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.
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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.
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*** 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.
http://www.diyaudio.com/forums/forumdisplay/f-20.html
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.