This simple Morse Code oscillator was found in a 1980s American documentation. The power supply should be powered with 5V and the integrated can be the 7400.
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...