This alarm is either activated or triggered after a certain amount of time, giving the owner time to exit or enter and disarm it. The circuit is from a Radio Electronics from April 1975.
Although it is a common configuration today, this circuit was taken from an old publication. The...
This configuration was found in an English magazine from 1965. It is valid for any junction FET. The...
The circuit in the figure is an amplifier with gain 10 for alternating signals using the 741. The...