This circuit was obtained from an American technical manual from the 80's. The integrated circuit is an operational of the time that can be replaced by a modern equivalent.
This additional bell circuit was found in the February 1994 Electronics Now magazine. The...
A delay of a few seconds to a few tens of seconds can be achieved with this circuit found in a...
This circuit uses a transistor to trigger the alarm from a low quiescent current sensor. The relay...