This circuit, from a 303 Circuits from the 90s, uses a telephone pickup coil as a sensor to capture power grid noise, thus making it possible to locate electrical wiring.
Using 555 integrated circuits, this alarm circuit was found in a 90s American documentation. The signal...
Found in the May 1988 issue of Radio Electronics magazine, this circuit is sensitive to small...
We found this circuit in an English publication from the 1980s. The circuit uses current...