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.
I found this circuit in an article in a 2003 publication. The circuit is an example of how to...
This 9 V amplifier has a gain of 20 and provides a power of a few hundred milliwatts. The circuit is...
Found in an old Elektor, this circuit uses two 7-segment displays to indicate the volume of an...