This circuit turns off a relay after a time determined by C1. The circuit was found in the December 1974 Radio Electronics magazine. The relay is rated according to the supply voltage.
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...