I'm trying to build an LCD projector on the cheap here. That means re-using a small, inexpensive LCD panel from a broken DVD player or a PSOne monitor or such. The broken DVD player is my resource of choice, find one that won't play DVDs or has no sound or something and pay little or nothing for it. DVD players can almost always take video in from an external source and display it on the screen. This gives you the screen and the input electronics, don't ignore the expense of getting RCA video to play on that old LCD computer monitor. I've actually got a couple old laptop screens laying around and a controler circuit to run them is going to cost $80, so I stick with the old DVD players for this first attempt. Besides, it makes a nice small projector.

Next cheap product is the lamp. Couple points here, first the human eye doesn't notice the color variations of different bulbs, forget about white balanced 6000 kelvin color perfection. When you are watching something from a halogen light it looks white to the eye, just like everything in your office under those flourescent bulbs look white. I've done a lot of looking and I've found the perfect bulb. A point light source 250 watt 120 volt halogen. The style is called JCD, exactly like the JC type but at household voltage levels. $5 at lightbulbsdirect.com.
The matching base is part number L80054 for $3, not listed in the online catalog.

You get about 20 lumens per watt with a halogen. That's 5,000 lumens. You can get 60 to 100 lumens per watt of metal halide, but the bulbs are $20 - $50 each and the ballast is from $60 to $150. If I can shell out $200 on lighting, I've paid for half of an eVo already (the eVo rocks, built around a $40 bulb instead of the typical $400 replacement bulbs, the whole eVo unit sells for $400 right now at lumenlabs.com).

What makes this design a little different is the lack of a collimator lens. Don't need to collimate the light if it's already collimated by the parabolic reflector. Don't need telescope quality here, just something to give a nice even field. I'm indending to use flexible mirrored aluminum, either by deforming it or by taking slices out of it radially. Of course you can avoid this if you prefer to use two fresnels, but you could also avoid this by going to the store and buying a nice LCD tv, but what fun would that be? Our $5 bulb is at the focal point 1" from the back of the reflector and there is a very tiny quarter inch reflector attached directly over the front of the bulb (if the bulb isn't hot enough to melt aluminum) to reflect uncollimated light back through the focus and into the parabolic mirror. The shape of the parabolic is interesting too -take a 9" deep dish parabolic and cut off the top, bottom, and sides to make a nice rectangle the size of your screen. I'll be making these available shortly as soon as I finish the parabolic mold.

Innovation doesn't stop there. Much discussion is given to controlling the noise of the fan and to controlling the leakage of light. The baffles take care of both these tasks. The fan is completly enclosed by the projector and mounted to rubber pads. Distracting fan noises are kept to an absolute minimum. Air flows in from the right, between the LCD panel and the glass heat barrier, over the hot bulb and reflector, and out the left. Extra light and fan noise are all contained within the projector.