DIY Video Projector

[MuzzMan]

nice stuff jjasniew, picture quality looks very good. The res looks great at 1024x768.

fender4:
I am not sure the LOA or equiv is the way to go. Basically the only problem I have left to sort out in my system is the contrast ratio in dark indoor scenes. From what I have read about commercial projector design, designers are always trying to find a light source with a smaller arc so it is closer to a point source. The raytracing I have done backs this up. It is not enough to get lots of light through the panel, you also need to ensure that light travelling through any particular pixel on the LCD will only hit the projection screen at one spot. Any scattering, or light from different angles will wash out the darker scenes, no matter what brightness source you are using.
I am going to work on improving the optics on the source side of the panel on mine, and when I have the configuration of lens etc. right I will build a decent enclosure and ensure all internal surfaces are black to minimise reflections etc.

[vdi_nenna]

Hi guys,

I gave the projector I found last night one more shot, and I got color out of it. It was set to PAl, instead of NTSC.

I'm not going to go on and on about this newly found toy, but I am going to give out as much info about it as I can to give you an idea what's going on.

First, this couldn't be a more basic projector. It only goes up to 640x480 rez. Uses a 250w metal-halide bulb that costs $385 on sale. It is rare because this proj. is from '96. It has 2 fans, one for intake and one for exhaust. They are about 2.5-3" in dia.

640x480???? It is good for viewing DVD's. I watched an episode of the X-Files last night from my DVD collection. AMAZING! 5'x3' image, but has a zoom to increase and decrease the image.

If you can get 800x600, you are set!! I took pictures. I will post if they come out. Probably develope the roll this weekend.

Vince

[skilzygw]

Great pics. Muzzman nice pics too. I love that arcade cabinet and racing game chair! 2 projects ive always wanted to do. Not to mention an enclosure for flight sims.

I tried to go the my own projector route while i waited for the damn ebay shipper to send my projector. But its to hard to find a bright light source that wont melt my fresnels. I am just going to wait for the damn thing to be shipped. I actually got a pretty big image going but my fresnel melted so i couldnt take any pics.

I have a cheeseball website ready for my pics and ill definately post them the second i get the stupid OHP. I hope the guy isnt trying to shaft me.

Questions regarding screens. Can I use oaktage? Can i use white cardboard paper? Can I use poster board?

Thanks! I have an old 50" pull down screen but I dont want to use that its to small a picture. Thanks!

[ds21]

jjasniew,

Looks good to me!
See that's all I ask, it's been like pulling teeth getting someone to show a screen shot of one working I was begining to wonder. Thank for putting faith back in this project!

[skilzygw]

ds21 i was feeling the same until i was going to put my pics up. Then boom melt down and never got a chance. Its pretty funny when your on the other side how things can get screwed up so quick.

But in a week i should get my OHP and hopefully ill have pics up too.

cant wait.

[jjasniew]

I'll try to elaborate a bit on my setup -

The image is plenty bright in a darkened room, like in a theatre. It is visible with 'the kitchen light on' (i.e. some ambient), but I wouldnt try to read a book and watch this at the same time...

I projected it agains a flat white textured wall. Screens are a couple hundred $ more; I've learned beware of the 2.5 gain ones that will reduce viewing angle - they are bright, if you happen to be "centered". The other screens are 1.0 gain; flat white.

4000 lumens is the overhead output. I dont know what it is after the light goes through the panel - maybe 400? It's quite reduced.

As I said earlier, I got it for $100 via shopping the web, not from ebay where there's a lot of people competing.

The "dodgy pixel" is actually my camera! I bought a bigger memory card when I was in Hawaii and that one just showed up.
(I havent put the smaller memory card back in to see what happens with it)

I agree with Andy's advice (if you want to go the "cement half A to half B" route) Buy an overhead projector 4000 lumens minimum. Buy an overhead active lcd projector panel 640x480.

If you search and shop hard, you can do it. $50-$100 a pop.

Or, of course, you could try projecting through a 15" TFT LCD monitor, at ~$300. That's what I'd ultimately like to do, unless someone explicitly tells me its _NOT_ the way to go.

The 56" measure is on the diagonal of the DVD image in "theatre mode". The whole 1024X768 image was, like, 66" on the diag.

Xung - have you tried your 15" panel atop a 4-8K lumen overhead? I'm very interested if this approach works!

Axeman - do you have the KDS apart? Did it seperate gracefully, or was it scary? Hope you have some success with the 2.5K lumen overhead. On a sunny day at my work, with the blinds closed, one of those wouldnt even show on the screen through the Z350 panel.

The smearing is exactly that; the image blurs and pixelates on fast motion scenes. Looking on ebay, I've seen specs like "tr 15ms, tf 30ms" and also 50 ms. I imagine this is one of the more important paramaters to looks for in a LCD panel monitor...

I'm still chewing on purchasing an overhead with twice the lumens I have now. I wish I could answer the question; at what point does the image just wash-out, as you try to push more light through, in an attempt to get a brighter show? I really dont want to spend $150 and find 4-5K is tops, 6-8K is too much for the Z350 panel.

Or, maybe the super-bright overhead finds its use later, when I attempt to drop a 15" monitor panel onto it, inspired by the success of others here

[gabriel]

Does any of you know if it is possible to make a cable to connect an LCD panel directly to the DVI connector placed on these newer vga boards? I downloaded some pinout descriptions for the DVI connectors, but I don't know what to do next. Or it's not possible at all? I mean I wouldn't have to buy a separate driver board for the lcd panel if I could hook it into the dvi...
Any idea?
Will I still need some sort of signal processor/converter between the vga and lcd panel, no matter which cable I am using?

[Axeman]

jjasniew -

Got the KDS apart last night. It wasn't too horrible getting it apart, but the design of the board layout means that you have to extend a ribbon cable in order to keep the boards from covering part of the screen. I did try it on the ohp though, and I was _really_ surprised how bright it was! I could see my desktop on my wall with the lights on. Didn't get much of a chance to look at it, as the ribbon cable came off(I think), and the image disappeared. I'm going to spend tonight trying to get the screen working again. Wish me luck. I'll need it. I'm going to try and extend the ribbon cable and, if it works, build a wooden enclosure to keep things from flexing.

Pixel response time is pretty good on the KDS- I could watch the matrix and other action movies on it without seeing any serious blurring.

[Axeman]

I've got some pictures of the disassembled board which I'll put on a page when I get a chance.

Phil

[Bitch]

Hello people,

Vince: I would too like to find a functional projector from a trashcan Really nice finding.-)

Originally posted by The Xung
I was thinking this ~14000 lumen 175 Watt Metal halide would be enough but apparently not. [/B]

I would think either you're not applying the light correctly or your bulb isn't 14 000 ansi lumens. My OHP bulb was rated 49 000 lm. Lm meaning totally something else than ansi lumens. The projector puts out 11k lumens.

Anyway, my wall (if you could care less) is more brown than it is white. So.. I attached a piece of white paper to the wall and did some comparing and the difference in colors (and somewhat in brightness) was dramatic. So yesterday I ordered 3 meters wide projection screen with motor and got it today but it'll probably take some time before it's operational.

I would want to try the 15" LCD (for the contrast ratio and res) if it wouldn't be so expensive. And people seem to have had some bad luck with them so it's 100% chance I would destroy it. One thing too is that can the OHP suck the whole 15" ? I think Myren had some problems with it but for a while Myren hasn't been posting anything, I wonder what's that about...

Pics from the 15" LCD deassembly would definetly be useful.

Okay, I'm done.