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Comment by bachmeier | Hacker News Reader

My son was scared as hell because he was hearing voices in his bedroom late at night. I used his bedroom as my office during the day while WFH during the pandemic. The speaker picked up a radio station and played it at low volume when I hibernated the computer for the day.

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When I was a teen I had a guitar amp that would, if plugged into an effects pedal with certain settings, pick up a Spanish-language radio station. No clue how!

Same happened with simply a cable plugged, I think the jack cable acted as an antenna.

The length of the cable would be a multiple of the right frequency or something like that, it'd catch a random AM radio

AM radio is such a simple modulation scheme that even a piece of grass can be used to demodulate it, with enough power. https://www.youtube.com/watch?v=b9UO9tn4MpI

Well, this article [0] shows a guitar FX pedal design that can be used as a radio receiver. Maybe you could get a shortwave radio signal?

[0] https://acidbourbon.wordpress.com/2021/04/11/a-74xx-defined-...

Mine picked up Cuban AM radio on cloudy nights. Never figured out how to tune it, though.

(The stations, not the guitar)

One of the transistors in the early stages of the amplifier (or effects pedal) acted as a detector for the AM signal probably being picked up by a cable that worked as an antenna. It worked essentially as a untuned crystal radio followed by a powerful audio amplifier. The problem usually is a result of bad grounding or screening.

Back in the early 2000's I'd get a 3 second heads up that my cellphone was about to ring when my speakers would make a 'buzzity buz, buzzity buz' right before a call came though.

That phenomenon still puzzles me. Why wouldn't it ring right away?

Probably some kind of handshake?

It's a pretty complex distributed system, where voice just one application carried over a generic network, and at start it's not even 100% sure what radio cell the handset is in.

https://yatebts.com/documentation/concepts/gsm-functionaliti...

Here is an interesting historical note on the subject: http://www.gsmhistory.com/chapter/chapter-22-unintended-cons...

The same effect was used to make stickers that lit up when you were receiving a call, with no battery needed!

https://hackaday.com/2022/02/26/heres-how-those-battery-free...

Countless years ago I had a boombox that, set to the right radio frequency, could listen in on nearby cordless phone calls.

I just looked it up out of curiosity, and the early phones used 1.7 MHz, right at the top of the AM range. That seems like it was asking for trouble.

In about 1996 I was doing the same thing with radio shack walkie talkies.

Some neighbor was on their phone all night, every night.

IIRC there was a time when radio signals were so strong, and bedframe coils so thick, that you could hear radio broadcasts through them.

Every so often I hear the faintest music when on/near my bed. First I thought maybe the neighbor (single family home) was playing loud music, but nothing when I went outside.

Then I figured it was audio/music hallucinations - but it only happens next to/on the bed, it's really faint but enough for me to hear whole songs. Once when I was really paying attention, during the pause between songs I thought I heard speaking/gibberish - not able to recognize words like the songs. Now I mostly just try not think I'm entering some psychosis state. I just dont know where its coming from

Had a similar issue in a band I was in, an electric guitar was picking up radio stations and playing them through the amplifier. For weeks I thought I was going insane until I figured out the cause.

I had this too when I was young! Fortunately I was old enough to experiment and play with the sound, it was some sort of Spanish speaking program. Crazy stuff.

My old computer speakers picked up passing truck radio, endless entertainment and sometimes chills

Reminds me of jump scare internet pranks.

I would sh*t myself

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