I am finally going to build my own projector, which I am very excited about! This is my idea so far:

-S15 Lens Kit
-15" LCD monitor (still looking for a good deal)
-500W Halogen light
-Pro Reflector

The idea behind this is that the halogen light is $10 which includes the ballast and everything and trust me when I say that they produce a very intense light. The main problem will be heat, which I will of course handle through plenty of cooling, but for the price, that leaves me with a big budget for cooling and bulbs only cost about $7. If you can see any flaw in the lighting part of my plan, please chime in; mind you, I am on a tight budget.

The other problem that the projector will be about 25-30' away from the wall. The wall is plenty big as I will be hopefully doing a 16:9 90-100" screen! There is only one window in the room as well, which can easily be blacked out so there will be no problem with light pollution. Now, the problem that I face is quality of picture. From what I have seen, the 15" LCDs are limited to 1024x768px; is this good enough for what I am asking from it? Is the lens even good enough for that?

Suggestions? Thoughts?

You are going to need to re-think your screen size. The S15 lens kit has a focal length of 320mm. According to the Focal Calculator || (http://www.lumenlab.com/forums/index.php?showtopic=7912), this would give you a screen size of around 340" to 413" at a throw of 25-30 feet. Even with the Pro lens (500mm), your screen size would be too big... 213" to 259". You would NEED to move the projector closer.

I would also recommend against one of those 500w halogen lights. From what I understand they don't produce a very useable light source, and are very difficult to keep cool.

Well shoot....good thing I asked then! Also good thing I broke out the tape measure!!!

The room is in fact 15 feet long, and a little over 12 feet wide (maximum width of screen). Being an apartment, I can not hang the projector from the ceiling, meaning I pretty much have no choice but to have it in the very back at 15 feet, though I could possibly have it 13 feet away.

The thing is that I am on a very tight budget. I do want HD quality, but my limit is $300 to $400 being the absolute max including the price of the monitor. This is why I was looking at the Halogen light for a light source as it is so incredibly cheap. If it will produce a quality picture, that is all I am worried about as the room itself can be very dark.

No it will not produce a quality picture.

It will be dim and yellow.

A quick google for 'halogen lumens watt' indicates that most Halogen lamps seem to be rated to produce 18-20 lumens/watt. Metal Halide lamps in the 400W range run anywhere from 75 to 100 lumens/watt.

This means, assuming the low end for metal halide, and the high end for halogen, that to equal a 400W metal halide lamp (30,000 lumens) you would need a 1500 watt halogen.

Your 500W halogen will produce about 1/3 of the light of a 400W metal halide.

The next problem becomes size. Since a halogen light is a filament lamp, there's a certain minimum length that the lamp must be. The shorter the fillament, the shorter the life expencancy of the lamp. Certainly a 500W halogen with a fillament of 30mm in length or less won't last long.

Yeah, they sure look bright when they're in a fixture, but run the numbers and you'll see that it's not the same.

Also, there's the matter of heat. A lamp dissipates the amount of energy that it's supplied. A 400W lamp dissipates a total of 400W, likewise with a 500W. Energy that is not dissipated as light is dissipated as heat.

At a 550nm wavelength (green) 680 lumens = 1 watt. So the 400W metal halide is dissipating 44.1W as light, and 355.9W as heat. The 500W halogen is dissipating 14.7W as light, and 485.3W as heat. That's a LOT more heat for the halogen for a lot less light...

Makes sense. I am starting to see that in order for this to work, I am probably going to need to double that cost to $600-800 for the projector quality I want. Sad to say, I guess this just isn't the right time in my life for a projector.

Don't get too down.
Try what i did and build with the low-end stuff but with plenty of room for growth. when you consider that 1024x768 encompasses 480p, which is regular dvd resolution, 1024x768 doesnt sound so bad. who has HD cable or a blu-ray player anyway? Leave a little extra width in your box and you're open to replace it with a 15.4" WUXGA in future. Leave some length in the box, or make the design easily modifiable to add length and you're ready to go to pro lenses if you want.

EDIT: I'd suggest that if you want to leave room to go pro (box length about 32"), just go ahead and start with a vertical design with a mirror at the top. Takes up less visual room in a smallish room. And always get some old cardboard and make a box the size your projector box will be and figure out if it will fit in your room without being an eyesore. I'm on my 3rd build (horizontal standard, vertical pro, now crazy folded small box hanging on wall) because the previous two just take up too much room in a small apartment. If I'd made a mock up i'd have realized how big these things can get, and started researching smaller panels and light path folding

I built a 720p projector for 545, this is with some extra supplies and 50 dollars worth of wood alone. I used an x2gen mw15a widescreen 1280x800 lcd which cost me 99 dollars. It is doable for under 500 in my opinion especially since this cost factors everything from wire to drawer sliders to a 12v power supply for my fans. On second thought, I had this stuff at my house and would have saved about 50 bucks. Just letting you know

If your room is really dark try using CFL's. I got decent results, and they are cheap.

Actually I'm about to decommision the 15" 1024x768 panel from my current setup. It's from an lcd tv, so it has all the standard american tv inputs, including component (RGB), vga, tv tuner, etc. No DVI. It takes HD signals and converts them. It's a good panel and it's always treated me well. I bought it, stripped it (no ffc issues), and removed the anti-glare. It's yours for $50 + shipping if you want it.

Otherwise just keep searching ebay for broken LCD TVs that have symptoms of a "good picture for a second but it flickers and goes away" or "you can see the picture but only if you shine a flashlight on it", anything that tells you it's a backlight issue.

Remember that the numbers I gave just show that the 500W halogen won't be as bright as a metal halide, so that basically lets you know that there's a place to improve later. The OHP will be more than enough to get a picture on the wall.

The thing about a DIY projector is that it can be improved over time.

anyway to tweek the setup for mor elight and less heat? just nosy

You means without getting a more efficient light source? No.

To make a lamp create light, it takes power. A given lamp type can only create so much light with a given amount of power.

Power in must equal power out. Power that is not dissipated as light is dissipated as heat. Actually, since we're only actually using a portion of that light, and only a portion of what we're using makes it out of the projector, it's really only a very small amount of power that does not get dissipated as heat anyway.

Of the energy dissipated as light, most of it gets absorbed inside the projector, where it's converted to ... Yep. You guessed it. Heat.

Of that which gets to the LCD, only about 4-9% goes through to the projection lens. Guess what happens to the rest.... Yup. Heat.

Keep in mind man, Most of the guys arround here have built many projectors. They really are Light Junkies. I am using Halogen as the first light source, because I dont want to dump a ton of cash into something I have not proven i can build. I am using the 500W Halogen bulbs till i see the results.

-TheTrustedOne

The point that I was making, TheTrustedOne, (This will go for you too) is that you can certainly use the halogen light source. If, however, you find that it's too hot, and not bright enough, not to be discouraged, but try switching to a MH light source. You'll get (As I worked out above) 3 times the lumens from a 400W MH than you will get froma 500W halogen.