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.
One flip-flop of the 4018 can be used as a frequency divider or counter as shown here. Frequency...
Found in a 1969 EEE, this circuit is based on an operational amplifier of the time and on old type...
This circuit was obtained from an American documentation from the 90's. The components can be...