using CRT electron beam for something other then display? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: February 25, 2024, 07:29:24 am
content: So the CRT allows you to control a electron beam on a grid.Rather then exciting phosphor, can you use it for some other purpose? there are many uses of electron beams.https://en.wikipedia.org/wiki/Electron-beam_technologyAssuming you can highly modify a CRTI imagined like sawing open a television with a diamond saw so you can put the front on a hinge with some kinda vacuum gasket and put stuff in therealso it would be good part of men in black or something if they find some aliens misusing TV's like that. they don't use that to watch the game, slick

author: wasedadoc
author_rank: Super Contributor
timestamp: February 25, 2024, 08:13:22 am
content: Before solid state image sensors were developed, for about 50 years all TV cameras used tubes employing electron beam scanning. Search using terms such as "image orthicon", "vidicon" and "Plumbicon".

author: Andy Chee
author_rank: Super Contributor
timestamp: February 25, 2024, 08:35:20 am
content: Quote from: coppercone2 on February 25, 2024, 07:29:24 amYou can use it to make some interesting youtube videos:

author: JustMeHere
author_rank: Frequent Contributor
timestamp: February 25, 2024, 08:39:06 am
content: Quote from: Andy Chee on February 25, 2024, 08:35:20 amWhy do I feel like I'm on the Black Mesa Compound tram?

author: tggzzz
author_rank: Super Contributor
timestamp: February 25, 2024, 09:01:50 am
content: Computer RAMhttps://en.wikipedia.org/wiki/Williams_tube

author: coppercone2
author_rank: Super Contributor
timestamp: February 25, 2024, 09:46:31 am
content: i mean can you make a manufacturing machine out of it some how. the page I listed has alot of process, as interesting as those are,Like milling etcI am guessing the focus is too poor to do small things, and power is well too low for welding (is it? its in a vacuum after all). But something like coatings, chemistry, materials prep (some kind of macro structures that require more focus then essentially putting them over a vat of boiling metal in a vacuum). Vacuum soldering with electron beam?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 25, 2024, 09:52:03 am
content: a-d converter :http://electricstuff.co.uk/glassadc.htmlAnother one was for TV pattern generators - similar to a camera tube but with a fixed pattern target

author: tooki
author_rank: Super Contributor
timestamp: February 25, 2024, 12:17:07 pm
content: The Eidophor and Talaria:http://www.earlytelevision.org/Yanczer/eidophor.html

author: jonpaul
author_rank: Super Contributor
timestamp: February 25, 2024, 12:53:01 pm
content: Numeric 0..9 readout, Nimo, 1960sENIAC 1949..1953 data storageTRW 1960s streak camera image converterj

author: wasedadoc
author_rank: Super Contributor
timestamp: February 25, 2024, 04:30:01 pm
content: Also standard for decades was the "flying spot scanner" for televising film and slides. A full brightness raster on the CRT faceplate, focussed onto the celluloid and then through optical colour filters to photomultipliers providing the video RGB signals.https://en.wikipedia.org/wiki/Flying-spot_scanner

author: tooki
author_rank: Super Contributor
timestamp: February 25, 2024, 04:32:00 pm
content: Quote from: jonpaul on February 25, 2024, 12:53:01 pmQuote from: wasedadoc on February 25, 2024, 04:30:01 pmThose both work by exciting phosphor, which is expressly NOT what the OP wants to learn about.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 25, 2024, 04:42:35 pm
content: https://en.wikipedia.org/wiki/IBM_1360"Data was written to the chips using an electron gun, similar to the operation of a television tube."

author: tggzzz
author_rank: Super Contributor
timestamp: February 25, 2024, 04:49:44 pm
content: Quote from: tooki on February 25, 2024, 12:17:07 pmI forgot eidophors.I saw one once in ~1985, at London Zoo. There was a conference about this newfangled thing, object oriented programming. One of the talks showed building a GUI plus application (in LISP, of course) on the fly, the first time I had seen anything like that.The projector was an black and white eidophor, which I expect was adequate with "natural" images. But with rectangular bars and text it was, um, suboptimal. The oil film couldn't cope with sharp edges blocks, and any change anywhere in the picture caused the rest to wobble.But nobody cared; the content was eye-opening.

author: tooki
author_rank: Super Contributor
timestamp: February 25, 2024, 04:59:31 pm
content: Nice! I wonder if there exist any working Eidophor units anywhere in the world. I’d love to see that crazy piece of engineering!(I finally got to see a Linotype this summer, after wanting to see one for decades. Then this summer I saw two different ones, one day apart, one of them working!)

author: MarkT
author_rank: Frequent Contributor
timestamp: February 25, 2024, 06:00:02 pm
content: Quote from: coppercone2 on February 25, 2024, 07:29:24 amBANG!!!No, don't do that. Watch this video on reconditioning TV tubes first:

author: tggzzz
author_rank: Super Contributor
timestamp: February 25, 2024, 06:09:53 pm
content: Quote from: MarkT on February 25, 2024, 06:00:02 pmYeah. Don't cut the ugly bit off a Tek 465 CRT.Often there is an easily snappable nipple inside the pins at the end of the tune.https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/

author: Gyro
author_rank: Super Contributor
timestamp: February 25, 2024, 06:54:47 pm
content: Quote from: coppercone2 on February 25, 2024, 07:29:24 amThe other problem is that the emissive coating on the cathode will be destroyed as soon as it comes into contact with air. In manufacture, it is coated with chemical salts and then the final forming is done under vacuum.

author: p.larner
author_rank: Frequent Contributor
timestamp: February 25, 2024, 07:30:57 pm
content: i thought electron beams needed a vacume to travel,so whats going on in the linked vid?

author: TimFox
author_rank: Super Contributor
timestamp: February 25, 2024, 08:29:24 pm
content: Electron beams travelbetterIn vacuum.High-energy beams can be useful in air, so long as the window between the source (in a vacuum chamber) and air is thin enough, or a “differentially pumped” exit aperture is used.In air, the range for an electron, depending on how you define it, is roughly 2 mm at 1 keV, but about 10 m at 1 MeV.Thus, energetic electrons from an electron accelerator can be used in radiation therapy, avoiding the low efficiency of Bremsstrahlung to produce x-ray photons (which have longer range in matter than massive electrons or ions).

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 25, 2024, 09:06:38 pm
content: Can we use a CRT as a giant triode?

author: Gyro
author_rank: Super Contributor
timestamp: February 25, 2024, 09:12:38 pm
content: Well a large screen one would take 25kV or so, but the cathode, and possible cathode current, is tiny. So not giant, no.

author: coppercone2
author_rank: Super Contributor
timestamp: February 25, 2024, 09:25:03 pm
content: Quote from: Gyro on February 25, 2024, 06:54:47 pmI would imagine so long you keep it dry its OK? Guess you would need a dry box to load this up.how strong are those electrons anyway. can it say weld foil possibly? say 0.001. In open air for a tig beam that is something like an amp, supposedly. A TV beam is something like 100uA. 0.0001 vs 1. But how much less do you need in a vacuum on thin material. It says EBW uses 50mA to 1A typically.So you need 500x overload on the beam gun. I guess that process is out.

author: cosmicray
author_rank: Frequent Contributor
timestamp: February 25, 2024, 09:27:38 pm
content: Back in the dark ages, of 1987-1988, I saw a piece of kit, that was apparently a very custom build. It read 9-track computer tapes, with print page images, then used a CRT beam (of some type) to directly imprint 35mm film. The film was then developed, and used to make printing plates. The plates were put on offset presses to print books containing television ratings, which were then express shipped out to advertising agencies and networks. It was a very refined system, with lots of disparate parts. The internet has likely demolished it.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 25, 2024, 09:30:13 pm
content: Quote from: cosmicray on February 25, 2024, 09:27:38 pmSounds like a kind of photo typesetter.https://en.wikipedia.org/wiki/Phototypesetting

author: TimFox
author_rank: Super Contributor
timestamp: February 25, 2024, 09:35:04 pm
content: Going back to the 1970s, Celco made relatively small screen CRTs with superb focusing that could resolve 10,000 lines. They were used either with high-end lenses or optical contact to expose 35 mm or 2.25 inch film.Celco still exists, mainly working with cinema applications.

author: Gyro
author_rank: Super Contributor
timestamp: February 25, 2024, 10:54:36 pm
content: Quote from: coppercone2 on February 25, 2024, 09:25:03 pmNope, it's contact with atmospheric oxygen, not humidity.

author: coppercone2
author_rank: Super Contributor
timestamp: February 25, 2024, 11:08:40 pm
content: that is even harder.Are there any unique masks or something that need to be exposed with electron beam rather then just UV light? paints?

author: David Hess
author_rank: Super Contributor
timestamp: February 26, 2024, 02:18:02 am
content: CRTs can be used for data storage, where the electron beam writes spots to the phosphor and then can be used to read them back.https://en.wikipedia.org/wiki/Williams_tubeThe bistable storage variation would have allowed the data to be retained without refresh. I have actually seen this occur on my storage CRT oscilloscopes where the previously stored image returns years later when I first power up the storage mode.

author: ikrase
author_rank: Regular Contributor
timestamp: February 26, 2024, 09:32:33 am
content: You would need to seal the tube to a vacuum manifold (the aperture of this should be a significant percentage of the overall size of the CRT) and pump it down (which means a diffusion or turbo molecular pump, and a rotary vane pump to back it). Vacuum is its own whole (very fascinating, somewhat expensive) thing.There are some cathode coatings which can withstand air, such as those used on ionization gauges that may be exposed to poor vacuums and won't instantly fail even if briefly turned on at atm. Probably those are not the ones used in CRTs.For people hacking stuff on their own with a box of scraps, I strongly recommend John Strong's Procedures In Experimental Physics from 1938 -- but I recommend you do not make your own blown-glass mercury diffusion pumps. The Fusor Forums are also a useful place for amateur experiments in this realm, even though they are focused, unsurprisingly, on fusion and fusors. Nowadays you can make some use of purpose-built vacuum hardware from ebay -- purchased new, this is $$$.If you just want to build your own electron beam, this might be easier to do yourself, inside a large steel, copper, or glass vacuum chamber.Electron beam lithography is used as a no-tooling-required method of extremely fine integrated circuit patterning. I believe the resists used with this are PMMA-based.That monster with the carts going through it is firing the E-beam through a window made of very thin material (and also tremendously powerful). This device is used for cross-linking plastics "radiation cross-linked PE" wire insulation is made by this method.

author: coppercone2
author_rank: Super Contributor
timestamp: February 26, 2024, 10:12:58 pm
content: is the e-beam in a TV capable of any unique process at its normal power level and resolution for manufacturing anything? I just wanna know , I know its not practical to hack such an apparatus

author: BrokenYugo
author_rank: Super Contributor
timestamp: February 27, 2024, 02:06:56 pm
content: An electron beam of around color TV energy demonstrated in air.

author: calzap
author_rank: Frequent Contributor
timestamp: February 27, 2024, 07:15:27 pm
content: If you wanted to go to the effort, you could use the backend of a CRT as the start gun of a high-energy accelerator. And yeah, you’d have to get it out carefully and keep it in an inert atmosphere or vacuum. The electrons can be accelerated by EM fields or microwaves. Then smash the beam into a high-Z target to get all sorts of radiation including high energy bremsstrahlung like used in radiation therapy. But if you had the expertise and finances to construct such a thing, why would you use part of a CRT rather than a custom gun?Mike

author: David Hess
author_rank: Super Contributor
timestamp: February 28, 2024, 03:48:43 am
content: Quote from: calzap on February 27, 2024, 07:15:27 pmElectron gun construction is pretty finicky. I have seen several projects that started with an electron gun extracted from a CRT for this reason.

author: HarryDoPECC
author_rank: Regular Contributor
timestamp: February 28, 2024, 04:48:32 am
content: Selectron MemoryVery cool I think, arguably a/the pinnacle of tube technology. RCA abandoned it to concentrate on TV stuff, much to von Neumann's disgust.Great site herehttp://www.rcaselectron.com/

author: SeanB
author_rank: Super Contributor
timestamp: February 28, 2024, 02:40:02 pm
content: How about this CRT, which was used as a medical imager of some sort, dating from around 1975. Used to write an image onto some form of thermal paper, with the screen brightness being used to write on the paper directly. Likely to fade fast, and I only have the one very old roll of the paper that came left in the Medelec unit. Screen has some rather severe burns on it, seeing as it was used at such a high beam current to get the light output.

author: Gyro
author_rank: Super Contributor
timestamp: February 28, 2024, 06:43:00 pm
content: Quote from: HarryDoPECC on February 28, 2024, 04:48:32 amWow, looking at the AFCRC (Air Force Cambridge Research Center Memory System), 14ft of rack and 6kW consumption for 5kb of RAM? It's a shame they didn't develop the 4kb part a bit quicker.

author: calzap
author_rank: Frequent Contributor
timestamp: February 28, 2024, 09:38:42 pm
content: The link below is to a video that has a good look at the electron gun of a therapeutic electron linear accelerator. The spooky parts of these machines are the copper microwave cavities that accelerate the electrons.Mike