hello all,

i'm new, a little info about myself, i'm a software engineerer who's a big diy guy when it comes to car/home audio, auto machanics, i also build houses with my old man...i'm 100% new when it comes to projectors though.

i want to build a super cheap projector just for testing purposes before i jump in and try a nice 1080p one...basically i want to get my feet wet...

question: i have a older e-machines 17inch 4:3 lcd monitor that serves no purpose right now and i want to use it...since it's a little big, i have the feeling most of you guys won't recommend me using the cheaper S15 materials. correct?

i'm thinking this:

cheapo emachines 17 lcd = free

cheap 400w ebay eballast w/mugol + light= $130 (will have to switch the 4K for a 5K)

310-360 variable focal lens. = $36

Lamp kit from M LCD = $40

550mm + 330mm fresnels = $25 + 25 = $50

fans/module/switches/lexan = $50

Total of $300ish

does this have the potential to be an ok budget set up? or is it ALL out of whacked?


thanks a bunch guys...and sorry in advance for the newbish questions...

My suggestion would be to keep an eye on ebay for broken or as-is 15" LCD TVs. Make sure to read the descirption of how it's broken to verify that it's a backlight problem (it might flicker on then die, and the seller can see a dark image). Obviously, we don't need a working backlight, so you can recycle someone's cheap LCD TV. Get an LCD TV because they have all the inputs for computer, tv, dvd, game systems, etc. I say 15" because that's the largest size the standard kit can accomodate. In fact, the fresnels are only about 20mm larger than a 15" 4:3 panel.

Oh, and you had the lenses wrong.

Get a 220mm fres for the collimator (collimator fres. takes the angled light rays from the lamp, and bends them parallel through the LCD). This is the shortest focal length you can get before you see a lot of vignetting, and the shorter the focal length, the more light you catch. 220mm is the sweet spot that the diy community has found through years of experimentation.

Get a 330mm fres for the collector (collector fres. takes the parallel rays that came to it through the lcd, and bends them in to meet at the focal point, at the triplet). This needs to match (roughly) the FL of the triplet, otherwise the triplet will need to be too far or too close to the fresnel, and the light won't be converged enough to fit through the triplet.

The varifocal triplet is an interesting choice. I bought one a while back from a member who has since been kicked, and he claimed it would work with a 15" lcd and a 400w bulb, but it was much to small, and light hit the box around the lens. If you're getting one, make sure it's diameter is about the same as the lumenlab standard lens. Any smaller, you'll lose light, get dark corners and a very dim middle.

Hey thanks chaos…

I will look for a lcd tv then…

I’ve looked on ebay and those “problem” lcd tv’s that you speak of are few and far in between…they’re kind of rare…but even a non broken one is not that bad…about $120ish shipped or so…one of the guys on here did link to a sams club westinghouse 15 inch tv that's 185ish total with tax...that doesn't look too bad...

Thanks for your explanations of the Fresnel’s…what i'm reading though is that i need to use the larger pro fresnels and lens kits with a 15.4 WS or larger...correct? so i ever wanted to do that set up, i should probably go with those lens/fresnels right away? can i substitute the s15 triplet for the pro triplet and use it temporarly until later?

So you’re saying the variable focal triplet is suppose to be variable as far as you can move the triplet back and fourth, but the diameter of the triplet is too small to collect all the light…correct?

Thanks