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Mobile phone metal detector

Discussion in 'General Electronics Discussion' started by nulik, Mar 3, 2017.

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  1. nulik


    Feb 9, 2016
    I am not very good at electronics but I want to make a cheap metal detector that would be used with a mobile phone. I am a good programmer so I will do everything in software. Kind of "give me the ability to send/receive data and I can will move the Earth". But how do I send and receive magnetic pulses from a mobile phone to the coil ?
    I was thinking to use the MIC(rophone) input of the mobile phone, but is it would be one way only, only input. The coil would have to have a device that would send electromagnetic pulses periodically and the mobile phone would assume the coil is working every time. The other way is USB. With USB I would control the coil , the frequency and whatever I want. But I have to have a microcontroller on the coil side and I don't know anything about microcontrollers. It wouldn't be cheap either. So, my questions are:
    1) Is it possible to use microphone input (MIC) on the mobile phone to read magnetic pulses ?
    2) How complex would have to be the circuit to send and receive magnetic pulses over USB ?

    I appreciate very much your input. Any ideas or suggestions to make a metal detector controlled by mobile phone are welcome.
  2. davenn

    davenn Moderator

    Sep 5, 2009
    hi there
    welcome :)

    have you actually read up on how metal detectors work ?

    first you need to build or buy a metal detector ... then look at ways to interface it to the
    phone via USA or Bluetooth. The phone will most likely only be used as a detection display
  3. nulik


    Feb 9, 2016
    I watched this video

    and it says the coil generate inductance that affects the frequency of the sound. This means object have been found. If the sound is an output of a metal detector why can't I input it to the MIC of the mobile phone ? It should work, right?
    But modern metal detectors generate a range of frequencies, so I must build a much complex metal detector, then somehow interface it with mobile phone. I was wondering if I could use the audio output of the mobile phone to instruct the metal detector to generate range of testing frequences. Because I want to avoid using USB at all costs, it is very complex interface and will increase the price of my device
  4. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    So what is the benefit of using a mobile phone as an interface to your metal detector? Why not just wear a set of earphones like everyone else does? Have you ever actually tried to use a metal detector? Finicky beasts they are. Huge range of prices and performance too. I like @davenn's suggestion to use a mobile phone, or more properly, a smart phone as a detection display, probably with a Bluetooth data interface. You should Google Mooshimeter to see what that's all about. Now go out and build a state-of-the-art metal detector with a Bluetooth interface to any smart phone and wait for the pesos to roll in. Forget the audio interface. That's not gonna float any boats, IMHO.
  5. nulik


    Feb 9, 2016
    the benefit is that you can make a 3D images by detecting objects from different points and build underground map of all objects. Draw different color for different type of metal.The benefit of having metal detector on mobile phone is that it is going to be cheaper because you do all the processing and analyzing in software.

    I do not very well understand why connecting with metal detecting circuit with audio wont work ? Using bluetooth will introduce a big delay and will add bad experience to the process.
  6. ag273n


    Nov 24, 2016
    i think this technology does not exist yet... currently the existing metal detectors cannot discriminate a metal to another. the common mechanism is an inductor -measuring its oscillation and any funky change means a metal is found - but this does not indicate the size and shape and the type of it...
    if you figure that out, then you revolutionize metal detectors! :)
  7. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    Not to mention the multi-billion dollar cell phone industry! Imagine it, everyone with a metal detector able to discriminate gold from lead, or copper from silver, or whatever and paint a 3D image precisely pointing where to find the valuable stuff. And all this from an audio signal piped into a mobile phone! Please, whoever figures out how to do this, post a parts list and assembly directions, maybe some nice photos too.
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