DIY Video Projector Part II

[woneill]

Hi Guys,

Good stuff! I was actually thinking here about using a laptop panel directly connected to a laptop - my primary DVD player IS my laptop.

It gives me progressive video at the 24fps of the original film, while automatically scaling up the video resolution to match the screen.

For many laptops, a second LCD panel can be bought fairly cheaply, and the idea of being able to wire my laptop into a secondary screen that was driven by a much brighter light source than the standard CCFL tube is interesting.

A standard LCD monitor is a more flexible, but possibly more expensive alternative.

The technical question is whether the issues of trying to remove the back of the monitor panel, performing micro-soldering to extend the ribbons, and then building a massive light enclosure to get even lighting across the back of the LCD, can all be avoided by "squirting" a high brightness light source down the normal light path that the panel's standard edge light would use...

In effect, it would bethe equivalent of turning up the brightness of a standard LCD monitor (or laptop panel) by a factor of 100 (guessing here) and using that light source with a fresnel and suitable objective to project an image.

Bill.

[biteon]

i like your idea with the aspect boards. getting rid of some of that extra uneeded light can help the projected picture look better to the eye, sharper apperance,& i think it looks like it changes the contrast to(i did some tests with some like that when i first started trying to get my tv to project a picture on the wall).also i dont no to much on this but im guessing it might help with blurry edge's on the projected picture.

i was trying to find out how to make a setup where i would have all the aspect boards attached in one unit,you just answered that so thanks.

[Marklar]

Originally posted by eebasist
Marklar, what type of lens did you use at the opening of the light source? Is that just sheet metal with a lens on it? Also can you explain how you decided where in the reflector to place the bulb? I dont quite understand what you said by putting your finger in and looking for flesh color.....I'm not copying your design...I plan on modifying it signifigantly, but need to understand yours better first

Yes I just robbed the lens that was in front of the light that was on the dukane 680. with the reflector I put my finger in the hole where the bulb goes and looked stright at the reflector and it reflects my finger on the sides of the reflector when my finger was at the focal point. My projecion lens is 327mm right now but Im going to get a 450mm so I can move my screen back.

[prjctr_builder]

Is having the 750 hour lifo on the 575W bulb out of dukane 680 the only disadvantage? cause i wanna try to use it. the reason is that i do not wanna spend any more money buying the ballast and other things.


aleksey

[woneill]

Aleksey,

The 575W MH bulb is actually quite nice for projection - it has a small spark gap (7mm - much smaller than the standard 400W bulbs) a high colour temp (5600K), and I have seen them for as little as $90 (ish).

It is a small bulb in comparison to the standard 400W modules, and can be mounted (with a little ingenuity) in a parabolic/elliptical reflector without too much difficulty - giving a VERY nicely profiled beam.

Osram now make them with 1000 hour life, but you pay much more for that.

Now the down-side: They are not compatible with the standard 400W ballasts; they require a high voltage igniter; and run very hot. It would appear that they run SO hot that the ballasts (usually electronic) and/or igniters fail prematurely. (I have encountered three dead ballasts in old projection equipment in the last couple of months...)

The ballasts/igniters are a pain to find replacements (or components) for, and those that can be found cost a fortune due to these bulbs being used in photo/film lighting equipment - such stuff costs a fortune...

Despite this, it is my bulb of choice when I can get suitable ballast components to drive it (cannibalised from DOA old projectors...)

If you have a system that uses such a bulb, and it is in good working order, then you are in luck! Treat it nicely and Enjoy!!!

Bill.

P.S. Forgot to mention the most important point: an output of 49000 Lumens...

[braxton]

I got a sharp qa-1650 off of ebay- purchased beginning of May.
I asked to have it shipped to my sister's place in the US so she could bring it when she came to visit (I live in canada and wanted to save on shipping-he quoted me $90 shipping to Canada-$20 to US). Because the guy didn't ship it until over 2 weeks after he said he would, it did not arrive at my sisters on time for her to bring it. Also, she didn't feel comfortable testing it other than to say it powered up ok. She came up to Canada again today so I could finally test it.
Unfortunately, the VGA input doesn't seem to work, and with the rca video in I only get black and white images from a DVD or VCR.
Im tried all settings from the panel and the remote (ie contrast tint color), but still only get black and white. Haven't tried s-video in yet-will buy a cable tomorrow.
Any suggestions as to what could be wrong?

The weird thing is that the startup screen appears in color and all colors are crisp. The menu is in blue and thats ok too. But screen only shows black and white???

Hope someone can help me. I'm not counting on the seller being very supportive- he never returned emails when I was trying to find out why my panel hadn't arrived when it was supposed to.
Thanks.

[cowanrg]

some of the sharps have "modes". maybe check the menus to see if its being TOLD to display only color.

just a thought.

[prjctr_builder]

i am afraid that my 600W ballast will give up on me and i will be left with a broken projector. i know that 575W MH bulb is buyable for $70, but if the ballast fails, i will be in deep touble.

also you know how in dukane quantum 680, the bulb is housed in between a reflector and a condenser lens, and the whole assembly is quite small. and the fact that they recommend changing the bulb after 750 hours, doesn't mean you have to.

so here we have. up and downs of 575W.

UPS:
small
is housed with reflector and condenser
49000 lumens
nice color

downs:
short life
expensive

it is kind of balanced.

also the 400W bulb gives off blue end of the spectrum, so it may display colors not as bright as they are supposed to be. and that thing is huge, i've seen it yesterday. if i put it in my projector, it will,be huge.

my main objective now is to decrease the size of the assembly, i wanna make mine about two times smaller than marklar's. no offence of course, but i think that we have spent a lot of time here and we have come to a STALL. i do not see a good alternative for a projection panel, so i will use it in my setup, but i will work towards making my design smaller. i will probably have a fold-away design for the objectives. also i am working out a design that will let me cut the focal length of the objectives i have right now with mirrors. it is a bit tricky, but if it works, it will decrease my projector's length by about, say 9", that's a lot.

also i am going to try to take the panel apart and detach the LCD screen form it. if i succeed, i will have a projector way smaller in a diagonal size than any of the ones made until today. DIY of course.

and now i have a question... do you think that i will break the panel if i try to take it apart? consider the fact that i am very handy and cautious.

because having to deal with a 10.4" screen is a lot easier than dealing with a 18" panel ( that's what i have)

and i am planning to get Shapr QA-1800 during the weekend. of course for a reasonable price only. that thing has nice contrast, pallette, and inputs. i hope it will serve me well, if i get it , wish me luck.


thanks...


aleksey

[Jason]

I assume that no news is good news and so the categories suggested by superZ are ok?

Screens
LCD Panels
Enclosures (OHPs, OHP mods, custom boxes)
Optics/Lenses
General

If this is ok for everyone I'll proceed...

[Gunawan W]

woneill,
as I mentioned before, there was no distortion on projected image, the image in perfect shape.
Distorsion came up when I looked directly in front of the fresnel panel, like using magnifiying glass.
The problem was, when I placed fresnel closed to the LCD panel (in my case = transparancy), it showed up moire effect. If I moved further away, the image became to big.
I don't know the benefit of this setup, maybe we can get
sharper image with less "lumens" light, maybe it will eliminate hotspot problem with big size LCD panel, if the result will make worsen image, then I will back to earlier setup.
Guys, who own 2 fresnel panel, can you make a test to confirm this setup? Please...

marklar,
you can use mirror to bend light 90 degrees, make sure using front surface mirror.
Actually I have similar plan. I will use hanging cabinet (cupboard?) behind my sofa.
The setup goes like this:
On top is Lamp housing facing downward, next is fresnel then LCD panel, before the beam hit the bottom of cabinet, I will place adjustable mirror to bend the beam 90 degrees to the cabinet door. The mirror also can use as keystone correction too.
Last, I will place the lens set (with zoom adjusment) at the cabinet door.
From the outside, you just see a hole with the lens set (around 3" diameter) at the cabinet door!

see you.