DIY Video Projector

[Tim]

Hey jjasniew!
Thanks for the link to Inventory Solutions.
I just got off the phone with Bob Buchanan and he will strip the optics form the overheads for us.
He will sell the fresnel and overhead optics for $25.00 US. He also has a few hundred working 640x480 lcd projection panels he'll take $50.00 US.
Check this place out

Keep at all. Were doing it.

Tim

[Bitch]

Hmm.. I bought VGA Y-cable today. Totally useless, cuts out the colors and brightness to half so I can't recommend one. ****!

[Axeman]

<B> Scot_lad,</B>

What you might want to consider is a single B&W CRT with a colorwheel. If you manage to split the video signal into three composite(or s-video...) signals that are R,G, and B, then you can just alternate the signal whenever the motor turns that section of the wheel around. No more convergence issues. The question is- can you find a FLAT, and BRIGHT CRT with the appropriate inputs and good picture quality. If so, share the source!!

[jjasniew]

Tim,

That's great - hopefully we'll get some reports coming in on the performance of those $50 640X480 panels! (Bet none too many are thinkin about those 5" or 7" 'car' units for 5X that cost anymore)

Now, to know your overhead projectors, because like most things, some are better than others. I think the optics on a Dukane 4000/4003 are better than that of my Elmo HP-A305, for example. I onky know that because I've had both units...

I got a Plas-tex 8X4 sheet. They didnt have the 0.060, they had 0.090, which is heavier and harder to hang. Cost more too - $29

Hey Axeman, you going to bid on one of those VP140s? Bet you can get one < $200 -

[lokost]

VP140

Does anyone know how the VP140 does 16.7 million colors with 6-bits each of R,G &B? Is black a fourth color to consider? Looks like the maximum colors ought to be 262,144.

[ryans]

How exactly do they compare?

[Scot_lad]

Axeman, (and everyone else who is interested)

I have considered CRTs because nobody else was doing so and I was presented with the opportunity. I think it is good to diversify, even if I'm the only one doing it, because it gives the forum a wider base of research and experience.

I have been considering all of the implications of CRT that have ever been mentioned here. As for the curved surface of the CRT... You can buy flat CRTs in colour, and if you used three of these you would have a very decent bright picture. Unfortunately these are more expensive than my free B&W CRTs and have a much lower resolution. I have a way to overcome the curved screen thing, which I will post when I investigate it further.

The reason I'm using three CRTs is 1) because I have three Delta III lenses so waste not want not... and 2) Because it will be 3x as bright,

As for the brightness issue, I have ways of making the screen brighter. Bare in mind that I only ever want to use it in a darkened room, so there is no need to make it as bright as a commercial CRT projector. To increase brightness you need to have an understanding of how the whole CRT system works. Fortunately I have a degree in EEE, so I can figure this all out. If anyone else is interested they can ask me, but so far nobody seems to be interested. I will be here for a long time however so please yourselves. Basically, you can amplify the input to the CRT gun or you can interfere with the decoder chip. This depends very highly on what kind of CRT you use.

As for RGB, it is very easy to split the signal up, or use the RGB out from a PS2 like I am planning. To get the sync signal, you use an IC which takes the sync from the green pin of the RGB, then input it to the chips in the B&W CRTs.

Right I'm off to bed now.

Chris.

[Scot_lad]

oh xblocker, you make me chuckle! In 2008 I will surely present my CRT idea when there will doubtless be some new technology to project a 40ft wide image from a device the size of a toilet roll tube, for the cost of a crisp packet....

You're right of course about the colour wheel - it would require a much higher frequency than three separate CRTs and so is unsuitable.

Oh yes, they all laughed at Christopher Columbus when he said the world was round...

[xblocker]

Scot_lad,

sorry, but it was Nikolas Kopernikus, who discovered and proved that the earth was round.

xblocker

[fender4]

Thanks for the "Inventory Solutions" link! I'm definitely checking into the 640x480 panels. jjasniew, you are right about abandoning the "car unit" LCDs...this is what I have been looking for. I just hope they have some with NTSC inputs.

jjasniew, let us know how the plas-tex screen works out. I've read lots of good things, so hopefully it will work for you.

Keep up the good work, everybody!
f4