circuit from an 80's documentation can be the BC548 or 2B222 and the...
Found in Radio Electronics, this simple indicator circuit uses general-purpose transistors common today....
This circuit was found in an Elektor from the 90s. The integrated circuit is uncommon today. This...