i am thinking of buying the kit to make my own pj, but in the meantime i am thinking of using an overhead projector, then attaching the lcd screen on to that. does any1 have any thoughts on my idea as the only prob i have seen would be brightness and the ohp's i have seen provide a theorectical lumens of 2100.

I not sure if 2100 is the limit but you might want to check out Tom's Hardware articles where they use a overhead projector claiming 3,500 ANSI lumens:

http://www.tomshardware.com/2004/11/13/sup...e_your_tv_for_/

http://www.tomshardware.com/2004/12/01/bui...a_projector_ii/

Tom's just quoted the rated lumens for the OHP, not the output with the panel on it. 3500 is complete bunk.

Yeah, my first set up was with a Dukane that was rated at 4000 lumens. Even when it wasn't projecting anything (no overhead sheet let alone LCD), it wasn't as bright as my LL projector starting up and watching movies was about 3 to 4 times brighter on the LL as well.

I guess if you won't be that far away from building a DIY pj, then don't bother with the overhead at all, unless you want to be really, REALLY grateful for your new set up.

I'm new at this too, so I don't claim to have all the answers. I have been using an OHP setup, and as soon as I get some of these springtime honey-do's out of the way, hopefully I can begin construction of a better projector. Brain is quite correct, you won't get the OHP's stated lumens at the screen (not even close), 5% if you are lucky. My OHP is a Buhl 108 using a 575W hmi lamp, so it's plenty bright, but produces an extreme amount of heat. If you place an lcd on an OHP, cooling of the lcd will be required to prevent damage to it. If light leaks don't wash out your image (not much of a problem with mine), the bright light around the OHP can be mighty distracting. I'm lucky my better half is amazed we can watch big screen movies at home. I wouldn't think too many women would tolerate an OHP and lcd on the coffee table. I went the OHP route to see for myself what is possible. Although results with my OHP have been very good, I believe I can do even better building a projector myself and tweaking it for optimum results.

Will be starting my ohp based pj and have a couple of solutions for heat and light.
Fitting an extra fan and replacing the existing fan to improve airflow should in theory aid in heat dissipation, 2 80mm fans should work, although this might increase noise level, also fitting 2 smaller fans either side of the LCD should help keep it cool.
Light loss is a bit more tricky but making a cowl running from the LCD up to the lens should help a bit, will know more when building and will keep all updated, as I said this will be a temp pj so I can work out the logistics.

thought i would post some of the pics from my ohp setup

the pics are not good quality and don't do it justice as it has to be seen to be belived but the best thing is that the girlfriend has approved it, so the next step will be to build a LL projector

http://ph.groups.yahoo.com/group/raven_275...s/view/501e?b=1

http://ph.groups.yahoo.com/group/raven_275...01e?b=2&m=s&o=0

http://ph.groups.yahoo.com/group/raven_275...01e?b=3&m=s&o=0