This alarm circuit triggers when S1 opens. The circuit from a January 1975 Radio Electronics magazine can be used with interrupt sensors connected in series.
This circuit was found in an American documentation from the 90's. What it does is provide at the...
Found in old documentation, this circuit is tuned to pass signals below 245 Hz with a level of...
This series LED circuit was found in the February 1992 issue of Radio Electronics magazine. The...