DIY Video Projector

[Bitch]

frankbatzen:

There's no standard in the fresnel lens sizes in OHPs. I've myself have had three different OHP:s all having different sized fresnels.

And now when I got to fresnels, you people might or might not(probably not) remember me whining about my fresnel in my diy-setup not taking the heat was put on it. Well my current OHP fresnel gets many times hotter and it takes it just fine. So either the fresnels have differences in the amount of the heat they stand or the "yellowing" effect is because something else as I recall some one lectured about, UV? But from the OHP I stole my bulb to the diy-thing there was no UV-filter, some sort of glass thing but that was with the bulb in the DIY thing too.

I bought a DVD-encoder card but I don't have too much to comment on it. The decoding is somewhat better. What I really wanted was to get it working with SBlive 5.1 which I have but it doesn't as it outputs audio only with cables and I don't have SPDIF input in the card. The card is some piece of **** and I wanted Creative Encore card but the shopper didn't have it. Although I'm not sure if it is doable even with that card.

I'm done for now.

[frankbatzen]

Hi, thanks for the reply.
I am sure that in Germany all OHP-fresnels do have the same size due to crazy industry norms. Do you remember what size your fresnels were?
Btw, I am spending so much more time on the housing and cosmetic work than on the technical aspects. That really is the most time-consuming part, next to gathering information.

[Assailant]

Ok, I stumbled across this link just before. What it is, is a PCB that connects to those horrible flex ribbon cables associated with LCDs, and adapts it to a row of header pins. So basically if someone had a cheap display that they couldn’t use for their projector because they couldn’t relocate the controller board, then you’d buy one of these converters/adaptors, hook a length of say IDE cable (those hard drive cables) then solder it to the main controller PCB (which usually have large connection/testing pads, which are easily soldered to). They also have (apparently) extension cables for the flex cables also available. And their prices seem very reasonable (17.00 Euro), the only problem (for me) would be getting them here to Australia…

I stole this from their site, it shows what i'm talking about


Hope that helps someone, I know it certainly helped me.
Shane.

[Bitch]

I was wondering if it's possible in the 15" Viewsonic monitor (or any other) to keep the original "back wall" in it, just make a hole to it, size of the LCD itself and maybe put some sort of glass in it or such, this way the thing would be enclosured and safe to move around and stuff. ?

frank: I'll have to say that I don't know the sizes of my fresnels.

[Myren]

your probably could cut out a hole the back wall. removing the cold cathode backlighting might be a bit tricky, but wouldnt be a problem since ultimately your voiding your warranty anyways if your cutting holes in the metal. should work great.

myren

[contrapasta]

I have been reading an avsforums user's critique of our project, and according to him, one of the projects biggest hinderances is that light is passed through the LCD at different angles (ie. the outer part of the LCD light path angles in, where as the inner is dead on) and of course LCD's are very sensitive to viewing angles. Not sure how true all of this is, but it did serve to confuse me, when I thought I had this already figured out. I attached a little .bmp file of what I think should be going on in an ideal projector.

Basiclly I don't think the fensel lens be in the way of the lights path AFTER it has stuck the LCD. Somehow I think the fensel will have a poor image quality. Let me know what you think. I guess I'm confused on how OHP work, if it doesn't serve light straight up to and focus light straight from the LCD panel, I got a feeling with a 15in or 17in I will be heading for trouble.

But if LCD's have advanced far enough that there veiwing angle is wide enough, I guess its a mute point...

[lokost]

Contrapasta

Hmm! I am just wondering why we have not seen class action lawsuits against the major projectior companies, by all former and current owners of LCD projection panels, because the technology of passing raw light through LCD sucks?

[jjasniew]

Got my unit and played with it extensively last night. The VB50, that is.

I'm fairly dissapointed and wouldnt overwhelmingly reccommend it.

It has one problem which is ridiculous, IMHO. They must have used 4 bits for all the controls, such as "tint" and "contrast", because the only setting that's reasonable is dead center. One bump up; it's too much green, one bump down, too much red. So effectively, you cant adjust these, because the @$^^$ steps are not fine enough. You have to make these adjustments on your display, because they are pretty much useless doing it through the remote control access on the VB50.

The other problem is that it does not work well with my Nview panel. On the CRT, colors look great, match exactly with the TV screen. On the panel, "blue" is this turquoise color and if anything's blue, from sky to someone's backpack - it's that color.
Also, apparently it cant make purple - or any shade of blue that's toward purple for that matter.

Now here's the kicker. The colors coming off my so-called "USB TV", which runs though my PC, are better. It can make purple. The colors on the projected panel image tend to correspond better with the colors on the TV screen. I do not understand; it's almost as if the VB50 knows what it's connected to and says "Oh, 256 colors for you!"

Of course, the colors playing a DVD through the PC are OK - I'm sure I would have noticed that it *sucks* if it did on that channel, and not gone off and posted up screenshots.

Because the colors on the CRT are correct, I'm still going to keep the unit. I'm not yet out of the game when it comes to experimenting with LCD panel monitor and CRT based creations.

Like some things, it's tough finding out after the fact what the nits are. I for sure suggest "try before you buy" with your particular setup, if possible.

IMHO,

[Bitch]

More about the 15" viewsonic, Myren.
Could you see the "pixel structure" of the LCD in your projected image badly? In my panel it's quite annoiyng with big image you can clearly see in between of every individual pixel a "space", actually now that I think about it I think there has been talk about this, "pixel spacing" in the lcd specs or such.? Anyway I have read that this "pixel-structure thing" (I don't know the correct word for it in english) is a problem in all LCD projectors. Anyway I'm just thinking since the Viewsonic's resolution is so much higher it shouldn't show up that bad?

[contrapasta]

Seems that a few of you have at least SOMETHING going on, could you please post pics please (of the picture)? In particular I was wondering about what others are also asking about, the screen door effect. How bad is it? Not knowing too much about it, I would imagine that this would be countered by line doubling (I never understood this, for a dvd this would mean 720X480 = 1480 X 960, what lcd is capable of 1480 lines???)

I have a uneasy ( and uninformed..) feeling that in our 'large' lcd displays, there is a significant amount of gap(to us) between the pixels that don't exist on on smaller (used by projectors) lcds of equal resolutions. Don't have any facts on this, so don't flame, just fishing to see if anyone know anything about this ( last poster called this pixel spacing)

Btw, any other place besides edmund optics ($$$ ~$80???) that sells decent quality fensels of large size ( to fit a 15 in LCD panel ~12 by 10) that are heat resistent??

Also on a side note I just bought bought an adjustable focas crt projector lens (atlas), not sure if its usefull for the project or not, just thought that it might be. Anyone one else have it, using it already??

And I am kinda hoing that someone will kindly explain to me how the fensels work in our lcd projector systems... and what a optimal system would look like ....