This circuit was found in a documentation for radio amateurs from the year 70. Its purpose is to produce a tone on a transducer when transmitting messages in SSB telegraphy.
This circuit is from a 1995 Electronics Now. It generates a 1 kHz sinusoidal signal. See in the...
Found in a publication by Gernsback from 1960, this circuit uses germanium transistors of the time...
This circuit is based entirely on SCRs. The circuit is from an American 80's documentation; and the PUTs...