I was messing around with my Arduino board and figured out how to make a cheap portable electromagnetic field (EMF) detector. It only requires a led, 3300000 Ohm resistor, and wire. As I approach an EMF the led gets brighter, so I can locate the source. Messing around with the code and resistor values I can change the sensitivity of the device; when I first made the EMF detector I could only find one place to stand in my apt where it didnt go off. I am working on getting a commercial EMF detector that spits out quantitative values so I can calibrate my version and have it do the same on a LCD. *UPDATE you can decrease the sensitivity of the device by making a loop with the antenna. Also the code can be found on my website, aaronalai.com

25 replies
  1. biltoddthesciencegod
    biltoddthesciencegod says:

    I suppose you could do that 🙂 I buy the 500-Piece 1/4-Watt Carbon-Film Resistor Assortment Pack from RadioShack. The pack will have 5 3.3 MEG resistors in it.

    Reply
  2. biltoddthesciencegod
    biltoddthesciencegod says:

    I would have to disagree, although I can see why you might think that. You should try building one to test different sources of EMFs. It’s a simple and fun project that is a great way to get into microcontrollers.

    Reply
  3. skierplaterandy
    skierplaterandy says:

    oh, my multimeter goes upto 2 000 000 ohm, and in my bin of resistors i found one that maxed it out. ill try it.

    Reply
  4. Halo2maniaccc
    Halo2maniaccc says:

    Any electronics website mouser, digikey ect…

    3,300,300 ohms is only a 3.3 mega ohm resistor nothing really special just a high resistance. Radioshack has them in the 500 pack if you don’t wana buy online!

    I built this and it works pretty good, I didn’t get very good reception though but it did detect EMF fields at close range.

    Reply
  5. skierplaterandy
    skierplaterandy says:

    yea i found one in my bin of resistors (its higher than 2 mega ohm anyway, because it maxed out my multimeter)

    and i built this and it worked. it detected my tv easily.

    Reply
  6. MyUniqueUsername
    MyUniqueUsername says:

    I was able to make this without using a resistor by just making some changes in the code, it works great.

    Reply
  7. betotedj
    betotedj says:

    hello, i am from mexico, i really like it your work, i try to do my own detector but didnt work well, could you please let me see your work? i hope that you have a really good week and thankyou for your attention and kindness. :d

    Reply
  8. pietzeekoe
    pietzeekoe says:

    do you know how to build one (if possible ) on a board of education with a basic stamp 2 from parallax?

    Reply
  9. 200010
    200010 says:

    Hola me podrías ayudar a construir uno como este ??? es para la escuela me están pidiendo uno y no encuentro diagramas o algo parecido.

    saludos

    Reply
  10. SteakANDBurger
    SteakANDBurger says:

    @Milegolasss
    check this out, this video takes inspiration from this one 🙂
    cheers
    /watch?v=y1Bke3750WE

    Reply
  11. AzBirdDog
    AzBirdDog says:

    I built this using the Arduino Nano v3.0, and you don’t need the resistor.
    This thing is Ultra Sensitive!!!!
    Just rubbing my big toe on my chair mat, it’s one of those plastic see thru ones, the detector picks that up!
    I’m experimenting with a few cool things on this, and I would have to say, this is not only easy, it’s awesome!
    Thanks for the upload!!!
    Next i’m going to try the LCD version.

    Reply
  12. meeperator
    meeperator says:

    I couldn’t find anything closer lying around, so I actually had to string 3 1M’s and 3 100k’s together to have this work.

    Reply
  13. SuperKWhite2009
    SuperKWhite2009 says:

    Would this be possible with a Parallax Quickstart Board. Ive found its somewhat similar to the Arduino. But the code is in proppelor and spin. One benifit is the board does have 8 LEDs on it already and can be individually programmed.

    Reply

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