Instructables

Portable EMF Reader

Picture of 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.
 
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Step 1: Putting it Together

Picture of 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

Picture of 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.
http://www.youtube.com/watch?v=---uCklQU9w
Flash Animation

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