How to Make a Metal Detector

Like looking for lost treasure? There's no need to break the bank for a high-end metal detector — just dig through your junk drawer!

Instructions

  • Step 1: Disassemble the CD case Carefully disassemble the CD case by removing the insert that holds the CD in place.
  • Step 2: Cut Velcro pieces On your radio, measure out an area centered on the back of the radio. Then cut a hook and loop piece of Velcro the same size.
  • Step 3: Mount the radio Stick one side of the Velcro to the back of the radio, and stick the other piece of Velcro to one side of the CD case. Then mount the radio.
  • Step 4: Mount the calculator Repeat the same process with the calculator, and apply the Velcro to the other side of the CD case. Then mount the calculator.
  • Step 5: Set radio Make sure the radio is set to the AM band and turn it on. Now tune it on to the highest end of the AM band, but not directly at a broadcast station. Turn the volume up and all you should hear is static.
  • TIP: If there is a broadcast station at the very high end of the AM band, get as close as you can so you're just hearing static.
  • Step 6: Fold CD case With the calculator on, start folding the CD case until you hear a loud tone. That tone is the electronic circuit in the calculator. It's producing a radio frequency signal that the AM radio is picking up.
  • Step 7: Move toward metal object Now slowly open up the case again until you can barely hear the loud tone. Then start moving your radio and calculator close to a metal object, and you're hear the loud tone again. Now the next time you drop something valuable, get your homemade metal detector and find it!
  • FACT: In 1881, Alexander Graham Bell used one of the first metal detectors to try and locate a bullet in President James Garfield's chest. He was unsuccessful because the metal bed Garfield was on confused the detector.

You Will Need

  • An AM or AM/FM radio
  • A calculator
  • A standard CD case
  • Some Velcro

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