This circuit that appears in several versions in this section and on this website was found in documentation from the 1980s. The transistors can be of any general purpose NPN type like the BC548.
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...