Both experts recommend checking the size of the metal detector coil, which spits out the electromagnetic ... even looking at ...

including a simple metal detector circuit. It’s a very basic concept that uses a coil of copper wire as a home-made choke — when metal or a magnet comes near the coil, it varies the output ...

This one differs by using an Arduino to read from the metal detecting coil. The circuit starts with an oscillator that produces a signal of about 160 kHz which is constantly measured by the Arduino.

An advanced metal detector coil encompasses the diameter of the sensor head. Passing current through the MD coil creates an electromagnetic field that induces an electrical current in any metal ...