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Is a CRT electron gun any use? Answered

Is it worth it to take the electron gun out of a CRT when salvaging parts? I've seen people remove the electron gun when they take apart the CRT but I don't know what they'd use it for.
What can you do with a CRT electron gun? What chemicals does the gun contain? (I know the screen has toxic phosphor and stuff but I'm talking about the gun itself).

Also, is it safe to vent a CRT tube? I have found that you should vent the CRT tube before working on it, by smashing the end from a distance, so that it won't implode if you happen to break it when working on it. But is it safe to puncture open the tube? There are toxic phosphors inside and I worry that venting it could cause toxic chemicals to go airborne.


You should leave the ctr intact it is not just the phosphors the mercury vapors are bad for you and the environment.

If you must open the ctr do it outside.

The only useful thing in a ctr is the metals and that is only if you have a good scraper that will pay you what it is worth.

The materials are worth more than copper but most scrapers only pay scrap steel price for it.

What mercury vapor? I thought CRTs don't have mercury vapor. They have a vacuum inside.

They have mercury gas of a lesser gas pressure inside the CTR than the atmospheric pressure making it a vacuum compared to the air around the CTR. So they have mercury gas under a vacuum, when you break the seal and the pressure equalizes mercury gas escapes .

And if you break it like UL does, the vacuum pulls the neck through the front screen like shrapnel as far as 12 feet, much like a glass grenade !

unless you keep the front screen facing downwards. When I scraped my neighbor's tv (24"); kept a thick plastic bag over the electron gun part and hit it slowly with a hammer until it cracked and imploded.

2017-07-31 18.47.47.jpg

Have you ever put a sledgehammer through a picture tube while the TV was running? It was cool.

I'm too weary of the vacuum.

Throwing out picture tubes, I used to safety break the neck nipple and listened for the tube hiss-in for over a minute..

BTW as I remember, UL would soften a 1/2" glass rod and press it against the top seam of the small scratch on the top of the picture tube for a minute heat-up and then pour a cup of cold water on the same spot to cause the tube to implode.

Then they would measure how much glass traveled to 4', 6', 8' 10'+

That was fun to see, thank you for locating such an excellent depiction of striping our old fun boxes.

Hope your going to have a great new year.

I thought you would like that.

You have a great new year also.

hmm mercury gas in crt. So bombarding mercury will lose electron (from the internal electron gun) and make gold. There would be gold in the CRT Tube?

What is an electron gun, And what is possible to make from it?

Google didn't answer my quastions...

An electron gun is a red hot tungsten filament that boils off a cloud of thermionic electrons in a vacuum glass tube.

If you also place a positively charged electrode in the tube the negative charged electrons will Shoot toward this electrode called the plate anode.

And you have an electron gun !

BTW if you shoot the electrons Very Very FAST at a massive metal plate, the electron GUN Impact reflects Xrays...


Click the pictures to see the full image...

Aha thanks, So it's basically like an incandescent light-bulb, But with a lot more in to it...

YES, and the filament is a different composition.

I would leave the CRT completely intact (assuming you have space to store it) until you come up with a proper use for it, or for its parts - don't break it or pierce it until you really need to, because you can't pump the air back out.

If you do decide to break the vacuum, I would use a file - wear safety goggles and gloves, then gently saw back and forth across a thin part of the glass until you hear a hissing sound as the air rushes in. After that, the only hazard from the phosphors is if you smash them and turn them into airborne dust.

lol why would I want to pump the air back out?

The heater of the gun burns out if it is hot and not in an inert gas. So you vacuum out the air and replace it with an inert gas.


2 years ago

Applied Science on youtube had made a Scanning Electron Microscope that actually (barely) worked, and he made it with some scrap components, however he used a few powerful vacuum pumps, and a diffusion pump to really pull every last airborne air particle out of the glass chamber, and a special high voltage power supply.

Electron guns are not too complicated themselfs, and I have seen guides online to make primitive CRT displays out of small bottles and things. Those tended to use MOTS for the high voltage, and phosphor from fluorescent tubes. They were also generally pretty small because anything much larger than a standard wine bottle would need a really strong vacuum.

1. The tube is inder vacuum.
2. I can't see how you would break the tube while working on the TV / monitor - unless you use big hammers to work on electronics...
3. I don't know of any value for the electron generator (your gun) for private use. If you would have a few hundred or more it might worth salvaging but usually normal people won't have the equippment to do so.


2 years ago

Just a vacuum, you cannot have gas chemicals (particles) that would impede and scatter electrons.