Build your own projector
I just loved the article, and I'm willing to try it out. Does anyone know of an LCD monitor which would fit an old overhead projector with a resolution of about 1600*1200 that's relativly easy to take apart?
I know it will be a little expensive, but it'll be waaay cheaper than a real projector of similar resolution. About 10% of the full price actually.
I know it will be a little expensive, but it'll be waaay cheaper than a real projector of similar resolution. About 10% of the full price actually.
I did find this...
The 319441-001 Compaq Presario 2100 15.0" SXGA Laptop LCD Screen. You'll find more information here
If anyone knows anyone in the laptop service industry, we could find out how hard it would be to incorporate this screen into the design.
I've been looking at OH projectors in general, and the mostly have a desktop size of 10.5" x 10.5". This gives us just under 15" to play with.
If we were to use a larger projector we could then use larger screens, allowing resolutions that would cost over $10,000US normally.
If anyone knows of an Overhead Projector with a 17" projector surface, it would be a lot easier to find a nice high-rez monitor for it. I'm still looking for one.
However right now I'm still researching. I'm thinking of building my first test rig this weekend. I'll let this thread know how it goes.
<P ID="edit"><FONT SIZE=-1><EM>Edited by clamps on 11/14/04 10:18 PM.</EM></FONT></P>
The way I see it if we want the highest quality projector we need to find the best components to build it. Everything seems to boil down to only two major things that dictate this according to article: the LCD resolution and projector ANSI lumens.
3 ways to get a higher resolution;
1. Find a 15” LCD display that has higher resolutions that the easy to find SXGA (1280x1024) monitors.
2. Figure out a way to use a laptop monitor with a UXGA or WUXGA resolution. If you could build or buy a board that would allow you hook up a laptop display to a PC and to power it then this would likely be the best option.
3. Find an overhead projector that has a larger stage aperture than 10”x10” which would in turn accommodate a 17” monitor or larger.
A bright projector being the other key factor in building a quality projector we need to find the highest ANSI lumen-producing projector we can.
*** Please post if you know of anyway to do or find any of the above. ***
I also would like to know: does brightness (i.e. 250 cd/m2) or refresh rate (i.e. 75Hz) make any difference in the picture quality? It does if your using it as a monitor but as a projector I just don’t know.
I doubt brightness of the screen matters much since we're not using the original backlight. Without them the screen probably looks like the Gameboy Advanced (not SP). Then we're using the projector's light.
I have an old Pentium 1 133 laptop with an SVGA LCD display (and 1 dead pixal!) which I'd really like you use this way. So can someone please say how we can use laptop screens?
Edit: Eesponse time means more than refresh rate and is what causes games and movies to smudge on the screen. LCD displays only refresh individual pixals, instead of the whole screen like CRTs do, so the refresh rate no longer means if the screen will flicker.
<b>Behold, Mine anger and My fury shall be poured out upon this place upon man and upon beast and upon the trees of the field and upon the fruit of the land and it shall burn and shall not be quenched<P ID="edit"><FONT SIZE=-1><EM>Edited by ytoledano on 11/15/04 10:52 AM.</EM></FONT></P>
Yeah this projector is the worst idea ever. At first glance it looked impressive. What they didnt tell you was how long the bulbs would last. Bulb life is approx 40 hours for a $30 bulb. That costs 75 cents an hour to operate. Compare that to my projector which costs 5 cents an hour to operater. ($200 bulb 4000 hours). Do the math and dont make this projector. You will regret it.
There is a treasure trove of information on the video section at DIYAUDIO.COM. You will find the answers to nearly any question you can think of in regards to doing your own projector like the one in this article. All manner of overhead projectors, suitable displays, etc.
I've done it using an NVIEW Spectra and an Elmo OHP. My Nview was only 150:1 contrast. That was a bigger issue than the 640 x 480. Something that Tom didn't mention when talking about cost of light bulbs. The buld for my OHP is about $25 but they are only rated 50 hours. That's fifty cents an hour.
I broke down and purchased a Benq 6200 XGA DLP with 2000:1 contrast ratio for $1150 (after rebate). The bulbs last between 2000 - 3000 hours and cost $400 to replace. That's a maximum of twenty cents an hour. It's just like being in the theater. You can project from 40 to 330 inches. I run mostly in the eighty inch zone. S W E E T.
This idea is not a novelty, in the beginning this type of lcd displays where produced specifically for overhead projectors. I guess the timing for this homebrew projector is right since prices have lowered. Nice project.
Well the old laptop display salvaging is an old topic but its is kind of a dead end. Simple answer: you cannot use your old laptop display, long answer you theoreticaly could, but you will need the lcd driver board (wich is not standart, and every manufacturer uses his own protocols/timings)or you could buy a lcddriver kit wich includes the driver/converter/cables but it will cost you alot.
Many people have thought about creating big flat panels composed of old laptop displays but all the display drivers are propietary, so the hardware is there but cannot be used.
Best alternative is used flat panel display.
Quoting Tomi Engdahl:
"Reusing the display unit from laptop is very much
harder task. Many people have recently started to ask how to connect an LCD screen taken from an old laptop computer. Unfortunately there is no simple solution for this conversion because the differences of the interfaces used in normal VGA monitor connections and the interfaces used in laptop LCD screen. The LCD screen on laptops typically use a special digital inteface between the graphics controller and LCD screen itself. Those interfaces can be special high speed parallel or serial interaces and there are many flavour of them in use. The graphics cards inside the laptops have that special interface compatible with the display in this laptop, but normal PC grpahics cards do not have this kind of interfaces. So the conversion between normal PC graphics cards and LCD display taken from old laptop is not generally worth of a try. To do that you would first need to get to know what type of interface that LCD screen uses, then get the specifications of that interface, then specifications of that specific LCD and then design your own interface for that. Very complicated and not worth of the problem to try to do that at least if you plan to do this for saving some money (maybe a good educational experiment for a very good hardware/electronics expert, but not recommended for any average electronics homebuilder)."
Konstantin<P ID="edit"><FONT SIZE=-1><EM>Edited by konstantin on 11/15/04 12:15 PM.</EM></FONT></P>
i have had a problem finding an appropriate lcd screen. They were lucky to find a screen designed in the way theirs was. 2 of my lcd screens i dissassembled would not work. The pcb cards that attach to the screen along one vertical and horizontal side of the screen also must connect to each other. In this article the pcb connects by a generously long ribbon cable at the very corner of the pcbs. In 2 screens and 1 laptop i havelooked at the ribbon cable is much shorter and the pcbs do not connect at the very corner. The pcb actually fold behind the illumination panel and then connect to each other with just enough cable to spair. In this situation the pcb would be in the direct light path of the projector and block about 2 inches on along the horizontal and vertical sides. So it would seem that many new monitors will have this problem because of more eficient engineering designs. If anyone finds a lcd screen that is still produced that does not have this problem please let me know. I was unable to locate the one used in the article.
This seems like a very interesting project. IÂ´m going to hold back a bit and hope that some other people who have access to the equipment can post their experiences. So far IÂ´m glad I didnÂ´t run into buying a 15" panel as cryptz has just posted having problems. I havenÂ´t been able to find any of these overhead porjectors either (I live in Spain and the spanish ebay has nobody selling any) Does anyone know good places to search for these? The life of the lamps is also a turn down. Do these really only last 40h? Hope we can get more input on this project.
It's interesting that you say that the life of the lamp is a very real issue. I believe you. However, this site says they have a 400W lamp that lasts about 20,000 hours on average. It costs $35 US plus $5 shipping) and puts out about 30,000 lumens. I would think that would be a sufficient bulb, wouldn't you?
Please let us know what you think.
We all want to try this, I'm sure.
Certain bulbs will not work with certain overhead projectors with out replacing the ballast and then there is still the issue of size and heat being compatible with the overhead itself. In some instances there are ways around this. I post a link to a resource that should be able to detail this better for you.
When looking at what we have learned so far it seems reasonable to assume that there some issues such as bulb life and incompatible LCDs which could negate the benefits of building your own projector if one does not select the right components. The solution to these issues seems to be just a matter of having the right information and finding the right components and in order to make this project work.
Sure there are projectors that can be had for a few hundred dollars to a few thousand dollars but to my knowledge none of these come anywhere close to the quality of a good DIY projector. The DIY projector can be built with a resolution of at least 1280x1024 and an 11,000-lumen output. Compare that to the current projectors on the market and it would appear that the DIY projector is better then a very expensive retail equivalent. This is what makes this project worthwhile.
*** Here is some of what I have learned so far ***
If the bulb is a halogen bulb it will tend to last under 100 hours. If you want a long life bulb like the one in retail projectors then you need to find an overhead projector that takes metal hydride bulbs.
3M makes two very powerful overhead projectors; the 9800, which has a 6000 lumen output and the 9850, which has the worlds highest output of 11,000 lumen. They can be had on ebay from time to time for between $250-$450. These represent the best out there and have triple lens (the more lenses the better, 3 being the highest).
I just found a forum that covers DIY projectors and has almost 41,000 posts! There is lots of talk on it about building you own overhead projector from parts. Buying a ballast and bulb and building the case for it. They also talk about how having 11.25x11.25 stage may still cut off parts of a picture on a 15” LCD. I did not think this was possible but I guess there are issues with the clips in some corners of the overhead. They also cover what are good LCDs to use. Link below.
Please check it out. There is a lot of detailed info from people who seem to have been doing this for years. I will learn what I can, sum it up, and post it here. It would be nice if others did the same so we can all compare what we find out. Also, as I find LCDs, overhead projectors, and bulbs that work or don’t work I will post what I have learned here along with their model numbers, please do the same with your own findings.
Projector does not equal economy compared to monitors economy.
Bulb life and cost are real factors.
And the sign says "You got to have a membership card to get inside" Huh
So I got me a pen and paper And I made up my own little sign</pre><p></font color=red>
As I noted earlier, and has been noted again, the HOLY GRAIL on info for this type project is diyaudio.com in the video section. They have almost every topic you can imagine from lenses, bulbs, panels, ohp's etc. IN GREAT DETAIL. It's where I started when I did my first Nview/OHP setup. I can tell you from experience that it's not nearly as easy as the Tom's article makes it out to be. You can read plenty of horror stories (and a few successes too) about how this can be done. Successful builders that used the 'from scratch' method (not what I did) are few and far between. If your budget can afford it buy an entry level DLP projector and be done with it. If not, prepare to spend a lot more time on this than is indicated by Tom's review.
It would be possible to make a fairly high resolution projection system (using a 20 inch LCD) with the right equipment. If copying how a normal overhead projector works, you would need :
1) A good overhead projector triplet lens with a wide field of view to be able to see all of the 20 inch LCD
2) A good 20 inch LCD (1600 x 1200 or better) that can be removed ala the article
3) A good quality fresnel lens that is big enough for a 20 inch LCD and matched to the focal length of the triplet
4) A nice bright white light source, with some sort of device to even out the light distribution across the image(mirrors / etc)
The triplet lenses on some overheads might work, although most are likely to only have enough usable field similar to the size of a transparency (about a 15 inch LCD). Probably have to go custom here for best results.
Plenty of 20 inch LCDs to choose from, main problem here is ease of disassembly and taking the risk
Good Fresnel lenses can be found that will fit a 20 inch LCD, but the focal lengths tend to be pretty large. You want to match the focal length with the triplet so that you catch the entire image and light into the triplet.
Light sources are fairly easy to do, cooling and evening out the light being the most difficult issues here. LED's might even work, but would likely have to be focused in order to get the total intensity required (and would cost an initial bunch of $$$). Some creativity here could reduce the thermal issues on the LCD, such as using infrared filters to either block or reflect any light outside of 400-700nm coming out of the light, thus reducing watts coming in on the LCD (but, once again, at the cost of $$$)
Should be able to do this with some effort (and a little $$$). It would be pretty cool to have a projector that has 1600 x 1200 or better for about $1500.00-2000.00 investment.
Maybe Tom's Hardware can do a follow up article if they read this?
I came across the same problem as cryptz. The damn ribbon is too short to connect the vertical and horizontal controlling pcb. If there was a way of getting a longer ribbon then it would work. I tried it with a Coretronic Corp lcd, never heard of them. So you want to avoid that if trying this project
Has anyone had experience using a reflective OHP?
I can get a cast off from work for free, but don't know if it'll work as well?
"Overhead projectors are of two types;
Transmissive This is where the bulb is positioned in the normal position underneath the glass surface with the light shining upwards through the foil. These units are rather bulky and best suited to use within one
Reflective This is where the bulb is contained in the head of the projector and the base consists of a thin reflective mirror. They are more compact and better suited to the mobile presenter."
Hey, I've recently purchased a good SXGA monitor with a dead backlight off of eBay:
Now the thing is, since this screen has a 17" display instead of 15.1", will I be able to mod the overhead to make the panel fit, or will the display come out weird since the screen is bigger than the glass? Or does anyone know of a place where I can find a 17" overhead projector?
Also, the monitor I ordered is an AOC LM700 LCD. Does anyone know anything about AOC, and if so, are they good for the job?
hey guys i just got a question. I have a 7" TFT widescreen LCD (Heres a link: http://www.bigbruin.com/reviews/lilliput/) and i was just wondering if this screen would work for this project??? thanks....
Well guys - I built many hundreds of these coomercially.
Dont waste your time - an LCD panel has about 5-6% transmission so your picure will need to be watched in almost darkness.
The contrast will be awfull because the light is collomated in an lcd projector but you will have scatter everywhere.
Another problem is that on an lcd panel the front polariser is diffused and really for projection we use non difused polarisers.
you will have a major heat problem as the LCD panel will fry without a laminar flow fan across hit. Because it only has 5% transmission it would be just like putting a piece of black card facing down on the OHP platform - feel how warm it is after 10 minutes.
Hope I have saved you some time and grief.