I have been researching low frequency electromagnetic fields and their effect on human health for a few months now. What could be more fun than to do my own monitoring? I bought a TriField Meter to scan my own home. The readings from the first scan were intriguing but not easy to understand. I got high readings from the entryway wall and the kneewell of my desk! What was that all about? Eventually I figured out where waterpipes were bringing high levels of EMF in from the street main, and that the readings jumped at night when a lot of people were using appliances, etc.
It became necessary to log the changes in the signal over time. Then it became necessary to build my own probes, and figure out a multi-probe set-up that could log up to 8 locations in the house for a 24 hour period. This set-up is a step in that direction.
This is the homebrew and amp set up, with the Dataq analog to digital board shown (The white box center right.) The breadboard is a Radio Shack sensor lab I picked up at a yard sale for a few bucks. It is configured with an op-amp for the input from the solenoid/antenna, an audio amp to take that signal and make it audible. I took the output of the audio amp and fed it into my data collection with an 8k sample rate. Once I had 30 seconds of sample from my work space, I ran a Fast Fourier Transform on the data to extract the main frequency components. See the next post for the sample I collected. My antenna/probe is the yellow solenoid on the lower right (which was pulled from a Cadillac's electric door lock, I was told.)
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