[vroom]

I just found out second hand that someone I know built a CRT projector. Anyone heard of DIY CRT pjs before? Any links perhaps? I'm just curious.

[Mikau]

Well unless its the 150inch bigscreen scam, don't know. Crts just aren't bright enough for projectors. Crt commercial projectors exist I think, but I imaging they use use a very intense CRT tube, I don't know where you could get one of those anywhere else. Unless someone figured out a way to modify a crt tv to increase the brightness, but thats probably a lot more sophisticated then a simple lcd projector.

It would be nice if it worked though, you can get a really high resolution crt computer monitors for very little money.

[minoten]

I've heard people using crt monitors at full brightness with a few fresnels and lenses and getting a decent picture. The room will have to be just about pitch black to see the screen, and the image cannot be larger than 50" i would imagine...

CRT's are bulky anyways!

[DR_BEV]

not exactly DIY crt but i know on ebay there is a fellow located in B.C (Canada) that sells refurbished crt projectors starting around $400 us but the shipping is rather steep due to the size/weight of these projectors.

[vroom]

Well I hope I can get some more information soon. We'll see...

[sjetski71]

There's a whole community of DIY crt projector builders and they're supposedly getting good results.

They seem to favor some 13" trinitron-tube television but here's the link if you want more info: http://groups.msn.com/diyprojectiontv/

I doubt they're getting as good results as lcd based PJ's but it may be a worthwhile project if you already have the parts lying around.

[Mikau]

Well the problem with crts is it shoots out light in all directions, not just straight forward. However maybe its possible to harness this. Some type of fresnel that is bigger then the tv and gathers light from all sides. This sounds complicated and I don't know why you do it with a 13 inch picture tube tv, when you can get better brightness, higher resolution, and a bigger projection with an lcd projector.

[sjetski71]

DR_BEV, on Feb 26 2005, 08:07 PM, said:

not exactly DIY crt but i know on ebay there is a fellow located in B.C (Canada) that sells refurbished crt projectors starting around $400 us but the shipping is rather steep due to the size/weight of these projectors.

yes,

Plan on buying one from him hopefully by the end of the year. going to try to see what $600-$800 can get me.

can't wait

[vroom]

Meh, I just found out that it was the cheap $5 method. Carry on folks.

[sjetski71]

vroom, on Feb 27 2005, 03:47 AM, said:

Meh, I just found out that it was the cheap $5 method. Carry on folks.

Actually many are getting much better results than the $5 ebay fraud, but i think you're attitude is correct. An LL style PJ will get us 10X better results.

The diy crt might be a good project for those who already own the correct parts, but not worth sinking money into (imho)

[GregMM]

It does seem like a pretty interesting idea, I know on tv's that Ive worked on there were some adjustable components on the flyback (generates high voltage for electron gun) that when my frinds TV was broken and only showed a line was able to make the line extremly bright, the problem I see from doing this is, though im not complely sure, is that the screeen will burn in very quickly, and the flyback probly wont last as long, but if changed to a beefier flyback might work pretty good, ill probly experiment a little on this with an old monitor after my LCD projector is done, a 2048x1536 projector, for $250 seems really awsome, probly not going to happen though, but theres no harm in trying it out on an old crt that doesnt matter if it fries anyway

[scubasteve2365]

GregMM, on Feb 27 2005, 04:54 PM, said:

It does seem like a pretty interesting idea, I know on tv's that Ive worked on there were some adjustable components on the flyback (generates high voltage for electron gun) that when my frinds TV was broken and only showed a line was able to make the line extremly bright, the problem I see from doing this is, though im not complely sure, is that the screeen will burn in very quickly, and the flyback probly wont last as long, but if changed to a beefier flyback might work pretty good, ill probly experiment a little on this with an old monitor after my LCD projector is done, a 2048x1536 projector, for $250 seems really awsome, probly not going to happen though, but theres no harm in trying it out on an old crt that doesnt matter if it fries anyway

be-carefull with that flyback. Ive repaired some CRTs in which that flyback was arcing siliently (and unnoticably), none the less ive gotten very close to getting shocked by those. Most Ive worked on have been DELL CRT monitors (Sony trinitron is manufacturer), and they had 25,000-30,000 Volt Flybacks, They dont call them flybacks for nothing ... cause you will Fly back.

Ive researched the turn the tube into a projector, and those that have invested lots of time still dont get very good results at alll. I was apart of the above mentioned DIY MSN forum before I found lumenlab, even though I never built a CRT Flip your TV upside down projector, Its easy to see that they are inferior to the LL design.

The main problem is the brightness. You can compare the difference in brightness from the source. Look into your triplet, and see how bright the LCD is with the MH bulb behind it. Compare that to a 13" CRT TV, and you can easily deduce how bright your picture will be.

[mantis]

Would love to own a real CRT pj. Best picture available.

[Whorse]

I just got a sony VPH-1030Q1 CRT projector for free from my friend... it weighs about 75lbs. My projector is old and is basically just 3 extremely bright red blue and green 5.5" TV's with lenses in front of each one. The picture quality is pretty good, its exactly like having a 100 inch tube TV, wouldnt you know

If you're talking about good projectors, the Sony G90 is a CRT projector that has incredible resolution.. It weighs about 250lbs and costs around $15,000. Instead of three 5.5 inch TV's like I have, this one has three 9 inch 2500x2000 resolution CRT monitors... Ive never seen resolution that high anywhere.

[Hyper Smiley]

I use to do it back in 1991 with CRT brighteners from MCM electronics when I was a kid reversing the polarization on the yoke. The results were lackluster. I really wouldn't invest any money into playing around with it even if you could obtain a quality large aperture lens. Fresnels by themselves don't make quality projection optics.

[ioio]

DIY crt are not a scam, I started this with that kind of pj, but I hate having a tv hanging over me, there is a guy nicknamed prof that has done incredible research, even made a multilayer screen that has a aprox gain of 10!!!! that's awesome!

check their forum http://tv.groups.yah...IYProjectionTV/

btw that link diymsnprojectiontv is where that forum started. I think that we all can learn from their experimentation to get more brigthnes. err sorry for all the typos, still learning english.

check the ultra high gain screen post.

ioio.

[MENIK162]

CRT PJs? I wouldnt even waste my time onestly.. LCD are cheap if you search for them and the LL PJ is the closest to the DLP I've seen.. Live long LL

[Simtech]

We use Barco CRT projectors at work and they are so bright that they need liquid cooling in front of the phospher. Fluid and high voltage = fun. The tubes last about 10,000 hours before they cannot be adjusted within our specs and they have to replaced.

Here's a picture of a tube that cracked and leaked liquid into the yolk and took out the high voltage power supply.

 MVC_002S.JPG (14.43K)
Number of downloads: 326

I don't think standard CRTs have the brightness capability to give a decent image. Even if you were able to modify them to produce more brightness, i would be concerned about lifespan.