We found this circuit in the Electronics Experimenter Handbook 1983 edition. The circuit uses common components and has several features.
The circuit shown consists of a power stage for relay excitation. 2N3053 can be a BD135 and 2N406...
This circuit, from a 1968 Electronics World, is fed directly by the rectified voltage from the...
Using a 4046 PLL this circuit was obtained from the October 1994 issue of Electronics Now...