EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: BitBangBro on December 06, 2025, 06:42:13 am
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I'm toying with the Start Trek "parallel timelines" concept and recreate the products that never were, but could have been, if the development turned the alternative paths at specific timeline points.
One part of that would be recreating CRT color monitor.
Alternate use of that sub-project would also be to offer universal electronics that could use CRT from various existing (defective?) monitors.
But for that I need datasheets, which I can't seem to find.
I'd also like to know :
- Do various tube properties differ significantly from the electronics standpoint ? Basically the thing is a vacuum tube and thre most of everything is determined by geometry, right ? So, various tubes from various sources should be similar ebnought to be drivable by the same electronics, right ?
- As a part of the project, I'd like to have dynamic picture correction, which means amongst other things replacng magnet rings on the neck of the tube with settable electromagnets. Is there soem data how are those rings magnetized and where exaxctly do the they sit and what do they correct ?
- Are there gotchas wrt electornics ? Can high-speed R/G/B gun drivers for CRT be made with currently available tech etc?
[Ii]Amongst other things, I plan to use bidirectional scanning, just like on printers. Which means that horizontal drive isn't sawtooth but triangle. It looks totally doable, probvided I tweak video source accordingly. Am I missing something ? [/li]
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Amongst other things, I plan to use bidirectional scanning, just like on printers. Which means that horizontal drive isn't sawtooth but triangle. It looks totally doable, probvided I tweak video source accordingly. Am I missing something ?
Your monitor will be very sensitive to non-linear distortion and hysteresis of the X deflection. I expect that it will be a pain to minimize comb artefacts in the picture.
Besides the bidirectional scanning, are there other "product that never was" aspects you have in mind? Color CRTs were pretty highly developed back in the day, so I am curious what you want to add.
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Your monitor will be very sensitive to non-linear distortion and hysteresis of the X deflection. I expect that it will be a pain to minimize comb artefacts in the picture.
Most monitors have linearity compensation.
Here it will be just somewhat more refined, I suppose.
Besides the bidirectional scanning, are there other "product that never was" aspects you have in mind? Color CRTs were pretty highly developed back in the day, so I am curious what you want to add.
Picture quality on CRTs was mostly shitty. Artefacts were all over the place, especially in corners.
With static magnets, one could never set the image to pinpoint accuracy in all respects on all screen areas.
Bidirectional scanning should massively improve scannign frequency and multiscan (variable scan rate), especially at higher scanning frequencies.
Dynamic display parameter tweaking per area (say 8x8 areas) should drastically improve picture quality and do it across whole frequency spectrum.
Also, most monitors had shitty drivers taht couldn't really match maximal pixel frequency, because innefective static adjustment resulted in many artifacts anyway.
Evne if one wasn't interested in my project, I suspect they could use it to rejuvenate dead CRT monitors with universal electronics.
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Dynamic convergence was pretty common, later monitors had dynamic focus and dynamic landing correction also.
The one unexplored improvement was magnetic focus. It was abandoned in favor of electrostatic focus during WWII to save copper. But electrostatic focus has the inherent flaw that you can't have bright areas and dark areas both in perfect focus.
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No offense, but I sense a bit of "I don't know much about this, so it must be easy." ;)
Anyway, best of luck with your project!
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Dynamic convergence was pretty common, later monitors had dynamic focus and dynamic landing correction also.
The one unexplored improvement was magnetic focus. It was abandoned in favor of electrostatic focus during WWII to save copper. But electrostatic focus has the inherent flaw that you can't have bright areas and dark areas both in perfect focus.
That's not nearly enough. And even that was mostly not dynamic with an area MxN field with separate settings.
Stuff that was set up with those ring magnets was most critical. And that was static.
I know only of one monitor series that had such dynamic compensation, it was made by Sony (also rebranded for Silicon Graphics IIRC) and its price was stratospheric. And those settings were interrnal - monitor had to be opened for a field of trimpots to be set.
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Dynamic convergence was pretty common, later monitors had dynamic focus and dynamic landing correction also.
The one unexplored improvement was magnetic focus. It was abandoned in favor of electrostatic focus during WWII to save copper. But electrostatic focus has the inherent flaw that you can't have bright areas and dark areas both in perfect focus.
I doubt you could have used magnetic focus on a color CRT, but it was used on the very best CRT projectors. It is true that focus was the main limiting factor on resolution. Most high end CRTs could physically scan at higher resolutions than were really usable because things just got too blurry.
I wish the OP luck, but I doubt an individual could do better than Sony at driving a monitor CRT. Sony, and their competitors invested millions, and had whole teams of engineers plus decades of experience. The main improvement that could have been made was spending more time tweaking the various adjustments that affected convergence, focus, and geometry. Most CRTs could be made to look much better with an additional hour plus of alignment. I regularly did this to my own monitors, and TVs, and occasionally for customers. The difference could be quite dramatic.
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Cathode ray spot is round with uncertain edge.
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No offense, but I sense a bit of "I don't know much about this, so it must be easy." ;)
Anyway, best of luck with your project!
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRdElZYGRdm0tgrK_9vBWCyRKg4a5BQJH_7KQ&s)
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No offense, but I sense a bit of "I don't know much about this, so it must be easy." ;)
Anyway, best of luck with your project!
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRdElZYGRdm0tgrK_9vBWCyRKg4a5BQJH_7KQ&s)
Are you sure you want to go there ?
Clarkson is great example.
He made this possible, amongst many other things.
"Clarkson's The Farmer's Dog:
https://www.youtube.com/watch?v=w8OJZXA_CfQ (https://www.youtube.com/watch?v=w8OJZXA_CfQ)
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Dynamic convergence was pretty common, later monitors had dynamic focus and dynamic landing correction also.
The one unexplored improvement was magnetic focus. It was abandoned in favor of electrostatic focus during WWII to save copper. But electrostatic focus has the inherent flaw that you can't have bright areas and dark areas both in perfect focus.
I doubt you could have used magnetic focus on a color CRT, but it was used on the very best CRT projectors. It is true that focus was the main limiting factor on resolution. Most high end CRTs could physically scan at higher resolutions than were really usable because things just got too blurry.
I wish the OP luck, but I doubt an individual could do better than Sony at driving a monitor CRT. Sony, and their competitors invested millions, and had whole teams of engineers plus decades of experience. The main improvement that could have been made was spending more time tweaking the various adjustments that affected convergence, focus, and geometry. Most CRTs could be made to look much better with an additional hour plus of alignment. I regularly did this to my own monitors, and TVs, and occasionally for customers. The difference could be quite dramatic.
Broadcast monitors at my old job at the TV always had that extra time spent on them, & the results were, as you say, "dramatic".
The monitors which were the hardest to get right were those used with the old AVA-Graphics suites, which
always used their RGB inputs, so PAL artifacts didn't make some errors less obvious.
They were big monitors, too--from memory, Sony BVM2000s.
The AVA operators were really strict------they would draw "squiggles" in the extreme corners of the display to check for any convergence errors.
If the monitor didn't didn't shape up, sometimes we could adjust them in the suite, with the operator putting up more "squiggles", but if that didn't work, it was "back to the bench".
Broadcast Picture Monitors were expensive & had operational lives of around 20 years, so they were pretty spectacular technological achievements.