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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It's been awhile since I've messed about with this, so I don't remember (and you may not either, so this is an open question), but wouldn't it produce the effect even if disconnected from an antenna?

If so...Would the same principle be in play of it picking up on general EM waves to cause the effect?

the effect can change slightly if you unplug or touch the antenna or the TVs socket for it, because it may change what contributes to the signal noise and how much. It can for example become brighter and the pitch of the audio noise can change.

Yeah, the same way a radio tuned to a station could be static until you plug in an antenna.

You could also get hums and interference from other sufficiently strong EMF sources, like how AM radios can pick up the sound of transmission lines

Your mom (or dad) using an electric knife to cut a turkey on thanksgiving would do the same. It was wild.

AM car radio can pick up the waves from your cars electrical alternator as well, which can cause the static to rise and fall in pitch as you speed up and slow down.

The display on the screen is the strongest signal. Without a strong signal from a TV tower, you just get noise from 60 Hz AC running through the wall, or radio towers, or power lines, or whatever else makes that radio noise.

Afaik the antenna is picking up the background waves/radiation and the TV is displaying that background waves/radiation. If you disconnect the antenna, the TV will have no signal to display, it'll be as blank as it can get.

Nah, the antenna is tuned to pick up vhf/uhf, but the wire / traces and even the legs of the amplifier are sufficient to pick up cmb