CuriousMarc - 2022-09-12
We explain how Cathode Ray Tubes (CRTs) were invented and how they work, and hook up a few to light them up. They are as intimidating as they are awesome. But did you know that they led to the discovery of the electron, and the birth of a new field, electronics? And of course the invention of the oscilloscope and modern TV! Link to Eric's scope clock design info: https://github.com/schlae/crt-driver Our sponsors - PCBWay: fast turn PCBs, https://www.pcbway.com - Electro-Rent: https://www.electrorent.com - Keysight: test instruments: https://www.keysight.com - Samtec: connectors: https://www.samtec.com Support the team on Patreon: https://www.patreon.com/curiousmarc Buy our merch on Teespring: https://teespring.com/stores/curiousmarcs-store Get more info on the companion site: https://www.curiousmarc.com Contact info: https://www.youtube.com/curiousmarc/about 00:00 Recap of previous episodes and high voltage warning 01:06 High voltage equipment and CRT basics 02:54 Geissler's discovery of the gas discharge tube 03:32 Crookes' discovery of the Cathode Ray Tube 04:41 J.J. Thomson's CRT explanation, electron discovery 06:22 Braun and Whenelt's development of a practical CRT 08:18 Main electrodes of our T527 tube 09:45 Why the cathode is at -4kV below ground 10:35 Why we need a cathode isolation transformer 11:26 First power on 12:04 Deflection plates 13:46 All the electrodes in a modern tube 15:01 How focusing works 16:30 Hooking up brightness 18:04 Displaying shapes! 19:40 Making an oscilloscope 20:57 Powering up a miniature tube 22:00 Large tube, Eric's CRT clock
Thanks for the great history lesson! I also really appreciate you getting the pronounciation of all the non-english names right. It shows the respect for the gigants on whose shoulders we stand.
If you adjust the focus bias in the opposite direction (opposite polarity) i.e. making the spot even more defocussed and bigger, eventually a sharp image that resembles a lunar landscape comes into focus. This is image a magnified view of the cathode. Effectively creating an analogue non-rasterised electron microscope.
This effect also exists in optics. A lens between a light source and a screen will have two positions of sharp focus. We are effectively exchanging u and v in the lens equation 1/u + 1/v= 1/f, where u and v are the distances from light source to the lens and the screen to the lens, and f is the focal length.
Oh I did not think of this. That would be a cool experiment to try!
@@CuriousMarc Please make a followup video on this, maybe a short? Pretty pretty please :D
wow, great video. Once a long time ago I made a (basic) osciliscope with an old 20" tv. I kept the old yoke connected to complete the high voltage circuit, then used a similar yoke on the neck of the tube (after sorting out the vertical and horizontal parts of the yoke). Then by aplying an amplified signal to the yoke on the tube, I had hours of fun displaying lisajou patterns on the screen. Audio signals were fascinating too. By varying the volume of the signals so many wondrous patterns could be displayed. Thanks for the tutorial and my trip down memory lane!
My love for CRTs has an incredibly fast refresh rate! This video was incredibly refreshing.
@1:00 - I can assure you - your production looks like an OSHA lab compared to Shango066. I really enjoy both varieties of approaches to high voltage.
12:49 DVD logo! I've had one of these small circular tubes sitting unused for years, this video is great inspiration to get it working.
Be careful!
“Did Jim say that I didn’t see it I SAW IT!”
The invention of the DVD logo
I don't know anything about electronics.
Yet I've seen every single video you posted.
These keep me on the edge of my seat every single time!
Thank you so much!
In my youth that first moving spot would have counted as entertainment. It brings back memories of the disappearing spot on old TVs when they were switched off. We watched that too.
That came back in the early years of Android phones, where everyone installed that App, when you press the power button for standby, it whipes the screen to a small line that then shrinks to a small dot like the old CRTs did. And I had it too on my very first Android phone, sure enough!
@@hamandwine Have you any memory of what that app was called, as I would like it on my phone. Or.. I could Goober it.
@@hamandwine that was the default behaviour of one of my old Android OSes' graphics. It looked so good - they really need to bring it back!
@@gloverelaxis it really did look fantastic on OLEDs. It’s a shame they removed it.
@@hamandwine I still have that phone in a drawer somewhere. It was my favorite thing about it, was devastated to learn the replacement phone did not have this quirky feature.
I wish I had this kind of equipment to play around with. I recently acquired 5 mobile data terminals that came out of 80s police cars. They all have 5" amber CRTs in them. Still work!
I used to have one of those. Wish I knew how to write to the internal flash memory.
Can you give me the model? Would love to see these work.
@@unmanaged Motorola MDT9100
@@unmanaged mine are MDT-9031
Do you have SCMODS?
This is a channel where, with every new episode, one can sit back with a bag of popcorn to enjoy the consistent top quality technical content. So much fun! Thank you Marc!
I'm amazed at how much technology goes into making the DVD screensaver. It's a wonder of miniaturization that it could all be packed into a tiny box that would sit in your media console.
Fantastic video! Thank you for explain in both historical, but also in electric-electronic way how the CRT is working.
I loved to watch this video, and many questions were answered for me! 🙂
CRTs are unreasonably cool. I particularly love the very last generation of them. FHD 1080i or HD 720P is truly a ludicrous thing to expect of a CRT but those crazy engineers managed to not only make it possible, but even make it relatively inexpensive. There's a thing about CRTs that you just don't get from any other display technology: a sense of depth. Because of the glass and the thickness of the glass between the surface and the phosphor layer you end up getting more of a "window" or "vista" effect than you do from any other panel technology. I love it, because the high-res CRT panels, particularly those from Sony and Samsung, have rich enough colors and deep enough contrast that you really feel like you're looking through a window into another world when you use them. If I could, I would absolutely have one of the old Sony 1080i widescreen CRT televisions for PS2 era emulation. I even have a PC that I've set aside just for such a purpose because the GTX9xx series was the very last one to support the DVI standard with analog RGB signaling. And an old i7 7700K with a GTX960 is a perfect platform to run PS2 and Gamecube emulation on.
I watched a video recently about a 4K CRT monitor somebody had, made by Siemens or Fujitsu IIRC for medical purposes. Monochrome of course, which makes high resolution easy due to not needing shadow masks.
What about CRT computer monitors? Some of them had high enough scan rates to do ridiculous stuff like 1536p at 85hz
@@mr.jamster8414 Yep, and those are also very impressive, though often in smaller screen sizes compared to the 1080i television tubes, since it wasn't deemed as necessary to make a screen that close to you particularly massive. The fact that they maintain a similar tube length allowed them to decrease the deflection angle and meet those high scan rates for resolutions even higher than FHD.
that makes a lot of sense! @@mndlessdrwer
@@mr.jamster8414 If you do find yourself in a position to acquire such a monitor and you have a place to display it, you should definitely consider it. Just make sure it works and isn't washed out or dim. A modest amount of correction can be made by fiddling with the adjustable resistors on the control board to increase the cathode ray gun output, but you can't really do anything about missing phosphors. If it's too dim or there's noticeable burn-in, then it isn't worth consideration. CRT displays are wildly fascinating to me and have a unique image aesthetic that you cannot get from any other kind of modern display, so they're still worth the addition to your tech collection. Even better if it's a monitor that features a VGA or DVI-I input for proper analog RGB signal transmission. It is also easier to find a digital to analog converter board or a cable with the DAC chip built into it if the receiving side is already playing nicely by featuring a connector as ubiquitous as VGA.
Edit to correct the DVI version referenced for analog RGB signal.
2:54 Yesssss! I've had a hankering for a good elevator music explanation.
I was talking recently to a fellow engineer how such a pity it is that so much research & the sheer amount of knowledge that has gone into the development & production of CRT related technology & it has all but virtually ended. Some of the CRTs i have in my personal hoard are just phenomenal pieces of art looking at the exquisite amount of stuff that has been done to construct it. I hope that oneday there will be something that calls for the technology to be revisited & i pray that all the incredible experience & knowledge is not lost by then!
best line: Which eventually led to this channel. Very interesting video as usual.
Great work as always from you all. I was reminiscing while watching this as I used to work fixing rental TV's here in the UK 40 years ago. I found it amusing when you were on about 4KV and being cautious, which of course is more than correct, and thank you for reiterating it to todays audiences, but we used to work on tubes\CRT's\televisions with 24KV on the final anode. Those were the days...
The current supply capability of most of those 24 kilovolt ultor supplies was around 1 mA, which is unlikely to kill but could still shock enough to make one jerk violently, which could lead to other injuries. The CRT aquadag capacitance alone could store up a nasty shock and some glass formulas would even be able to build a charge back up after one discharged it. I ended up taping foil to the 'dag and using a clip lead from the anode button to the foil to ensure it was kept discharged.
@@seekingthelovethatgodmeans7648 You are happy to say that it was unlikely to kill. While that may have been the case please explain to my late work colleagues family. The inside of a TV cabinet was often a sharp and dangerous place, especially with chassis built the way they were. One shock could and did rip the wrist open , thus enabling a painful death. Might I suggest that while you appear to have knowledge of CRT's, and yes we always discharged them before touching them because they did manage to store up their own charge, you have not worked in a high voltage environment and are in fact sprouting what you think is important to you. If you had worked in such an environment, then you would have known, and therefore not commented in such a glib fashion. You may reply and apologise or just stay quiet. This reply is posted In memory of my old work friend. p.s. This is available to be read by everyone else therefore, think about how you wish to be seen as an evidently religious person with a name like yours.
@@stephendavies923 Deary me, what a completely unwarranted, sanctimonious lecture. Well, I did work in that environment, and he's absolutely right in what he said, the shock from a TV anode causes a violent jerk response which could lead to other injuries. Why you took it on yourself to take such offence to that is a mystery. He's got nothing to apologise for, get over yourself.
24kv is getting into the pretty hard X-ray level isn't it?
@@zyeborm yeah, but X-ray warning sticker felt long time ago, making the tube safe for operation.
My Dad worked fir a company back in the day called D:E:R. You used to rent your TV or fridge or even washing machine from them. I can remember him doing private jobs repairing tv’s on the kitchen table and always making sure he discharged the crt once he’d unplugged the trippler. By contrast his step father used to repair vintage valve radios and would work his round the anode caps, touching them with his bare fingers, until he found a dead one. !
It's more likely those weren't anode caps, but grid caps. Unlikely to have dangerous voltages on them, and touching one with a finger would inject some mains hum as a test signal.
Yeah, they were sold to a newer competitor named l'Easy. Then the brand was turned into a money lending company.
Wow. Arthur pronounced correctly. (And all German names as well.) Impressive.
Also: We teach kids in school, how a CRT works, including the nature of electrons... how far have we come.
Smokin' oldies! CRTs were awesome, but their time has gone.
As a test tech, I worked at a test bench with a big, heavy Tek 541 scope blowing hundreds of watts of hot air on the bench. My fingers got blisters then callouses from constantly turning the knobs as I was going through the tests. It was a great day to celebrate when the company replaced them with HP 1740 series scopes, which were much easier on the fingers. Now the same capability scope fits into a small fraction of the space.
I LOVE CRTs! Fascinating stuff, indeed. And that clock looks super!
5:44 love that radius measurement right there (the same concept we learned in school). Thank you for putting this together.
What a treat of a video, fun to see you playing along with these old tubes! Haven't handled a live CRT since mid 90's, so I really enjoyedwatching
Using a filtered DC supply for the heater supply may reduce that noise. Great Video!
Thank you very much for telling us the History and the function of a crt. I remember Back in the 90's when i was a kid i asked my Patents how a TV works and None of them could Tell me. So i looked it Up in an encyclopedia and there was a small Text about a Kathode and Anode and a small picture. That was it! Now try to understand that as a kid without any other explanation😅
Enjoyed the good explanation and demonstration. An early interest in CRTs lead me into a life long interest and career in electronics.
The worst jolt of my life -- it really could have killed me, was coming in direct contact with a deflection yoke. If someone wasn't there to cut the power I might not have made it. Since then, I've stayed away from CRTs -- at least the back of them
I'm 17 and so far I have yet to be shocked in the three years of being around them. Specifically in the Macintosh plus, I fear for the day I too will be shocked.
@@BottomGear2 My dad was probing around a chassis one hand in a pocket rubber mat etc.. Then the dog walked up behind him on the concrete floor with a wet nose. Not sure who was more surprised :)
@@BottomGear2 Simply respect electricity, both high potential and low potential. Some can shock, some can burn or fry (conductors or expensive electronic parts if not you) and some can do both. As much as possible, avoid touching any circuitry that is not known dead and discharged except in the manner it was designed to be touched. While it's not generally a problem with modern equipment with proper grounding, older electronics could unexpectedly bear a high voltage potential to a ground that you might contact in some other manner, so insulated sole shoes and watching what your other hand might be touching (keeping it behind the back is a good idea) are additional precautions when dealing with equipment that is connected to the line. Electricity is a coiled snake ready to bite you in the suitable circumstances, so don't give it any opportunity to enjoy such an event.
@@1boobtube zap! YIPE!
Deflection yokes hurt really really bad. I feel your pain ;)
The tiny oscilloscope reminds me of my uncle's sweet 70s quadraphonic Marantz tuner.
I've been wanting to fix a 1949 round Admiral CRT and I have a tektronix oscilliscope that doesn't have any deflection. I want to learn to fix them so that I can better support my currently working Philco Predicta Princess 17". I love that thing, so this channel seems like something I'll love too. I kinda want to fix them back to stock and then use the regular inputs to put computers and syntehsizers in. I already do that with my Predicta, I have a raspi and converters so that I can put youtube videos on it. It's a trip watching modern content through a 60 year old TV.
This was such a great video. It helps me appreciate Marco Reps comments a lot more when he discusses the equip me covers.
You guys are awesome! I was raised around CRT's and I love 'em too.
They're majestic and elegant... Despite the clumsy envelope 🤣
I really miss them showing up on the side of the road to play with haha... I have a trio from a projection set that are just keeping the air out... want to see them live a new life. Rather versatile I figure, can either drive them full tilt for some projection (still on the lense frame) or pop them out and dial them back for direct view... No worry about burn in for the latter methinks 😁
Great video as always!
It's nice to hear CRTs history for refreshing knowledge.
Cool setup for running tubes on table! 👍😎
Super cool stuff! Great job explaining how they work!
If you want to know what electricity can do to you without seeing gore then I highly suggest watching Big Clive's video about people that use microwave transformers to do wood working art and paid the (sometimes the ultimate) price. Be careful out there.
Looking forward to the episode where you show the episode on a tube, record that on a modern camera and put it on youtube.
Paging Adrian Black and Paul Carlson!
He's going to make his own slow scan TV for the Apollo ground station ;-)
@@zyeborm Yeah, basically two sawtooth waves for deflection (at exact frequency multiples), then apply the received intensity signal to the modulation grid. So really basic triode amplifiers for the high voltage amplified signals.
Thank you for this! It made understanding CRT electronic voltage input much easier for me to understand.
Thank you for motivating me to work more on my own CRT project - based on the tiny D3-11GJ (only 500-1000V). I am currently planning to design a proper deflection amplifier & a better (resonat switching) power supply for it.
That's definitely a unique clock. :) I was never fan of CRT's but this video made up a lot for them. ;)
I loved the story time you made! More of those, please!
Great video! Thanks for the no-nonsense, easy to follow tutorial😊
and again, 'thumbs up' before watching 😎
Totally awesome =D A joy to watch this channel!
All observations to safety of course, but I was still happy to see Eric's use of the magic fingers to diagnose the focus. 👍
I've gotta say, this whole video's been a real treat. It's hard to pick favourites when there are so many good ones, but this is definitely one of them. I've been interested in CRT displays and the technical aspects of their operation that most typical guides gloss over or just ignore. But it was also difficult to find anything (on Google) that wasn't dumbed down content. There's a great app note, AN-656 but that's more a teaser than anything. I came across a paper from the US Navy that was maybe 30 or 50 pages long that seemed very promising. But I haven't been able to find it since then. I'm thinking aside from this, I should look for a book on CRT displays.
[EDIT] Well there we go, I just found a volume of the MIT Radiation Series that I have that happens to be about CRTs. I think I've just struck paydirt.
What an excellent video, had me hooked all the way through!
I have a cool scope that projects onto a curved surface to make it more compact, I'd love to figure out how to get it running. This video helps a bit, but still need to do some more searching
I've been collecting CRTs and equipment containing CRTs for a while; my current favourite is the CRT from a 1950s Ekco aircraft radar with an orange phosphor.
If you can get a hold of any old military aircraft displays theyre often CRT and can be pretty cool because of the history and application. Radar/B-Scope displays, or Radar Warning Reciever displays come to mind.
Thank you for the history lesson!! Fascinating stuff
@fxtrader7856 - 2022-09-22
Nice video...
I am 74 years old and retired, but in my youth I worked in Tektronix technical service for South America.
Working with CRT's was a regular part of my life. I have worked with all kinds of models and know them very well.
I can say that, although today they are obsolete and oscilloscopes are mainly digital, a good analog tube oscilloscope is invaluable.
Among my memories, I have a small Philips DG7-36 tube, and several microwave triodes. For fun, I'm thinking of building myself a small oscilloscope... Things we retired people do when we have a lot of free time...
@Spanu96 - 2022-10-29
What a lucky man, radiofun just made one with the same tube. Here is the link to his channel https://www.youtube.com/user/radiofun232
@johnwest7993 - 2022-11-09
I'm 72, and I built CRT's for HP in Colo. Springs. I play with longwave radio in my dotage. :)
@neolerades2987 - 2024-02-13
I'm 27 and I really like analog CRT oscilloscopes (and things), I personally prefer them to the new LCDs. I know that the newer ones have their advantages (I work with them in my work, I'm an electrician), but I prefer CRTs for my "hobby" home use, as they are beautiful and have their own charm. I have several CRT oscilloscopes, a CRT cardioscope, tube CRT televisions from the 50s and several screens at home.