| King_Martini |
Hi all!
First time poster, n00bler and all that shhhtuff...
First of all, thanks to everyone who has posted and provided such a great resource. You have all taken this particular DIY subject and turned it into a viable and cost efficient end result. It is however rather scattered.
My goal is to build a projection setup with only a RCA video in.
I want to project approx. 50" wide at 17' away from the wall/screen with moderate to nil light in room. So in essence the Divx movie of projectors, good for general viewing without the care if some detail is lost. Minimal ghosting at fast action scenes is OK.
Initial materials listed below. PRICE GOAL: $200 or less.
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LCD
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PS one (without VGA Mod) or liliput, 4"-5"
with brightness and contrast adjustment a plus.
** from a non-ebay source**
Actually, totally open to input here. I'll be happy with a VHS quality projected image.
I reiterate, not looking for HDTV here, just VHS quality... Need a low cost, mid-level LCD with RCA preferably built-in however I can do mid-level soldering and a visit to RAT-SHACK if needed.
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LIGHT SOURCE
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Halogen 12v 50W dichroic lamp with
8000lm and 3500k color temp :rolleyes:
Light temp a little low but I close enough for me.
I realize that MH Is the recommended/successful way to go here BUT... I don't want to feel like i need to replace a $$$ MH bulb because I know in the back of my mind it is at half life. I want to avoid using a ballast and am found of "buying a few bulbs" from home depot hence the quartz halogen decision.
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LENS SET
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• FUJINON COPY LENS, 240MM FL
PRICE: $11.00
• FRESNEL
(x2) Bausch & Lomb
Magna Page Magnifier, 8-1/4"x10-3/4", Clear Acrylic
PRICE: $7.00 ($14)
Cut down. One in front of Lcd, one in back...
• 60mm condenser
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HEAT DISSAPATION
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(x2) Ultra Silent 80mm Stealth Fan
Fan Size: 80 x 80 x 25mm
Bearing Type: Double Ball Bearing System
Air Flow: 27 CFM
Speed: 2050 RPM
Noise Level: 21 dBA
Rated Voltage: 12V DC
PRICE: $10.00 ($20 Total)
One for Lamp and one for LCD...
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ADDITIONS
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• An integrated fuse system
• Quick access to bulb for easy change
• TV tuner will be provided thru VCR
• Any need for Macrovision decoder since I
will be running from DVD player to RCA video in?
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BASIC BUILDS
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Kicking around a direct build:
Light condenser Fesnel/LCD/Fresnel Fujinon
<@ ----- > () ----------- > |[]| --------------> :::[)
But I am leaning toward an idea I had for a tower build:
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__[_]__ <-- OHP head objective shoots forward
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| === | <-- Fresnel/LCD/Fresnel
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| _|_ | <-- Condenser
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| @ | <-- Light source
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++++++++ (Base/floor)
*** Wooden VHS Cassette Storage tower will make a VERY attractive MODable housing ;)
I am thinking the tower build will have many benefits:
One - it is already rasied to a projection level (3' 5")
Two - The VHS storage towers have a peg system to lower and raise components.
Three - wood, sleek, sexy...
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Well thats about it for now, brain hurts after a few days of searching the posts. Hope I get some kind advice instead of getting hammered back into the betamax age (thats like B.C. right?)
Thanks again for your help and time!
(PS, A hunch tells my the DIY projector community has driven up the price of the PSone screens... anyone selling one somewhat cheap?) |
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| bulldog5046 |
| quote: | Halogen 12v 50W dichroic lamp with
8000lm and 3500k color temp |
i think you'll find thats 8000cd not lm... also i use halogen alot and i've smashed the reflector off my bulb and used my own reflector made from alu foil and it works a hell of alot better and thats with a 10.4" lcd and projecting to 90".
Cheers,
Ryan Edge
P.s. Ace please get back to me |
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| King_Martini |
| Thanks for the corrections and I'll take your advice and use a nice reflector! |
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| King_Martini |
Sorry to double post...
How many feet are you projecting from and whats your halo bulb specs?
ciao |
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| bulldog5046 |
| quote: | Originally posted by King_Martini
Sorry to double post...
How many feet are you projecting from and whats your halo bulb specs?
ciao |
its around 9ft with my varifocal 310 - 360mm triplet.. the bulb with its original reflector was 4750cd but i have no idea what it would be now.
Cheers,
Ryan Edge |
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| Guy Grotke |
Buy a low end projection panel on ebay. You can get a 640 by 480 type with RCA input and 1.4 million colors, pretty cheap. Then all you really need is an old overhead projector. You can leave it alone, change to a longer living bulb, or gut it to build a DIY projector with the optics. This should look pretty good and be <$200.
If you do build your own projector, don't forget to protect the LCD from IR & UV. Buy a piece of UV-coated lexan at a home materials store. Make your own water-filled IR absorber. Both very cheap.
One (also cheap) suggestion if you use a dim light: Buy or DIY build a small spherical reflector to put behind the lamp. This effectively doubles the light output.
You might also want to try a simple DCX (ie. magnifying glass) lens to see if you really need a triplet. The chromatic aberration may not be noticable. These tend to be around 330 mm fl and $5 from surplusShack (or WalMart!). |
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| King_Martini |
No OHP setup for me. I am in no rush to get this done and I want to make it nice. My wife would shoot me if we had an OHP sitting in or living room :P
Going to use a Pyle 4" TFT/LCD for my setup.
HEading to Ikea today to look at small recessed light fixtures and such...
Post pics later... |
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| King_Martini |
Tasty deal: www.surplusshed.com
4.75 cold mirror
FUJINON COPY LENS, 240MM FL
PLASTIC DUST COVER / FAN GUARD FOR 90mm 12VDC FANS
and shipping.
Total: $23.02
Remaining budget: $177 |
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| dengez |
im sorry but a 4" lcd will get you garbage quality...nowhere near even vcr quality...and the crappy page magnifier doesn't help much either...if i were u i'd get a projection panel and ohp and put them in a box so that the ohp isn't visible if ur wife would get mad...it would be WAY better and cheaper...jus mah 2 cents...
dengez |
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| bodgy |
I think you'd be stupid to go with a psone screen, like has been said the quality will be lacking, probably to the point where you wont want to watch it very often.
The only advantage of the screen is its size. A proper projection panel will run you less $$ and it will work properly, wont lose contrast because its getting too hot etc, and will create world peace amonst all nations.
I reckon you should go with dengez and guy grotke |
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| Guy Grotke |
In your initial post, you said you wanted a 50 inch wide image from 17 feet away. If you do use a four inch diagonal LCD, then I think you either have to change your lens, or change one of those goals. I calculate that a 240 mm fl lens would give you a 66 inch wide image from 17 feet. If you must stick to 50 inches wide from 17 feet, you could use a 282 mm fl lens with a 4 inch LCD, or you could you could use your 240 mm lens with a 2.4 inch LCD. Or you could use a 9 inch LCD (ie. an nView Spectra C OHP panel) with a 790 mm lens!
Of course, maybe your goals are not that strict. Then you can just accept a 74% dimmer 66 inch wide image, or move your projector forward to 10.6 feet from the screen.
17 feet is a tough design goal! I have a similar problem: A room size and shape that demands a 59 inch diagonal image from 14 feet. I just finished making my own 580 mm fl achromatic doublet from two surplus shed lenses. Initial testing looks good and it cost me $7.50 + shipping, a couple of inches of 4" ABS pipe I already had, and two hours of labor to make the mounting. |
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| dengez |
if you really don't want to use an ohp then just buy a projection panel and incorporate it into the homemade lcd projection setup...or try to find a cheap 12-15" lcd panel...i bought a great projection panel 640x480 16.7 mil colors 3m 6400 from $50 US on ebay...u can really save yourself from crappy quality if u get a better lcd panel for less $ and ohp or you use the lcd in a homemade lcd system as i said in my previous post...
dengez |
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| Guy Grotke |
Besides the resolution and response time problems, there is another reason to use larger LCDs: An LCD with integrated color filters will absorb at least 2/3 of the light falling on it (unless you only use totally white images :D ). To make an image with the same size and brightness, a small LCD has to get the same total amount of light as a large LCD. So the small LCD will get much more heat per square inch. Since the area changes by the square of the size, this can get extreme at small sizes.
For example, my 15" LCD has (9" by 12") = 108 square inches. Your proposed 4" LCD has (2.4" by 3.2") = 7.68 square inches. So your LCD will get 14 times as much heat per square inch! Both LCDs can only operate to not much above room temperature. So you will either have to accept a much dimmer image, or do one heck of a job cooling your LCD.
This is the reason that small-format LCD projectors go to the expense and difficulty of using three panels. Each color's LCD only variably twists the polarization of the light through each pixel. This does not involve much absorbtion. Then the polarized light goes through a seperate polarized filter that does absorb the light from "dark" pixels. These polarized filters get a lot of cooling air, and they can operate at high temps. |
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| King_Martini |
First and foremost, thanks for input everyone...
Guy Grotke:
Thanks for alot of time and detail in your posts, I really appreciate it. No I am not totally limited as far as projected size so the 240mm should still be OK. I acatually have a good space if I need to project closer. Lets put it this way, right now I am stuck with a
19" TV. So anything is going to look bigger/better :P
Also, looks like I will try and find a bit larger LCD... However I have seen some screen shots of peeps projects using
a 4-5" LCD and It didnt look bad at all. In all fairness they were projecting cartoons which dont have much detail so maybe movies would have looked very crappy...
I am planning on incorporating some PC case fans for cooling. Will start with 2 and use more if needed. The cold mirror should help too.
----------remaining comments----------------
Actually, I am already building the unit in fully adjustable sections. So in other words the light source (halogen socket, parabolic reflector, and condensor lens) will be one piece. -- See the pic --
Building it in sections give me ALOT of freedom to switch out or adjust what doesn't work.
Still need to do some work on it however because I dont have the proper tools to mod the reflector... have to wait 2 weeks and a 2 hour trip to the parents :(
Finally, I will be doing alot of trial and error on this project. That's what makes it a fun learning experience. Just because everyone has success plopping a projection panel on a OHP doesnt mean I should or will. I am buying the LCD last. I can run alot of tests before dropping any considerable money into this project as far as how big and how bright my projected image will be. (and yes I realize light will be lost when shooting through the lcd...)
As far as now, the best advice I can use is finding an inexpensive LCD (not from eBay) that is small and will project an OK image. |
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| loke33 |
I would say Ebay would be your best bet at getting an LCD pretty cheap. I got a 15" XGA(1024x768) toshiba panel from an auction for $80. There were 2 of them selling at the time and now i wish i would have bought them both. :( Oh well still a good deal.
My advice would be to keep checking the auctions daily, you will eventually find something. But, as always, try to ensure that the panel is DIY friendly. Mine was, but it needed a FFC extension cable.
-Tony |
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| King_Martini |
WOOHOO!
The light engine is 98% finished (except right now I have a glass disc in it untill I get my condenser lens in the mail)
Final size is 4"x4"x5"
After 30 minutes of being lit, the frame is cool, the parabolic reflector is hot but you can still indefinately touch it, and the glass disc (which the condenser will replace) is about 105œf/40œc without any type of cooling fan **but it isnt enclosed in a case yet.***
Posting 2 more pics after this stay tuned... |
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| King_Martini |
Grrrrrr when are my post gonna stop being moderated???
Hopefully before I finish my Projector :P
Ok one more pic, a side view with the light off. |
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| King_Martini |
Who would have thought a cheapo reflector would work better than a high polished stainless steel one?
Well I am actually happy and this is what's nice about working piece by piece. Installed a different reflector and got so much more light. It appears reflectors shaped like < work a heck of alot better than ones shaped like this (
So you DIYers go for polished metal funnels over soup ladles ;)
Also heed aces prior post in the newbie section about keeping the filament of the lamp as close to the reflector base as possible.
Will post pics later this week after I get my lenses...
On a side not, anyone see those fresnel magnifiers that duplicate the image over and over in small squares? I wonder if it would make the light more even than the plain fresnel.
ciao. |
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| dave123 |
King_Martini,
where did you buy your funnel? |
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| King_Martini |
IKEA...
the round reflector is actually something they were selling as a napkin holder.
Ikea also had a great high polished funnel which I think I am picking up tomorrow.
Don buy the roud parabolic reflectors shaped like this (
Get a funnel shape like this <
night. |
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| dave123 |
| quote: | Originally posted by King_Martini
Tasty deal: www.surplusshed.com
4.75 cold mirror
FUJINON COPY LENS, 240MM FL
PLASTIC DUST COVER / FAN GUARD FOR 90mm 12VDC FANS
and shipping.
Total: $23.02
Remaining budget: $177 |
I thought they ran out of the FUJINON COPY LENS, 240MM FL ? |
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| Guy Grotke |
>so much more light with < reflector
You might get more light, but it may not be useful light. You will find out when you look at a projected image. What you need is even illumination going through all the LCD pixels in a uniform manner. It may be perpendicular to the LCD panel, or it may be converging (or even diverging) toward the objective lens. (If it is not converging, then you need an upper fresnel to make it converge.) But the key word here is "uniform": It does you no good (and probably does harm) to have any of the light not on the same set of paths.
For example, if the reflections don't come to the same focal point as the light directly from the bulb, then they won't end up at the objective lens. This is why good light engines use only a few specific designs. Test your < reflector with fresnels and a piece of paper at the proper focal distances. See if you get a reasonably uniform spot about the diameter of your objective lens, with the paper at the right distance. If you get a lot of other patches of light, then "more light" is not doing you any good.
The four useful light engine designs I have read about are:
1) Spherical reflector + condensor lens: Reflects the arc image back exactly along the direct path, so the condensor lens "sees" a twice-bright image of the arc. Needs both fresnels to converge light toward the lens.
2) Parabolic reflector: Makes a uniform perpendicular beam the size of the LCD maximum dimension, but the direct image of the bulb may result in a hot spot. Needs an upper fresnel to converge toward lens.
3) Eliptical reflector: Makes a uniform beam that converges through the LCD toward the lens. No fresnels, but again the direct light may cause a hot spot.
4) No reflector at all: Just a higher-wattage bulb + condensor lens + fresnels. |
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| King_Martini |
DAVE123:
Looking at the invoice, Surplusshed sent me
B&L copy lens 9-1/2" FL f/4.5 with the text "L3003 Sold out replacement" underneath, so it must be a similar replacement...
Guy Grotke:
Hmm where to start...
Well, the parabolic ( reflector collected the light very poorly. With it, I ended up with a dim center and a bright ring of light on the outside. So my light engine has undergone some changes, one being the addition of the < reflector. This change alone created an even and intense light. I have found that having the condenser lense (alone) at the right distance from the bulb perfectly displays an image of the bulb and text that is stamped into the reflector on the ceiling. Add a fresnel and it removes any and all patchy light (no image of bulb or text on reflector displayed on ceiling, just pure bright even light).
Now I have been testing putting a 6" ruler on top of the fresnel and suspending it over the light while holding the copy lens above it all. I can get a perfect sharp outline of the ruler HOWEVER some of the ruler is cut off. This means problems for me down the road I suspect.
So I move the condenser closer to the bulb so the light radius increases at where the fresnel/lcd will be. In BOTH of the condenser lens heights I am most certainly getting an even and intense light and right now I can get sharp outlines of whatever object I place on the fresnel while holding the copy lens above them.
I just need to tweak the condenser lens height with the fresnel height so I don't end up with dark corners in the projected image. This of course will correlate to how big of an LCD I decide to use. I am designing for a 6"-7" wide LCD.
I am about as novice as they come with this project, just trying to use common sense and hope for the best with the following premises:
1) Create a bright, even light thats radius can cover the LCD
2) Keep the heat down to a very low minimum
3) Keep it all adjustable for tweaking.
So far I feel the light engine is very successful so far. Using one or two fresnel will be be future tests when the time comes.
BTW thanks guy, I really appreciate your help and interest in my progress. From what you mentioned in your post (and from what I understood) so far everything is a gogogo...
Night! |
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| Guy Grotke |
Using a parabolic reflector is an interesting option. Theoretically, you could make one the diameter of the maximum LCD dimension, that would supply a uniform and perfectly perpendicular beam to the LCD. No condensor or lower fresnel would be needed. (In fact, trying to use a smaller reflector and lenses to "blow it up" to the size of the LCD would would be VERY difficult.)
The hard part is the light coming from the lamp: Even with a perfect parabola (and the lamp at the exact focus), the lamp itself would either block axial light to make a central cold spot or else supply it directly and make a central hot spot (since the direct light is brighter than the reflected light).
It may also be very difficult to make a "perfect" parabola. The light reflected near the center would strike the reflector at a pretty steep angle, while the light reflected at the far edges would strike the reflector at a much lower angle. So the reflectance may be different.
One problem is that you can't judge how well you are doing by looking at a piece of white paper at the LCD position: It may look even, but if a region is lit only by rays that are not perpendicular (or converging the same way as all the other rays in a design without a fresnel above the LCD), then that light will not end up at the objective lens.
I think a spherical reflector, consensor, and lower fresnel may be a lot easier to get right, compared to a parabolic reflector. This combination does put about 65% of the available light through the LCD in a useful manner. A parabola would have to be quite deep (and very reflective!) to collect that much light, and don't forget that the rays coming directly from the lamp are only useful near the center of the image, the rest don't hit the objective lens. |
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| King_Martini |
--> snip <--
(In fact, trying to use a smaller reflector and lenses to "blow it up" to the size of the LCD would would be VERY difficult.)
--> snip <--
Guy, must you always be right!!!! Well maybe all is not lost, but I think I stumbled across the problem you mentioned in your prior post.
What is odd is that:
lamp+reflector= even light
lamp+reflector+condenser = brighter light with cold spot in middle
However when I play with the projection lens and a small piece of fresnel (3"x4.5") and put a film negative on top, the fresnel edges wont fit into the lens.
My only thought is that since the light circle my setup makes can cover 6-7" in diameter, using a second fresnel might get everything into the copy lens, guy am I wrong on this?
Otherwise it's back to scratch for me :(
At least I got to the point I could reflect a film negative.
If you have the patience I can use your advice in a few days... |
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| Guy Grotke |
I think I understand why point sources work better than big "blobs" of light. It is true that any light going through a particular LCD pixel (in any direction) that then strikes the objective lens, should then be focused to the same point on the screen by the objective lens. That means that every part of the projected image would be lit by rays coming through many different parts of the objective lens. The problem with that is that the lens would have to be perfect, and there is no such thing! So some of a pixel's rays will end up a bit off in the image.
If you can make sure that the light traveling through a pixel strikes only a very small area of the objective lens, then objective lens aberrations will have less effect on the image. Then you get a much sharper image.
I will try to attach a drawing. The top part shows a point-source design. Each example point (A, B, & C) in the image are lit with rays that follow a unique path for each pixel, so each ray uses only a tiny part of the objective lens.
The bottom part shows a design with a big blob of light source. Some rays like #1 do not hit the objective lens at all. The central ray strikes the center of the LCD and the center of the lens. So far, so good. But the outlying rays (2 & 3) travel through the same central pixel, but fall on outer edges of the objective lens. This focuses them near the central point of the image, but not exactly on it. Thus a blurry image. |
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| Guy Grotke |
>Guy, must you always be right!!!!
No, I'm wrong about a lot of stuff. Just ask my wife! :D
I just have read thousands of these posts on several projector forums, read many websites on optics, tried to remember my college physics, and run some lens experiments. Guess how many sucessful projectors I have built: 0 so far. I have a stripped LCD panel, but no FFC extender to run it. (HINT HINT, JCB!!! Where's that darn FFC extender I ordered? :xeye: )
I have a DIY achromatic doublet I built with surplus shed lenses. I have the ballast, but my MH bulb hasn't arrived yet. On the other hand, the big fresnels I ordered from LL have arrived. So I have been experimenting just like you with a little halogen lamp, trying to fill my transparency film "LCD" with uniform light and getting a very non-uniform and truncated projected image.
Keep trying. Getting there is 90% of the fun. I think you can succeed with a parabola, but it will have to make a parallel beam as wide as your LCD diagonal measurement. And you will have to fiddle a bit to get the central spot the same brightness as the rest. |
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