Using the name of varactor this circuit was found in the Radio Electronics magazine of July 1982. Varicaps of any type can be used and the components selected according to the component.
Delayed Pulse Generator This can be considered an "advanced" application where two 555 integrated...
We found this circuit in a 1994 publication. It makes use of a divider for 16 384 CMOS type 4060. By...
This buffered version of the previous circuit appeared in an article in the September 1989 Radio...