This article was taken from the December 2011 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
Professional metal detectors are simple, but require a bit of work to make. But you can build a pared-down handheld detector using a calculator, an AM/FM radio and some masking tape.
Tune in
Turn on the AM or AM/FM radio and set the frequency as far to the right as you can, and then turn the volume up so that all you can hear is static.
Move around
Turn on the calculator and put it back to back with the radio.
Move it around until you hear the note of the static change to more of a constant tone.
Tape up
Keeping the calculator and the radio in the same spot, tape them together. if you want to be flash, you can house them in something like a CD jewel case.
Turn on
It's now ready to use. With both the calculator and the radio turned on -- and the volume up -- your detector should beep when it gets close to any sort of metal.
Listen up
The closer you get, the faster it beeps. it's the calculator's circuit board that sends out the signal, which bounces off the metal and is picked up by the radio.
This article was originally published by WIRED UK
