| SuperDave |
Fender...The bulb isnt really the problem...I really need to find a balast to put these small bulbs in...does anyone know where I can find a cheap/complete solution. Or at least a high output and small balast???
But that link does rock...they got lots of stuff....thanks. |
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| fender4 |
SuperD,
I probably didn't explain it well...I think the DYS bulb does not need a ballast. You can just bypass the ballast/power supply that your OHP has and apply 120v wall power to the bulb. This is what the schematic that I posted earlier showed. So, basically, this could be an all-in-one solution to get higher output for your OHP for cheap.
Hopefully I am understanding you correctly...let me know if I am not.
undream,
Yeah, I am getting the feeling lately that this has become a 'How to juice up your OHP' thread, but in an indirect sort of way, it is applicable. The OHP design has the minimum number of elements that are needed for projection with large panels, so any attempt to improve on their application could be useful. It's probably more boring than designing things from scratch (which I am STILL trying to do, but things are going slow these days...school :( ), but it's something.
Without a good reflector (look at the high precision of small projection lamps for an example) large enough to harness most of the light from the MV or MH bulbs, they will not be very useful for our purposes. It is possible, but it will take some work. I designed and built a fairly accurate, horizontal-plane elliptical reflector yesterday, and it wasn't as efficient as I thought it would be. If it was 360 degrees instead of a folded rectangle of metal, results would be much better. But I'm at a loss as to how to do this. Any ideas? Myren?
Anyways, good luck everyone! Hopefully, we will see some real innovation from the bright minds around here. :)
-f4 |
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| xblocker |
If you wanna built reflectors, why not try a vacuum reflector. A round vessel, attach a reflecting foil (mylar...) pump out the air from from it until a parabolic or elliptical shape is reached. There exist DIY Vacuum Torus screens, why not vacuum reflectors. Also I've read about this on an astronomic hobby site, they also need large reflectors, but more spherical ones.
a limititation of this approach can be the choice of material due to the heat.
xblocker |
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| Marklar |
4" LCDs
these look like a winner bout i donno what the resolution is :/ |
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| oftheend |
| Based on the wattage that LCD projectors use (the ones you buy), i believe that a projector that provides say 1200 lumens, is not using a 1200 lumen bulb. These things run at like 175 watts, so i think the acutal bulb produces higher lumens itself, but once the light goes through the lcd, the brightness fades, as is the problem with our setups. It would be nice to work up a calculation that would tell how many lumens of bulb light are equal to the lumens of the projected picture. This would allow us to chose a light source better. |
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| xblocker |
The brightness of projectors isn't measured in lumens of the bulb, it is defined as ANSI-lumens. Thats complete different ! A projected white image is divided into 9 square parts and the brightness of this parts is object of measure. The lumens of bulbs is a general value, which is irrelevant here and can only give rough estimations.
So many older single panel PJs often have MH-bulbs with 575Watts and tens of thousends overall lumens but only 200-300 ANSI lumens !
The rest is blown in the wind.
Hope this clears things up!
xblocker |
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| DPW666 |
| Hehehe I see that Marklar reads HardOcp;) |
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| MuzzMan |
I am still trying to design a lens system to use my 5" lcd in a rear projection scheme. The key parameters are:
* approx distance from lens to screen about 1 to 2m
* Screen size (image size) 1.7m diagonal
I have looked at a few surplus available PCX and DCX lenses, and done some simple calcs and raytracing, and think I need a complex lens system made up of two or more simple thin lenses. I understand that to design a multiple lens system, the image produced from the first lens becomes the object for the second lens. Using simple lens equations you can work out image heights, distances etc. from focal lengths. I wonder can you actually use a virtual image from the first lens (with a negative distance to image) as the object for the second lens?
Does anyone have any experience with designing multiple lens systems to achieve the short throw required? |
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| Marklar |
Yes I visit there daily :P i also found some stuff I thought was very nifty that I could put on the white sheet Im useing for a screen.
http://www.goosystems.com/
This sounds like some really cool ****. |
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| oftheend |
| Does anyone have or know where to find instructions on operating the control buttons on the 810 or 820? Every time I change the color settings they do not stick, I think i am probably missing some operational knowledge. |
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| Assailant |
there was a whole heap of PDF files on the proxima website of the instruction mauals for those particular panels. i'll have a look for them
edit: i can't find em. i really don't understand it. they are somewhere. i can't be that drunk |
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| oftheend |
Assailant:
Yeah, I am an idiot. Check the website first (duh!). Got the info, thanks...
I have tried many times to navigate that website. It it hard to find something specific. User friendly does not apply. |
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| Assailant |
| yes the site is poor at best. i'm pretty sure i found them by accident in the first place |
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| oftheend |
SuperDave:
Without the reflector, I got practically nothing... Thats why i was ready to totally dismiss the MV when I first got it. With the included reflector, i got a bit of a picture, but as you could see from my last pic, I have the bulb vertical, sot the included reflector was mounted on the back wall, and as such was pretty much useless. With the coffee can parabola, brightness increased significantly. Unlike the halogen i used, however, the light kind of fades in with the ambient light when the lens system is out of focus. With the halogen, even out of focus, there was a light spot on the wall. With the MV there are two focus spots, one in which the image is focused, and one in which the filament is focused, but at all other points the light just mixes with ambient light. I think it has to do with the different color temp. So, play with the lens distances. If i move the lens even 1/8", i can lose the pic totally. Last night i built another reflector, a 4 sided, tapered rectangle, kind of like the one built into the halogen worklight. Light leakage was considerably reduced, but even so, the picture was dimmer than with the parabola. The parabola is definatly the way to go. I connected an N64 at about 3 in the morning, and watced as the N64 symbol was about a 2 1/2 square. The picture is almost watchable now, the higher wattage lamp should finalize this deal. BTW, I found a pdf that says an MH can be plugged into an MV ballast, and vice versa, at the expense of some lumens and bulb life. |
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| MuzzMan |
just found a link that might be of interest:
http://www.uspl.com/uspl_pdf/CRTPAPER.PDF
It's about 5mb.
This white paper from US Precision (now owned by Corning) seems to have lots of general info and I think it also has some optical specs for the delta lenses. |
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| Timtimes |
[QUOTE]Originally posted by gtwolf99
[B]Marklar if you are interested in the 4", have a look at this one,
http://www.partsexpress.com/pe/psho...r=205-050&Did=7
good price for what you get...
Don't know about the second panel, but the first one has a contrast ratio of 30!! Somebody around here says that is way too low for these purposes. Also, the response times may be a huge problem.
GO MINIMALISTS. I'M ROOTING FOR YOU.
As an aside, I bid on an Ebay panel late last week. Got beaten at the buzzer (Whew! or Dam?) It went for something over $300. Can't remember the exact model but it was one of the 1.4 mill color models. |
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| Scot_lad |
Hello again,
I've got no ground breaking news to report. Apart from nobody wants to fix my CRT projector so I'm going to have a go myself. If I don't post anything for the next two months then send somebody round to my flat to poke me with a stick and make sure I've not electrocuted myself in the process...
Wee thought on your bulbs - if you want to avoid a hotspot in the centre of the image say, could you not mirror the end of the bulb? I've stuck a picture of an example - obviously this is a very low power light bulb but the point is, if you mirror the end of it, you're not going to get a bright hotspot in the centre of the picture are you?
Some notes on CRT progress...
I was thinking the other day, how easy it would be to go the LCD route instead. Actually I was thinking "Christ, this is complicated!" I think the CRT route could with time give a better quality picture than the LCD, but it's so much more complicated is it worth it?
Well, since all you guys are doing LCD then somebody's got to investigate CRT, and it's going to be me. I like the idea of having a big three-gun projector like they do in the pubs for big screen footie, instead of an OHP like they do at school. I can see why you all want to hide them away at the back of the room.
Anyway, I have made progress. I have figured out the inside of the TV, and can now compress or stretch the image as much as I like, right down to a tiny dot in the middle of the screen. I can also move the image around the screen and to a certain extent control the geometry of the image. This will prove invaluable for converging the three images at a later stage.
It has to be added that at the moment, controlling the horizontal picture size is a bit of a fire risk. But I just need a ceramic resistor and a heatsink and that'll be sorted out.
One comment on people trying to get a decent image with high ambient light levels...
WHY?! Surely you won't be using it in broad daylight? The whole point of having a large screen is surely to emulate the cinema, is it not? Why would you really need to watch films with the lights on? Or are you planning on doing presentations in your own home?
Can anyone in the UK recommend a cheap OHP to me? I can't find any on ebay. It is for a friend, and it doesn't have to be very high light output at all, as it's just going to be for projecting acetates.
Cheers, |
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| Scot_lad |
| OK here's the image... |
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| Marklar |
Well I was watching a movie and POP my OHP died and yes thats the sound it made :/ so I took the ******* thing apart.
OMG what a mess Id say thats the crapiest ballast I have ever seen wtf is up with all that **** in there!!
after taking EVERY THING apart I find the fuse deep inside that has some getto plastic cover on it so you have rip it off before you get to the fuse.
Id say thats a bad fuse would't you? Who in thier right mind would put a fuse in such a spot. |
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| jjasniew |
I got a cheapy OHP -it's even a Dukane, 2 new bulbs - if your friend will pay for shipping from US. joejas@ihpc.net
So are you going to replace the fuse, put it back together and see if it still works? |
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| Marklar |
| Yeah I hope nothing else is broken :/ |
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| Marklar |
I made it easy to change the fues now incase this happens again
BUT DAMN IT the fues keeps blowin something else is SCREWED!! |
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| jjasniew |
...that something has shorted out in your electronic ballast. I'd check the bridge rectifier for one of the 4 diodes shorted - maybe you get lucky and replace this and she runs OK again.
The next thing will be a power transistor, probably the one that does the switching, in order to boost voltage up to run the arc lamp. Without a schematic, I really cant say which specific component to check next.
Do you know any technical people who know how to repair computer power supplies nearby? They might be better able to fix this or help you out than I can, typing ideas of what to look for into here. |
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| Marklar |
| how do i check these diffetent componets I do have a real nice fluke mulit meter but I donno what a bridge rectifier is and donno how to check anything. |
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| jjasniew |
It's the square thing mounted to the heat sink (the silver finned thing) on the left in your picture.
If it's a good Fluke, you should be able to put it in resistance mode and press a button with a diode symbol, to put it into diode mode. The symbol looks like --->|----
There are 4 of these in the bridge. The bridge also has 4 posts. Two should have a + or - printed nearby, while the other two have ~ or AC.
A good bridge will show ~ 0.7 READING (slight variation like 0.58 is okay) with the red lead connected to either ~ (ac) and the black lead connected to +. Also for the red lead connected to - and the black lead connected to either ~ (ac). If the reading is 0.00, for any of these connections, then a diode is blown in the bridge, which would blow the fuse.
You can probably get a replacement at Radio Shack if this is the problem. |
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| jamie |
well i ve been trying different types of projection there all soso but i didi luck out this sunday ,a guy will be allmost giveing me a couple of projectors store bought! the up side is one works he said but goes off and on hmmmm? the other has something wrong with it but i dont care cause if the lcd and the lens work ill be fine thanks to this wonderfull forum who knows maby ill even get a good bulb:) well its friday and i feel like a kid waiting for christmas 48 hours:( JUST A HINT I THOUGHT PASS ON
CONFRENCE ROOMS UPGRADE PROJECTORS A LOT I KNOW WE are building our own in hear but why should the big guys have all the good parts! seeya all!!!!!!!! ps does
anyone have good pics of there work post it , id like to see a good screen shot of a big screen with something in front to compare size!!!!!!!!:D |
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| Marklar |
| Well if i did it right then I think its broken i dont have a diode button i just put it on ohms 200 and did what you said and I was getting readings from .0 - .5 so i guess it broken :/ |
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| Marklar |
| I have removed it and tested it and seems to be dead I guess so I contacted Warner Power the people who made the ballast and asked them where I could get the replacement part so hopefully it will be fixed soon and thanks for the help man I thought I was gonna be up **** creek without a paddle. |
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| tomithy83 |
hey everyone i was going through ebay looking for an lcd to use and using yahoo to research them i came up with the greenspun board a couple of times and i realized the knoledge lost there so i was thinking of compileing a list of good/bad lcds and i need you guys help if i could get everyone to email me with lcd's that you have tried and what you think of them i'll sort through them and put it all together in some type of presentable form and redistribute it.
email me if you want a copy when i'm done i'll also send a copy to all that contribute uless you let me know otherwise |
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| tomithy83 |
thanks didn't know about that but i'll still compile the list |
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| Xdreamer |
Hello...
hi there...i was wondering if anyone knows where i can get an lcd monitor to be stripped off the driver board? I have just purchased a 21" UXGA lcd monitor but i dare not do it myself...
I have been reading the board for quite some time now and i am in the pursuit of the ultimate Projector (Larger than Cinema scale)...ideally it would be a drive-in-theater close to my housing area...The spec would be something like this..
Resolution : UXGA / QXGA
Brightness : 1 million ansi lumens
Screen size : 2100m X 1200m
i will be updating my website soon...the cost of the project is estimated at US$8,000....
till then.....cya
:D :D :D |
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| Undream |
check this out. I went to Lowes and picked up a 12" by 18" piece of aluminum sheet metal. It wasnt very reflective, it had a brushed look to it. I was skeptical about what I might be able to do to it. plus, it was $13. suck. Anyways, I was at Walmart later in the day, and picked up some Mothers Aluminum/Mag metal polish in the automotive aisle. Its pretty good stuff. Well, 2 hours and a sore arm later, check this out. I only did 2/3 of it, so you could see the difference. first pic with flash, second without, third a reflection of me taking a pic right at it.
This could seriously be a real possibility. Its reflecting like 80% ++ of the light I shine at it (I shined a flashlight at it). just eyeballing it, but, it really does a nice job!
it is easlily bendable -- I can take it and make a U out of it with just my hands. My goal is to make this thing into an elliptical reflector.
Also, for those interested, I've started a website for my friends to track my progress. I've been keeping it very well updated. the address is:
http://www.dreamlash.com/DIY/ |
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| Assailant |
| ok, i stumbled across this link, and yeah they have 1.8 inch lcds (sadly with a res of 280 * 220). they would require some input circuitry, which wouldn't be too hard to build with some intermediate knowledge of electronics. i don't know, at $100 AUD (like $50 US) someone might like to get one and have a bit of a play. the only downside i can see is the res. |
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| Myren |
hey everyone. catching up again. sorry bout being so out of the loop, between working on the projector and school, i've had just over zero time for my computer.
reflector. the magic piece.
ellipsoidals are perfect. does everything we want:
i've paint sketched how an ellipsoidal reflector works. see attachment at bottom of post. top image shows how light at one focal point all bounces to the other focal point. now just imagine that the part that's red on the bottom photo gets cut away, drop a 250w metal halide at F1 and install the LCD.
i drew how the optics have to work too. in the bottom image, the light bounces off the reflector, goes through the lcd and collects at the lense. the lense needs to let the light fill the four corners of the screen, while focusing the surface of the lcd onto the surface of screen. exactly like moving the knob on your overhead to set focus. in effect, the ellipsoidal is just like a fresnel, except much higher quality on a number of different levels (better light uniformity/dispertion, sharper, no trougth lines).
grab a good lense design book available at your public library if you want to really do the optics properly. its well worth the effort spent. it makes all the different between "an image" (sometimes "barely an image") and a mighty fine image.
zoom optics are definately a fun route too, but a huge pain in the ***.
by the way, stuff is hot. so yeah, be careful. sheet of glass alone works wonders at blocking heat. if you wanted to be just that cool and use a 400w mh or 1000w mh for the image of perfection, make the reflector a cold mirror then put a hot mirror directly between the LCD and the light source. that should keep the important stuff (see: lcd) cool in the uber-setups, while letting the heat bleed off. some fannage should be sufficient in most reasonable cases though.
fender4: you mentioned some lense design work. what're you up to. right now i'm trying to optimize a cooke triplet for a nice sharp zoom setup.
bravo undream for beautiful explanation of why candlepower is so damned misleading.
thank you Gunawan. your <a href="http://www.gwidijanto.fcpages.com/reflector.htm">listed site</a> was the perfect thing. i had been thinking i'd have to use a circular ellipsoidal reflector, and that site showed me that a non-circular one will work too. its <b>perfect</b>. really cant thank you enough, its made my world.
oftheed: the most quoted figure i've heard is that the final picture is 8%-12% as bright as the light that gets put through the LCD and collected.
tired and whatnot. goodnight all. look forwards to being back on the board.
myren |
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| MuzzMan |
A while ago I posted a link to a white paper from US Precision, the makers of the Delta lenses. It's taken me a while to get through it, there is a lot of really good info in there.
Although it is centrally aimed at all aspects of CRT projection, there is a lot of info that is relevant to us here. I found formula and design notes on both front and rear projection, not to mention lens design pointers, and the reasoning behind the basic delta lens design itself.
However it has left me confused on one point: If I understand the document right, the smallest CRT raster diagonal used is 5", therefore any of the surplus CRT projection lenses available should be OK with a 5" LCD. However my Delta 77 lens is clearly not OK, with only the central approx 1" square of the LCD area in focus and the rest very blurred, and pin cushion distorted.
The document does describe liquid coupled lenses, but I don't think my Delta 77 is one of those, so I can only think of two possibilities:
1/ I am missing a bit :D Maybe Delta 77 is used with another lens normally.
2/ The lens has been designed to cope with a non flat CRT or something like that (doubtful in my mind)
Sorry for going on about a problem that may only be specific to my setup, but I thought with the number of people reading this forum now, someone's bound to be able to help! |
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| Jaro |
Hi undream
If you want the prefect reflector you might want to go down to your local engineering work shop and ask for a bit of .55 mm thick BA stainless steel sheet, should be cheap enough, would probably project 100% of the light and it is already polished for you.
Sorry I did'nt say this before, but have'nt read the forum for a while, could have saved you some elbow grease:(
Cheers for now
Jason |
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| Undream |
hmm. so your saying I did a lot of work for nothing, eh? :)
all the stainless steel sheetmetal I have seen around have been unbelievably dull. I figured, Aluminum is the stuff used for telescope mirrors and the whatnot, and is supposed to be better than the homemade chemistry experiment process that is silvering.
well, maybe I will go checkout what you say. My piece of aluminum is still far from perfect. Last I heard, many people were stuck on the reflector part of it - surprised nobody mentioned what you just told us before! |
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| gav |
great site undream!!
i'm still waiting 4 my panel.....3 weeks and counting :( |
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| jamie |
| i agree wonderfull site undream ,,, well guys i went to get some old projector parts from a guy yesterday hes got lenses old projectors reflectors i mean everything cause he rent lights , projectors and so on well he says i got this old projector that dont work for 800$ noway i say ,well ive got this 4000$ view sonic but if you push on the top it freaks out so i cant rent it ..hummm iwas scared to ask cause the one that didnt work at all was 800$ but i asked 400$ he says so i offered him 300$ he says yes.i took it home and this thing works perfect i mean perfect!!! was he looped i dont know? BUT HERES THE KICKER AND MABY THIS WILL HELP SOME OF YOU ,THIS PROJECTOR WORKS IN DAYLIGHT. DOORS, WINDOWS OPEN LIGHTS ON 600 LUMENS ALL 8000 LUMENS ITS ALL HYPE HE EXPLAINED TO ME PROJECTOR LUMENS ARE A LOT LIKE AMP WATTS,,, 4000 WATTS BUT AT WHAT FREQ? TRUE WATTS TRUE LUMENS? BOTTOM LINE IF ITS BRIGHT AND IT LOOKS GOOD EVEN IN HARSH LIGHTING AND ITS ONLY 600 LUMEN THEN SO WHAT IT LOOKS GOOD :) KEEP UP THE GOOD WORK UNLIKE A LOT OF PEPS THAT GET PROJECTORS AND FORGET ABLOUT BUILDING THERE OWN, I WONT ! IM STILL BUILDING MY OWN & NOW I HAVE SOMETHING TO COMPARE IT TO :) |
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| Undream |
| I don't doubt that the projector you got is fairly bright. However, you must realize that all commercial LCD projectors are rated in ANSI Lumens. That number has more to do with the end brightness of the image projected than it does with the light source. The light sources of the average LCD projector is probably in the thousands, if not tens of thousands of lumens for brighter projectors. |
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| jamie |
| this is basicly what i was meaning to say what you just said it matters what kind of lumen rating :) however just trying to clear up some stuff for the guys who may have been led to think they need 1000 to 8,000 lumens to get a good picture thats all |
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| Marklar |
Well I have that Dukane Quantum projector it is SUPER bright even in day light but when you put an lcd on it light output drops majorly like prolly less than 1/4 of the light passes through the lcd with no lcd this thing can make a whole room look brighter than daylight but the LCD does some major damage to the output. If you want one to work in bright light i suggest getting a nice projection screen that has the reflective beads in it they will more than double the brightness of the projected image.
http://www.goosystems.com/
I think I posted this site before but here it is again this stuff is real neat you can make a screen on about anything. |
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| Xdreamer |
hi guys,
So is it true that you can make a elliptical reflector like what gunawan mentioned? More like the ones you find in flood lights?
BTW i have a question...does using a relfector increase the light output? and secondly how much heat is cut using a cold mirror reflector and a hot mirror between the lcd and fresnel ?
and lastly...does anyone know where i can get the driver board to be stripped off my lcd monitor?
thanx..:) |
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| Xdreamer |
Hi marklar,
that goo system is pretty damn remarkable but damn expensive...i need it in large quantity...do you know of any paint that would do the job for less the money...(something like 1L that would do 1000 sq ft or more and cost like $2 per litre...?
thanx... |
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| dragonhalf |
I think this page has someething that may be a solution to the issue of LCD sucking so much light.
http://www.nasatech.com/Briefs/June01/NPO20824.html
However I havent researched it enough to see how doable it is.
I am only up to febuary in following the thread. |
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| fender4 |
Hi everybody. I don't have any real progress to report, but I wanted to drop in for a bit.
Xdreamer,
Sounds like an ambitious project! For a cheap, large screen, do a search on www.avsforum.com for DIY screens or something similar. I think there are several types of harware store paint that some have had success with. Just a thought.
Also, a reflector, of course, will not increase the actual output of the bulb. It will, however, make more of the light usable for our purposes. Without a reflector, more than half of the light will not be striking the LCD surface (radiating elsewhere), resulting in a very inefficient use of the light output. The purpose of using a well-designed elliptical reflector is that the light rays can be directed towards a focal point (near the projection lens), and hopefully this will allow us to leave out the frensel. Myren's pic a few posts ago is a good way to get the idea. On paper, it definitely can be done, but I haven't had any real success with it yet. I have only tried a rectangle of silver metal folded into the shape of an ellipse (roughly....within 5%). It was MUCH better than no reflector, but it didn't make that much of a difference. BTW, this was with the MV bulb.
Undream,
Is the metal you are using aluminum or tin? Mine looks similar, but I think it is tin or just some sort of sheet metal. I don't think it really matter...just curious :). Good job on the polishing!
It was mentioned earlier that the CRI (color rendering index) of mercury vapor bulbs was not very good. I think this might be related to some of my problems. Just looking through the front of the LCD, it seems like the colors are not very "dynamic"...too much blue, no reds, etc. So in my opinion, I think that MH should be a BIG improvement over the MV. More efficient, better color, etc.
Myren,
Right now, I am just waiting for my OHP to come in so I can butcher it :cool: . Since the LCD area is smaller than the OHP fresnel, I would like to raise the bulb/reflector assembly to concentrate its light only on the LCD (possible? I'm not sure yet). Then I would like to "crop" the fresnel to the size of the LCD (once again...I don't know if that is possible. Maybe too fragile?). At least this would make for a smaller package and higher efficiency if they both work out. Pretty boring, but until my board exam is over, that will be the extent of my lens experimenation.
One other thing. In my lecture hall at school (about 250~300 seats, auditorium style), we have a screen that is larger than most movie theatre screens I've seen. About 95% of our lectures are on Powerpoint with some video, and there is always a fair amount of ambient light (more than enough to take notes with). Even with the full set of lights on, it is still viewable. So I got into the projection room the other day and saw that they used an Eiki LC-X1000 LCD Projector. I couldn't believe how small and quiet that thing is! The specs show 3500 ANSI lumens from a 200 watt bulb. Now THAT is impressive. :eek:
Good luck, everyone! Especially with the reflector project.
-f4
p.s. hey assailant--are the white stripes big down under? |
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| Marklar |
XDream yes there is a way you can make the paint your self basicly you start with a flat surface put a coat of white or light gray paint on it then you get some thing called reflective glass beads this is what they put on the painted stripes in the road to make them reflect your head lights I have seen it being sold on ebay search for "glass beads" you sprinkle them on the paint and shake off the excess.
http://cgi.ebay.com/ws/eBayISAPI.dl...item=1730686078 |
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| Undream |
| It is in fact aluminum. And, I think that you may be right about the MV bulb. When I re-wired mine, I used all new wire, so, I saved the old stuff just in case I had to re-assemble the thing to take it back, and, I think I am going to do that. Too bad too. i am just not getting good results with it at all. |
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| jamie |
thanks for the info, but i allready had a luma screen before i got a projector. thats what got me into wanting to mAKe a projector in the first place i had a lonely screen with nothing to shine on it :)
anyway everyone here rocks! great info, great ideas, cool people! |
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| ZeCo |
dragonhalf: You found the solution !!!!
Im brand new on this forum as poster but have been reading for a long time.
I've done some research (not big research, but enough to know you found the solution)
here is a quote from a website:
In most LCDs linearly polarized light is needed. A polarizer in the rear of the LCD will transmit light from the backlight system only if it is used in the same orientation. In a LCD, the rear polarizer will absorb roughly 50% of the backlight's output before it reaches the display. A reflective polarizer (RP) is employed to reorient the backlight's lost (absorbed) output, thereby matching the polarization of the display. In a backlight, light in the orientation of the display's polarizer will transmit 100% of the light. Light oriented 90 degrees opposed will be 100% blocked. All light in between these two orientations will pass at some level. A reflective polarizer reflects backwards any of the backlight light that is not in orientation. Reflected, the light is compensated or rotated slightly. With its new orientation, the light is brought forward again to go through the polarizer. If it is in the proper orientation, it will pass and if not, it will be compensated again (and again) until it is finally in the orientation of the rear polarizer. The use of a reflective polarizer, the display's brightness can increase by 45%.
All we got to do is to forget about the reflector and go after the reflective polarizer using mirror and quarter-wave retarder. We'd gain 45% of brightness. That IS a great increase. |
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| mountain_nz |
Its been very interesting reading over the past days looking into to the way everyone has been focused in the LCD way. Yes it does work to a degree but alas the old resolution and dollars equation makes it a bit costly and the fact to get good res you need large panel area which makes the unit a bit obtrusive.
My thought and findings was to go with an old TV chassis (10" DC/AC powered) remove the LOPT and the CRT etc. I have made three mirrored tubes (RGB) (hi grade stainless) and in one end fitted a bank of 60 10,000mcd leds with a focusing lens at the other end. In the middle of the Leds I have placed a Fibre optic cable this feeds the focused light to a prisum that combines the RGB into one light source that is feed by a mirror to two small servo mounted mirrors to give vertical and horizontal deflection.
The DC supply to the three light sources is modulated from the RGB output of the TV chassis via a 10 ohm resistor and a 1uF electro. This give the luminance information to the individual light sources.
The combined output go to a beam focusing lens from on old Slide projector. The out put is strong enough to be clearly visable during daylight.
I am an the moment building one using diode laser modules, this should be able to project the image upto 200m ( why I dunno, but a picture thats 60'x40' will be great a partys)
PS total cost for the LED version was a little over NZD$300 or USD$140.
;) |
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| Atomos |
I am new to the forum and I would like to say thanks to all you guys for doing this. I don't really want to read the 1000+ posts on this forum so could everyone
here who has a working projector post the parts and configuration. I am eager to build mine but I want to make sure it works well. I don't have enough money to
experiment otherwise I would.
Thanks
-Atomos |
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| fender4 |
mountain_nz,
Wow! Do you have a website or someway we could see some pics of your setup? I'm very interested, impressed, and confused :confused: . Is this similar to the DIY "Laser projector" project?
Thanks!
-f4 |
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| mountain_nz |
fender4,
I am unsure of the DIY Laser projector project as I am still sifting through all the interesting chat in this site.
Can you give me directions were to find this laser project, no doubt I am not the only one to think along these lines.
I am not that greater fan of LCD projectors especaily the tri-LCD (RGB) type as it gets real hard to get the convergance right across the picture. Which equals picture clarity.
Were as the scanning LED/Laser is much simpilar as we are not re-inventing the wheel as such only the output medium.
No I am afraid I do not have pictures of my current working version-yet anyway.
Most of the LCD projects listed that I have read thus far suffer from the same main problem- how to pack enough LED's in a fixed area. My solution to this was to put 80 odd 8.5cd White LEDs perpandicular to the LCD axis then have a mirror on a 45 angle to reshape the beam into the LCD, this worked well and space was saved.
HINT-: stagger the packing of the LED's then you dont need to diffuse the light into the LCD, else you get bright and dim lines in the output image which is anoying to say the least.
PS you can fit a White LED assembly to an existing LCD projector you just need to rethink your number of LEDs per string and resistor values as well as add a suitable full wave rectifier ahead of the LED string. Becareful as the volts across the string can be upto 300v DC in some countries. The benifit though is have a light output comparable to the old buld but lasts 10,000hrs for only 12watts!!! consumption.
Cheers
People will keep every whos interested informed best I can
:cool: |
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| oftheend |
Wow, Interesting setup! I too, am slightly confused however. This is my best guess as to your setup(essentialy):
---LED---------------TUBES------------PRISM----(servo etc)----LENS
=========|--------------------|---|||||||||||||||
(red leds)--->>>>>>>>>>>>>>-||||||||||||||
=========|--------------------|---|||||||||||||||
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,|||||||||||||||>>>-|++++++++|
=========|--------------------|---|||||||||||||||>>>-|}}}}}}}}}|>>
(blue leds)-->>>>>>>>>>>>>>-||||||||||||||>>>--| }}}}}}}}| >>
=========|--------------------|---|||||||||||||||>>>-|}}}}}}}}}|>>
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''|||||||||||||||>>>-|++++++++|
=========|--------------------|---|||||||||||||||
(green leds)>>>>>>>>>>>>>>-||||||||||||||
=========|--------------------|---|||||||||||||||
And The red, green, and blue leds are driven off the color circuitry of the TV.
And i Must ask--Are you an engineer? Any more details you feel like adding would be really appreciated (especially by those less skilled than you obviously are.) Sounds like an awesome setup, i think you probably have ALL of our minds going right about now. |
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| oftheend |
I saw a post on AVSFORUMS that, correct me if i am wrong, was written by you, concerning using 4 sheets of Plas-tex (polywall) as a screen, mounted vertically. I was planning on using three panels in my setup. My plan is to hang the middle panel securely on the wall (or backer), and apply a thin bead of silcone caulk to the sides. Each remaining panel would then be slid into place, and squeezed tight to the next. With a soft cloth, i would wipe away excess caulk. There are a few things to consider before trying: the color of the caulk should be tested prior to use, to match the panel. I have seen several slight color variations between manufacturers. Then the color should be stable over time, which is why i am thinking silicone. It is used in exposed areas of bathrooms sometimes, and i believe certain ones claim the color will not change. Plus it is flexible and durable.
If you find any better solutions, i would enjoy hearing about them. I should soon be building my screen, so i am looking now. |
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| remp |
Mountain-NZ
You can find the Laser projector site by selecting threads last 75 days.
We are all most impressed with the description of your projector. The servo mirror assembly you are using for horizontal scan must be of an advanced design, solving problems previously found to be extremely difficult if not impossible. Your projector using LED units being able to give a clearly visible picture during daylight is also a considerable breakthrough. We would be most interested in further particulars. This site is for DIY people who spend much time and effort gaining knowledge, trying different things, interchange of information and presentation of results good or not so good in a concrete form such as pictures or diagrams so interested people can benifit from each others efforts. I am sure many others would much appreciate some further details of your remarkable breakthrough. |
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| oftheend |
Here are my specific questions:
The light from The leds got to the prisim and is then passed to the servo-mirrors. Are these servos how the image is actually produced, IE you need a red pixel at position 34, 200, so the red light is passed to the horizontal and vertical to produce the red at that spot? Or am i missing something?
If that is the case, how do you keep the refresh rates to something reasonable on the eyes?
And how are the servos controlled? Do they require some extra circutry?
Is convergance a problem? It would seem to me that the best setup would have servos for each inividual color, converged at the prisim.
How is the resolution of the projected image, is it equal to the TV resolution? If so, have you considered using a CRT computer monitor? |
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| Tokter |
And here are my questions:
How did you make the xy scanner unit or did you use expensive galvanometers?
Is the horitonzal frequenzy not to high for the scanner unit?
Tokter |
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| Scot_lad |
Yes we're all very impressed and frankly I'm dying to know what you've done. I understand where all the light is coming from, but not how you got the servos to move at anything like a high enough rate to project an image. I reckon you'd need a horizontal refresh rate of above 15kHz for a decent image. How on earth do you get servo motors to refresh at that rate?
As for the mirrored tubes - what are they for? And surely an optical fibre isn't very thick so quite how you get all that light focused in the end I don't know.
Good plan and it's certainly livened up this forum (you have to admit it's become stale to say the least), but get some pics so we know you're not talking bollocks.
Cheers, |
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| Tokter |
| It seems by what i read in the internet that it's only possible to make the horizontal refresh rate with a rotating polygon mirror. Maybe it's possible to use the one from an old laser printer... |
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| Marklar |
| so the picture is made by the 3 different colored LEDs then you squeeze it into a fiber optic cable? Im really not familer with this design but if you shine it in a fiber optic cable the output wouldnt go very far. I have some fiber optics I got from a bank that closed and was messin with it I shined a red laser in one end and at the other end it was only visable if you shine it on a surface 1 foot away in complete darkness. This was a very bright laser to i can see it in daylight when i point it at a building 300 feet away. |
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| Undream |
| hehe, maybe hes just taunting us with impossible ideas just so we spend a week tripping over our thoughts :) |
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| Axeman |
Well mountain_nz, you certainly have sparked some interest! I would be very interested in seeing your results. I've been thinking about the same mechanism for months now. I was thinking about rotating cube mirror on an Athlon CPU fan. Each surface=scan line, and the fan rotates at 5000 rpm which works out to 20Khz. Another motor running at a slower speed could scan from top to bottom. Adding surfaces to the mirrors could increase maximum scan rate, and circuitry could be designed to sync with whatever signal was sent to it.
*MY* question is- do LEDs modulate fast enough to draw out an image? I was looking at using lasers, but I was researching laser projectors and they were using Acouto-optical modulators- which implies that the laser diode cannot modulate quickly enough. But the article I read was about something constructed in the early eighties, so things might have changed.
Excellent work- can't wait to see pictures. |
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| fender4 |
Here is the "laser projector" thread:
http://www.diyaudio.com/forums/show...=&threadid=1149
Started by remp! Very interesting read. I wonder how close that is to mountain_nz's design? This could really shake things up if it works out.
Good luck everyone.
-f4 |
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| Gunawan W |
I have a problem with refraction.
It's cause projected image on the screen can't get sharp enough, for example: when I projecting black line to the screen, there was blue and red line following on each side of the black line.
All I know it's because of single lens I use, the lens will bend light spectrum with different angle.
To elliminate this, we should use more than one lens with different refraction index (is this what we call doublet, triplet or multi achromat lens?).
The question is, how to choose correct lenses so the final result is sharp projected image. (maybe it will need some calculation, but can't find the formula).
I would like to know, is this problem also happen in OHP lens?
Undream and Fender4, since your setup use single plano-convex lens, did you have the same problem as I had?
Waiting for help. |
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| Xdreamer |
Hi marklar,
thanx for the info...and myren what kind of a screen were you talking about in avsforum ?
Would like to know more..and if anyone is interested the XBO short arc xenon bulb produces
6500K color temp and a CRI of >95 ...but the down side is lifetime of the bulb is short...
ps: mountain-nz , would like to hear fr u as well
kool idea...hope its worth while |
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| aggrojosh |
hey,
i'm goin to be taking on this project soon here...
but first some questions...
Whats a fresnel lens?
would the lens out of a projection tv work?
Ive seen some projects with a 5" lcd and a a lot smaller lens.. does that still work if the lcd is bigger than the lens?
Thanks Guys....
-Josh |
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| Xdreamer |
Hi mountain_nz:
What is the main advantage of using laser projector? You mentioned using a 60'X40' screen but don't you think the light output from the led would be to low to achieve an exceptable image?
and what about resolution? What kind of resolution can you expect from a laser projector? UXGA? QXGA?
i have just purchased a 21" UXGA lcd panel for my lcd based pj...pls tell me that i did not waste $2,700...but if the laser projector can produce a better image quality..then count me in..
would love to hear about it?
my estimated budget was $8,000 ...
:cool: |
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| theArchGu |
Does anyone have opinions on Florescent lights? I would like to start on this project, but I'm not sure on which lights I want to use for this project.
Thanks! |
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| tomithy83 |
floresent baadd
point source good
try metal halide(mh), murcery vapor(mv), or plain halogen lights
watch out on halogen they get hot and can melt the lcd |
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| tomithy83 |
i'm sorry i didnt explain why flo lights are bad
the light from the bulb spreads out from many points and striks the lcd @ many different angles bluring the image |
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| Scot_lad |
I still reckon a point light source is only use if you're using a fresnel. I think if you use a bigger light source with some kind of polarizer you could be fine.
Commercial LCDs don't come with point light sources do they? And they've got the best image of all - if you could get that quality on the wall you would be happy.
I read recently about some company (forget who) managing to create a thin and flexible LCD which is very cheap to make. It is almost as easy as printing onto paper. Look out for giant cheap LCDs in the future.
But this will be years in the future and just how "cheap" they will be remains to be seen. I wouldn't buy one anyway. I bet people who bought plasma screens for upwards of £17k will be ****ed off now they're available less than half of that. |
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| Xdreamer |
Scot_lad,
I think the commercial lcds do use point source lights like the UHP lamps thats the reason that they have high uniformity ratio...using dispersed light source is ok but you will only utilize like 25% of the light source so it is unadvisable...
:) |
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| Xdreamer |
and scot_lad,
one more thing is that the commercial units use a small lcd panel with high res...0.9" XGA, SXGA..
and they utilize multiple panels(3) to achieve that kind of image quality...0.9" lcd panel of XGA res is pretty damn expensive if at all available to sole buyers.... |
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| dragonhalf |
| quote: | Originally posted by ZeCo
dragonhalf: You found the solution !!!!
Im brand new on this forum as poster but have been reading for a long time.
I've done some research (not big research, but enough to know you found the solution) |
I cut out the page quote.
| quote: | | All we got to do is to forget about the reflector and go after the reflective polarizer using mirror and quarter-wave retarder. We'd gain 45% of brightness. That IS a great increase. |
Actually someone else posted this same link back in mid febuary, I hadnt read that post yet when I posted the link again. So credit for first post of this page goes to that person.
I only caught up just now, solid reading all yesterday and today.
Still I'm surprised that only 2 of us found it.
To understand a bit more about the issue, take a digital watch (LCD screen) and a pair of polarized sunglasses (tinted wont work, they need to be true polarization). Place the unglasses on the watch and look at the watch through the glasses. Now rotate the glases or the watch(only rotate one for simplicity). you should find that one way you can see the watch clearly, and at about 90 deg from that you will find the entire watch screen goes black. |
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| SuperDave |
Someone was asking about the DIY screen. Here is the link.
http://www.avsforum.com/avs-vb/show...?threadid=93780
It is a product called Plas_tex (something like that) from Parkland Plastics. They sell it in Lowes or Home depot for about $20 for a 4' x 8' sheet. This stuff is supposed to be amazing. I have bought a sheet a while back but have not tried projecting on it yet. If you want more info you should only need to read the first few pages on the link above.
I'm hoping to do some more work on my projector again...I've left it alone for a week or two. I bought a roll of aluminum a week ago to build the parabolic (OK quasi-parabolic) reflector to see if it help any.
I do have a question for Myren... What type of reflector are you using?? Also what type of light are you using and where did you get it?
Finally a general question....I'm not too concerned with heat and I am getting frustrated with getting enought light output. So...does anyone know how I can go about getting a light and ballast (flourescent I guess) like the ones in the projectos... that is ready or close to ready to use. I would like to get the thing going and then I could work out a cheaper light source in the futrue after I have watched some movies.
Good luck on your projects...
Dave |
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| tech head |
Superdave
I don't know how much you are willing to spend but a quick search for MH lights came up with this.
http://store.yahoo.com/elights/40philsupmet.html
I think that 4300k light temp would be accepable. but that 's just me. :-) |
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| tom1356 |
I finally have some time to get this projector up and running. I want to buy a computer with a hi def vid card to run the whole thing and I am looking for sugestions. I would like to keep it fairly reasonable. Can the computer be done for less than $2000.00? What would be the minimum specs it would need to do a great job.
Thanks
Tom |
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| Myren |
marklar: thank you. the glass beads link is the greatest thing i have ever seen. do you have any personal experience with them? what sort of coverage can i expect?
fender4: 3500 lumens for 200 watts.... whoa, just whoa. thats totally over the top. how's the contrast?
oftheed: yeah, thats me. you're doing what i'm planning on doing. annoying though, cause i move around a bit, and having to keep rebuilding will be a pain. thinking of maybe just trying to make a nice painted screen with glass beads. less work to move, assuming the glass beads dont fall off.
gunawan: the black lines on the last post i made showed where the light has to focus from and too. the formula is: 1/(focal length) = 1/(destination focus distance) + 1/(source focus distance). again, set focus distance between the lcd and lens, then the lens and screen, as illustrated by the black lines in the image on my last post.
xdreamer: theres a poly-wall sheet that can be had for fairly cheap that supposedly has fairly good screen characteristics. check out avsforum.com's screens section for some really good diy materials and info
second off, as for using a cold mirror reflector with hot mirror between lcd and panel.... you'd probably keep 96% of the heat from getting to the LCD. it should offer some serious protection. but not a cheap setup. also, thankfully, by no means is it required, for anything short of 1000w metal halide systems.
superdave: my "stable" setup is just components from a projector. my experimenting - the stuff that really counts in my book- uses solely ellipsoidal units. i've got about four different reflectors setup. i'm using a 250 w mh that fell into my lap and a 400 w metal halide unit that i bought off ebay.
tom1356: theres a hipix hdtv card thats really really nice. $300 or so. if you dont want hdtv, just get something supported by dscaler. there's a list of compatible cards on their site. i'm a fan of some of the happague cards, personally. and man, you can build the computer for under $1000, if you try hard enough. priority priority priority. if you want a really nice AV grade system though, expect to spend around $1500 to $1600. $2000 will buy you some nice stuff.
Myren |
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| SuperDave |
Tom1536...Myren is right about the $1000 price. Check out this link...
http://www.pricewatch.com
I have been finding dealers from here for years. It is not as GREAT as it used to be but it still has the lowest prices around... I generally don't give out the link to too many people because I dont want it to get too comercialized like those other sites. All you need to do is decide what parts you want and then order them from a few different people. Just find the lowest combination of prices...one person will lose money selling you memory so buy the memory there and some other things they have cheap...then buy the other stuff from someone selling hard drives really cheap. Good luck.
BTW...I have no connection with this pricewatch (I even thought about building my own site to compete with it before). I just thought it would be helpful since people will need to have a computer to run their projector and I have bought a lot of cheap stuff from here over the years.
tech_head...Thanks for the link. That may be an option for me....However, I really want to get something a lot smaller than these MV and MH beasts. The lights in regular projectors are nothing like this are they?...If I cant find what I'm looking for I might just go with the bulb you linked me to...Oh I dont know much about color temp...what do you guys think about it having 4300K color rating...is that bad or is it OK?
Thanks,
Dave |
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| Timtimes |
| quote: | Originally posted by Atomos
I am new to the forum and I would like to say thanks to all you guys for doing this. I don't really want to read the 1000+ posts on this forum so could everyone
here who has a working projector post the parts and configuration. I am eager to build mine but I want to make sure it works well. I don't have enough money to
experiment otherwise I would.
Thanks
-Atomos |
Since you have more time than money, I would suggest you read more of the posts. That said, the only SURE and EASY solution at the present time is to buy an LCD panel off Ebay and and an overhead projector to go with it. Hope this saves you some time.
Enjoy. |
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| tech head |
SuperDave
Have you thought about using a light and balast from an ohp?
Or maybe a replacement bulb for a projector. I have seen them on www.projectorcentral.com for as little as $30. |
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| ZeCo |
Off topic:
-------------------
What is the least response time I should look in a LCD pane?
I haven't been able to start my project cause I am still waiting for my LCD to come.
I got my LCD as a bargain ($25): Polaroid Polaview 1800. It is 8.4" 640x480 (can also display SVGA graphics), 2.1 million colors, 40ms response time and 100:1 contrast ratio.
Although the contrast ratio is "low" I figure that most TFT panels have this same ratio. What I am wondering is if the response time is too slow to display smooth video.
Could you guys post your LCD panels specifications? On the other thread specific for people to post it, not many has done so far :(
Thanks
PS: Has anyone found a reflective polarizer cheaper than $45? Im going to mess with the polarizer instead of reflector cause from what I read, reflectors are good when the LCD is small and polarizer should work better with bigger panels. |
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| Marklar |
Well I decided to buy 3 can of those glass beads i think that will be enough for a 9'X8' screen as soon as i get it made i will take some photos of the reflective screen next to a plain white sheet.
BTW three 25 oz cans for $36 dont seem to bad I hope it is enough :/
Oh yea i cant remember if I told yall that the OHP I got the bulb in it puts out 49000 lumens I saw that and almost fell over I thought it was some other kind of measurement but I called sylvania and they said yep thats lumens. Keep in mind it has a nice parabolic mirror behind it so it uses almost all the light. |
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| SuperDave |
tech_head....I have thought of that and that is what I orginally anticipated doing. I was going to rip my OHP apart and use the lamp/ballast. Unfortunately it is not bright enough. I have considered buying a much better one off eBay but they still arent too bright I dont think like 2-4 thousand lumens. Once it goes through the LCD there wont be much left. If I can find one powerful enough I would like to get the assembly and light from it. Anyone have suggestions on a model that is strong enough??
Marklar...did you get your light out of an OHP?? If so...which make and model?? I would love to get something that right with a reflector built in...please please tell me more specifics on it and where I can get one for myself.
Thanks,
Dave |
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| Marklar |
Superdave,
It is a dukane quantum OHP uses a 575W MH 49,000 lumens 6000K color temp and a life of 750-1000 hours |
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| Darth Willis |
I'm new here, and I probably won't post much (if anything) outside of this message, but I think I have the answers that everyone is looking for on the DIY LCD projector... but I don't think you're going to like them.
When I came across this yesterday, I was really excited and wanted to go out and start buying stuff and build... but I then asked myself a few questions as to why things were as they were, and the answers came to me. Anyway, I'll apologize for the length of the post now... but please, do read it all.
Anyone wonder why such a high lumen light source is having to be used, yet the final product is still dim and slightly darker at the edges?
Anyone remember how LCDs work off of polarized light?
Anyone know why you're using fresnel lenses to focus the light down to begin with?
Here's the problem: The light is not being used efficiently... and the worst part is, it CAN'T be used efficiently on this scale without investing a LOT of money on high grade optical lenses.
The source of your problems is in the LCD display itself. Don't get me wrong, a DIY LCD projector is possible, but it'll likely cost just as much to build a good one as it will be to just buy a used LCD projector.
Here's why: The LCD panels transmit light in only one direction. Advancements have been made in image quality at angles, but on a whole, the light is still only flowing in one direction through the panel, and only one direction.
To improve light efficiency, you have to focus the light down to a point where the projection lens is. That's why you place a fresnel lens behind the transparent medium you're projecting... it's cheap, it doesn't have to be an optical grade lens, and it's effective... but it immediately twists almost all of your backlight into a direction that can't pass through the LCD panel due to the polarizing filters. There's where a majority of your 90% of light loss is occuring. The rest of the light loss is from the fact that what light does pass through the LCD panel is now going straight and no longer being focused down to the lens. The projection lens has nothing left to work with outside of mostly ambient light. That's why your final image is so dim.
With the most efficient method of lighting, you should be able to get away with just around 3-4000 lumens... but it requires having the lens that focuses down the light right AFTER the LCD panel which means it has to be big, optical grade, and precise to avoid distortion if you use a large LCD panel.
This poses a problem. Large optics are expensive and heavy. Anyone who's looked through an Edmund Scientific catalogue can attest to that... so if you use the LCD as passthrough, the only cheap way to do so is to have a small panel so you can use smaller optics... the smaller the panel, the cheaper the optics... but inversely so, the smaller the panel, the more expensive the LCD display.
From an optical cost effective standpoint for the DIYer, you'd need an LCD screen not much larger than 2" on diagonal. But even the low res ones are expensive.
From an LCD cost effective standpoint for the DIYer, you'd wind up buying LCD screens with at smallest, a .20 dot pitch... giving you 5" NTSC or PAL resolution screens, ~10-12" SVGA and ~15" XGA resolution screens.
Either method costs a lot of money to do properly. You can brute force your way around the limitations, leave out certain steps and get a lot of projects using a pass through the LCD screen method that weigh in under $750, but you wind up with other problems that occur like rediculously bright lamps for mediocre output, heat issues from the rediculously bright lamps, size of the final projector and overall image quality for the money spent.
Another route to investigate would be using a reflective projector that you'd sit down on top of a reflective LCD screen, but again, you run into serious heat issues due to the enormously high light intensity needed.... it's six one way, half a dozen the other. Either cheap route will cost you in something, and most likely won't get much better quality than a well built 100" TV project you'd get the plans from off of Ebay.
I applaud the work and efforts put in by all of you... and if you had limited success, congratulations. I think it'd just be cheaper and easier to just go drop a couple grand on an LCD projector instead until postage sized full color XGA LCD displays only cost about $100... well, at least that's just my opinion. Best of luck to you all. :) |
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| oftheend |
Darth Willis:
What are you, a corporate spy from Epson or Sony's projector divisions? :) Sure, some of us are taking more complicated routes to building our projectors, but the fact remains that it can, has, and will be done, and for a lot less than the 750 you have stated. In the simplest incarnation, drop a projector panel on an overhead. VGA-$<100 SVGA- $<200 XGA-$<350. I choose to build the case myself, for flexibility. I was watching my 14 foot picture last night, and loving it. My total projector cost: about $90. And yes, I will be adding quarter wave retarders and reflective polarizers to my setup: ~$70. My optics are high grade as well. I just got them at auction for a steal of a price ($10). The way i see it, if i spend less than the price of a 32" TV (450), I am getting one heck of a deal. I started thinking about this when i decided my 27" TV was way too small for my new living room. With projection tv's in the thousands, i decided to wait before i bought. Thank god i did, I almost went to rent-a-center to rent a 60" rpj when i found my first info on DIY projectors. In my mind the time is unimportant, the money is better spent, the movie expierience much more enjoyable and realistic, not to mention I have aquired a lot of scientific knowledge i would not have otherwise. Some guys restore 74 Camaros, some build projectors. To each his own, they say. |
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| tom1356 |
Myren-
Thanks for the help. Any idea what I would need to do high definition?
Do I have to put it together myself or does someone sell a specialized PC? |
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| Darth Willis |
| quote: | Originally posted by oftheend
Darth Willis:
What are you, a corporate spy from Epson or Sony's projector divisions? :) |
Nope... just a realist. :p
Oftheend, I'm curious to know what you did exactly... what hardware you used, projector, LCD screen, optics and light source... not to mention image quality and how dark you have to have your room to use it at 14'... as well as total cost, hours spent working on it, cost to run, etc.
I'm an image quality freak... I do graphic design and video editing, so if I'm to do a project like this I want it to work right and look good without having to reinvent the wheel.
I never said it couldn't be done, but honestly, is the end result really good enough to bother trying? Yeah, it may look great as a $200 projector, but how does it faire as an (insert format style) projector? For cost to assemble, use, maintain, replace and reproduce? And honestly, if you didn't get extremely lucky on bargain stuff and had to pay retail like regular shmoes reproducing it (because let's face it, if a good working one could actually be done for that little, all the cheap sources for the used parts will disappear... remember the i-opener?) how much would it actually cost? Besides, if it's actually this cheap and easy to do, why hasn't it been done, mass produced and put on the market already?
I think it's cool that you're trying and you're happy with your work. It's nice to take pride in the hard work you do yourself... that's why I assemble and service PCs in my spare time. Just remeber, nobody likes what you make more than yourself.
</rant>
If you've actually been this sucessful, please prove it to me. I would love nothing more than to eat my words and my hat... and have a beautiful XGA projector for under $500. :D |
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