What produced the old dead channel tv static audiovisuals on tvs?

ALostInquirer@lemm.ee to No Stupid Questions@lemmy.world – 174 points –
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3D render of old tv set with animated static on its screen, as if tuned to a dead channel.

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If you put a TV in a Faraday cage that blocked the relevant radio spectrum, would there be no static on it? I expected the answer to be a quick Google, but it wasn't.

That is a good question, but I suspect if you tried this in real life it would still show static.

  • The waves are amplified with a circuit that attempts to find a signal even if it's very weak (so you can get a picture even if you're close or very far from the tv station)
  • At a certain point, the electromagnetic field from the running TV itself would start to get picked up

I suspect a better thought experiment would be if you just disconnected the input and amplification circuit entirely from the CRT tube, in which case you would probably just get white as the electron beam scans back and forth without any modulation.

Let me turn that around:

Would a TV still show static if you disconnected the input and amplification circuit outside a Faraday cage?

Likely a uniform white picture since the impedance of the input wire is too high for ambient noise on the line to result in any differentiated interlacing.