CRT Thread

Do you miss good old days when monitors were bulky and analog? Video related - simple composite video input mod for an old portable TV.

>>3980 >Do you miss good old days when monitors were bulky and analog? Ha ha ha, no! I used to have to tote those things around sometimes in my work. Even just moving one around at home was an effort. I'll take the lighter, slimmer gear, please. Oh, but one thing crt terminals were good for was taking them out back and throwing rocks at the screen until it imploded. Boof!

I don't miss them, because I have hoarded literally dozens and use them all the time. But I do like the je ne sais quoi that old tubes have. Here you have this big, heavy lead-glass jar filled with outer space and rays of lightning, a lovely grid of flickering phosphor, a crackling dozen and a half kilovolts which causes the glass to hiss and tinkle and raises the hairs on the back of you hand when you put it near the screen. The thrill and slight danger of implosions, high tension, and soft x-rays. The insane refresh rate. The old-school science fiction terminology, with particle guns and deflection coils and shadow screens. The way the image collapses when you turn it off, shrinks into a tiny spark of light in the center of the screen before fading away, like the USS Enterprise blasting into warp. They have so much tactility and character and fascinating and clever functionality. >>3981 This is definitely the drawback, though lol. But I mean it's not super fair to appraise them based on having to lug them around for most applications. Nearly all displays get set down once, moved maybe once or twice, but otherwise remain unmoved for their entire lifetime. But I also work in film/commercials, and for my job I'm definitely also thankful for nice, lightweight flat panels that don't implode. I sure am sad about those CRT terminals you destroyed with rocks, but I'd be lying if I said I didn't do that once or twice back in the day either lmao Aight I'm just gonna dump some sexy Braun tube pics now. And various other lovely wonders.

>>3982 >je ne sais quoi cool turn of phrase >elegant description of CRT you're a poet of the machine. So true. I've got one in cold storage, limited to 1024x768, but I've got a machine to drive it in cold storage too. There's something magically nostalgic about booting it up and hearing the whine and hum and clicking of an old machine.

If I can get through the dumb automated post filter at least

A fun dual-electron gun tube from an oscilloscope to draw two signals at once without having to cycle back and forth between the two

Would hate to drop this one and kill everyone in a fifteen-foot radius lol

>>3987 aren't they evacuated of air, causing an implosion? Or am I off?

An electrostatic plate model, also from an oscilloscope. You can really clearly see all the deflection geometry in this one.

This was about as compact as they got as far as depth, which is pretty atrocious by flat-screen standards. But look at that electron path; as you can imagine, it's a pretty extreme deflection to snake that beam around through the neck and out into the envelope and aaaalll the way to the corner of the screen. The beam length was also incredibly varied when comparing a pixel in the center of the screen to one in the corner or edge. It's a result of some really clever engineering and design.

Still technically a cathode ray tube; this one just shoots a ray from an electron gun which glows purplish and loops back all the way to where it started. Need to find an image of it turned on.

For a while around the turn of the century, they build cathode tubes with little arrangements of glass flowers painted with uranium and other heavy metal pigments so they'd be fluorescent under the shower of charged particles. The little mirror vanes above the flowers spun with the slight pressure created by particle impacts, which ended up deflecting the beam around like a disco ball and making the glowing flowers shimmer and flash and sparkle.

>>3988 Yeah, they implode. But for the really old tubes (before they designed in some safety mechanisms) that still ended up throwing big shards of poison-coated glass all over the place. They'd either collapse together and ricochet outwards or shoot through the center and continue flying in the other direction. So it was an implosion, but it still scattered shrapnel like an explosion in the end. Newer ones have way less volume, have clever variations in the envelope thickness to control where the glass breaks thus creating fewer and smaller pieces, and structures to catch or dampen the resulting shrapnel.

A lovely little educational model with nice fifties graphic design and a tidy layout of the envelope, electron gun, and deflection components. Would love to have gone to school and had one of these to play with and learn about. That would be a good day of class imo.

A strange tube which I'm not totally sure of the function of. It has a really long envelope ahead of the electron gun with what appear to be multiple anode sockets. Seems to have a bunch of grids like an old vacuum amplifier or photomultiplier tube or something to control the beam in additional ways? It's amazing the variety of tubes there were back in the day. So much was developed before they settled on the wonderful Trinitron design, which was honestly very advanced still has some advantages over even modern displays in certain areas. There were even a few designs that boasted better qualities than the Trinitron, but they didn't catch on for myriad reasons (not the least of which was extreme manufacturing complexity).

One of the even more advanced technologies that only made it into a select few tektronix oscilloscopes (which is a shame, since it's way too good of a graphical display to use on such a simple tool) was the nucolor vector CRT. Using ingenious polarized electron beams and filters, it was able to create full color on a vector display! So no shadow screen, no little clusters of red, green and blue pixels. Theoretically the resolution could be infinite, limited only by how tightly your hardware could focus the beam and how quickly you could manage to scan it across the screen. In addition to raster graphics it could also create ultra-crisp vector graphics like the Vectrex, but unlike that machine it could of course do full color. Because of how the polarized filters worked, there was absolutely no artifacts from color blending pixels. Red, green and blue points of light occupied exactly the same space with no offset, so even up close the color stayed true and didn't split into aberrations, such as a line that is supposed to be pure white actually having a red edge on one side and a blue one on the other. Would love to see one developed to the current day in like 8k resolution.

Early camera tubes, like this awesomely-named iconoscope (don't you miss when people gave cool names to things instead of just like acronyms and model numbers?) were like a CRT in reverse. They still used an electron gun and deflection coils to scan the beam across the screen—synchronized with the exact rate of NTSC or PAL scanning on an accompanying CRT, so that the signal could be piped right in without any processing. But the screen wasn't coated with phosphor; instead, they had a grid of cells that utilized an effect where the conduction of electrons from the beam to the anode screen was modulated by photons striking that screen. So a set of optical lenses focused the image on that screen, and the beam figured out where the regions of light and dark were. With three of them in an array along with colored gels and a beam splitter, a color video signal could be produced. This specific iconoscope pictured was pulled out of an old missile guidance system.

Ever wonder how they made the test patterns on really old TV broadcasts, before a lot of fancy video graphics were developed? They came from a specialized CRT called a monoscope, which was kind of like a camera tube in that it wasn't mean to display an image but instead to scan the beam in the same way and then generate a video signal from the beam striking an anode instead of a glowing phosphor screen. In this one, instead of a blank screen that a camera lens focused light upon, you simply had the classic "Indian head" test pattern etched into metal. When the electron beam struck metal, it would conduct and the signal would show a white pixel. When it shot through the etched sections, there'd be no current and the signal indicated a black pixel. The TV studio had one of these and some driving circuitry (also all vacuum-tube based, of course) enclosed in a big metal case with video outputs, and they'd switch over to it after they were done with the day's programming and leave it running overnight.

>>3999 Wait, that's not the Indian head lol. Well you get the idea ;)

Same general idea as the monoscope, but this one has a font and some special characters engraved instead. The operator could select which part of the anode is scanned to produce a specific letter, then after that the signal could be shifted to another specific part of the video field to position the character on the actual display that it's ultimately connected to. That's how they made some titles back then before After Effects or the older but still digital character generator workstations before that. Otherwise they'd just make letters and logos out of shiny magnesium or something like that and photograph it on a black backdrop.

I've got some broadcast graphics background, so a lot of my stuff is from that field. This is a vectorscope, which is what they used to do color analysis and correction back before computer stuff was more common. It used a vector-type CRT to show a scattered image that was derived from what colors were in the video field, which you'd reference on a separate raster monitor. The different directions from center and distance from center indicated the color and saturation. There were little fields that indicated certain key colors and tic marks to determine quantifiable values. It was like a little radar screen. Still have one, and it displays some crazy stuff but it's not calibrated and isn't really doing what it's supposed to. This image is like kicking dead whales down the beach, btw.

>Do you miss good old days when monitors were bulky and analog? Not really. My temporary setup consists of a LaCie ElectronBlue II (DiamondTron tube, currently running at 1600x1200@85Hz) and some random peripherals because I just moved in and all the LCD monitors are in boxes. So far I'm really liking it, It had been years since I used this monitor on a daily basis, and didn't remember it being this nice. The contrast game ridiculous. The 100W+ power consumption is a bit of a bother, though. >>3999 And even cooler, the EVR. It's pretty much a tube-based telecine, designed for home use. https://www.youtube.com/watch?v=1XTDBRc-Wp0 https://www.labguysworld.com/Motorola_EVR.htm

>>4003 Oh nice! That's a pretty good old monitor. Yeah, the contrast was very veeery nice on the later tubes once they figured out how to make the phosphor a nice dark color instead of like light grey like the old ones. Contrast is kind of something we've suffered through with flat panels, although that's finally changing with AMOLEDs or whatever. And yeah, that's the little gadget you'd use to transfer your old 8mm home videos to VHS or whatever, right? I remember having one of those around at some point. That write-up mentions the "flying spot" system for scanning photographs, which is also how they sent the first images of the far side of the moon back to earth. It's difficult to overstate how much of an improvement and convenience modern digital photography is lmao

No, and this is a strange fetish.

>>4005 I mean I won't deny it. Everyone's gotta have somthin

>>3992 what an odd place to add something so pretty

>>4007 Hey, it's technically a cathode ray tube.

Gotta love an old monochrome phosphor vector display. Ugh. I want all my interfaces to look like this thing.

And speaking of green mono monitors, here's one from my collection with an image someone on this forum posted a while back. It's on top of a 70s CRT oscilloscope as well.

Rly intresting tubes lain, recently foundthis video of a guy building crt based VR glasses: https://www.youtube.com/watch?v=p12QaZUZDnM

>>4017 I was hoping for something much different. Although it makes for interesting trivia about old shoulder cameras.

God no, recently I went to a computer museum and passing by the old CRT monitors was a headache - from the screen flickering having become too obvious to my eyes and the constant high pitched sound they make.

>>4014 Made of pure love. (._.¡)

>>4019 These are issues which aren't present on higher end/late CRT computer monitors. The screen flickering (to me, at least) stops being apparent at around 80Hz vertical refresh rate. Most late CRT monitors could operate at 85Hz without an issue. On lower end ones you'd have to lower the resolution, though, as their electronics weren't able to handle high signal bandwidths. The whining you heard is caused by the flyback transformer operating at the frequency of the horizontal oscillator. This is around 15KHz on consumer TV sets, well within the human hearing range. However, pretty much all computer monitors since the late 80s had horizontal sweep frequencies of at least 21KHz, meaning they don't whine audibly. This is another case of "Remember how VHS looked all grainy and how the VCRs always ate your tapes?", "LPs wear out", "LCDs have awful colors". It's just people being exposed to the lower end equipment and never experiencing the peak of the technology. Of course, this doesn't mean all CRTs are great; quite the opposite. Most consumer crap was worse than its modern equivalent, and anyone who thinks otherwise is suffering from some serious survivorship bias.

I miss things not breaking easy and also the old ratio of 4:3.

>>4017 Contrary to another lain, this was exactly what I was hoping :) I have a bunch of those old viewfinder picture tubes too! The smallest one I have is no larger than my thumbnail. It's still full resolution. Since it's a mono CRT, the pixel density is still absolutely insane even by modern LCD or OLED standards. If you made a black & white HMD, you would have literally zero issues with the screen door effect and such. And I believe you'd avoid most of the x-ray flux since A. it's a very short tube (low-voltage anode) and B. the prism means the tubes are pointing at 90-degree angles, so the x-rays aren't pointed directly into your head :P Not that x-rays were ever really a problem with CRTs anyway. It was mostly just an engineer's joke that turned into layman paranoia. >>4019 The refresh rate on late CRTs was faster than current displays are. That's why some smash bros players still demand to play on them. You're probably falling for some kind of hypochondria; to be honest most people who complain about "flickering" (be it from displays or from LED light bulbs) are fooling themselves. This has bore out in double-blind tests. People are very good at convincing themselves that they are falling victim to a barely-perceptible problem. But the high-pitched sound is a legitimate problem. Many could be dampened properly, and they got really bad only when the circuits got old and a lot of the inductors in the high-tension side started singing. But that could be fixed pretty easily. And if you're over 25 it's outrageously rare that you can still hear it... unless it's one of those absolutely ancient sets that was never ever maintained. I have several and there's one from the fifties I can definitely still hear at 32. It's pretty bad. It makes my neighbor's dogs bark, so I don't really power it up very often at all. >>4068 God I miss 4:3 too. Honestly 16:9 or 21:9 (Ugh, why isn't it 7:3? Reduce your fractions you plebians) is a pain in the ass. Reading text ѕuсkѕ: paragraphs are either reaaaaallly wiiiiiide and super short vertically, or they're all lost in the middle of the screen inside absurdly huge margins. Closer to square works for more applications. And we wouldn't have such a discrepancy between horizontally vs. vertically-oriented devices like we do now with mobile media and web design. I realize this is an unpopular opinion though, some people really like their wide screens. I still use a 4:3 display on one of my boxes in 2020 and I find it pretty workable.

I'd like to get into CRTs but I don't know where's the best place to start and this thread is intimidating me because I am a dumb baby.

>>4225 My route was just picking 'em up off the side of the road and plugging them in. Then just look up some safety instructions and schematics to know which parts are no-touchy. And remember the first rule of high-tension electrical work: keep your other hand behind your back so you don't touch it with both hands and make a circuit that includes your heart. It's really not as scary as it's made to sound. Best of luck and enjoy!

Not really, I like my text clear and my pixels crisp.

>>4227 You must be a fan of the CRT then

I want to modify some of my old CRT tvs into rull RGB. Such as the European SCART. I have seen some where people modified the input to the electrode gun, and others where people modified the OSD to act as an RGB input since those use true RGB. I found schematics for some of my TVs in the manuals (imagine finding schematics for a modern LCD). Also one of my TVs use a chip that I coincidentally found in an old electronics book from my Mom's time in tech school. The book was from 1968. That is how commonly used and old that chip is and mind you this TV is likely from the 90's. But I have the full spec sheets on this chip which will make modifying easier.

>>3980 Yes I do. We didn't have feature creeping to the point that no ratio fits your current monitors. That, and those old CRT's would never break even after decades of use, and you could drop one and it'd still work. Their only downside is wattage use. They even made high resolution for computer use. It's sad that no one makes them, but they last so long, with time being money and all, it's not a good business venture. That and politicians like to spout the green earth stuff. Money and politics go hand in hand. I have no doubt if I were to start a CRT production line myself some rich guy would buy me off rather than let me be a competitor, the excuse would be "the environment suffers due to over use of wattage". This is not the real reason though. They last too long.

>>4437 >wattage use In fact a lot of CRTs use very little energy. Depends on a lot of factors. I have one that draws around half an amp at +12v, which is 6 Watts. I was a bit shocked. It's a little 5" monochrome, though. Depending on your backlight setup and such, flat panels can sometimes eat more power. There's a lot of variables as I said, such as color and resolution and anode voltage and how efficient the circuitry is that converts the signal and drives the deflection coils—but tracing a subtle beam of electrons onto a phosphor screen through a vacuum is fairly low-power.

>>3980 CRTs are cool, but I prefer my higher definition screens which are larger, have better viewing angles and have more colors than CRTs, but I can still see the appeal for them in a lot of ways.

Yes, the good old days :) 0 imput lag, what a beautiful things. I remember that john karmak programmed Doom on a 1080p crt monitor :) Nowadays i use one of my old crt monitors to watch old anime shows an for programming... Via an hdmi to vga converter

>>4457 Very few flat panel technologies have a better viewing angle; crts don't change color or fade from any angle. They made fairly high def ones but not really compared to current high end pc resolutions, that's fair. As for color resolution--that really depends. The display itself has rgb pixels just like anything else. Depending on the driving circuitry and input, you can easily get trillions of colors or whatever. I mean it's analog. But most consumer models probably don't support that without modding. ViewSonic did pretty good with vga over bnc though, both in terms of resolution and bit depth. But there are definitely drawbacks and inconveniences compared to new flat panels. I wouldn't expect somebody who doesn't have unconventional tastes to be using a glass titty in the year 2020. But I definitely have an irrational love for them. Found a nice 27" Trinitron on the side of the road the other day. Needs degaussing and maybe an rgb mod, but it's promising. Currently running my n64 and Dreamcast emus on it.

God I sure do OP

>>4460 > Found a nice 27" Trinitron on the side of the road the other day. god I wish I were you

hot, bulky, and give me a fuking headache to look at for some reason (many LCDs do this too). that said some CRT monitors were gorgeous. Some, but not all. Most had awful screens.

Only thing I miss about CRT are colors and refresh rate. Some Quake 2 zaelots play only on CRTs because fastest possible visual response.

>>3982 Very nice post anon. You put the comfyness I feel into words I never could. I have a few and use one semi-daily, but it's too big for my desk so I have to pic related.

>>4491 The gods of thermionic emission will smile upon you as well one day my friend. Just keep detouring through crummy apartment complexes and looking by the dumpsters.

>>4227 Fuzzy text is usually just a resolution mismatch; I've never seen clearer text than on a monochrome terminal properly calibrated. E-ink perhaps, but that's not emissive after all. Feels more like reading a page. >>5441 Thanks! Like your setup too! How long have you had that thing?

>>5443 Hadn't finished reading the thread when I posted that. This stuff is my jam, you're so knowledgeable about tubes! Now I want a vector display. The monitor is a Dell UltraScan 1600HS. It was my first monitor from 2008-2013 when I got a LCD, because I was 14 and the Dell felt archaic. But thankfully I never threw it out, it was a terminal at my Dad's work for reading aircraft part diagrams. I am concerned it might be dying because its much more red than blue, as if w10 night light or f.lux were on (but they aren't). I can't seem to calibrate it properly but I don't have a color sensor for a serious go.

>>5446 I can usually calibrate by eye by putting it side-by-side with a known monitor with great color, like the ones I have at work. There's some sensors lying around but usually I don't mess with them much. That one sounds like it's pretty far off... Hopefully it's not the cathodes but there's lots of things to try. There will be a lot more tuning pots inside the case but be careful in there, especially around the mains capacitors in the power supply (actually far more dangerous than the voltage in the tube, 'cause those can supply a lot of current at voltages that still go through skin) and the anode cap/flyback transformer. Look up what the tuning pots inside do before you start turning them blindly. Some of them do weird stuff like horizontal scan rate or deflection coil potential and can really muck things up if you're not following some kind of plan. But around the CRT stem on the board connected to its little noval socket or whatnot, there's usually a few trimpots for the three electron guns for the colors and they have a lot more range than the pots on the back do. I'd also check for a lot of dust gathered up around all the wires and components inside by static electricity. You can look up how to properly discharge the thing and then go around cleaning up dust. After many years, it adds up to a surprising amount of parasitic current at those voltages and can throw everything off. The static charge means everything in the case draws it like a magnet. Wear a respirator for this, it's like cleaning off a billion years of cigarette smoke and soot. Also would check around for swollen caps and such. Some people are nuts about re-capping old electronics, but I tend to be more skeptical unless of course there's a big bulging leaky one that's obviously shot. If it is cathodes, then that's kind of a tube lifetime issue and pretty hard to fix. There used to be a bit of a coin-toss operation where you'd hook up a much higher voltage source to the filament and give it a very short (like microsecond) jolt, which would either somehow knock off some of the oxidation that dims that electron gun (and thus color) or it would blow the filament to pieces and the tube would be done. It was always a gamble. A safer way is to just tune down the other cathodes to match it, then get used to using it at a slightly lower brightness... not ideal, but after all they're old machines. Here's some basic troubleshooting: https://www.repairfaq.org/REPAIR/F_monfaq9.html And the gizmo that attempts to vaporize cathode poisons and restore brightness to the different electron guns: https://blog.timowens.io/crt-rejuvination/ Got one lying around somewhere, but I tend to try not to use it.

>>5448 Wow, thats a lot of advice, thank you! I'm pretty hesitant to open it up, I won't pretend I have any idea what I'm doing, but I wouldn't be surprised if its very dusty inside. When I get enough courage I'll definitely look into that. With bias at R80,G100,B100 and gain at R80,G100,B100 its closer to the LCD but still off. Here's a picture of lainchan to show what I mean. I must admit I actually like the "wrong" colours of the CRT better, its much easier on the eyes. But if its broken and getting worse I'd like to fix it.

>>5454 Agh, I'm sorry to double post but this is hard. With every bias and gain value at 100 the *colours* are more accurate, but the blacks and whites are tinged red even worse. Either way, I assume this means the blue gun is going.