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 found in a Radio Electronics magazine from November 1991. The circuit operates at 2.2...
12 V battery chargers provide higher unregulated voltage. With the regulator shown, obtained from...
The indicated circuit generates frequencies in a range from approximately 500 Hz to over 5 kHz...