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DIY Metal Detector

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Looking for a light project to teach young hackers some very basic electronics? Here’s a quick and easy weekend project, a simple metal detector!

We all know 555 timers are very useful and pop up in a wide range of projects, but did you know a metal detector is one of them? [vonPongrac] stumbled upon this handy guide, a free eBook on 50 555 Circuits, which contains many cool project ideas, 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 frequency, and the 555 timer in turn, varies the output sound, alerting you of the presence of something metal nearby.

After the break there’s a video of it during its testing phases. If you don’t have a 555 on hand (tisk tisk) but still want to have some treasure hunting fun you can also build one based on an Arduino.

A cool project, but we don’t think it’ll be powerful enough to find hidden treasure on a beach!

Comments

  1. Tom the Brat says:

    Oh, I was wondering where the arduino went! :D

  2. boot says:

    i like the 555 projects, cheap, easy, 42 years old and still going strong

  3. juno says:

    Currently working on a metal detector hack myself, but there’s little progress and free time so I’m going to share the idea:

    metal detector coils in the soles of the shoes. You can operate it everywhere you go without having to wave the thing in front of you. Instead of audio feedback there’s a vibrator motor you strap to your leg.

    • James Hobson says:

      That sounds really cool! Make sure you submit it when it’s done!

    • sparkygsx says:

      I have almost no experience with metal detectors, but I think you need more than just a yes/no signal for it to be useful; our ears are very sensitive instruments, and we are very good at detecting changes is the frequency of a sound, while filtering out noise. I’d think it would be pretty difficult to get such selectivity in an analog or software controlled detector.

      The idea of having the detector coils in your shoes is interesting; it would allow you to search for things inconspicuously. They would rather suck for mine detection, though.

      If you want to have a detection coil in each shoe, you’d probably need to alternate between them, to prevent interference.

      • juno says:

        You’re correct on all points.

        The detection would only happen during “foot down” which can be determined by using an accelerometer.

        The original idea was to map an area or path. On each foot down the reading is stored, get back home and visualize it. The vibrator was an idea to mark spots as you walk, e.g. as you stroll along the beach where the result should be yes/no.

    • Tom the Brat says:

      Shoes? Who wears those?

    • static says:

      Why bother with strapping the vibrator to your leg when having remain in the shoe would alert the wearer just as well. Having the detector in hand would do wonders to clue the public in it is that you are walking in circles etc. .

  4. Hirudinea says:

    Cool, and the great thing about this is after you’ve found enough coins you can buy a real metal detector!

  5. static says:

    Somewhere I have an older electronics magazine that has plans for security style detector wand. Then the kiddies can play TSA agent rather than doctor to learn about the human anatomy of the opposite sex.

  6. boot says:
    • Johan G says:

      Hmm, I’m sceptical about some of their detectors operating modes: :-P

      ” During the detection of gold the Bionic Detection Method interacts with the Bio-Energy of the operator’s body to analyze minimum changes of object substances. ”
      (From the Bionic X4 Long range gold detector product page.)

  7. Ben says:

    How far is the range on something like this? I’ve been looking for a cheap semi-far range (2-3 feet) metal detector for a project.

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