That’s just basic electronics stuff. It doesn’t take a terribly large charged capacitor to zap you dead. IIRC, there are some high voltages in CRTs, but if you know how to discharge caps and to never ever work on electronics while plugged in (especially anything AC or DC over even 12v running), you’ll be fine.
Making them, however, is a whole additional technical and mathematical set of skills.
The outer envelope layer of a CRT itself is a capacitor, and depending on the tube size, can hold ~13,000 to ~25,000 volts. What makes it worse is that you can properly discharge the tube, completely remove it and put it on a storage shelf somewhere for months, then come back to it and the motherfucker done managed to recharge itself from the fucking atmosphere!
Any sufficiently big capacitor does this and that’s why you short them out for storage unless you want to die.
The biggest ones I worked with were 75 kg slices of stinkiness when they leaked and had to have two separate loops of wire on the terminals for safe disposal.
It’s really not that dangerous. There’s a big capacitor called the flyback capacitor which can store a deadly amount of energy. You disconnect the power (obviously) and then discharge that cap and everything else is relatively safe. To discharge a capacitor, bridge the leads with an electricians screwdriver. If you don’t like sparks, hold a resistor with pliers between the two leads. (It will go slower but also get hot AF.)
The capacitors are the same ones that are in every desktop PC power supply.
The flyback is a complex transformer with the thick cable sending the high voltage to the tube’s second anode.
The CRT itself can act like a giant capacitor. Eventually they figured out how to bleed the charge out when the TV is off.
1990s-2000s tubes: I discharge but don’t worry too much. 1980s-1990s tubes: I discharge several times, over the course of an hour or two. Those Sanyos that Nintendo used hold a nasty charge that comes out with a big SNAP!
The way they bleed the charge off when the TV is powered off is through a very high resistance resistor. This works perfectly well most of the time, but those resistors can and do fail. The same is true for microwaves, which also have flyback circuits. Always treat these things like the bleedoff resistor has failed.
From what I’ve heard we are actually forgetting how to make CRTs. Not sure how valid that claim was though as I didn’t research it at all.
In any case if you’re thinking about getting a CRT you might as well get one while they’re relatively cheap. Here in Poland you can get a used CRT from anywhere between 50-100 USD for the hypercommercial models up to 200-500 USD for the enthusiast ones. And I doubt they’ll be getting any cheaper.
They’re really simple electronics, but there are likely a lot of little trade secrets that made them better. At the end of the day, it’s a cathode ray tube with a couple of electromagnets to divert a pulsing electron beam to hit different parts of the phosphor-coated end of the tube. The signal fed to the magnets is analog, and the beam sweeps the screen line-by-line every frame. (Or every other line for interpolated signals.)
They use old tubes though. No manufacturing plant is tooled anymore to create new tubes and that’s why they probably won’t make new ones unless a super rich retro gamer funds the endeavor or something. The TVs would have to be expensive as fuck to cost justify that for niche retro gaming.
Huh, ok. I don’t understand the appeal. So it obviously doesn’t turn a modern TV into a CRT because they’re completely different technologies and that’s not possible, it just visually makes your display sort of look like a CRT.
Does anyone make CRTs? What would it take to make one? Is this beyond hobby level?
Well beyond, I believe. Like, even trying to repair one can kill you
That’s just basic electronics stuff. It doesn’t take a terribly large charged capacitor to zap you dead. IIRC, there are some high voltages in CRTs, but if you know how to discharge caps and to never ever work on electronics while plugged in (especially anything AC or DC over even 12v running), you’ll be fine.
Making them, however, is a whole additional technical and mathematical set of skills.
The outer envelope layer of a CRT itself is a capacitor, and depending on the tube size, can hold ~13,000 to ~25,000 volts. What makes it worse is that you can properly discharge the tube, completely remove it and put it on a storage shelf somewhere for months, then come back to it and the motherfucker done managed to recharge itself from the fucking atmosphere!
Any sufficiently big capacitor does this and that’s why you short them out for storage unless you want to die.
The biggest ones I worked with were 75 kg slices of stinkiness when they leaked and had to have two separate loops of wire on the terminals for safe disposal.
It’s really not that dangerous. There’s a big capacitor called the flyback capacitor which can store a deadly amount of energy. You disconnect the power (obviously) and then discharge that cap and everything else is relatively safe. To discharge a capacitor, bridge the leads with an electricians screwdriver. If you don’t like sparks, hold a resistor with pliers between the two leads. (It will go slower but also get hot AF.)
The capacitors are the same ones that are in every desktop PC power supply.
The flyback is a complex transformer with the thick cable sending the high voltage to the tube’s second anode.
The CRT itself can act like a giant capacitor. Eventually they figured out how to bleed the charge out when the TV is off.
1990s-2000s tubes: I discharge but don’t worry too much. 1980s-1990s tubes: I discharge several times, over the course of an hour or two. Those Sanyos that Nintendo used hold a nasty charge that comes out with a big SNAP!
The way they bleed the charge off when the TV is powered off is through a very high resistance resistor. This works perfectly well most of the time, but those resistors can and do fail. The same is true for microwaves, which also have flyback circuits. Always treat these things like the bleedoff resistor has failed.
There’s one company still making CRTs, but only for industrial and medical equipment, not for consumers.
https://www.thomaselectronics.com/faq/
From what I’ve heard we are actually forgetting how to make CRTs. Not sure how valid that claim was though as I didn’t research it at all.
In any case if you’re thinking about getting a CRT you might as well get one while they’re relatively cheap. Here in Poland you can get a used CRT from anywhere between 50-100 USD for the hypercommercial models up to 200-500 USD for the enthusiast ones. And I doubt they’ll be getting any cheaper.
They’re really simple electronics, but there are likely a lot of little trade secrets that made them better. At the end of the day, it’s a cathode ray tube with a couple of electromagnets to divert a pulsing electron beam to hit different parts of the phosphor-coated end of the tube. The signal fed to the magnets is analog, and the beam sweeps the screen line-by-line every frame. (Or every other line for interpolated signals.)
They use old tubes though. No manufacturing plant is tooled anymore to create new tubes and that’s why they probably won’t make new ones unless a super rich retro gamer funds the endeavor or something. The TVs would have to be expensive as fuck to cost justify that for niche retro gaming.
There are filters/shaders now that turn modern TVs into CRTs. Its an interesting technology.
What do you mean by “turn into”?
I use this from time to time:
https://github.com/libretro/glsl-shaders/blob/master/crt/shaders/fake-CRT-Geom-potato.glsl
There’s also physical filters with HDMI input. Its cool that we have so many options.
Huh, ok. I don’t understand the appeal. So it obviously doesn’t turn a modern TV into a CRT because they’re completely different technologies and that’s not possible, it just visually makes your display sort of look like a CRT.