I've had alot of experience with DIY projectors and spent around a year actively pursuing the dream of big screen at low price.
During the project I was active in the video forum of
http://www.diyaudio.com/
, where alot of good thoughts were emerging on the subject of custom projectors - not purely OHP+LCD panel type setups. The five vital factors required to build a decent projector were found to be:
- Good heat dissipation
- A long life, decent color temperature lighting setup
- A well designed reflector
- Decent optics, aligned according to the basic rules of projection (using such items as fresnel lenses, PCX lenses, doublets etc.)
- The highest res. transparent LCD you can afford.
My setup was a custom built upstanding unit, using an OHP Data panel (see-through LCD) and a rather large PCX lense which I am very proud of - it came out of an American tank targeting system and weighs a couple of kilos - it can throw the light from one blue LED about 20 meters!!. I used a 400W Metal Halide bulb with suitable ballast - very bright white light! and fashioned an ellipsoid reflector out of mirrored alu sheeting.
The results? See them at the following link which includes pictures from the very beginning of my tinkering:
The projected image was huge and bright, but the optics system required alot of tweaking. Heat was also a major problem and I melted a few fresnel lenses in the testing stages. Due to university starting up again, I copped out and bought an OHP for some instant gratification. Results of that system can also be seen at the above link.
There's lots of theory behind building a projector, but at the end of the day, you can build one easily if you do your research and can handle very basic geometry. There are many other types of custom build units, including ones using stripped down LCD monitors, fluorescent lighting, very small LCDs etc etc. DIYAudio is a great resource with lots of enthusiastic people posting their thoughts and results.
Slashdot Mirror
During the project I was active in the video forum of http://www.diyaudio.com/ , where alot of good thoughts were emerging on the subject of custom projectors - not purely OHP+LCD panel type setups. The five vital factors required to build a decent projector were found to be:
- Good heat dissipation
- A long life, decent color temperature lighting setup
- A well designed reflector
- Decent optics, aligned according to the basic rules of projection (using such items as fresnel lenses, PCX lenses, doublets etc.)
- The highest res. transparent LCD you can afford.
My setup was a custom built upstanding unit, using an OHP Data panel (see-through LCD) and a rather large PCX lense which I am very proud of - it came out of an American tank targeting system and weighs a couple of kilos - it can throw the light from one blue LED about 20 meters!!. I used a 400W Metal Halide bulb with suitable ballast - very bright white light! and fashioned an ellipsoid reflector out of mirrored alu sheeting.
The results? See them at the following link which includes pictures from the very beginning of my tinkering:
http://www.imagestation.com/album/?id=4291451499
The projected image was huge and bright, but the optics system required alot of tweaking. Heat was also a major problem and I melted a few fresnel lenses in the testing stages. Due to university starting up again, I copped out and bought an OHP for some instant gratification. Results of that system can also be seen at the above link.
There's lots of theory behind building a projector, but at the end of the day, you can build one easily if you do your research and can handle very basic geometry. There are many other types of custom build units, including ones using stripped down LCD monitors, fluorescent lighting, very small LCDs etc etc. DIYAudio is a great resource with lots of enthusiastic people posting their thoughts and results.