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Homebrewed LCD Projectors
pseudofrog writes: "Seems the new thing to do may be to build your own LCD projector. For a couple hundred bucks, some guys are making projectors similar to the professional ones that cost thousands. And it looks pretty simple, too."
I guess they should also build a server to go with that LCD projector, just for such an occasion.
I got a dozen bulbs (4000 lumens) for my setup for about $75.
Interesting. Now is this confined to hobbyists because the LCD companies are too slow-moving to have thought of it first? Or is the whole idea fundamentally flawed?
What I'd really want to see in the article is: Joe Blow built his own LCD projector for $350, and the image quality is better than what a good projection-screen television delivers.
Instead, there are lots of plans from hobbyists making their own, but no clear word about whether even the best of these designs produces an acceptable image.
One key thing: most of these designs call for a miniature 800x600 LCD monitor. Once projected onto a wall, how does that compare to the dots per inch of a regular projection TV? I bet it doesn't compare favorably at all.
The big question I came away with after reading this is: why aren't the big LCD companies developing this kind of product? Maybe it's an idea that, even with big-budget R&D, won't produce an acceptably good image.
I'm generally "Interesting," "Insightful," and even "Funny" here. What the hell happens to me at parties?
I bought a panel projector from a junk dealer for 10$. This is an older model, 3M 6150, so it's TFT 640x480 18 bit color.
Then I bought a smashed laptop screen for 5$ to get the backlight out.
Put the two together and I got a 15$ LCD monitor, this is fine for messing around with older gear like the Commodore 64, or a PC in 800x600, which the LCD panel can scale.
I'm pretty happy.
CAUTION: Raw LCD panels are very sensitive to static discharge! Use a wrist strap.
Here I thought the headline was "Homebrewed LSD Projections"... having to do with homemade LSD visions.
WWJD.... for a Klondike bar?
See this page cached@google :)
http://meshier.com/mirrors/www.audiovisualizers.co m/madlab/lcd_proj.htm
Just think, you could have the Windows "Clouds" wallpaper all over your room! Imagine that! Gee, if that were my wallpaper, I know I'd feel like I was actually in the clouds.
Really? If I had the Windows "Clouds" wallpaper all over my room, I'd feel like I was in Hell!
Moderation Totals: Flamebait=1, Troll=1, Total=2.
I hereby place the above post in the public domain.
Sounds like these guys are not aftercooling the bulbs. Most projectors I am familiar with allow one to shut it off, and if it remains plugged in, will keep its fan on until whatever internal thermal parameters for prevention of heatsoaking are satisfied.
Allowing the bulb to heat soak is just as bad as running it without cooling.
David
You can get 800X600 lcd projectors on ebay for less than $500.00
and these dont need a computer, just plug in composite video.. (I can hear it now the videophiles that have their 2048p projectors that use fiberoptic digital video and HDTV ready HD-DVD players will whine that it's grainey,low light because it's lower than 95,000 lumens and doesnt have glass lenses made by Plossol in germany... Go to hell videophiles..)
The dayton hamfest is coming up very soon, you can get a (GASP) old technology video-tube projection tv for probably less than $300.00 that works fine. (granted, it's a coffee table, but hey...)
the golden rule is that you scroung for a used one first, then look for cheap new, and THEN create it by hand.
Do not look at laser with remaining good eye.
diyaudio has a 100+ page discussion of this. Most people are using an overhead projector with their standard lightsources, or mercury vapor or metal halide bulbs. The OHP's fresnel lenses get around the problem of having an LCD panel and lens with different sizes and not wasting a lot of the light(but they're kinda big). Pretty good results have been obtained. However, there are some caveats, the contrast ratio of lcd panels from desktop monitors are pretty poor(under 300:1), decent commercial projectors have contrast ratios > 1000:1. Although I haven't built one yet, I think this can lead to washed out images. Also, nobody has found a supplier for the nice 1-2 inch LCD's used in commercial projectors
My main interest is playing movies on the wall of my living room.
This project looks nice if I can find someone to do it for me that is.
I have a few concerns though.
1) Aren't dvd players using Macrovision to forbid a signal to be output on anything else than a TV? The signal going to a video capture card seems to be a slight problem. Is this a reason why every one in the article is talking about LD and VCD, these two older media not suffering of the Macrovision "virus", er copy protection.
2) Is this really cheap? I mean a dedicated P800 in the living room (cpu speed to cope with descaler complex algorithm)+capture card+LCD panel, etc... I don't even mention the electric bill.
3) Noise level: Getting a Pentium noisy as an air carrier next to a TV and adding the noise of the fan(s) for cooling down the bulb(s), does that meant that I will need to listen to the movie with a pair a noise cancelling headphones?
4) Space: I imagine that the distance from the projector to the screen needs to be consequent. I can't find data regarding the minimum size of a room to use the projector.
I still like the idea though.
PPA, the girl next door.
-- I feel better now. Thanks for asking.
That's one thing that is cool about projectors, they don't devaluate very rapidly (check on ebay for anything 1-2 yrs old) compared to high-end TV. Plus it's not a pain in the ass to move around, plus you can have the size of screen that you want when you have 800+ lumens and good screen. (well obviously the more lumens the better if you're to do 15' diagonal :) )
:).
When I see people buying HDTV TVs at C$5000+ I don't understand why they aren't looking a medium range projector with HDTV support. Okay you don't buy anything under XGA resolution because with all the resampling it'll screw up the quality big time, but still, at 5K you have a nice tv, but at 5K you have a BIG refurb projector that can do both progressive playback of your dvd, give you an image that has easily 4 time the area covered, and best of all, you can play quake at wall size!.
In my case I've been trying to grab a cheap DLP XGA projector for a while, I don't want a 60 inch tv that will be a pain to move around, I want a 90 inch "tv" that I'll be able to plug my computer on it and also have fun watching movies like in the theatre
The replacement lamps are very expensive, but then again, when you look at the "kit" they sell you for 400$, it's basically a specific lamp with specific properties (metal halide, etc etc) at a specific voltage, plus a little crappy plastic holder... there's no optics (you read "lamp module" you'd think it has some collimating lenses or something) and you can buy these same lamps from a third party at 1/5th of the price, and you just have to mount it back on the plastic thing that was attaching the old lamp. If you have to break it, so what, nothing a high-temperature epoxy can't fix.
Anyways, nice to see articles like that, but LCD sucks, DLP is the way to go for video projectors, too bad parts are still expensive, anyone here knows a 3rd party supplier that won't only sell developper kits at 3K$?
--- Metamoderating abusive downgraders since my 300th post.
How about setting up this configuration, not with an LCD screen, but an old CRT monitor? Would the output be too dim? Could you crank the brightness, or would you then loose contrast?
:-)
A guy I know has done this. Yes, it works. Yes, it's too dim to make very much bigger than the CRT.
He used it to project the visual swirly displays things of mp3 players onto the ceiling (dark room) at a party. That's probably the best use for it. Cheap and easy though - all you need is a fresnal lense
Please note that the monitor suggested for the experiment (at this link), claims to have a resolution of "960(H) X RGB x 240 (V)=230400" which can be a bit misleading if you're not too tech-savy on these numbers.
Note that the horizontal resolution is NOT 960 pixels, but rather 320, since they're counting each RGB pixel as THREE pixels (very sneaky indeed).
So just be warned in case you thought this was the deal of the century.
COP: Tell me son, why exactly were you purchasing a metal halide lamp?
GEEK: Well sir, I am a hobbyist, see
COP: interrupts A hobbyist, huh?
GEEK: yes, I am making a homegrown
COP: interrupts homegrown, huh? Son, you have the right to remain silent...
GEEK: LCD PROJECTOR! SIR!!! A HOMEGROWN LCD PROJECTOR!!! YOU KNOW, one of those things that projects computer images on the wall.
COP: Images on the walls. Hmmm...you must be pretty good at your "hobby"
cat
Yeah, some of them too simple maybe. Like those plans that were scanned (about half way down the page)... If I'm reading those plans right, he has two 75-100 watt incandescent light bulbs in the box, but not behind the LCD projector - they are in front and to either side. I'm really confused how that is supposed to work. I've seen this sort of thing before from inexperienced people making those upside-down TV & Fresnel setups who think "If I have more light in the box, the image will be brighter" (yeah it will, but so will turning on the lights in the room - and it's obvious why you don't want that).
Anyone got a clue on this? It looks to me like those incandescent bulbs would destroy the image. At the very least the light coming from those bulbs would have to make two trips through each LCD, so the color density would be off. Not to mention the fact that those light bulbs being off to the side would not tend to radiate light that the LCD monitor would direct out of the box. Looks like someone put a lot of work into the design, but it's wrong.
Education is a better safeguard of liberty than a standing army.
Edward Everett (1794 - 1865)
Sure, you can use a fairly normal lamp and a fairly normal LCD panel to produce large images on a wall. Heck, you can do it even cheaper with a bunch of colored markers, some saran wrap, and a light bulb.
If you absolutely do not care about video quality, it's easy to get/build a projector on the cheap.
However, today's typical $3500 projector includes:
- A truly full-spectrum lamp. Retail price: $425. Wholesale price: $300. Manufacturing price: $250.
- Built-in line doubler. Most LCDs have 768 vertical pixels; some have 600, some have 1024. DVD's have 525 vertical lines. VHS has something like 240 lines. How do you get from 525 or 240 to 768 or 1024? Anyone who knows anything about computer grahpics will realize that the answer is not "double every 1/X line". Line doublers interpolate lines on the fly.
- Progressive scan support. Again, not a huge big deal, but the way I read the article, not supported.
- Component video in support. Like progressive scan, increasingly critical for decent video.
- Distortion correction, especially trapezoid. It's very rare to be able to project from the geometric center of the screen. Most of us have to live with projecting from the ceiling or floor, and use optical or digital means to correct the image for that.
Sure, you can build a "projector" for $400. Heck, you can probably build one for $100 (see earlier lightbulb, saran wrap, and markers note). But if it were really that easy to produce a home theater quality projector for $1000, don't you think any of the mass producers would have done it? For less than the cost of a one-off? (Anyone who responds that all 8 major projector manufacturers are colluding in price fixing should be laughed at).
Cheers
-b
There is some reasons for the high bulb cost. As noted in other comments, heat is a killer to LCD's. ;-)
The high lumen projectors have 3 things special about the bulbs. 1 is point light source. Light from a point can be focused with the mirror to get most of the light to the LCD's instead of scattering. (A mag light can be focuesd to a bright narrow beam. a flourescent tube can not focus tightly and is not useful for projectors). Porjector lamps are usualy manufactured as a prefocused assembly so it is user installable without a difficult alignment procedure.
2 is a cold mirror. The light from the bulb has to hit a cold mirror reflector to get to the LCD's removing the IR component. This allows a higher power bulb to be used without killing the LCD's. The light from the arc does not directly go to the LCD. The end of the bulb with a terminal faces the LCD's shielding them from the IR output of the bulb. Cold mirrors are not inexpensive. Try buying one.
3 is it is a discharge lamp. This produces more visable light over an incandecent lamp of the same power. Discharge lamps are usualy rated for 2000 hours instead of the typical 8-24 hours for a 3400 degree incandecent. They also have better daylight color tempeture (5600 degree typical) for better color so the pictures can provide a true rendition of the blue screen of death.
The truth shall set you free!
I'll try to list them.
You need a metal halide light bulb and ballast. Metal halide light bulbs are many many times more efficient at turning electricity into light, and thus produce far less heat. They also provide a 'whiter' light than a standard bulb. These are about $200 from hydroponics shops, and range in power from about 200-1000watts.
You need a 'cold filter' to block out the UV rays the light produces. Without this, the ultraviolet rays will actually start killing pixels. This happened to my projector. These little peices of glass alone cost around $200. But without one, you will cook an LCD very quickly, especially with higher powered lights.
By the time you get a decent lense, so you can actually get a decently sized and focussed image, you are starting to get into the sort of money that a decent 2nd hand projector goes for, without all the pitfalls.