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.
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...
With 3 transistors, this sensitive circuit was found in the July 1990 issue of Radio Electronics...
The purpose of this circuit is to produce a quick discharge on a shorted battery to attempt its...