Listen to Electronic Device "noise" With an AM Radio

by Roaraar in Circuits > Audio

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Listen to Electronic Device "noise" With an AM Radio

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This instructable will teach you how to hear the sound of electronic devices.

So, I was trying to make an AM transmitter yesterday (failed...), to test it I had my am radio on it's lowest frequency, 531khz. Unfortunately, instead of hearing music from my transmitter, I heard just static and a squelchy sound at random intervals. After a while, I realised that the squelch was in sync with my laptop. This made me curious, so I put my phone in the am loop antenna, and there was nothing, then I turned the screen on, and suddenly my room was full of white noise from the "sound" of the screen. (probably the sound of the inverter for the back light)

I investigated further, and realised that anything electronic could be heard if close enough to the antenna. 

The most awesome thing I found was that If you point any infrared remote at the antenna (at close range), you can very easily "hear" the pulses of infrared waves. Why has no one seemed to discover that you can do this with just an AM radio??

Below is a recording of the sound of pointing a TV remote at it, and a recording of my laptop power supply when you unplug it from the mains.

So, How Do You Do It?

You turn on your AM radio, put it on it's lowest frequency (works on higher frequencies, with a lot of static), and put whatever electronic device next to, or in, if possible, the antenna loop. And that's it! Hopefully you'll hear it. (it seems to work best when there aren't many electronic appliances on in the house.)


If you don't believe me, try it out for yourself.
Please feel free to leave comments.

Troubleshooting:
1.If you get lot's of static, change the frequency, also, having the A.M. loop on it's side rather than upright made a huge difference for me. You may want to move the antenna in different directions
2.Ask me if you have any trouble.

Thanks for reading!