Create my own DIY or buy a used one?

[athan00]

Hi,
I wonder before I continue on making my own DIY does it worth the money? I am going to spend around 300-400$ for it (ok for me are Euros). In the e-bay I can find used 640x480 LCD projectors for around the same money. So does it worth? Will I get a better result creating my own?

Athan

[pvtparts]

Those 640x480 projectors you tend to see on ebay at best usually have weak light-sources and DSTN screens which are *not* capable of moving images.

When you go the next step up to modern projectors, you get a higher resolution but you find that the bulbs cost up to $400 and only last 2000hrs.

In the case of a DIY projector, you can build it for the same sort of price but using MH/HQI bulbs you get simmilar light-output that lasts 12,000hrs and costs just $30-40 to replace.

The quality of a 15" DIY projector could be as-good as modern commercial units but it will obviously be significantly bigger.

The running costs of a DIY should be far-far lower tho.

[cbm5]

Even if the cost of a DIY projector was the SAME as a commercial projector, the bulb costs alone would be a good reason to do this. You should be able to use your projector as much as you want, without wincing at the number of hours or limping along with a really dim bulb.

I'm 2/3 done with my projector, I projected my first image through the LCD last night. The way I plan to use this projector, it will be on nearly all the time I'm home. It'll be a live data wall showing TV, weather radar, stock market performance, and incoming email. I'll surf the web from my couch with a wireless keyboard. I'll have Xbox parties. A commerical LCD bulb isn't going to last a year like this. I'd rather dump $40 every few years than $450 every year.

[athan00]

Well what I m thinking of is to get an Innovatek 7" screen wich is 800x480 physical resolution (2400x480).
-Will that be enough for DVD movies?
-Will I have a good picture quality?
-Up to what size sharp clear screen on the wall will I be able to get?
-If I'll get an LCD with less resolution, the picture quality will drop dramatically? I m always talking about watching DVDs and TV on PAL system.
I prefer 7" since the final result will be much smaller I guess!

[pvtparts]

As long as you get the 800x480 screen, you should be okay for PAL. Be aware tho that there is also an Innovatek screen with a roughly 460x230 resolution which would be a bit iffy for projection.

PAL is 720x576 (or thereabouts) natively so you're not far off with the screen and it should look okay for movies etc.

The general concensus here seems to be, the more pixels, light and contrast ratio you throw at the problem, the better the chance of a good result.

I haven't found any details of the innovatek screen's contrast ratio but aiming for 200:1 or better is a good bet.

As for your maximum screen size, that depends on several factors.

1) You light source - brighter and 'hotter colour' provides better projection at larger sizes.

2) Your optics; you need a lense system that allows you to create a given size of image for a given distance from the screen.

3) How close you sit to the screen - Screen-door effect or 'SDE' is the visible seperation of the pixes; most apparent when sat close or projecting to a large size.

And to answer whether lower-resolution screens will reduce the projected image quality; yes they will and the bigger the projected image, the more apparent the loss of quality becomes.