i have just realized if you attempt to describe cathode ray television sets to anyone born after around 2000 you just sound like maniacal evil scientist
@twitter when I was younger telly didn't broadcast the whole night, and the TV transmitter was switched off to save electricity. The announcer warned people to turn off their TV set - partly for economy but also because many British TV sets in the absence of a signal to lock onto could go into thermal runaway mode (some protection circuits were omitted to save costs), the set could overheat and sometimes even catch on fire!
@vfrmedia @twitter This sounds like a horizontal and/or vertical flyback circuit problem. Some early multi-sync monitors would lose its magic smoke if you fed it a signal with the wrong HSYNC or VSYNC frequency, because the power amplifier circuits would fall out of resonance, and all that excess power was dissipated through the transistor instead of through the flyback coils on the neck of the CRT.
For those wondering why modern TVs (even CRTs) switch to a flat, blue screen in the absence of a recognized signal (or any signal at all), this is why.
interestingly German and Japanese TV sets did seem to have some protection against this failure mode (I've seen the circuit in a 1970s circuit applications book from Siemens that I found in a charity shop) - I suspect a lot depended on how much the end user would pay for a set (and maybe also if they were in the habit of drinking to the point of passing out whilst watching, leaving the set switched on...)
@twitter …the electrons first hit the phosphorus screen and emit the visible light, then continue moving and hit the thick layer of glass, where they finally stop and emit X-rays, which you can't see but still absorb…
@twitter …quite some of the electrons get trapped in the glass and may then spontaneously discharge…
@twitter you know fluorescent lamps? Those long tubes where inside there's a lightning emitting UV and then the white goo on the glass pipe turns that UV into visible light?
Well a CRT is like a big fluorescent light except instead of UV there are electrons, and there goo is RGB instead of white, and split into pixels, and there are electromagnets directing the electrons to hit a particular pixel.
Ditto if you’d tried to explain LCDs before 1990.
(And from around 1990 to 2000, you’d have sounded like a really bad startup pitch.)
then you can treat them with definitely-not-our-timeline steampunk version of https://en.wikipedia.org/wiki/Mechanical_television
This Mastodon instance is for people interested in technology. Discussions aren't limited to technology, because tech folks shouldn't be limited to technology either!