This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from an approaching storm. The circuit was taken from a Popular Electronics from the 90s.
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...