This circuit for very long-time intervals was found in the March 1993 Radio Electronics magazine. Times of several days or even weeks can be achieved depending on the value of C1.
This circuit of an ancient American documentation is intended for cathode ray display analysis of low...
We found this circuit in the January 1994 Electronics Now magazine. It uses general-purpose...
Found in a Popular Electronics from the 80's, this circuit makes use of a time integrated to...