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 series sensor circuit is from 1995 Popular Electronics. The circuit can use any SCR and the...
We found this circuit in a 1968 Electronics World. It fires a buzzer if the ignition key is turned on...
This circuit for analog video signals was found in a Linear Technology integrated circuit manual. The...