This 40-second delay switch was found in a 1965 Electronic Design. The unijunction transistor might be the 2N2646 and the SCR a sensitive modern equivalent.
We found this circuit in the Electronics Experimenter Handbook 1983 edition. The circuit uses...
This little-known regulator today was found in a Radio Electronics circuit from December 1978. The...
This circuit was obtained in a 1982 Maplin magazine. The circuit can be applied to equivalent power...