Electromagnetic Field Microphone

Introduction: Electromagnetic Field Microphone

An electromagnetic microphone is an unconventional tool for sound designers, composers, hobbyists (or ghost hunters). It is a simple device that uses an induction coil to capture and convert Electro-Magnetic Fields (EMF) into audible sound. There are some commercial ones available, such as the Elektrosluch which is strong enough to capture ambient EMFs and some cheaper ones that need to be close enough to the source of the EMF.

This tutorial demonstrates how to make such a microphone, that captures the environmental EMF and converts it into audible sound by using an amplifier. It may not have the quality of an Elektrolusch but is still a fun project with which you can get some interesting sound effects (See videos in Step5).

The project is suitable for beginners. I made it having very little experience with circuitry and soldering myself.

Materials:

  • An old pair of headphones.
  • Battery holder. This depends on the amplifier you choose. If it is the model mentioned above, you are going to need a 6V holder. I recommend choosing one with an on/off button to make your life easier. Example: http://tiny.cc/crsjfz
  • Sandpaper or nail file.
  • 4 x AA batteries

Tools:

  • Soldering Iron and solder wire.


Optional:

  • Access to a 3D-printer. This is to create a protective case for the copper wire. You can download the design from http://tiny.cc/p69kfz. I also have a few spare ones I could post if you contact me (UK & Europe).
  • Tube shrinkers to cover as much as possible of the naked wires. This will reduce unwanted noise significantly.
  • Glue gun.

Step 1: Prepare the Connections

Since the wire is enamelled, you will need to file the two ends using the sandpaper/nail file.

Next, you need to cut your old headphones.

You are going to need two pieces of cable: one that includes the phone jack on its one end and one bare cable.

You can use the sandpaper/nail file to get rid of the covering.

Step 2: Protecting Your Microphone (optional)

If you have purchased the optional case for the batteries and amplifiers, you need to drill two holes and squeeze the cables through them before you keep on with soldering.

If you haven't got a driller, like in my case, you can also try with a needle and a hammer. The plastic in these cases is usually thin and it should not take long to drill through.

Once you have drilled two holes, pass through the two cables from the previous steps.

Use the photo of the ready product as a guide.

Step 3: Solder the Connections

Follow the pictured schematic to solder the connections (obviously, designing is not one of my strengths...)

The red wire on headphones is usually for Right, the copper for Ground and a black, white or green for Left. If the headphones you used had a microphone, you will find an additional wire (just ignore this wire, no need to connect anywhere).

Don't worry which end to use between the copper wire for Left and Right, as it doesn't matter.

For the ground, you can either solder it along the Left wire or leave it unconnected.

If you don't want to follow the optional steps for housing, just add the 4 x AA batteries and you are ready to go!
You can connect the jack to any recorder or computer.

Step 4: Protecting Your Microphone (Optional)

If you have followed step 2, you should now have a similar result as in the picture.

Try to squeeze in the battery housing and the amplifier. You can use some glue to keep the batteries separated from the amplifier as in the picture.

For the copper wire, either use the 3D printed case or find a cap from a bottle that fits the enamelled copper wire.

You can use a glue gun to ensure the case won't come off, but also to make the microphone waterproof.

Close the case, connect the jack on a recorder and you are ready to go!

Step 5: Have Fun!

Once you connect your microphone to a recorder, turn on the battery power.

You should be able to hear your surrounding electromagnetic noise!

Note: If you are using headphones, please make sure to have turned down the volume of your recorder before wearing them as the noise from the microphone can become too loud and damage your hearing.

Ideas:

Try to use your microphone close to electronic sources, such as washing machine, lights, computer, phone, wifi router.

Did you know that you can hear noises with an EMF microphone underwater? Check out the videos!

Digital Processing:

The captivating thing about recording EMF is that the frequency spectrum you will get is by far richer than the one you'll get from a normal microphone (check the attached spectrogram).

This means that you can use extreme pitch shifts and get results that sound completely different from your original recordings.

Check out an example of some extreme pitch-shifted emf recordings on the attached .wav files, with which you can make music!

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    8 Comments

    0
    colinrobot
    colinrobot

    1 year ago

    Hi quick question ... is the copper wire uninsulated ? I've found some which is a UK seller but it has a choice of both, but the uninsulated is called Natural . All are enamelled . I'm assuming it would need to be uninsulated as to pick up the fields ?

    0
    soundwise
    soundwise

    Reply 1 year ago

    Hi, thanks for your question.
    A copper that is enamelled means that it has a thin layer of insulation.
    The one I used was only enamelled, with no extra insulation.
    I am not an expert, but I don't believe the additional insulation will significantly affect the results. Instead, it will offer an additional protective cover for long-term use.
    I guess the best thing is to try with both types of wires and see whether it makes any difference. If not, then go for the one with the thicker insulation.
    0
    colinrobot
    colinrobot

    Reply 1 year ago

    Was the wire any particular length?

    0
    soundwise
    soundwise

    Reply 1 year ago

    Hmm I can't recall the exact length.
    The longer the wire you can get, the better the sound results you capture. If you follow the link I've posted you'll be able to find a wire similar to the one I've used. http://tiny.cc/9nsjfz

    0
    colinrobot
    colinrobot

    Reply 1 year ago

    Yes I had some turn up today 3x 0.10mm rolls but they seem like there's not that much on the rolls.. you can see the plastic through the wire. Any how Thanks for the Instructable ..just waiting for the battery compartment then it's a go!! I just finished a contact mic on here too so my flats going to be hopefully quite a sound source .Cheers! :)

    0
    soundwise
    soundwise

    Reply 1 year ago

    That's great! Thankfully these rolls are very cheap so you can always purchase from another seller if you're not satisfied.
    Would love to see & hear what you'll get out from your microphones.
    Enjoy your recordings!

    0
    Penolopy Bulnick
    Penolopy Bulnick

    1 year ago

    Nice job putting this together :)

    0
    soundwise
    soundwise

    Reply 1 year ago

    Thanks a lot! :))