We found this circuit in an old documentation for radio amateurs. The circuit uses an analog indicator. The characteristics of the coils are given next to the diagram.
We found this circuit in the April 1975 Radio Electronics magazine. The circuit has a latch and...
We found this sophisticated home alarm in a 1994 documentation. The circuit supports sensors of...
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...