DIY Video Projection 101
Allright class. Everyone take your seats and let's begin.
Video projectors rock. You can project a huge image practically anywhere, and they've got a really big "cool" factor with them. Unfortunately, they also have a really big "cost" factor with them. Therefore, as DIY'ers, we say "Hey! I want to build one for less, and make it better anyway!" So that's what we've set out to do.
There are two main approaches to video projection that people have successfully done on this page. Keep in mind THERE IS NO HARD AND FAST WAY TO MAKE YOUR OWN PROJECTOR. Everyone finds different deals on parts, everyone has different technical abilities, everyone has different budgets, and everyone has a different requirement for picture quality and brightness. With four degrees of freedom like that, keep in mind that you will probably NOT find a step-by-step tutorial on how to make your own custom projector on this page. What you WILL find are great discussions with people giving their progress reports, their research findings, and great input so that you can design your own.
Allright. Let's get down to business, and discuss a couple ways that people build their own projectors.
Method #1: The OHP/Projection Panel Method
Remember before when I said you wouldn't find a step-by-step tutorial to guide you through building your own projector? Well I lied. The OHP method is by far the simplest, the easiest, and sometimes the cheapest method you can do to build your own digital video projector.
Step 1: Buy a projection panel. These are LCD panels that go on an overhead projector in order for the LCD to act as a transparency. Generally used in schools and by travelling businessmen, they are being phased out in favor of newer portable video projectors. This means they are being sold at college surplus auctions, by local schools, and some business auctions. Many people have found them at office surplus stores, and there's always a great selection on
https://www.ebay.com .
Step 2: Buy an overhead projector (OHP). These are the boxes with the glass and the big arm thing that come out the top and you can lay a transparency on it, and project the transparency up on the wall. Also used in schools and businesses. Shipping can be as much as $20-$50 for one of these from e-bay, so keep that in mind when bidding on them. If you can find one cheap locally, that's fantastic. You'll want as bright of an OHP as possible, so do your homework and find out how many watts each OHP outputs before you buy one.
Step 3: Hang up a bedsheet, slap the projection panel on the OHP, and watch your favorite DVD of choice. It's really just that simple. The only hard part is figuring out if it's a good projection panel or not. As long as it has good true color (try to get at least 600,000 colors... 32,000 colors or lower just isn't as quality of a picture), it will probably be okay. 640x480 resolution is the most common, but if you can find one that's higher resolution, it will definately improve your picture quality.
Well that's it. That's the simplest method to building your own digital video projector. Several people (including myself) have accomplished this method with less than $150 in parts... although that involves alot of shopping around.
Method #2: Designing your own custom projector
If the overhead projector/LCD Projection Panel Method isn't what your looking for, there's many other ways to make a custom projector. The most simple method is using a small LCD scren, a wooden box, a bright light source, and a projection lens(Most people use a surplus lens from a projection TV). This is how it works.
Step 1: Remove the Backlight from the LCD panel. This way only the clear LCD Panel is left. This must be done VERY carefully, if the ribbon cables connecting the LCD to the circuitry break you're pretty much out of luck. They are next to impossible to repair.
Step 2: Construct a wooden box. Most people make their boxes out of plywood. The box inside should be spraypainted black. A hole big enough for the lens must be cut in the front.
Step 3: Assemble everything. Put the lens in, mount the LCD screen behind the lens. Put your light source behind the LCD, don't put it too close so it doesn't overheat the LCD, but don't put it too far away, you want too lose as little light as possible! Most people use a light source from 300-500 watts. I've heard there are some worklights that work well and put off little heat, but there are many types, you just have to find what is right for your projector. You might want to consider adding fans if your bulb runs too hot for the LCD screen.
Step 4: If all goes well, this is where you plug your projector in and try it out. It will likely take some fooling around with.
This is by no means a comprehensive guide. There are thousands of other ways to build a custom projector. Many use advanced optics and fresnel lenses to achieve the best image quality. The other basic method of buliding a custom projector is to dismantlte a 15"-17" LCD screen and rip out the backlight, then plant it on a modified overhead projector. Some people have achieved stunning image quality with this, but be aware it is very difficult and much more expensive than the method mentioned above.
