DIY Video Projector Part II

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#602
100:1 ratio is not bad. The highest sharp projection panel is 150:1 (QA-2500). Sony may have a screen with 3000:1 ratio but that could be counting each pixel and multplying that by 3. 3000:1 is a bit excessive I think. Although more is always better I sure don't want to pay the price for that sony. 🙂
 
#603
Hello ppl, just wondering if any of you could help me out with something.

I have an NView Spectra Pro. When using it with my ohp, there is a small (but quite irritating) white spot in the middle of the screen (about 2inches wide on a 2metre screen diag)

I think that this is an image of the filament projected, however it must have something to do with the polarizers on the lcd. When i turn the panel over, the spot disapears. I have a rear-projection setting on the panel so inversing the picture is not a problem.

My question is, will operating the panel like this damage it? Is there some kind of heat blocking substance at the back?

One other thing, took the panel apart today out of interest, seems the lcd module inside is manufactured by sharp 🙂 i do have a sharp panel after all 🙂)

If anyone has a Sharp QA-2500 for sale, please email me
 
#612
Aleksey,

If cost is an issue, why not go for a cheaper option: Spectra C and $30 OHP from ebay. If you looked around, or called Inventory Solutions direct, you could probably do the whole thing for $100. (Small rooms = small screen = brighter image from cheaper bulbs...)

At least, that way you stay in the game...

Bill.

P.S. You're doing good for 16.
 
#614
SUPER CHEAP DIY PROJECTOR

Wouldn't it be a lot easier (and cheaper) to simply take a used Slide projector, and insert a small LCD screen (such as one from a $100 hand-held tv) where the slide would normally sit. I know that some of the wiring for the lcd would be a little tricky. Anyways, just a thought.
- deven
 
#616
Just a Thought

I have been trying to find out the easiest and cheapiest way to build a home theater, and I thought that would be the best. So far a have:

Sony 5.1 Reciever - $20 off ebay, becuase of bad relays.

RCA Progressive Scan DVD Player - $25 off ebay, needed laser alignment.

My TV, Speakers, Subs, VCR, DishNet Receiver, ect.

only thing that is missing is a Projector. So I thought something like:

$20-40 for an old slide projector off ebay or somewhere.

$20-100 for an lcd screen w/a tv tuner.

I dont know, becuase I dont have a lot of experience with optics, it is relativly new to me. Anyway, I was wondering if anyone had any good reasons why it wouldn't work / wouldn't work well.

Thanks for the replys - deven
 
#617
This has been discussed at much length on the DIY small panel projector thread of this forum.

The main problem is resolution. TV panels commonly have 340x240 or similar resolutions. My LCD panel has 640 x 480 and I can still vivdly see pixels. Believe me, its not worth throwing your money on something unproven. Get yourself an OHP and panel, and you will be happy 🙂

cya,
 
#618
devenfore......did you lie when you posted saying you searched the forum before posting?

Look at the DIY small panel projector. or DIY projector 1. THe answer you seek lies within......i'll sum it up for you......you can strip a lcd tv to fit inside the slide projector....but don't go asking for a long life or high resolution as the heat will eventually kill the panel.
 
#619
perfect reflector ?

Hi jco9w,
You should put the fresnel 12" in front of light spot (point where you burned the cardboard), with this setup you get parallel rays come out from fresnel panel.
For condenser lens, you should find lens with short fl, shorter is better, because it can spread the light widely at short distance from fresnel.
Actually, if your reflector can produce small enough lightspot, you can put your fresnel directly 12" in front of the lightspot and you get the same result.

Hi Redevil,
So with my drawing#2 setup (fresnel-LCD-fresnel) the result was not good compared with your original setup?
Even with Woneill suggestion (fresnel direction and fresnel distance from LCD)?

thanks.
 
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