This circuit, which controls both the temperature and the level of a liquid in a reservoir, was found in an Electronic Design from the 90s. The circuit is based on a double 555.
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...