vintageTek Demo of a 1930's 905 CRT
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- เผยแพร่เมื่อ 25 ส.ค. 2024
- This video documents the creation of a demo for the vintageTek Museum of a 905 CRT (cathode ray tube). This CRT was made by RCA in the late 1930's and is one of the few CRT's made with a clear glass envelope. See the Museum webpage at www.vintagetek.org
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In the future, when you absolutely positively *need* a CRT for a game, and all old CRTs are broken, these dead-simple circular CRTs (that could conceivably be produced without heavy industry) will be what we use.
Get 3 of them, put color dyes in the phosphors, put lenses in front of them, bam, crt projector with a huge image
so many people are interested they will learn to rebuild the CRTs (it's possible)
@@tankmchavocproductions6907 you'd probably be better off just picking different phosphor colors for each tube: red and blue phosphors exist
If industry is that bad off we will have more important things to worry about than computer games
Just rebuild old crts with a new electron gun. The industry only stopped because of reduced demand meaning no profit was possible.
Thank you so much for _not_ adding background music.
it's the first time to see an tube with no coating on it , good one nice to see the tek logo
Love CRT technology. Nice bit of work there! Great to see inside one when working!
Man we need to get these back in production
Go to andeman
No
I agree, I would love to have a brand new tube circuit crt
Maybe not these but color tubes for sure
... why? They look like shit, use a ton of electricity, take up a ton of space, and overall lack any of the quality with current technology.
I guess people are into the crap and degradation of vinyl so makes sense they'd be in to CRTs too?
Transparent, electrostatic deflection, without a third anode ... beautiful.
It's amazing from light bulbs to television and so much more from the vacuum tube.
Very nice the clear CRT, gives good look inside.
How exciting it was to see a picture like that.
I live in Portland and look forward to you re-opening so I can visit. Thank you for posting this !
very impressive...it's like a internal laser show
More like a particle emitter hitting up the phosphor.
I *really* like your XY graphic generator! The old Tek logo is the wallpaper on my laptop, and I've seen the wizard in the schematic in one of the manuals I have (can't remember which one). I've played a little with XY and Z on some of my scopes, with simple graphics, marker generation and video display.
Love vintage tech--brilliant project! Well done!
Very nice project and what a beauty of a CRT. Thanks for sharing.
I ran into the same "wobble" issue when I build my scope clock.
First help was to replace the standard transformer by a toroidal transformer. That helped alot and the wobble was nearly gone. I then put the toroidal transformer into a MU metal can. That shielded the rest of the dirsturbing magnetic field. Result was a stable and razor sharp picture on the CRT.
I used an old Heath kit built solid state oscilloscope for an oscilloscope clock using a small CRT driver board and the CRT has a shield over part of it with the power transformer mounted under the chassis in a copper or copper plated can with most of the scope chassis being of the same material.
No wobble that I can see.
It really is cool to be able to see through the tube in operation.
I built a TV years ago using a 913 tube. Unfortunately, a 1" CRT doesn't show a lot of detail...
yes, size is very important. anyone that says otherwise is a lier.
How did you make it?
This is truly awesome work. LCDs these days. CRTs were using tiny changes in voltage to change a magnetic field to change where the electron beam went. Obviously LCDs can produce a higher quality but the CRT was a HUGE jump in technology.
Most advanced CRTs can display pictures with HD res, and some professional ones can even output something comparable to 4K !
Wow now that really really cool, being able to see what happens inside a crt screen, that’s pretty awesome, great work.
These machines are incredible
Great video! I love old tube stuff!
Pretty impressive considering that that older crt was not considered for an image display other than that which was used for measurements. And that flicker, I am sure, sure grabbed folks attention!
That's very awesome!...nice rig for the Museum, too.. and safe from implosion danger to the visitors, too...I noticed by the whitened getter areas I can see on some of them that the bare CRT's on display next to your rig had been aired, ... for visitor-safety, no doubt.
awesome gotta love that old CRT!
I've always been fond of non coated CRTs.
I collect 405 line valve tvs of the 20 I own 3 are 1940s sets but sadly I haven't managed to get a set fitted with one similar. in the UK some 40s sets still had partly non coated CRTs I believe some 40s Ekco sets did but I can remember the model numbers.
Thanks for this upload it was a real Treat :-)
The Sony Watchman actually had a CRT that was viewed from behind. It projected onto a phosphor screen angled at 45 degrees.
A similar if not the same tube was used in a lot of low profile wall mounted video door intercoms before LCD monitors were invented. The screen was curved and closer to 30 degree angle and I always enjoyed playing with them, it was so cool to watch the picture through the vacuum. Tubes are still available NOS crtsolutions.ecrater.com/p/10644463/04jm-4-flat-b-w-crt-tube
Wow that is so cool. 👍
Imagine a colour CRT like this!
Now THAT I would LOVE to see!
pure CRT ASMR
It is interesting to see the old age technology
Very cool video brother.
WHAT A BEAUTY
Outstanding
I've always been curious about behind the scenes. of a CRT
By the way, Tektronix could learn how to manufacture LCD screens able to last as long as this CRT tube does.
I have a 905 tube here also doing nothing... Fun to see one at work
Beautiful!!!
What a calming voice
Television 📺 used to run off the light 💡 fitting which is a coaxial circuit..there all lightbulbs! Good video
This was realy cool!
Super! Thank you very much!
very enjoyable video Bob! I'd love to come to the Museum someday!
What, if any, is the danger of creating x-rays working with one of these?
x-rays are only a problem if the accelerating voltage is over 20 thousand. This tube is running at only 1200 volts.
Perfect but I was taught never to put the CRTs screen down like the row you have at the back because any particles in the tube would stick to the phosphor coating.
Yes I see what you mean. Pity for them to have lasted so long for a few decades old particles to flaw them. On the other hand those tubes have more than fulfilled their intended service lives by now. Perhaps upright storage can only add to their continued longevity?
Maybe they are end of life anyway. One of them has a white patch so may have gone to air.
That's so cool - wish I bothered to learn electronics
I still remember the dot disappearing on our tv after it was turned off
This is the best ASMR ever
Well done sir
i would have added a button with a timer so it is on only when some one wants to see it working.
Yes. I'd hate for that 90yr old tube to suffer burn in after surviving this far.
Can you actually see the electron beam in dim light
Neat - wish I could have done something like that with the 3FP7 WW2 surplus CRT that I (aged 12) got for $1 in 1959, but it "wanted" something like 4-kv for its post ultor hv. As far as I got by 1963 was to use a Tesla coil for that and put full-line AC on the deflection plates (all w/o the convenience of a diheptal socket!). I cringed a bit when it looked like you might be reaching over some of your hv circuitry to plug in the transformer (think Ross Hull). BTW, a gap in the aquadag coating on my 3FP7 let one see the "inside" of the phosphor face (bright-blue short persistence and longer yellow-green afterglow as designed for radar displays).
We must be close to the same age, and therefore the same as the age of Tek's first scope, the 511, which came out in 1947, the year I came out.
For a 8 year old video it has very good quality
Feels weird to think I spent a large part of my childhood being 'shot at' by one of these things :)
There is also a small electrostatic deflection CRT called the 913 which was made in an octal tube format.
Wow What Beautiful Proyect :-)
Oh i live in portland, too! this is great!
Cool! I prefer a CRT TV over an LCD TV.
This is very hard work
This vintage technologie so much more understandable than the modern display.
I can show kids a this video and they will understand how CRTs worked (at least the clever ones) but a TFT is a totally different thing.
Only because it's larger. If you saw an LCD (tft is a type of LCD) that was scaled up to this size (about 50x50 pixels in a 8" x 8" form factor) you'd be able to see just how simple it is. Like holding a hand in front of a flashlight, but replacing the hand with an rotating paper that is controlled by electricity.
I've often wondered how much the accessibility of early technology fed back into the culture and helped propel the industrial revolution. How many curious kids could sit and watch a steam engine for an hour or so and get a pretty decent idea how it worked, be inspired, and go on to a career in the field and maybe invent something of their own. Now? All of the most ubiquitous tech is basically invisible.
Instead the kids that would have grown up to create interesting and useful physical products and building projects start useless tech companies that make us all more depressed and angry. (Not all of them, YT is amazing for sharing knowledge just like this, but there are plenty that are entirely needless.)
What a beauyu ! And the interference from the mains is a bonus .... in this case 😊🤝🏻🇳🇱
Magic.
Why didn't they make more clear CRTs? It's so much more interesting when you can see it working from the inside.
They need to have the aquadag and the lead in the glass to have good picture
Otherwise they would look like shit
Nice work.
Nice work
this is awesome 👍👍👍👍👍
This crt would probably be capable of 50 lines in guessing
Little more volume please if you can, it's difficult to hear even at full volume. Very Interesting project.
very cool!
wow awesome!
How did this tube work? I had thought that aquadag was the conductor connected to the anode button and provided acceleration for the electrons. What's accelerating the electrons?
Is it required to have a voltage on the deflection plates to get a dot to appear?
+Robert Haas I used to get stuff for building projects at the techtronics country store back in the 70's.
I still own one of those solder irons
I still don't understand why the electrons don't go directly to anode but instead fly right past it.
How does the microprocessor drive the image that is being displayed on the CRT?
Why doesn't this sort of CRT have the coating on it? Or perhaps i should say why do most CRTs have the internal coating?
Great video by the way, absolutely fascinating.
CRT'S after this one had a conductive aquadag coating (graphite paint) connected to the highest positive voltage. This gave the electrons a place to go after giving up energy lighting the phosphor. In this older CRT, the electrons either wandered back to the deflection plates, or collected on the screen, giving it a charge that could affect the image.
thanks very much for your explanation.
I was watching another TH-cam video about restoring old CRTs and they put a coat of aquadag on the outside of the tube as well as the interior, why?
totally understand if you haven't the time to reply, quite frankly I'm super happy to get one question answered.
thanks again for the great content.
An outside coating would be grounded. With the inner 'dag this would form a parallel-plate capacitor that would act as a filter for the high-frequency high-voltage supply. On color TV CRT's, the coating was usually lead, which would be both a capacitor plate and a shield for X-rays.
Fuck, I need to go to Portland to check this place out.
I liked your T-shirt
You know those emit röntgen right?
It's not a shocking amount, but you are getting a dose
I think the output of the voltage doubler is too low for x ray emission. Makes me wonder though, how much ionising radiation have I actually absorbed from an average 3-4 hours daily viewing of CRT's in 60 years?
@@roberthorwat6747 it's not to low, but the energy is so low in later commercial units that you'd get a dose only if you're within a few cm of the screen.
X-ray doesn't really travel well in air. A 120kv source is only detectable upto about 4 metres.
@@Jan-mu6vs 👍
That is cool"Just a curious question though"What would happen with a ferrite yoke?
And/ or a Faraday cage.
@@gregjones3660 Agreed yet they are = and opposite reactions " either way it would be an interesting outcome?
@@gregjones3660 My guess a Faraday cage. being of an outcome of non interference might make a sharper crisper beam ?
How monitors show that kind of pictures and letters? How code it ?
how come the static charge doesnt build up until the screen start repelling electrons ?
do you crt tube making home please
Very good 😇❤❤❤❤❤
But can you play crysis on it?
The problem comes from the beating between the mains frequency and the vertical deflection (frame rate) frequency. If you try to synchronize the picture generator to the mains I think that the problem will completely go away. That's the same reason for which the old analog TV was always synchronized to the mains frequency. Try this if it is possible.
This is not a raster-scan display, it's X-Y, so there is no separate vertical deflection rate. Instead the overall refresh rate would have to be adjusted, which is tricky. I plan to re-do this exhibit to reduce the number of mains-frequency transformers, which will reduce the stray magnetic fields.
I thought that it is using the standard raster scan principle. That's true that in this mode it's more difficult to synchronize the refresh rate to the mains because maybe it depends on the picture that is showing at the display and is no fixed relation to a clock frequency on the board. Really in this situation a SMPS or transformer rearrangement in the box (or magnetic shielding) should solve the problem.
Why not locate the transformers in a separate box and make a cable to connect them to the circuitry?
That way the transformers are away from the CRT.
Wow. Good
This is ALIEN tech.
Where is the Tek Museum located?
In Portland, Oregon at 4620 SW Beaverton-Hillsdale Highway. See the website at vintagetek.org
We have moved onto the TEK Campus at 13480 SW Karl Braun Drive, Beaverton, at the northeast corner of the campus, contrary to where Google Maps shows this address.
what does the Wizard of Ido mean?
Wonderful! Love seeing the phosphor from behind. What was deflecting the dot from precise middle?
While it is interesting to see a CRT working from the inside, HOW does it work without the conductive black coating? (I'm no expert on how these work)
The secondary electrons emitted by the screen are collected by the deflection plates, which are the first positive elements they found close to the screen. Old tubes without the internal aquadag film are prone to distortions on the waveform displayed due to the stray currents caused by these secondary electrons when they flow through the relative high resistance path associated to the deflection plates.
Hi, where can I obtain a eletric circuit to mount this exeriment? I still have a Dumont oscilloscope crt mixed with a lot of tubes, mostly used in tv sets.
I found this trying to increase my appetite for clearvoince
Can you actually see the electron beam in a tube like the one here
No. You might if the tube were gassy, but the beam would be so diffuse it would be nearly invisible, anyway.
One physics teaching supplier puts a bit of helium in their clear-wall CRT tube, forming a glowing green beam. (Two magnets can spiral it up, forming a magnetic bottle!) But this greatly reduces the cathode life, because of ion bombardment. Search: teltron fine-beam
good project👌🏻 i wanna do this,but need to vertical and horizontal ocillator circuit board or schema.do u have link about it?
lol would be cool to hook up a video camera tube directly to the crt and make a green mirror
Would ion burn abe a concern with the CRT set up like this?
The accelerating voltage is so low that ions wouldn't have much energy. Ion traps were only used in TV CRT's with very high accelerating voltages, typically over 20KV.
Next mission objective: Play ATARI Star Wars on it :D
I know the you have vertical and horizontal deflections plates that must run on B+ the electron gun on B-?
Hey its the early prototype of the PipBoy from Fallout :P