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.
This circuit was obtained in a manual of the used old operational amplifier. However, the same...
This circuit is from a 1992 publication, but can be mounted very easily today. The circuit is...
Using the LM3909 this circuit was found in the January 1992 issue of Radio Electronics magazine....