Instead of using one board to contain all your LED's. How
about building several smaller ones then bring all the light
together with a fiber optic bundle? I don't know what the
expense would be, but it seems to me that with this approach
you could probably expand the light source significantly.
Not to mention that you would have a much tighter source.
Just a thought.
about building several smaller ones then bring all the light
together with a fiber optic bundle? I don't know what the
expense would be, but it seems to me that with this approach
you could probably expand the light source significantly.
Not to mention that you would have a much tighter source.
Just a thought.
I'm no expert, but it seems to me that the LED's would be only reduced by using fiber optics. I like Vince's original idea of using either 2 clusters of leds at 45 degree angles to mirrors, angled into the projector, or just bite the bullet, buy halogen lamps and hot mirrors, and get rid of the led's...again, just my opinion
The halogens aren't a bad idea. You'll just have to change them more often, spend more cash for bulbs over time, and deal w/ the noise. But, as long as it works, you save a few bucks, and ultimately DIY who cares?
(I have myself an expensive light bulb that will last me for a long time.)
If you use halogans, try to build a sheet metal cage around the bulb. If you look at replacement bulbs, they mostly come w/ a surrounding metal cage.
Also, remember to use spot lamps like Faidzir said.
Vince
(I have myself an expensive light bulb that will last me for a long time.)
If you use halogans, try to build a sheet metal cage around the bulb. If you look at replacement bulbs, they mostly come w/ a surrounding metal cage.
Also, remember to use spot lamps like Faidzir said.
Vince
It is just that you loose so much light through an LCD screen, I mean alot of light! Halogen gloabes are what I have in my overhead projector but will be mounting it all in a box like you did Vince and getting a lens, if you mount halogens inside a metal box it is an idead to use a high performance heat sink around it, most data projectors have this, it would help a alot, I don't think that with a halogen globe you need cold mirrors becausemy overhead projector does not, you just needs fans, the LCD Data projection panel has it's own fan to keep it cool as well so it you may get away with it! Where can we find pics of your projector vince?
It would be helpful to have some kind of heatsink. I have seen cylinder type sinks for CPUs. If the diameter is right, they may provide a point of contact.
As for the cold mirror, they are necessary because the bulb and LCD are in the same enclosure inside a projector in close relation. In an overhead system, the panel is not in the same place as the bulb. There is some seperation. A UV filter would help.
I hear there is about 10-15% loss of light through an LCD.
First I need to figure out this optics issue, then I'll work on the light source.
Vince
As for the cold mirror, they are necessary because the bulb and LCD are in the same enclosure inside a projector in close relation. In an overhead system, the panel is not in the same place as the bulb. There is some seperation. A UV filter would help.
I hear there is about 10-15% loss of light through an LCD.
First I need to figure out this optics issue, then I'll work on the light source.
Vince
Good stuff fellas
Like many others who have been reading the posts in this forum, I am extremely interested in other people's efforts. Thanks to Vince for keeping us posted on his progress.
Just a trifling matter, regarding Vince's lack of webspace. If you like, I could host the images on my httpd, no problem. Not amazing bandwidth, but I doubt that the traffic will go above 80Kb/s ;b
I am really tempted to order an LCD as soon as possible so that I can start tinkering with this interesting stuff. ;b
Contact me if you think you would like me to host them for you, anytime.
sdood@home.com &/or burnout@jungle.breakbeats.org.
Like many others who have been reading the posts in this forum, I am extremely interested in other people's efforts. Thanks to Vince for keeping us posted on his progress.
Just a trifling matter, regarding Vince's lack of webspace. If you like, I could host the images on my httpd, no problem. Not amazing bandwidth, but I doubt that the traffic will go above 80Kb/s ;b
I am really tempted to order an LCD as soon as possible so that I can start tinkering with this interesting stuff. ;b
Contact me if you think you would like me to host them for you, anytime.
sdood@home.com &/or burnout@jungle.breakbeats.org.
Web Space
That is a very cool offer! Thank you, burnout! I think I got it though. I signed up for Geocities. I have to find sometime to get my stuff from my PC to Geocities (Yahoo).
I'm going to take a short break from this stuff for a bit. After 16 hour of working on it for 2 days, it got me a bit mental w/ all the problem solving. Now I'm sick w/ a painful sinus infection!!
Thanks!
Vince
That is a very cool offer! Thank you, burnout! I think I got it though. I signed up for Geocities. I have to find sometime to get my stuff from my PC to Geocities (Yahoo).
I'm going to take a short break from this stuff for a bit. After 16 hour of working on it for 2 days, it got me a bit mental w/ all the problem solving. Now I'm sick w/ a painful sinus infection!!
Thanks!
Vince
a weak hypothesis..
Thanks for the quick reply V. ;b
After reading the contents of this forum, I started looking around for LCDs available from online sellers. One surprising finding was that any number and assortment of relatively high quality LCDs that were once used for laptops are available on ebay for _very_ small amounts of money. Now, I realise that having one of these LCDs would be rather useless unless I had its specifications and knew how to connect it to a video source. Some mention LVDS inputs, and most of the descriptions for others are lacking any mention of input type at all.
IIRC, LVDS hasn't been mentioned as a reasonable video source input type in this forum, so I wonder what the other available LCD screens might use as their input sources / connections.. Pardon my ignorance if I've made some false / stupid statements here.
Why am I mentioning all of this? Well, in my readings, I took a liking to the idea of using an overhead projector as a light source. So I was wondering if any of these LCDs would be classified as light transmissive once their backings were removed, and furthermore, if the common connection type for laptop LCDs is something reasonable (not LVDS, unless LVDS is simple, and I'm missing the whole point. =)
I will admit that my plan is comparatively quite "ghetto", and still all up in the air, with its sweeping generalizations and conjectures. But I like the idea of dropping less than $40 CDN for a 14" TFT 1024x768 LCD that I could slap onto an overhead projector..
I'm sure that all of you projection DIY gurus are laughing or crying after having read this post. I thank you kindly for your consideration, and again for your helpful contributions in the past. All the best.
btw, this veritable slew of LCDs can be listed by simply searching for LCD on ebay ;b - thanks again.
Thanks for the quick reply V. ;b
After reading the contents of this forum, I started looking around for LCDs available from online sellers. One surprising finding was that any number and assortment of relatively high quality LCDs that were once used for laptops are available on ebay for _very_ small amounts of money. Now, I realise that having one of these LCDs would be rather useless unless I had its specifications and knew how to connect it to a video source. Some mention LVDS inputs, and most of the descriptions for others are lacking any mention of input type at all.
IIRC, LVDS hasn't been mentioned as a reasonable video source input type in this forum, so I wonder what the other available LCD screens might use as their input sources / connections.. Pardon my ignorance if I've made some false / stupid statements here.
Why am I mentioning all of this? Well, in my readings, I took a liking to the idea of using an overhead projector as a light source. So I was wondering if any of these LCDs would be classified as light transmissive once their backings were removed, and furthermore, if the common connection type for laptop LCDs is something reasonable (not LVDS, unless LVDS is simple, and I'm missing the whole point. =)
I will admit that my plan is comparatively quite "ghetto", and still all up in the air, with its sweeping generalizations and conjectures. But I like the idea of dropping less than $40 CDN for a 14" TFT 1024x768 LCD that I could slap onto an overhead projector..
I'm sure that all of you projection DIY gurus are laughing or crying after having read this post. I thank you kindly for your consideration, and again for your helpful contributions in the past. All the best.
btw, this veritable slew of LCDs can be listed by simply searching for LCD on ebay ;b - thanks again.
Hello All,
i have bought a used projector now. The optics is no good for me to DIY. I can do alot with electronics but mechanics is just not my thing. So i got a Polaroid Polaview 105 projector, 400W metal halide bulb, 640x480 for about 500$.
We will see how the bulb holds up. The noise is really annoying... However, there comes not much light out of the lens, so yes it seems the optics and LCD panel is very lossy.
BTW; i was just looking around for possible cheaper light sources and found metal halide lamps for about a third of what projector makers charge. These lamps are made for projection lights (light shows).
Also, the car "xenon" lights, or generally car lights, might be an alternative. These bulbs are cheap and should be quite bright. Power supply for the 12V versions is easy. The life time of the car bulbs is very high (7500 h).
Well before i think about a replacement light bulb i need the service manual for the projector. I hope this is available.
If there's any interest i'll let you know what i do, and what i can find out from the service manual.
later,
Timo
i have bought a used projector now. The optics is no good for me to DIY. I can do alot with electronics but mechanics is just not my thing. So i got a Polaroid Polaview 105 projector, 400W metal halide bulb, 640x480 for about 500$.
We will see how the bulb holds up. The noise is really annoying... However, there comes not much light out of the lens, so yes it seems the optics and LCD panel is very lossy.
BTW; i was just looking around for possible cheaper light sources and found metal halide lamps for about a third of what projector makers charge. These lamps are made for projection lights (light shows).
Also, the car "xenon" lights, or generally car lights, might be an alternative. These bulbs are cheap and should be quite bright. Power supply for the 12V versions is easy. The life time of the car bulbs is very high (7500 h).
Well before i think about a replacement light bulb i need the service manual for the projector. I hope this is available.
If there's any interest i'll let you know what i do, and what i can find out from the service manual.
later,
Timo
has anyone considered using an old 35mm camera lens?
...seems to me you could probably pick up a pretty high quality lens for an older/common mount like Canon FD, Pentax, Nikon etc., and have some really nice quality optics. Even something with a large aperature probably wouldn't cost too much. Of course, you may have to worry about using another lens before the LCD to direct more light into the lens. Something like a fresnel lens would probably do for that purpose. I did recently come across some plastic fresnel lenses in a dollar store, so with enough hunting, you can probably find fresnels for a very good price as well.
[Edited by hifiZen on 10-13-2001 at 02:06 AM]
...seems to me you could probably pick up a pretty high quality lens for an older/common mount like Canon FD, Pentax, Nikon etc., and have some really nice quality optics. Even something with a large aperature probably wouldn't cost too much. Of course, you may have to worry about using another lens before the LCD to direct more light into the lens. Something like a fresnel lens would probably do for that purpose. I did recently come across some plastic fresnel lenses in a dollar store, so with enough hunting, you can probably find fresnels for a very good price as well.
[Edited by hifiZen on 10-13-2001 at 02:06 AM]
Halgoen Globes
You can get 100watt 12volt Halogen globes very cheap, here in Australia they are $3.45 at Jaycar electronics but probably cheaper at a light globe replacment store so I am sure they would be cheap in America. You could set 4 of them up all with reflectors aimed at a cold mirror and you would have a really bright 400watt light source ! A few fans, maybe house each globe inside a metal case with a heat sink! The only downside is thta they last about 300-400hours, but since they are so cheap it is not a huge problem!
You can get 100watt 12volt Halogen globes very cheap, here in Australia they are $3.45 at Jaycar electronics but probably cheaper at a light globe replacment store so I am sure they would be cheap in America. You could set 4 of them up all with reflectors aimed at a cold mirror and you would have a really bright 400watt light source ! A few fans, maybe house each globe inside a metal case with a heat sink! The only downside is thta they last about 300-400hours, but since they are so cheap it is not a huge problem!
hmmm... one problem with many light sources is that they need to be colour balanced (eg 5000K colour temp.) in order that the projected image has the right colours. So, I don't know if automotive Halogen or Xenon bulbs will give a white that looks white... I think this may be one of the reasons that projectors use expensive bulbs.
However, upon further consideration, i can think of a few things which need true white light sources... like scanners and photo lighting. Obviously, photo flashes are out, but studio lighting may provide some useful clues. Photography lighting techniques prescribe different colour correction filters for various light sources. The usefulness of this is debatable, since another filter would just be subtracting more light... But, the scanner light source could be useful - they often use these cold-cathode flourescent tubes, and it may be possible to find a bunch of these and hook them up in an array to make a large flat rectangular light source, which would be colour balanced and probably very bright...
However, upon further consideration, i can think of a few things which need true white light sources... like scanners and photo lighting. Obviously, photo flashes are out, but studio lighting may provide some useful clues. Photography lighting techniques prescribe different colour correction filters for various light sources. The usefulness of this is debatable, since another filter would just be subtracting more light... But, the scanner light source could be useful - they often use these cold-cathode flourescent tubes, and it may be possible to find a bunch of these and hook them up in an array to make a large flat rectangular light source, which would be colour balanced and probably very bright...
Lenses
I have been experimenting with this whole lens thing...using an 8 1/2 by 11 fresnel and a delta 68 projector lens and my bank of leds... I get the light shooting through the fresnel and lcd (8.5''), but I have to increase the distance between the led bank and the fresnel and the fresnel and the projector to get the image small enough to view the whole frame through the lens...from leds to fresnel/lcd to projector was over 4 feet long ( even though it was placing the whole image on the wall...
I have been experimenting with this whole lens thing...using an 8 1/2 by 11 fresnel and a delta 68 projector lens and my bank of leds... I get the light shooting through the fresnel and lcd (8.5''), but I have to increase the distance between the led bank and the fresnel and the fresnel and the projector to get the image small enough to view the whole frame through the lens...from leds to fresnel/lcd to projector was over 4 feet long ( even though it was placing the whole image on the wall...
It was kind of blurry, but I think that may be the spacing between the leds...I got them fairly close, but it's hard to get the individual beams to "converge" in to one picture. My array is not yet complete. As far as the whole panel, it was there, but just fuzzy. I think I might be having the same optics trouble as you Vince...I need to tast later this week when I can add more leds for additional brightness...
[Edited by dwalls32 on 10-14-2001 at 08:13 PM]
[Edited by dwalls32 on 10-14-2001 at 08:13 PM]
Just a thought, has anyone tried using Photographic condenser lenses, (for example out of an enlarger) This might give better light passing than a fresnel, the only real probem I can see with this is the large size of LCD display that most people are using.
Also, for a reasonable Display, partsexpress have some small modules for about $150, they also have a wide screen module, now that would be cool!
Nick.
Also, for a reasonable Display, partsexpress have some small modules for about $150, they also have a wide screen module, now that would be cool!
Nick.
xenon bulb
im still waiting good results for white leds experiment. Any good news?. i will spend a lot of money if succesful.
* i play arround with flashlight camera, i built high speed
flashlight at 50 hz. Result is very very bright and white source light. May be can be used as a light source to project lcd?. Any suggestion?.
im still waiting good results for white leds experiment. Any good news?. i will spend a lot of money if succesful.
* i play arround with flashlight camera, i built high speed
flashlight at 50 hz. Result is very very bright and white source light. May be can be used as a light source to project lcd?. Any suggestion?.
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