Explore by making #2

For this week I decided to build the induction amplifier I mentioned last week. It's meant to be some sort of a data-collection device that's detecting electromagnetic fields (EMFs) generated by nearby electrical devices. All electrical devices, when they operate (i.e. are on), create electromagnetic fields around them. These fields are essentially invisible waves of energy produced by the movement of electrical currents. The tiny currents generated by induction are too weak to hear directly. So, the induction amplifier takes this weak signal and amplifies it, making it strong enough to be played as sound through speakers or headphones.

I'm interested in recording different environments, different devices, seeing the range of things and experimenting with different sensitivity levels. However I'm not sure I'm particularly interested in the sound itself, but in the data it carries. So the next step after gathering samples is to analyze them using Fast Fourier Transform, which is way of breaking the samples down into specified number of buckets, from which one could analyze and compare the different frequencies. This could allow me to visualize the electrical signals that the original objects emitted.

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I started by trying to build the following circuit:

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I didn't have the same exact components so I had to replace some of them with different variations or slight differences.

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At first it didn't work at all. I couldn't figure out why (though it makes sense that I built it wrong, or that some of the components I replaced just didn't work as I had hoped), but then I realized there was a contact issue with the audio jack (the part that goes to the Zoom recording device), and I played with it a little bit and realized that when held a certain way — I suddenly get radio!

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I wasn't expecting this at all. So I experienced with it a little bit; I changed the capacitors again and tried to walk around a little bit and get different things. The audio jack contact issue is a bit too sensitive but I can redo this part if I move forward with this.

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Here are some recordings that capture both radio and EMFs: (1) mostly radio; (2) radio & some EM noise; (3) mostly EM noise from my laptop. PLEASE TURN THE VOLUME ALL THE WAY UP. Sorry about that.

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I'm looking forward to keep exploring this direction! I'd like to keep experimenting and find ways to fine tune it, or even add potentiometers where appropriate so that I could fine-tune in real time while recording.