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.
This circuit is from an old technical documentation from Spain. The circuit uses a FET that is...
Found in a documentation from the 90's, this circuit already includes an amplification stage. The...
This circuit, called Kames Dandy, can mix signals from a wide range of frequencies and is...