DIY Video Projector

[fender4]

Good crab, Vince! Let us know how the scavenging goes.

Muzzman,

Thanks for posting some screenshots! They look good...the colors are impressive. Could you give some details on your converter circuit? I am especially interested in the line doubling that it performs. Thanks.

-f4

[vdi_nenna]

Pictures coming out B/W, not color. The menu settings are color however. Input was coming up PAL, not the American standard NTSC. I'm going to try for the RGB inputs another time.
Wasn't a bad picture at all and it's best w/ lights out. I am happy w/ the picture.

[Grumpy_Git]

Scot_Lad:

Any information I've ever found on RGB for video (as opposed to computers) state that the sync is on the green, not sure how any of this works and that all voltages are around 0.7V pp. Then again just about every piece of literature I've seen on video standards is home made and almost identical.

If you really want info, have you tried looking at datasheets for video sources to find out the connector specs, this might give you more info. I'm sure my sony CRT has some info in the manual but it's about 400miles away. Oh well......

Hope thats some help.

Vince: You are a lucky man, keep working on them, I've been looking around Campus and asking a few people but no luck yet.

Nick.


Scot_lad:

You could also have a look at the appendices of :

http://www.tektronix.com/Measurement...ponent_Puzzle/

For more info.

[MuzzMan]

I used the RGB splitter cos I don't have a DVD player yet, and the VCR has only composite outputs. When I bought the PS1 screen, I actually thought all the different brands would use the same panel, and all would internally support composite inputs whether they had an external AV in connector or not. Alas, my one was RGB only. The PCB's that were inside the PS1 screen, but not part of the LCD panel/driver, ie boards designed by MadCatz, had all the chip numbers rubbed off, so I pretty much had to use them in my design. That was the only way I could work out what the inputs were - obviously PS1 AV connector is easy to find out, panel connections are harder...
Someone asked about the sync inputs, playstation one outputs RGB and composite at the same time, and the sync is taken from the composite input even though the picture comes from the RGB inputs. So my circuit takes the composite, splits it into RGB, and also passes the composite straight through to the panel.

f4-
The line doubling is not done by my RGB splitter circuit, or even the PCB's designed by MadCatz - its actually a function of the driver PCB attached to the panel. I think all of the smaller video specific panels do this. Basically each alternate field in a PAL or NTSC frame is displayed on the same 234 or 240 lines one after the other, and the brain merges them much the same as it does with interlacing on a standard CRT.
The best source of info on this and general video, RGB waveforms etc I have found is actually an older SHARP application note. I got it off the web, but I don't have the address now, it is called Interface & Interconnection for 4-inch & 6-inch TFT/LCDs, the doc is numbered SMT92026. Hopefully it is easy to find on the sharp site. I highly recommend getting this app note, it goes way beyond the SHARP lcds, and explains a lot of general video information in a really clear way.

[fender4]

Thanks for the Sharp application note tip, Muzzman. It answered most all of my questions concerning LCD's and signal processing. I posted a link to the pdf on my webpage, along with a few new updates.

Well, I received some optics bits and pieces today, and I also have ordered an LCD. I plan on using a fluorescent array of small compact twin bulbs that will hopefully outperform the LOA. The trick will be finding the right ballast. If that's not practical, I will just fall back on the LOA. I am still taking the "small" approach, but I'm not planning on burning my "rig" down . I will post and update my webpage with any major progress notes.

-f4

[jjasniew]

Hi all,

I'm hoping to participate here a little more, so here's some screen shots of my "cement half A to half B" projector project. Nicole Kidmann from "Moulan Rouge"...

http://pws.ihpc.net/joejas/projector/NK1.JPG

There's also NK2, NK3...NK6. This is a Nview Z350 at 1024X768 atop a Dukane 4003. Appx 56" diagonal. Still images taken with an Olympus D340 at 1024X768, handheld.

The setup has massive pixel smearing at 60hz refresh, better but not perfect at 75 hz, however watchable.

I'm still thinkin about a latest technology 15" LCD panel monitor with the backlight gutted out, atop the same dukane 4003. Anyone care to speculate on the possibility? Anyone actually done it?

Anyway, thought I'd share.

[Type-E]

wow, sweet, how much did u buy that projector panel for?

[Axeman]

Good work jjasniew!! I would be more than satisfied with that quality picture for regular viewing.

How bright is the picture? Can you watch it with ambient light, or is it barely visible? I wouldn't think that 4k lumens would be bright enough, but that doesn't look bad at all.

Also, what do you mean by pixel smearing? Is it that there is excessive blurring on high-motion scenes??

I hope to borrow an overhead projector from work tonight(~2500 lumens- just to evaluate image quality) to try it out with my KDS 15".

[The Xung]

@jjasniew: is that 56" of the diagonal 4:3 or just 56" of the image. Those are some nice pics though.

about lcd monitors. I am having considerable difficulty getting enough light through my 15' lcd monitor. I was trying to project a 6'-7' wide picture, but so much light is loss through the lcd and it's rather difficult to get light through such a wide screen. I was thinking this ~14000 lumen 175 Watt Metal halide would be enough but apparently not. I am gonna try to redirect more of the light in the right direction this weekend but this is harder than I thought.

[andrewjames1000]

Hi All

I think some people might be having trouble getting the maximum out of their light source because I have a great 5ft by 3ft image using a 5000 lumens OHP. This isn't even shining on a projector screen. Just saying dont rush out and buy an expensive light unless your sure everything else is sorted.

Also jjasniew was that a dodgy pixel i spotted on your screen shots? If so I found that putting bluetak (stuff for sticking up posters) on the wall where the pixel is showing covers this up pretty well. It is a good comprimise for dark and light movies.

Final point (I'v said this before) anyone looking and thinking I would like some kind of projector but this all looks hard work, expensive and a lot of trial and error:

Buy an overhead projector 4000 lumens minimum.
Buy an overhead active lcd projector panel 640x480 is fine.

Put these together and you have the ability to project whatever is on your pc onto a wall, great if you have a dvd drive.

This can be done for sub £100/$150 very easily. I did it for £45/$70. Will post some photos some time soon.

I know that not everyone wants this route as its not very portable etc but its a great start and you can always sell the stuff you've bought back on ebay.

Andy
p.s. Its harder getting the ohp lcd panels in Europe (i'm in UK) as there are not that many on ebay but the bargains come along every now and again, keep your eyes open.