Author Topic: Unexpected weirdness...  (Read 740 times)

Offline AdeV

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Unexpected weirdness...
« on: March 17, 2018, 12:02:20 PM »
Have you ever had something completely unexpected, and quite possibly inexplicable happen to you?

Here at home, my computer is plugged into an amplifier & from there into 2 speakers. I also have a second input, which I plugged into my laptop. I couldn't get it to work (found out eventually the computer was sending audio own the HDMI cable to the speakerless monitor. Not terribly useful!), but whilst I was fiddling with the connection at the laptop end, I discovered that if I had it half-in, half-out of the laptop socket, I could hear a football match over the speakers!!! What's weird is, my amplifier is NOT a tuner amplifer, it doesn't have a radio in it at all. So what the hell was plucking a radio signal out of the air, demoduating it into amplifier-friendly signals to the point I could hear it!?!?

Note: It wasn't the laptop (once I figured the correct audio path, that works perfectly); and it only happened when it was literally half-in half-out of the laptop; unplug completely and it went away, plug in completely and it went away.

As the title of this thread says: Unexpected weirdness! Anyone else experienced anything like this? Or weirder?
Cheers!
Ade.
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Online awemawson

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Re: Unexpected weirdness...
« Reply #1 on: March 17, 2018, 12:56:29 PM »
The BBC long wave transmitter at Rugby (198 Khz ?) when it was in use was pretty powerful. There were reports of peoples radiators in nearby houses demodulating the signal.

I assume the copper pipe to iron or steel radiator junction had some copper salt crystal acting as a rectifier :scratch: I think this transmitter also used (perhaps still does) carry the ULF signals used for transmission to submarines.

 
Andrew Mawson
East Sussex

Offline philf

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Re: Unexpected weirdness...
« Reply #2 on: March 17, 2018, 02:45:41 PM »
Ade,

Many years ago (40+ years ago) I had a hi-fi system in my bedroom. My Mum complained that the FM radio downstairs was picking up the music I was playing on cassette upstairs.

For some reason my hi-fi was transmitting. If I repositioned the cable between the cassette deck and the amp it changed the frequency!

I managed to move the frequency away from broadcasting over radio 2 and could listen to music in the garage.

I've also heard of church organ pipes picking up radio signals.

Andrew - Where's the 198kHz signal being broadcast from now? In the early 80s I made a receiver to pick up the signal and then wrote a program in BBC Basic to decode it. I'll still have it all somewhere. (Inc. 3 BBC Model Bs!)

My wife and I were on a cycling trip last year and came across a derelict VLF radio station at Criggion near Welshpool. This was used for submarine communications at the time of the Falklands War. http://www.oswestry-history.co.uk/criggion-radio-station.html

Phil.

Phil Fern
Location: Marple, Cheshire

Online awemawson

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Re: Unexpected weirdness...
« Reply #3 on: March 17, 2018, 03:06:05 PM »
Your Mum listened to Radio Two  :bugeye: Good heavens man there is no hope for you  :lol:


The Rugby Transmitter Aerial Farm was very visible going up the M1 about junction 18 /19 just before the Watford Gap Services. I don't travel like I used to so not sure if it's still there or has been replaced by endless boring 'different but the same' housing estates for the population of Eastern Europe !

Andrew Mawson
East Sussex

Offline philf

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Re: Unexpected weirdness...
« Reply #4 on: March 17, 2018, 03:11:27 PM »
Your Mum listened to Radio Two  :bugeye: Good heavens man there is no hope for you  :lol:


The Rugby Transmitter Aerial Farm was very visible going up the M1 about junction 18 /19 just before the Watford Gap Services. I don't travel like I used to so not sure if it's still there or has been replaced by endless boring 'different but the same' housing estates for the population of Eastern Europe !

I must admit I listen to Radio 2 when I'm in the car. Can't be doing with Radio 1 with too much (C)Rap rubbish!
Phil Fern
Location: Marple, Cheshire

Online awemawson

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Re: Unexpected weirdness...
« Reply #5 on: March 17, 2018, 03:15:18 PM »
You're DOOMED man  :lol:


. . . . .prefer the Home Service personally  :ddb:
Andrew Mawson
East Sussex

Offline John Rudd

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Re: Unexpected weirdness...
« Reply #6 on: March 17, 2018, 04:20:05 PM »
Rad 2 gets my vote too....Aint listened to R1 since my teens.....

Must be an age thing.. :coffee:
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Online awemawson

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Re: Unexpected weirdness...
« Reply #7 on: March 17, 2018, 05:24:46 PM »
Radio 1 didn't exist during my teens - it was The Light Program  :clap:

Home Service - Radio 4 - but even that's gone down hill
Andrew Mawson
East Sussex

Offline JD

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Re: Unexpected weirdness...
« Reply #8 on: March 17, 2018, 06:30:39 PM »
I listen to planet rock in the car and the workshop  :thumbup: (that's the only places I can get away with it) the rest is classic FM my other half's domain. JD
If you cant fix it hit it with a bigger hammer

Online russ57

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Re: Unexpected weirdness...
« Reply #9 on: March 18, 2018, 12:00:51 AM »
Congratulations, you made an amplified crystal set. ( remember them?)

A 'dirty' joint, with an oxide layer between, will act as a rectifier. (metal oxide rectifiers were common in battery chargers, welders, etc). A blued razorblade can be used to make a crystal set.


The partially plugged cable must have made a semiconducting joint, and a local station strong enough to create enough audio.






Russ


Offline chipenter

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Re: Unexpected weirdness...
« Reply #10 on: March 18, 2018, 03:59:00 AM »
Planet rock I thought that died will have to retune , Alis Cooper as a DJ was cool .
Jeff

Offline AdeV

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Re: Unexpected weirdness...
« Reply #11 on: March 18, 2018, 06:46:44 AM »
Congratulations, you made an amplified crystal set. ( remember them?)

Coooool! Yes, I remember them (I never made one, though, sadly). Until now, that is  :zap:

A 'dirty' joint, with an oxide layer between, will act as a rectifier. (metal oxide rectifiers were common in battery chargers, welders, etc). A blued razorblade can be used to make a crystal set.


The partially plugged cable must have made a semiconducting joint, and a local station strong enough to create enough audio.

I'm surprised at that. I thought the purpose of the crystal was to set the frequency you were tuned to?

Planet rock I thought that died will have to retune , Alis Cooper as a DJ was cool .

It's on DAB only as far as I'm aware. Along with a whole load of other "genre" stations - my wake-up-to station is "Absolute 80s". It's also crystal clear, unlike any FM station around here, which tends to fade in & out.
Cheers!
Ade.
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Online russ57

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Re: Unexpected weirdness...
« Reply #12 on: March 18, 2018, 07:16:02 AM »
A typical crystal set has a coil and a capacitor which set the frequency. Adjusting one or the other 'tunes' it.
The diode acts as a demodulator, extracting the audio from the Rf carrier.

Works great for am, tolerably well for fm.

Dab not a hope...

Am can cover long distances. So not necessarily a local station, especially with an amplifier in the picture.

I remember reading of people where a metal tooth filling acted as both the demodulator and the speaker.







Russ


Offline JD

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Re: Unexpected weirdness...
« Reply #13 on: March 18, 2018, 07:09:27 PM »
Yep planet rock is still alive and kicking on DAB radio  :headbang: A good mix of all ages, AC/DC thru Slip Knot up to today's Rock/Metal  :thumbup:.
JD 
If you cant fix it hit it with a bigger hammer