Why did old TVs produce an awfully loud static noise and weird visual when they had no signal rather than showing nothing like newer TVs do?
In: Technology
CRT televisions fire an electron beam at a mesh of phosphors that glow when they get shot by the beam. when the CRT is turned on, that beam is aimed by the TV signal. when there is no signal, the beam is still on, and ambient radiation is enough of a signals to cause the electron beam to flail about wildly, striking randomly and creating the “snow”
an LED screen has a small computer that can understand when it’s not getting real data. but even if they didn’t, and you were able to run the hardware, it would just be solid white. getting anything other than the solid white backlight requires multiple signals working in tandem, and background radiation can’t do that sort of coordination. that’s why the LED needs the built-in computer to begin with.
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