| mhelin |
| quote: | Originally posted by Henry Braithwai
Do not think the LCD as an optical device, lens or some kind of a multicolored weird filter, as it is not. |
That's BS we are reading on these forums too much these days.
The LCD *is* a very complicated optical device including polarizing filters, color filters and actual twisted neumatics TFT's, transistors which twist the lights polarization angle letting more or less light through the front and back polarizers. |
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| Henry Braithwai |
| quote: | Originally posted by mhelin
The LCD *is* a very complicated optical device including polarizing filters, color filters and actual twisted neumatics TFT's, transistors which twist the lights polarization angle letting more or less light through the front and back polarizers. |
Yes, of course the LCD HAS optical devices IN it in order to work, and you could of course use it as a complec color filter or such, but we are NOT doing that. LCD is an object that has an image on it, just like a dia for example. The LCD itself is NOT an optical device when used in a projection setup. The lcd is the real object and the image on the wall is the fake object on the other side of the lens. That is very very very basic physics. I think that basics are something that is good to know and understand before trying to understand and develope anything else concerning projecting and optics.
Regards
HB |
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| brainchild |
| quote: | Originally posted by Henry Braithwai
Yes, of course the LCD HAS optical devices IN it in order to work, and you could of course use it as a complec color filter or such, but we are NOT doing that. LCD is an object that has an image on it, just like a dia for example. The LCD itself is NOT an optical device when used in a projection setup. The lcd is the real object and the image on the wall is the fake object on the other side of the lens. That is very very very basic physics. I think that basics are something that is good to know and understand before trying to understand and develope anything else concerning projecting and optics.
Regards
HB |
I think you're wrong in this case. If the lcd were the 'real' object we would be reflecting light off of it to make our projection. Instead we pass light through the lcd, and the light that gets projected is being modulated by the panel itself. We treat the lcd as a 'real' object meaning we place it at the focus of our projection optics, but the fact that light travels through the panel and the light is controlled by the panel itself makes the lcd an optical component. It's a semantic argument however...
~cheers |
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| Henry Braithwai |
| quote: | Originally posted by brainchild
[B]I think you're wrong in this case. If the lcd were the 'real' object we would be reflecting light off of it to make our projection. |
Yes, that is doable. You know it as well as I. The main problem of that kind of system is the fact that the lcd is transparent and designed to be backlit, thus the illumination of the screen is easier and much more efficient when illuminated from the opposite side of the viewing point/lens.
| quote: | | the light that gets projected is being modulated by the panel itself |
Well, this is a guess but I am pretty (almost 100%) sure that you cannot "modulate" normal incoherent light like that, you can filter it, and change a color of a light beam or such but the light is not in any kind of a organized and focused pattern before or after the lcd. If it would, you would not need the projection lens after the lcd. With lasers you could do that, with a kind of a laser scanning system with really really sharp red, green and blue laser beams scanning the whole screen you'd get the result where you would not need the projection lens, because the laser beams would be modulated with the pixels on the lcd.
HB |
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| brainchild |
modulate = light is on, off or somewhere in between
optics
\Op"tics\, n. [Cf. F. optique, L. optice, Gr. ? (sc. ?). See Optic.] That branch of physical science which treats of the nature and properties of light, the laws of its modification by opaque and transparent bodies, and the phenomena of vision. |
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| prjctr_builder |
HI guys...
I am selling 2 new ballast kits...
1) Holophane 400W metal halide ballast
2) Advance 250W metal halide ballast
they are both still in the box...
If you need any one of these, please email me at ikutuyev@sbcglobal.net
thank you:) |
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| tmitch007 |
If a BenQ measures 15" diagonally, what are the "real" measurements once stripped? Width and height and Depth?
I'm building my enclosure before the BenQ is delivered.
Tom |
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| jcbklyny |
| The measurements of active screen area will not change once stripped. If it's labeled as 12x9" active area... that is the actual size of the LCD panel plus about 1/16 of a inch for the outter rim. It would be wise to wait for the LCD before making your mounts. Because besides the actual LCD size you may have to make changes when mounting the PCB and power supply that connects to it. |
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| tmitch007 |
Did you ever work out the problems with that 508mm fl lens that you bought? I used the caclulator and that's exactly the lens that I need also.
You said it makes the right size image, but the corners were messed up. Messed up how? Did you ever play around with it and get the corners right?
tmitch007 |
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| forestsoul |
I've been reading this site for the past week and I'm looking at trying to build my own projector sometime. Right now I'm looking around for parts, but I have a question:
I was wondering if anyone has tried a headlight reflector from a car or other vehicle as a reflector for a Metal Halide or other bulb. Anyone think it could work?
Thanks :) |
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| allinside |
Hello
I m sorry, i m french and my english isn't very good.
Here is our web adress http://allinbox.free.fr
We are a small french team and we work on the same project.
Have a nice day |
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| diylabs |
| quote: | Originally posted by mhelin
The LCD *is* a very complicated optical device ... |
A while back, I found an excellent explanation of how LCD's work at http://www.howstuffworks.com/lcd.htm. I HIGHLY recommend reading through it - it's written in such a way that it appeals to people with all levels of current understanding about LCD technology.
| quote: | Originally posted by tmitch007
Did you ever work out the problems with that 508mm fl lens that you bought ... You said it makes the right size image, but the corners were messed up. Messed up how? Did you ever play around with it and get the corners right? |
I must admit that I didn't look back to ready about the 508mm lens that you're talking about, but I'm almost certain that these problems are because this is a single lens instead of a doublet or triplet assembly. Single lenses are simply not going to cut it for video projection - they're made for focusing near-point-sources, which our LCD panels are certainly not. You really need a doublet or ideally a triplet lens to project good video. Of course I sell them on my website, but feel free to look for them elsewhere - I didn't leave this comment to try and make a buck.
| quote: | Originally posted by forestsoul
I've been reading this site for the past week and I'm looking at trying to build my own projector sometime. Right now I'm looking around for parts... |
Okay now I'm gonna try to make a buck (jk). I've got a pretty good collection of parts on my website at www.diylabs.org/projector/ , but you can find various parts elsewhere. The two advantages that I think are useful about purchasing from DIY Labs is that you can save money on shipping if you're going to purchase more than a couple of items by emailing me with your order instead of ordering individual parts from multiple sources, and also you can save money because many of the parts that us DIYers need are often very expensive if you purchase from another vender - I sell my parts very close to "at cost" ... I make no money at all on some of the parts I sell - especially during sales.
Even if you don't want to buy from me, feel free to email me if you need help finding a part - I've got a pretty good list of places to get certain parts.
| quote: | Originally posted by forestsoul
I was wondering if anyone has tried a headlight reflector from a car or other vehicle as a reflector for a Metal Halide or other bulb. Anyone think it could work? |
I have thought about doing this, but the refelctor in the headlamp assembly that I have is ceramic, so it would surely crack if I tried to drill it for use with a double-ended metal halide. There are small bi-pin metal halides that look very much like a halogen auto lamp, but they are too low power/output in my opinion. The main problem with using car reflectors is that they are too big ... a good reflector would be about 3" in diameter or less - roughly smaller than the projection lens you'll be using. Another good way to boost output, regardless of the reflector you're using, is to add a condenser lens. If you go with the condenser lens that I carry, then this is a really inexpensive upgrade, too. One last thing I'd like to add is that I think people are putting too much emphasis on the exact shape of the reflector. Yes - there is an ideal shape and size for the reflector, but perfect reflectors don't exist and really good ones are usually very expensive. Most people who have tried my $8 soup ladle reflector find that it gives noticeable increase in light output. I've found companies that will manufacture better reflectors, but usually at a cost of around $100 per reflector! I'll stick with the soup ladle! On the other hand, it would be awesome if someone could figure out a different inexpensive alternative that worked as well - making those reflectors is a pain sometimes!
As a side note, I hope that everyone knows that I keep mentioning my parts and services in an attempt to help, not to profit. I like profit just as much as anyone else, but that's not my main purpose with my website. If anyone ever emails me wondering if there are alternate places to get parts, I'll be very open with advice about where else you can get certain parts, but typically I believe that I have the best prices online because I don't mark up my prices any more than I have to in order to stay in business. In fact, you benefit from most of the markup in the form of frequently updated FREE information on the website. The rest of the money (which really is very little) I use to try out new ideas and report on them so that other people don't have to waste their money trying something that doesn't work.
Hopefully everyone had a Happy Thanksgiving! If anyone needs anything from me, please email me at diylabs@hotmail.com since I don't visit the forums on a regular basis - too much to do and so little time! |
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| mathias |
| I have tried a headlight reflector, actually it was an extralight. But it was the most stupid thing I have ever done, it was expensive too. As a reflector for parallel rays it works very good, but for a 15" TFT itīs useless, as you can see it has a big hole in the middle where you place the bulb, but if you want the light to spread from the reflector to fit a 15" TFT you have to move the bulb a little bit backwards in the reflector, when you do that the rays that should be reflecting straight ahead comes in the hole, and the result will be a circle of light on the TFT. An other thing is when you use it with a halogen bulb, you get a very very hot spot that destroys your tft in a second.:hot: |
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| diylabs |
| Actually I think that a condenser lens would probably fix your problem with the hotspot ring in the middle. You could additionally try to use fresnel splitting, which also does a terrific job of evening out light. Since I don't know for sure whether a condenser lens would fix your problem or not, I'd be willing to send it to you free of charge as long as you pick up the shipping expenses. It would be great if you could try out the condenser lens and let us all know if it fixed your problem. I don't know for sure how large that reflector is or how tall your lamp is, so there is a change that you couldn't get the condenser lens close enough to the lamp to competely eliminate the hotspot, but I'm willing to eat the cost of the condenser lens in order to find out. Let me know if you are interested (emailing me at diylabs@hotmail.com is best). |
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| ace3000_1 |
heya allan, im interested in trying out your condenser for different aplications for free, ive got 12 different types of condensers here i could maybe make u a reconmedation on it if u get them custom made and what changes to make to the actual lens, (if there was a problem with it) now if your interested email me at ace3000_1@hotmail.com
Trev |
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| [RPD]-Killer |
| quote: | Originally posted by allinside
Hello
I m sorry, i m french and my english isn't very good.
Here is our web adress http://allinbox.free.fr
We are a small french team and we work on the same project.
Have a nice day |
There are some nice pics of a projector build with aluminium.
Some technical improvement and this design would really rock! |
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| diylabs |
| that's a really cool lookin' projector. How does your lens focus, or is it mostly a fixed-lens system? How did you construct your projector (did you use someone else's design or go for it on your own). Thanks! |
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| [RPD]-Killer |
| I found those pics on the french website mentioned in the quote above. My own projector is still in the first stage of construction - in my mind... :) |
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| dracul |
| Can you tell us how to get hold of the designer creator of the aluminium projector? |
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| Kim |
150W-T-HQI lamp (6500k lamp),
8.4 auo pannel & displayworks adc board
Case : acryl 5t
f: 34 frenel lens
OHP lens
size 450 * 350 * 250 mm
4 gain screen |
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| [RPD]-Killer |
Maybe I found a replacement for the collimating fresnel lens. I have no idea what this lense is called like in english, but in german it's called "Integrationslinse". On Google you can't find **** about it with this word.
Some german guy wrote about it here.
Looks like this lense kills the hotspot effect. ;) |
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| diylabs |
| My condenser lens at www.diylabs.org also kills the hotspot effect. Also, splitting your fresnel lens seems to greatly improve how even your light distrobution is, but I don't know if it would cure a hotspot. |
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| dracul |
| What hotspot are you guys talking about? I thought we were suposed to get decent commercial quality images with these optics? |
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| peri |
[RPD]-Killer,
Could that possibly be a fresnel lenslet array? They are available--I've wondered from time to time if they would be helpful in making the light more even against the LCD--especially if more than one light is used in the light engine. If I remember correctly the lenslet arrays are available in a variety of forms (hex, rectangular, etc.). But I have never gone ahead and experimented with one. I do have one on order--I'll try to play with it in the next month or so. Should be interesting though...?
p.s. I'm new to post here--right now I am working on a rather different type of setup. If it works out, I will post images of it's setup and results. If not... well I'll just keep my embarrassment to myself! :cool: |
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| dracul |
| And why are we geting a hotspot anyway? Is the ideal light source a laser beam bright enough but hitting only the center spot of the first fresnel say a half milimiter diameter? |
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| diylabs |
Indeed you should! I've never had any problems with hotspots with my setup, but the hotspots are usually a biproduct of the placement of the elements as opposed to their quality. For example, you'll probably get a hotspot if you put the lamp too close to the first fresnel lens or if you have a reflector that isn't positioned correctly (usually too far away).
If you ever purchase a DIY product and it doesn't work like it should, I will always be available to help you figure out if it is a positioning problem. If a part is bad, then of course I'll simply buy it back from you. I'm hoping that DIY Labs will be around for a while, so I'll always do my best to ensure that you are happy with DIY Labs! |
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| freeupyermind |
| peri dont keep ne thing to yourself, i personally love different designs and think that whether it works out or not we should know where you were going with it so we kan help you or rather steal your designs and make it work and call it our own:D ! |
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| diylabs |
i agree. Letting the community know about your ideas can be invaluable for many reasons. Obviously if you find something that works, we all want to know also, but i'm equally interested in knowing what doesn't work. That saves others the time it takes to try a method that we know doesn't work - that helps us all find something that does work much more effeciently.
With regards to peri's lens, i think you or anyone else should definitely try it. The only reason I haven't tried it yet is that i just don't have the time! Let us know what you find or if you have any questions. I know that www.surplusshed.com often has those types of lenses.
Happy new year everyone! |
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| peri |
Hello all :-)
Yes, I checked with Surplus Shed (I've purchased a few lenses from them already) but unfortunately Fred wrote back indicating that they were not available at the moment; however, I am to check his site (daily? weekly? I'm not sure about the frequency) and perhaps they will one day be available. There are alternative sources, though.
I would love to post about everything that I'm doing--as I go--but I think I would be more comfortable posting after something is rather more complete, when I have more to say other than "testing this out" etc. The reason being: I have spent literally the last 5 days reading every post here (yes, there are a few, and yes, I did have plenty of free time!) and gleaning as much information as I could. I have learned a great deal from all of the posts, to be sure. However, I would rather post something different, something new, instead of just a repeat of prior posts :xeye:
Needless to say--I am photographing everything as I go, as much as I can. I have a few different LCDs and lenses and bulbs and ballasts (the shop next door is an electrical shop, and the owner likes to experiment, so I have some help there). Much of it is still on the way, a bit of it is here. As soon as everything is here I can really begin testing different combinations. Plus, I have a few old projectors, both overhead and slide, and I'm interested in seeing what different combinations I can pull from those sources, just for fun. Right now, my photographs are mainly just of components, not of any casing or shells.
Regarding the cases or shells, I've drawn up 2 general plans--just pencil on paper, no "blueprints" per se yet (won't do that unless something works). One is for a larger LCD, and one is for a smaller LCD--12 to 14" and 4 to 6" respectively, thereabouts. They are--at least in my opinion--a bit "unusual" :blush:
I was interested in a 10.4" LCD, but apparently most of them are lower resolution--I am trying to stick with XVGA and up. My first preference is for contrast of 400:1 as a minimum; anything higher preferred (my experience is that, dollar for dollar, higher contrast gives a better picture over any other consideration--at least for movies). By the way, does anyone know anything about this: http://cgi.ebay.com/ws/eBayISAPI.dl...egory=1498&rd=1 -- !NeW! 10.4 TV screen only DVD LCD monitor--. I have emailed the person twice, but haven't received a response. I have a JILI type LCD controller card--which in theory would work with a compliant LCD panel, if that is indeed such a panel. However, I am concerned that the item listing indicates "TV" rather than monitor--I am thinking therefore that the quality of the LCD would be lower--but this is just a guess (based on my mentioned research into 10.4 LCD available specs).
Alright, I've rambled on a bit. Hope I haven't sounded too stuffy! If I do, it's probably because I'm a crotchedy old grandmother!
Best to all--hope everyone has a fun and safe New Year's,
-Peri |
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| diylabs |
I like your philosophy about trying a method before commenting on it. If you are photographing your work, then I think you can help everyone out a lot! If you ever need anything (parts, advice, or otherwise) then just let me know by emailing me at astaples@diylabs.org. If and when you get your projector running, I could create a section on my website for your projector, including steps you took, results, and anything else you might want to contribute.
That LCD panel that you were asking about might be a good panel, but you'd need a compatible LCD controller for it since it doesn't come with one. I've never put together my own LCD/controller kit, but I do know that you'll need a power supply (usually easy to get or make) and you'll need to make sure that the LCD and the controller support the same resolutions and that the controller you use has the correct connector for the LCD ribbon cable. If you do use this LCD panel, just make sure to keep it cool by pusing cool air over both sides. You may even want to use an IR filter or a cold mirror. www.surplusshed.com has a few cold mirrors for a little money right now. I got one and it looks pretty "cool" ;) |
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| mccamp82 |
Hi,
I am new here and I have a few questions for you guys. First, I wa wondering if there are any basic dimensions to use when building a custom box projector. For instance, are there specific basic distances used for mounting the bulb, fresnels, LCD panel and projection lens? Like how far should the first fresnel be from the bulb? How far should the LCD be from the fresnel? How far should the second fresnel be from the LCD? How far should the second fresnel be from the projection lens? Does having a reflector and condensor change these dimensions at all?
Couple more questions:
Do any of you have any good pictures that show how you mounted the LCD and Fresnels in to the box? I have many different ideas on how to do this, but I want to know the most common way.
Is it better to use a 4oo watt MH bulb or a 250 watt MH bulb? I am sure the 400 is better for daytime watcing, but doesn't it get a lot hotter? They are about the same price, so that doesn't really matter
Does the triplet lens used for the prjection lens have adjustmesnt? I guess what i mean is...How do you focus the image when projecting it? Does the projection lens turn similar to a camera lens or what?
Has anyone used the XGA Theater to hook up DVD players and TV tuners to your DIY projectors? Does it work well? What does it do exactly?
How do you change the contrast after you have already built the enclosure? Do you open the box and change the contrast a little at a time?
Well, that'll do it for now. Thanks for you help. I am starting to understand all of this, but still need some of that newbie help. I am probably going to buy the guide at lumenlabs.com. Then one day I may customize it or something.
Thanks again.
Later |
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| forestsoul |
| Just wondering if anyone knew the stats of the Infocus 2600 projection panel. Anyone have any experience with one or consider it a good enough panel to use, please lemme know. Thanks. |
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| diylabs |
| I'm not familiar with that paricular panel, but as long as it has the video inputs that you need (VGA vs. RCA/Svideo) and it can render at least several thousands of colors, then it would be okay. Ideally you'd want to have a panel that can render upwards of 1 million colors, but I've built projectors that were fun to use that could only display 4,000 colors. If you have an eBay auction link, feel free to email it to me if you want an opinion about a particular panel - sometimes I see fine print that others don't see or perhaps I'll have used that particular panel before, in which case I can give better advise. There is also an LCD read me on my website at www.diylabs.org/projector/ if you click on the "LCD" link in the site's menubar. |
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| forestsoul |
Thanks for the reply and the link.
I finally found some info on the panel and only needed two words to tell me it isn't the type of panel I'm looking for: "passive matrix"
:whazzat: |
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| The Alchemist |
Hi you guys!! Again another, nothing knowing, newbie;
My name is Frank live in Holland and study chemistry.
I have read my wy around this forum and I must say it is GREAT!! Big applaus for you all. I realy learned a lot and learing still more by reading more topics. I realy love the subject; single vs multiple lightsources.
Also one thing i have to say is: It is hard for a newbie to read up to 114 pages of replies.
Ok i also wanna ad something to the board. I found more information on the MOVIN 2001/2002. It is still sold in germany (second hand). It is the last single panel projector (as early was told in this topic)
Contrast: 500:1
ANSI-lumen: 250
4x50W Xenon lamps |
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| The Alchemist |
Ok my computer was faster then I wanted it to be so some more information through pictures!
Oh the size is 11,5"x11,5"x23" Not very big |
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| mathias |
| I have now for a long time though about how to get the most light out of the bulb, the OHP-design most of you are using is only using a very little bit of the hole light the bulb produce. Even with a very big condenserlens you loose over 40% of the light. The new idea is to use a normal PAR30 bulb, cut the bulb and place the HID-bulb in the middle, move it a little backward so you get a wider spread angle. The problem is that you canīt get as wide angle as with the ohp-design, so it will only light up the middle of the screen. The soulotion is to move the hole buld and reflector backwards so the light fills the hole lcd. But if we move the light backwards, the fresnellens will focus the light in the wrong place, depending on the focuspoint of the objectlens. And the big new thing is to remove the splited fresnel in front of the lcd, this will restore the light focus point to the objectlens. The only problem with this light-design is that the distans from the bulb to the fresnellens will be the double. But there is a soulotion to that also, use a mirror in 45 degrees angle, and the distans is the same as before. Iīm using this thing now and itīs very bright only with a 150W HID bulb. You can use this design even with small lcd:s. Itīs time to leave the OHP-light engine ! |
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| mathias |
| There is another very nice thing with this design, the reflector is a coollight reflector, so all the heat is going backwards, so you donīt need to cool the lcd any more !:bigeyes: |
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| diylabs |
what type of bulb are you using in that setup? The only similar lamps that I could find were 150w and I could never find the ballasts for them. I'd appreciate your help. Thanks!
I think there may be an issue with using only one half of a fresnel...
the focal length of a single half of a fresnel lens probably doesn't allow for this configuration. Recall that the fresnel lens focal length has to roughly match the focal length of the objective lens that you are using. I suspect that if you do things this way, the light will converge onto a space that is way beyond the objective lens - if it even converges at all.
Having said all of that, I agree with you that our light engine is still inefficient. Adding an "okay" reflector was the first step to improving it; then adding a good condenser lens helped a little, but now I think it's time to go back and find a different reflector. I'm currently working with a manufacturer to see how much it would cost to have one made that would work with the condenser lens in a much more efficient system. I fear that it wouldn't be cheap, so nothing may come of this. For the meantime, the soup ladle reflectors really do work pretty well. No matter what we do, we'll never have 100% efficiency - I assume that theoretically we can't even come within about 20% of that, but losing only 40% of our initial light really isn't too bad! |
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| mathias |
The bulb is a cdm-t 150W, itīs equal to a HQI-T 150W, but you can also find HQI-T 250W in the same size, but they are pretty new once.
I have measured the focuspoint of the splited fresnellens, and itīs the double the orginallens. The design works very good so the 1/2 fresnellens do itīs work. But itīs important to turn it right. Another thing I have noticed is that I canīt see a singel circle from the fresnell that I did before. |
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| mathias |
I maybe need to give you more information on the PAR30 light engine design. To get this thing to work, you can NOT use whichever you like of the two half splited fresnellens. It must be the half close to the bulb, that half have a focal length that will fit the objectlens exactly (you can have the objectlens at exactly the same place as before.). To get the best picturequality you have to turn the fresnelhalf around, the grooves must be towards the bulb, otherwise you get rainbow pattern at the edges.
The reflector Iīm using is from a PAR30 halogenbulb 75W (OSRAM), it must be the 30 degrees version. You donīt have to use the coollight version, the normal version of the bulb is much cheaper, but the lcd will get hotter, but try the cheaper first, it can be a bit tricky to cut it right the first time.
An other thing, donīt use a condeserlens with this design, it will never work, condensers collect light, we need to spread it, with this reflector design.
This PAR30 design is my final design after 3 years work with home made projectors, and I donīthink itīs possible to get more light from the bulb, than this will give you. Those PAR30 reflectors are done professional and done to give as much light as possible from the bulb, they are also made to spread the light even on a surface. I hope you all try this design, it will give you a nice boost in brightness. |
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| diylabs |
| but don't 74 watt halogens only produce about 4,000 lumens at best? |
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| mathias |
| A 75W Halogen PAR30 30 degrees give 2400 cd. I if you change that 75W bulb inside the reflector with a 150W-250W HQI, it will give much much more. Lumens is not used with reflectorbulbs. |
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| The Alchemist |
Using a parabolic lamp (PAR) has been in my mind for some time now. Only the heat i think in a normal par would be a problem. BUT i found a site: http://www.lampbrokers.co.nz/parpdr.html which cleams to have a halogen par lamp which can be build into a enclousure. The 100watt version give's off 10.000 focused lumen, which is enough i think for a 7" projector. I could not find a price yet. Could this be an option for a light source?
What about the new MH PARs? to expensive? |
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| mathias |
| I used a 100W halogen PAR bulb in my first projector, with a 5" TFT 3 years ago, but one day I droped it in the floor and it was dead, but a can tell, it was good that I droped it, because I almost burned up my 5" TFT with that bulb. So if you are going to use it try the coollight version, that will maybe save your lcd. But anyway I donīt think the light output will be enough from that 100W bulb. If you replace the small halogen-thing in the middle of that bulb and place a 150W HID/HQI-bulb there instead you get 8 times more light ! |
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| diylabs |
| quote: | Originally posted by The Alchemist
What about the new MH PARs? to expensive? |
I'm working on finding 250 watt mini MH lamps that would work in such a reflector. Also I know of some different manufacturers that make the reflector with any spot angle you wish, so it wouldn't be necessary to chop a halogen reflector and risk breaking it, nor would you need to place the lamp far from the fresnel unless you needed to. The only problem right now with these 250 watt MH lamps is finding a supplier. I can get plenty of the 150 watt kits if anyone wants them, but I really want to get the 250 watt babies - those things would be BRIGHT and without much heat (because they are metal halide instead of halogen and because the reflector can be a cool reflector as Mathias mentioned).
Also, about reflectors for a moment, I've determined that a spherical reflector is ideal for double-ended lamps if at all possible. I will have a diagram about this on my website in about a week (too many things to do right now), but I really do feel strongly that spherical is the way to go. |
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| mathias |
I agree with Diylabs on the fact of the double-ended lamps, the only way to use them is with the ohp-design, but again, you loose much light, as the picture below show.
What I wanna say is that you will get the same light output from the projector with a 150W 1-ended bulb in a PAR-design, as you get with a 250W double-ended in a ohp-design. Because the 150W bulb is much cheaper, here in Europe anyway, there is no point using a double ended bulb, but if you already have a double ended, keep using it.
250W 1-ended bulb, is availible here in Europe as MSD250 Philips and HSD250 Osram. But if you can find them in USA I donīt know.
Also, do you think you can get a manufacturers that makes the reflector with a 90 degrees angle, because thatīs what we need if we donīt want to move the lamp backwards. The widest angle I have seen is 60 degrees, there must be a reason why they donīt make it wider. |
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| msx-2 |
| a osram hsd 250 has a life of 2000 hours and a price of around 250 dollars, its better then to buy a real projector(same price for lamps , ) |
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| chasse |
mathias
I am building a projector with a 7 inchs LILIPUT.I am going to use a 150 watt cdm single ended lamp,i have cut two fresnels 4 inchs by 7 inchs and put them together between two pieces of glass to get six inchs focal lenght to the bulb.Does the beam coming out from the PAR 30 be enough to cover the back fresnel?
How do you remove the rear of the PAR30! |
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| diylabs |
jcbklyny and others,
I like the 250 watt single ended lamp even though it costs about $75. It has a higher color temperature and would probably be easier to use a reflector with. Do you happen to know what the diameter of this type of lamp are (they still look too wide to be used with a common PAR reflector)? Also, would anyone be interested seeing them available at DIY Labs for $65 if I can get them that cheap? I won't bother ordering them if people don't think it's worth the extra $$, but I'll be glad to help by offering them cheaper if there is interest in it. Please email me back at diylabs@hotmail.com or post something here if you think I should look into it. Thanks! |
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| jcbklyny |
phillips and osram have pdf specs sheets on their site. I have my own contact for ordering those lamps, so I wouldnt be interesting in buying somewhere else. They are both as small as the phillips 150 watt single ended as I have seen and used them both.
Those 2 lamps are used in almost ALL Intelligent stage lighting units made by high-end and martin lighting.
[edit: I attached one of the phillips 250/2 lamps I have on hand. |
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| The Alchemist |
That lamp look great. But i am still not convinced that only MH lamps can be used in the projector. I still like the halogene par idee. It is possible to calculate how mutch cooling (fan's) you need, I will search for the book and do the calculation. i will post the answer soon.
by the way: http://www.73.com/a/0069.shtml Is this something? Maybe voor DIYlabs? (They don't sell to individuals) |
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| mathias |
Feel that I need to explane how to cut the PAR30 lamp without to crash it. The first thing you must have is an angle-cuter, with a disc to cut ceramics (picture 2), and the angle-cuter must have some adjustment for the speed, if it rotate too fast you will crack the lamp in wrong place.
1. Remove the metal base with a scissors and a small screwdriver.
2. Start to cut the back of the lamp at the place I show in the picture 3, if you cut it more backwards the HQI-bulb will not fit. Cut it thinner and thinner equal round the lamp, at the end it will break in the place you cut it, if itīs equal thin round the base. If you cut too much at only one side, it will break in the wrong place and a part of the reflector will get lost.
3. Remove the frontglass, this is the most difficult part, the frontglass is extremly hard, so you canīt just smash it. Use the angel-cuter and cut a stripe across the lamp (the green in picture 4) then cut a little at the edge a bit from the stripe, the front glass will break in small parts that you easy can bend away.
Use some sort of protection goggles, very sharp glasspieces can hit your eyes, normally there isnīt any glasspieces with this bulb but, but be carefull.
The hole in the middle is 21 mm wide, and the HQI-bulb is 20mm, so it canīt fit better. |
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| mathias |
| Chasse, yes the light from the PAR30 will cover your back fresnel, itīs very easy to adjust the light angle from the bulb so it fit all size of lcd:s. Move the HQI-bulb 1mm backwards or forwards, in the PAR30 reflector. 1mm is doing big diffrents in light angle. |
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| diylabs |
| nice - i can't wait to try the 250 watt single-ended |
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| The Alchemist |
As promised.
Ok let me first say, that this is a aproximation. The real stuff is mutch more complicated.
So we want to calculate how much flow our fan has to give when we use for example a 1000 watt halogene. So lets start.
What we want to calculate is the volume air per second we are gona need to cool the lamp. So we rewrite the equation into this:
We can now fill it in:
Let say that we lose 90% of our halogene light as heat so
Q=0,9 kW. Cp and the density of air we know. Let say that we want the temperature inside to be max. 40 C and the outside temperature is 20 C. So the temperature difference is 20 degrees.
So the flow we need is ~0,05 m^3/s that is ~90 CFM (cubic feet per minute)
This would be correct if there was no resistant to the flow, but we al know that this is not true. The resistant causes a higher pressure which causes a lower flow. (see fig)
So if you want to be safe, you have to at least double the needed CFM.
So in this case 2x90=180 CFM
A normal 60mmx60mm fan http://www.coolerguys.com/ProductDe...x?productID=485 only moves ~18 CFM. :D
A 80mmx80mm fan does ~39 CFM
And the best i found was a 120mmx120mm fan with 78 CFM.
"Oh no problem! I just install three of them!!"
This is not true, 3 fans does not mean automaticly 3x the flow.
This depents if you place them in serie (so side by side) or in a push and pull situation. But to now which system to use can only be measured and not predicted.
So a 1000 watt halogene can be cooled but you are taking a big risk.
For more information:
http://www.comairrotron.com/engineering/airflow.htm
The next graph shows the relation of CFM against kW halogene.
Remember. To be save double the CFM value.
Ps. This is just a calculation in real live other factors as conduction and raddiation also take place, so some spots in the projector can still get a lot hotter. |
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| The Alchemist |
No reactions? I would realy love to hear if people measured the heat (temperature in the cabine), so if this makes any sence.
I hate myself at te moment, i went to a fleemarket last saturday and i bought an ballast for MH. The transformator, starter and condensator where nicely put in a metal box so i could't see how many watt it was. There where two types one with only the text 70VA and one with the text 250VA and i bought the 70VA one (for less than 5 dollar). After opening the metal box a read that 70VA is the same a 70W (P=UxI) :S. So I could have had a 250W ballast for 5 dollar and now i am stuck with a 70W one :S. Can i trow it away? or is 70W (55000 lumen) enough for a small projection (90" or so)? I now it will not be a bright projection with aprox 55 lumen output. |
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| The Alchemist |
I found this: (on the site: Image Brightness guide for projection )
Here are some reference figures:
Movie Theatre with emergency lights on approx. 50-80 LUX
Typical office theatrette 120-150 LUX
Ballroom 150-200 LUX (dimmed for presentations)
Training room dimmed 200-250 LUX
Training room full light 350-450 LUX
So if I only gona project 0.75 square meter and darken te room it will be enough? |
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| mhelin |
There's one design that I've been considering lately. That's using a parabolic reflector (with the lamp in focal point) and a negative fresnel after that with the same FL than the lower fresnel have but with negative sign.
As reflector you could use PAR64 or PAR56 relflectors which are widely available, cheap (< $/10) and can be fitted with 150/200/250W type MSD / HSD bulp with a RY 9.5 connnector (I've seen one with double-ended rx7s connector too). That way I think you could get first the collimated light from the reflector (well, almost, as the direct light isn't very collimated) and then widen the spot with negative fresnel for the fresnel & LCD. That way also a larger LCD (15") could be used, with good efficiency, too. |
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| mhelin |
| Also if you move the bulp backwards you can widen the spot. PAR64 has 64/8 = 8" diameter, so I guess it works directly with 7" and smaller LCD's, and for 15" you need to back the bulp just a little (I'm not sure if it will work without the negative fresnel or not). |
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| mhelin |
How about this 12" parabolic reflector?
$15.25 |
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| The Alchemist |
I found This programm.
it is a java applet where you can see what happens when you change the distance or size of you (spherical) reflector and wat happens when you add a lens.
As I can see it: your light source in the center of your spherical reflector is the best way. |
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| mhelin |
| I had something like this in my mind (this without negative fresnel, bulp inside focal point of speherical or parabolic reflector). |
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| mhelin |
This with the collimated light source (spot) and negative fresnel / lins.
The frst without neg. fresnel surely suffers from hot spot in the middle of the image. |
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| mhelin |
| This is the current design with point source and bulp in center of the spheerical reflector, without condencer lens, split OHP fresnel (=two fresnels). |
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| mhelin |
... and finally with the condencer lens.
- Mikko |
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| mhelin |
| ... and this is the problem with the parabolic / spherical reflector with the bulp inside the focal point. There are virtually two vertical point sources ... |
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| mhelin |
With negative fresnel some of the light is lost but image seems better.
Nice Java prog. |
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| The Alchemist |
Ah,indeed. The program only uses a (almost) half point source.
As i see it; you loose a lot of light when you place your lamp at the focal point. Or atleast the picture wil be blurred.
Place the light source in the middle of the sphere would be the right way i think.
But also then, the exact middle has to be found otherwise you also get unwanted results.
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| mathias |
Itīs a very nice program you have found ! But itīs only use the half light from the point source, what about the light going up and down wards ?
What you are simulating is a double-ended bulb or a halogenbulb. A 1-ended bulb has the most light going up and downwards because you have turned it 90 degrees. As you can see in my diagram on page 117, a 1-ended HQI-bulb doesnīt spread the light very much directly from the bulb, the most light will bounce in the PAR-reflector. The light directly from the bulb will go in a straight beam to the fresnelllens. |
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| mhelin |
| quote: | Originally posted by mathias
A 1-ended bulb has the most light going up and downwards because you have turned it 90 degrees. |
So you think that when using a bulp inside the focal point the direct light will not be a problem? How about if you use HSD/MSD type MH bulps? I must order one PAR64 (or PAR56) reflector to try with it.
Maybe it's possible to get the source code for the Java app and modify the light source. |
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| The Alchemist |
A PAR reflector is a PARabolic reflector and that is diffent for the spherical reflector. And I agree with mathias that this program can only be used for dubble ended tubes. I found the orginal adress of the program including mail adresses from the makers. So go on and mail them, maybe they can add a parabolic reflector to.
http://webphysics.davidson.edu/Appl...ics4/intro.html |
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| mathias |
I canīt see any problem with the bulp inside the focal point, I get a very sharp picture with my PAR30 reflector, the direct light beam from the bulb actully compensates the light that should bounce into the hole of the reflector.
I havenīt seen any spread-data for the HSD/MSD-bulbs, but I think they works the same way, because of the arc-tubes edges. |
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| danrufus |
what about this lens setup for a 7" LCD?
PAR30 + 150 CDM-T + Fresnel + LCD + Projection Lens |
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| mathias |
I think that is the absolute best way you can build a diy-projector. But use the coollight version of the PAR30 when using a 7" tft because you press much more light throu a 7" panel than a 15" panel. The 7" will get much more hot than a 15" tft. Of course you can build it like Ace do, with a ohp-setup with a strong condensorlens, but that will be around 40% darker than the PAR-design.
A PAR30-coollight version with a 7" tft will be very bright,very quiet, (we donīt need to cool the lcd so much) and small.
Can we wish for more ? |
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| ace3000_1 |
| quote: | | Can we wish for more ? |
ahhhhhhhhhh more room? lol in my design i dont have a fan on the lcd so it wouldnt make it any quieter, the light would actually run hotter in your design being the reflector getting so hot from filtering ir and therefore u would need to cool that very eficiently, i do have a design for a par30 type system, ill bring that out later on if i keep going with projectors, the size of the projector will be the same mine is now and will use a cold mirror.
Trev |
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| mathias |
I donīt think you have to cool the reflector so very much, the reflector is made to handle very much heat, the orginal 75-100 halogen thing in the middle of the PAR-reflector gets much warmer than a 150W HQI-bulb. I think the only fan needed is a fan that pull the warm air out of the pj-case.
But I think the main reason to use a PAR30 design is that it is cheap and easy to find part for. They have PAR30 bulbs with a coollight reflector in all lampsshop, but you have to ask for it.
A PAR-design use all light you can use from the bulb, and we need all light we can get!
I bought a commercialprojector yesterday, I couldnīt resist, the price was only what you pay for two 15" tft monitors, and that unit is marked with 800 Ansi-lumens, and itīs much much brighter than my DIY-projector even with the PAR30-design, so a DIY-projector will not be brighter than mayby 150-200 Ansi-lumens as most even with a 250W bulb. |
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| ace3000_1 |
| quote: | | so a DIY-projector will not be brighter than mayby 150-200 Ansi-lumens as most even with a 250W bulb. |
hmmm u might want to bring that up with cruser as his is totally watchable in the day, his must be about 800-1000lm i recon, anyway about the reflector, to me i think the parobolic design u have is the best for the cdm-t bulb, the reason why is because the cdm-t's center arc tube is ceramic, no light can pass through it when using a spherical reflector as its not clear, using a parobolic in the type u have chosen is the best for that bulb as the light from its sides can get freflected forward, in the spherical its blocked when the bulb is at the focal point as the light cant pass through the ceramic center, so realy your reflector is the best and the reason above is 1 reason why its brighter, the other reason is because of the reflectors shape and size, it can capture nearly all of the light at this size there fore giving us a gain of light output, as for the cdm-t being used on a shperical reflector u cant run it at its focal it must be off set either in or out of focus to get the best results so the light can pass under or over the ceramic arc tube, now with a 250w hqi they have clear arc tubes, the spherical reflectors on these work wonders as the reflected light can pass though the arc tube, u wouldnt get much gain with a paroblic reflector of this design on a 250w hqi, being only the light that isnt captured by the shperical reflector caught by the parobolic, then u would also have a problem with a double ended bulb as the socket would cause u a shadow in this configeration, the best reflector to use is an elliptical, they arent cheap and hard to find, only then we will be able to use 90% of the light source, so realy i think for a cdm-t setup the parobolic setup u have designed mathis is the way to go, and for the 250w hqi the spherical is the way to go.
As for the heat it will be very hot, anything that filters or absorbs ir will take the heat, that reflector will get nearly as hot as that bulb after a couple of hours use so an adequite cooling system would be required, thats somthing thats easy to over come with abit of common sence and the right design structure.
Trev |
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| ace3000_1 |
| quote: | | I donīt think you have to cool the reflector so very much, the reflector is made to handle very much heat |
Very true and so are condensers but that reflector will heat other things up, just like a condenser does, anything metal conducts heat so what u mount that metal too will get the heat from the metal mounting holding the reflector, a cleverly designed metal heat sinking frame would be the go to remove the heat from the source.
Trev |
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| The Alchemist |
| quote: | Originally posted by ace3000_1
Very true and so are condensers but that reflector will heat other things up, just like a condenser does, anything metal conducts heat so what u mount that metal too will get the heat from the metal mounting holding the reflector, a cleverly designed metal heat sinking frame would be the go to remove the heat from the source.
Trev |
I didn't know that the source of such tubes (HQI-TS and CMD-TS)
where not clear, thank you for telling. (I had almost bought a spherical reflector).
About the heat disposal:
What about taking a metal grid:
like this and use it in this way:
Ok we have to find a way to block the light going up. |
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| ace3000_1 |
hmmm maybe my new idea will too lol mathias do u have msn messenger? i want to talk to u about this.
nice post AL by the way, maybe we could use a stainles steal funnel to make a wider spot beam for a reflector.
Trev |
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| ace3000_1 |
Well guys here is some info on reflectors, no doubt u would know it and have seen it before, as u see the sphericals can be used as a parabolic if the light source is at half of its radious, now what im going to do is atempt lol to drill a 22mm hole in a large sperical reflector for this cdm-t bulb, i think it will work and the reflectors sure as hell have the right coatings so it should reflect alot more light then when it was used as a spherical.
http://www.awi-industries.com/relectors.html
Trev |
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| mathias |
This is a picture of the UHP-lamp unit in my commercialprojector, surprising they use normal plastic around the lamp and in the lamphouse, so I really wonder if the heat is a such big problem.
Ace if you want to talk about the reflector, please mail me, I donīt use msn (Icq is much better, Microsoft always try to copy things and destroy them). |
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| slize |
| quote: | Originally posted by The Alchemist
Mathias I think you hit the jackpot with your par design. look at this profesional lighting (disco) equipment:
From this site:
http://www.inter-son.fr/scn800hqi.html |
so my question is: where do we get such a high reflective reflector like this one in the picture the alchemist posted? |
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| mathias |
| Here is a such reflector, damn shame to take it a part, itīs a very useful thing to have. |
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| ace3000_1 |
ive been looking at those mathias but most arent made from glass unfortunatley.
Trev |
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| slize |
that was my thought too; don't they melt at the heat the lamp produces? i would like to have reflector like that, but unfortenately the reflectors are not sold seperately :-(
http://www.mega-licht.de/115951.pdf
and as far as i know this things cost a fortune |
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| mathias |
| quote: | | most arent made from glass unfortunatley |
I donīt really know what you mean ?
| quote: | | that was my thought too; don't they melt at the heat the lamp produces? |
The reflector is made of steel and it wont melt, the bulb used in those lamps is a 55W halogen and that bulb will be very hot. |
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| slize |
| how much does such a "light canon" cost? |
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| mathias |
| I payed 15 last summer for that lamp. Buy two of them if you are going to take one of them apart. But yes it is not so cheap for a reflector. |
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| ace3000_1 |
| quote: | | I donīt really know what you mean ? |
most torch lights reflectors are made of plastic, sorry i was unware yours was a halogen search light, infact its the first that ive seen being a haologen.
Trev
P.S i installed icq to chat to you but it seams either you are too busy or you dont get my messages. |
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| slize |
| quote: | Originally posted by mathias
I payed 15 last summer for that lamp. Buy two of them if you are going to take one of them apart. But yes it is not so cheap for a reflector. |
What measurements does it have? i am searching a reflector with a max. dia of 70mm at it's widest...
i guess these have 130mm or something, which is too big, cause i want to build a compact projector this time. |
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