Quick question about lcd panel..

[escalade182]

in the attachment:
http://www.diyaudio.com/forums/attac...amp=1069595816

is the lcd panel floating? (obviously not FLOATING) by that I mean...Is there any support in the gaps? if not. wouldnt that warp in the heat?

[Guy Grotke]

It has to be supported around the edges, and you use a little computer chip fan to blow some cool air between the OHP stage and the LCD.

But the LCD itself is glass, and will not "warp" until you get it up to the melting point of glass. The liquid crystal material is temperature-sensitive, so it would stop working at a much lower temp. Like maybe 120 degrees F.

[escalade182]

thanks. thats what I was wondering....

BTW, its a cpu fan, no a chip fan I bought a box of 12 CPU fans (bulk price) and they are very efficiant...I plan on running 6 fans...

should be picking up the OHP tomorrow and have an 8" LCD....So I'll need 2 frensels and a brighter bulb....I also plan on enclosing the OHP so light cannot escape and therefor, not having an illuminated celling.

[Guy Grotke]

Just different jargon from different disciplines. People who install microprocessors on motherboards and then sell the whole computer call them "CPU". I guess that sounds more impressive than "microprocessor".

Us folks who work in the digital design field call them all "chips", as in "We plan to tape out the next chip in February." Even if the "chip" has a couple of ARM 9 RISC processors and a DSP on it.

CPU is actually an archaic acronym from back in the days that the Central Processor Unit was in one box the size of a fridge, and all the I/O and mass storage units were in other boxes about the same size. They did not use tiny little fans, they used air conditioning rated by the ton, and it was very noisy! You would freeze your butt off if you had to work in the computer room for very long, so the keypunch machines were all in a "human-temperature" room.

Back on the subject: Is your LCD a Hami? An 8" LCD should look really good on an OHP. Don't forget to mask around the LCD so you get a nice black border.

[escalade182]

yes I know A LOT about computers. built many in my days... but cooling fans these days are commonly refered to as CPU fans...just like some expressions that make absolutly no sense(cant think of one off the top of my head.) lol.


whats a hami? lol. sorry I'm really a newb with lcd's. I'm familier with the basics though... I have two 8" screens.
1) polaroid portable DVD player...
2) tview flipdown

I am aware of the dissasembling process (so your not wondering why I would I would use these...the polaroid's casings cracked and the tview's casings too cheap looking to go in any of our cars)

Heres some pictures of the polaroid DVD player compared to our 52" HDTV RCA widescreen.

[escalade182]

obviously the flipdown isnt nearly as nice of a picture as the HDTV but I am going for a movie-theater-like enviroment and I think this should be perfect...But the portable DVD player's picture is phonominal, as you can tell in the last picture. even on basic cable, which is usualy terrible on smaller lcd's...the pictures amazing.

also. to answer another expected question... the 52" is in our family room, theres a 40" in the living room...but we have a 10' x 14' room with wasted computers stack on top of eachother...and 2 beautiful suade couches.... plan on having a nice theater room to relax in and get together with friends...

heres my layout...gonna rise the back a foot to give a movie theater feel and for better visibility.

[Guy Grotke]

Hami is the manufacturer of an 8" LCD TV that gets sold on eBay quite a bit. Some builders have used it instead of the more common 7" Lilliput monitor to build a small-format projector.

Does your DVD portable have a TV tuner or an S-Video input, so you can also watch TV, or will this be a DVD-only projector?

It is possible to make some optical keystone correction with a split fresnel projector design, but you would be much better off if you can put your projector perpendicular to the center of the screen. DIY LCD projectors (even with 8" LCDs) tend to be much bigger than commercial projectors. Not many people hang them from the ceiling.

[escalade182]

rca input. I plan on hooking it up to a tuner (i.e. a vcr...) or an external dvd player with a tuner...

but some news just occured that my brother can get his hands on a 1997 sony...something(model number: unknown)..commersial projector...for free. but the bulb is burnt out and the bulb cost $500 and isnt worth it so I'm going to try to trick the bulb sunsor and use a halogen spotlight/OHP bulb in its place.. If I cant trick it...then I will use the casing and lense as a starting point, keep the precut fresnels and use my own lcd and lightsource.

sound like a good plan?

[Guy Grotke]

Depends on the size of the Sony LCD(s)! Most commercial projectors us three seperate monochrome LCDs that are between 0.75" and 2" diagonal. The optics are all designed to split the light into three paths (red, green, & blue), send each path's light through a color filter, an LCD, and a pair of polarizers, before recombining the three beams.

A few are built like like our DIY projectors, using one larger color LCD. If the Sony is this type, and you can find a good enough LCD of the same size, then you could use the optics.

What you can't do, is to use a 5" LCD with optics designed for a 2" LCD: All you will see on the screen is a 2" portion of the LCD!

Hopefully, you can figure out how to fool the projector into thinking the lamp is running,and then retrofit it with a short arc MH lamp.

[escalade182]

thank you so much for your help. I'll find out on monday if the projectors in stone.