The input and output frequencies of this circuit depend on the coils and capacitors of the tuned circuits. The circuit is from Electronics Now magazine, February 1997.
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...