We found this circuit in the April 1979 Radio Electronics magazine. Note the filter capacitor bank that can now be replaced by a single equivalent value capacitor.
The circuit shown in the figure is suggested by Allegro Micro (www.allegromicro.com) and consists of...
This circuit is a variation of the common grid dip meter, having been found in a 1975 publication on FETs....
The time obtained in this circuit, from a 1978 publication, depends on R3 and C. R3 can have...