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.
The voltage regulator circuit described is highly accurate and uses discrete components...
WWV is the standard frequency station of the United States government. This station broadcasts a...
Based on a 555, this 80's American documentation circuit detects the voltage of a battery and can then...