Portable EMF Reader


Introduction: Portable EMF Reader

Want a quick and easy EMF reader? All you need is an amplifier and a microphone. The mic will pick up the electromagnetic noise from around you and the amplifier will turn it into something audible.
Obviously this isn't a precise way of measuring, but if you're lacking a gauss meter, or just want to cheaply investigate the EMF in your home, this is a fun solution.

Step 1: Putting It Together

I used a suction cup telephone mic [generally used to record telephone calls] and a battery powered  mini amp I picked up from Radio Shack.

Plug the mic into the input jack of the amp.

Step 2: Using It

Turn the volume of the amp to about halfway. If you're not in a Faraday cage, you'll hear a low level buzz. This is the 60 hz background noise that's typical in city dwellings.

Step 3: Example

Position the mic over the EMF source you'd like to listen to [a PC is pretty interesting] and you'll hear the feedback change.

Check out the video for a live demo of what you can hear.
Flash Animation

[Sorry about how dark it is, light receptor on my camera's burned out].



    • Woodworking Contest

      Woodworking Contest
    • Make it Move Contest

      Make it Move Contest
    • Clocks Contest

      Clocks Contest

    We have a be nice policy.
    Please be positive and constructive.




    Hmm... I don't see how this picks up EMF :S Normally, EMF induces voltage within a coil, I suppose if its a dynamic mic? Cool thinking though :)

    1 reply

    The sensor (in the suction cup unit) attached to the audio-amplifier is a small coil.

    Nope, the one in the demo is battery powered.

    Another readily available thing you can use > Just use a portable hand held radio or walk-man on AM tuned between stations or to a station. It will detect ANY Electromagnetic Anomaly>>>>

    1 reply

    Just tried this out with my hand-crank emergency radio. Definitely picked up some interference when the antennae is pointed at an EMF source, but the mic makes it much clearer. When rested against the PC you can hear modulation from the HDD- with the radio, it was much more subtle.

    we used to use those in the phone company, use a coil on the end of the cable and a signal generator to find metal on metal contact that shouldn't be there. Very good and simple.