First off for those that have said that you can not build an LED projector you're wrong. Go to www.ledpj.com. You might want to go to http://babel.altavista.com and translate it from Chineese (SIMP) to English. Also if you want a kit he is selling them on eBay at http://cgi.ebay.com/led-boards-for-...ryZ71587QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
If you ask me that's a damn good deal considering you would pay far more for a bulb ballasts, etc. It would be really nice to see people start to build these things. I'd buy it from eBay, but I can't right now because taxes are coming up soon
If you ask me that's a damn good deal considering you would pay far more for a bulb ballasts, etc. It would be really nice to see people start to build these things. I'd buy it from eBay, but I can't right now because taxes are coming up soon
That's great, but it's also not going to take as much power and it's going to last longer. Plus those are the lumens that are off the screen after it's been projected if my understadning is correct. Sure you'll get better results with another lamp, but they all have the pros and cons. And also if you did your math right you would have known that that board not for a 5" lcd screen, but bigger. I'm not advocating that leds are better. I'm just saying that there are people out there that are interested in projects like this because they DO have advantages over other methods. Lastly, if you look at there results they're not bad at all.
as far as most peaple are concernd its not a viable option for a good watchable projector ... at least at this time ... 20-30 lumens isnt good even if you are getting that to the screen ... the sure they take less power ... but if you cant afford the .15 cents a day to run a 400 watt bulb then you prolly cant afford to do this project. as of now the cons far outway the pros as far as im concernd anyways. we just need brighter leds is all then it might be more of a option.
I agree with 99.9% of the people here. Leds are not worth the hassle. Of course you can make a projector for one, but try watching Doom or some movie like that with it. You will see all black the whole time. I mean you can make a projector from a lighter if you want, but it doesn't mean it is gonna work well enough to waist your money. I have personally tried everything from led's to flourescents. Just save yourself time and money and go with the halides.
Oh, and I also agree with people about electricity. I have a 875w halide, and I can run that everyday for a month, and still not pay as much as one day of running my air conditioner. So the electricity shouldn't be a factor.
Oh, and I also agree with people about electricity. I have a 875w halide, and I can run that everyday for a month, and still not pay as much as one day of running my air conditioner. So the electricity shouldn't be a factor.
But I think it's an excellent idea to work on LED projector NOW. If all that's standing in the way is the brightness, LEDs are getting brighter by the month. Soon there will be an array of LEDs that are cheap enough and bright enough to beat a MH bulb.
There are HUGE advantages with LEDs. EXTREMELY durable; especially compared to a MH, HPS, halo bulb.
Directed/focused beam (less wasted light). This is one of the best features of the LED because the LEDs don't have to be as bright. So instead of a 16% (ish) efficiency with bulb / reflector (300 lumens on screen; 36,000 lumens from bulb; 90% efficiency field fresnel; 8% LCD; 90% back fresnel; 90% UV; 90% IR), you might get 80% efficiency with LEDs. So if you have a 36,000 lumen bulb, only 5,760 lumens are utilized in this projector. So if you could use 80% of the light (20% wasted) from LEDs, you'd only need 7125 lumens to compare with a 400W MH bulb. If you have 1000 LEDs, each would need to put out 7.125 lumens. These numbers are just rough as projectors differ from build to build.
More even distribution over the LCD. No need for a back fresnel / reflector / IR glass / UV glass. That removes about $60 from the cost (maybe more). This also results in a smaller form factor.
You can control the brightness of LEDs very easily.
They are available EVERYWHERE.
You can apply a heat sink to an array of LEDs to cool them.
The list goes on I'm sure. It will take more time to create an array of LEDs compared to screwing down a base and screwing in a bulb. If it's just brightness that is the problem... create a dim LED PJ! Tweak it out so when bright LEDs are readily available, you just swap out the LEDs and BINGO! You've got a bright LED projector. Just IMHO.
There are HUGE advantages with LEDs. EXTREMELY durable; especially compared to a MH, HPS, halo bulb.
Directed/focused beam (less wasted light). This is one of the best features of the LED because the LEDs don't have to be as bright. So instead of a 16% (ish) efficiency with bulb / reflector (300 lumens on screen; 36,000 lumens from bulb; 90% efficiency field fresnel; 8% LCD; 90% back fresnel; 90% UV; 90% IR), you might get 80% efficiency with LEDs. So if you have a 36,000 lumen bulb, only 5,760 lumens are utilized in this projector. So if you could use 80% of the light (20% wasted) from LEDs, you'd only need 7125 lumens to compare with a 400W MH bulb. If you have 1000 LEDs, each would need to put out 7.125 lumens. These numbers are just rough as projectors differ from build to build.
More even distribution over the LCD. No need for a back fresnel / reflector / IR glass / UV glass. That removes about $60 from the cost (maybe more). This also results in a smaller form factor.
You can control the brightness of LEDs very easily.
They are available EVERYWHERE.
You can apply a heat sink to an array of LEDs to cool them.
The list goes on I'm sure. It will take more time to create an array of LEDs compared to screwing down a base and screwing in a bulb. If it's just brightness that is the problem... create a dim LED PJ! Tweak it out so when bright LEDs are readily available, you just swap out the LEDs and BINGO! You've got a bright LED projector. Just IMHO.
Any time you get to the point of getting enough light to equal what our metal halides put out, you will have as much heat or more. Just put a bank of them together and run them. There will be no more benefit from them at that time. Not saying there won't be another light that will be better than what we have, but not for a very long time. So meanwhile you have a projector that you can't watch. JMHO> I will stick with a projector with maybe 400-450 lumens rather than 20-30.
That must be most stupid remark I have seen on this forum in like 4 years? It's so stupid .. it's allmost funny if it wasn't sooooo sad ..
How many watt-hour is there for an average Ugandan family ... how soon do you want to turnm this earth in a complete dessert...
how ignorant and selfish can a human be.....
It was a comparison, not saying that electricity isn't a factor of the earth. And if you think the use of electricity is the reason they suffer, you need to think again. It was a comparison of what the reason for using a led compared to a metal halide, and how much that will truely save or cost someone in comparison to other things that are used daily. But since you asked, I would love the earth to end right now. I know where I would be. The new earth is perfect.
You are missing one crucial piece of info. LEDs are directional lighting. Out of 36,000 lumens, the light engine utilizes 5700 of it. This is before the glasses, fresnels, LCD, etc. That's an efficiency of around 16%. If you can get the LEDs to have an efficiency of 80% (due to them being directional and evenly distributed across the LCD), you only need 7200 (ish) lumens to produce an equal brightness on the screen. That's 1/5th the power. 1/5th heat. So if your bulb cooks at 500 degrees fahrenheit, it'll cook closer to 100F - 150F with LEDs. Still needs cooling, but not nearly as hot.
I'd be the same thing if you could drive the efficiency of a MH up. You'd get a MUCH brighter picture. If you could get 80% efficiency with a light engine that uses a MH bulb, you'd have a picture that was:
36,000 x 0.80 x 0.90 x 0.90 x 0.90 x 0.08 x 0.90 = 1511 lumens!!
This is a bulb, uv, ir, fresnel, LCD, fresnel setup. Like I've said before, more smarts, not more power.
I'd be the same thing if you could drive the efficiency of a MH up. You'd get a MUCH brighter picture. If you could get 80% efficiency with a light engine that uses a MH bulb, you'd have a picture that was:
36,000 x 0.80 x 0.90 x 0.90 x 0.90 x 0.08 x 0.90 = 1511 lumens!!
This is a bulb, uv, ir, fresnel, LCD, fresnel setup. Like I've said before, more smarts, not more power.
LEDs not as efficient as you think....
People are quoting device efficiencies of high watt white LEDs at 55 lumens/watt in 1 watt packages. What they don't tell you is that the junction temperatures are 25 degrees C (because they did an instantaneous measurement) and they were running it at 100 mA or less (less than 1/3 watt.) So, if you run a "1 watt" LED at 1 watt, you get about 35 lumens with a junction temperature of 25 C. Unfortunately, unless you have a huge heat sink with fans, your temperature is likely nowhere near 25 C. More like 85 C. And now your efficiency is 20 lumens/watt.
Ooops, and wait, you have to convert AC to DC, so mulitply that by .9, and then there is the LED driver, so multiply it by .9 again. Now you are actually approaching real world performance: 16+ lumens/watt.... which is darn close to a halogen cycle incandescent lamp. Yes they are directional, and yes they will last longer (although they will probably depreciate their output just as fast or faster than MH), but that's a really expensive directional long lasting 1W halogen bulb you just bought. And the color rendering is really poor. No where close to state of the art halides. Check this for a really nice lamp:
http://www.nam.lighting.philips.com/us/ecatalog/hid/pdf/p-5432d.pdf
There's no LED company publishing REAL WORLD data (system efficiency including all losses, thermally stabilized) that comes within 1/3 the efficiency of good metal halide. Anybody who tells you different is selling you something.
A lighting guy.
People are quoting device efficiencies of high watt white LEDs at 55 lumens/watt in 1 watt packages. What they don't tell you is that the junction temperatures are 25 degrees C (because they did an instantaneous measurement) and they were running it at 100 mA or less (less than 1/3 watt.) So, if you run a "1 watt" LED at 1 watt, you get about 35 lumens with a junction temperature of 25 C. Unfortunately, unless you have a huge heat sink with fans, your temperature is likely nowhere near 25 C. More like 85 C. And now your efficiency is 20 lumens/watt.
Ooops, and wait, you have to convert AC to DC, so mulitply that by .9, and then there is the LED driver, so multiply it by .9 again. Now you are actually approaching real world performance: 16+ lumens/watt.... which is darn close to a halogen cycle incandescent lamp. Yes they are directional, and yes they will last longer (although they will probably depreciate their output just as fast or faster than MH), but that's a really expensive directional long lasting 1W halogen bulb you just bought. And the color rendering is really poor. No where close to state of the art halides. Check this for a really nice lamp:
http://www.nam.lighting.philips.com/us/ecatalog/hid/pdf/p-5432d.pdf
There's no LED company publishing REAL WORLD data (system efficiency including all losses, thermally stabilized) that comes within 1/3 the efficiency of good metal halide. Anybody who tells you different is selling you something.
A lighting guy.
from everything if have read and heard leds are just not good enough yet .. they will be soon .. and when they are they will be the way to go. i would think but then again if a ushio just cost $20 instead of $50 ... i dont think id switch anytime soon just because one ballast and one socket and one bulb is sooo easy.... VS a million leds to connect and there power source ... ill give them one thing right now and that is they are durable ... ok 2 things.... directional light .....i think more work on making a ushio more effecient is a better way to go as of now anyways.
MH are just as bad and they don't decrease the lumens as you say they do here. It simply uses more power from the wall. MH have a transformer (your 90% efficiency loss) and they have to run it through a starter / capacitor.... Another 90%. That's beside the point. The bulb doesn't get dimmer. It still draws the same current from the wall, the components (ballast and starter in MH; AC-DC and driver in LEDs) just draw ADDITIONAL current. So if you have a 400W bulb, you draw 450W from the wall due to overhead (ie the components use some juice too). So you WILL get the 55 lumens (from your example) like the spec sheet says.
Also, spec sheets state a certain lumen rating based on a certain current and voltage. See here:
http://www.lumileds.com/pdfs/DS34.pdf
On page 3 you can see a chart (Electrical Characteristics at 700mA) stating that at 700mA, the voltage is 6.84 volts (typical). At this rating, the light produced is 145 - 160 lumens (depending on the model LED you buy). There is no funky misleading info here. You just have to read the spec sheet. This would be the same for less powerful LEDs. Just look at the spec sheet.
believe what you like
700 mA x approx 7 V = 4.9W, 160 lumens is still only slightly over 33 lumens/watt at a 25 degree C junction temperature, which you will never achieve. Drop 10 lumens/watt based on a junction temperature that is 60 degrees higher. Then add conversion losses and driver losses. Yes, you really will be in the 15-20 lumen/watt range. (25 lumens per watt if you have a really, really good thermal design.) Honest, I do this for a living.
And yes, MH lumen depreciation curves really do mean that at the end of life the lamp is only outputing 60% of its initial lumens. For a projector it's not as important what the lamp is doing at 15-20K hours, but it's still true.
P
700 mA x approx 7 V = 4.9W, 160 lumens is still only slightly over 33 lumens/watt at a 25 degree C junction temperature, which you will never achieve. Drop 10 lumens/watt based on a junction temperature that is 60 degrees higher. Then add conversion losses and driver losses. Yes, you really will be in the 15-20 lumen/watt range. (25 lumens per watt if you have a really, really good thermal design.) Honest, I do this for a living.
And yes, MH lumen depreciation curves really do mean that at the end of life the lamp is only outputing 60% of its initial lumens. For a projector it's not as important what the lamp is doing at 15-20K hours, but it's still true.
P
It is totally possible to get good thermal cooling for an LED. Also, I'm not talking about over time. Of course the MH bulb loses brightness over time. And it is totally possible to get the full brightness of an LED. Trust me, I do it for a living too (computer / electrical engineer). Like I said, you'll be pumping more juice from the wall to compensate for the loses due to conversions, but the bulb will still be just as bright. You just need to apply the correct amount of current to the LED, regardless of HOW the current gets to it.
I totally agree that 33 lumens per watt is nowhere close to a MH, BUT! When they do get a better lumen/watt ratio, I think they will become a better option than MH.
I don't think LEDs at this point are the end all answer, but I believe they will become a very good solution in the near future.
I totally agree that 33 lumens per watt is nowhere close to a MH, BUT! When they do get a better lumen/watt ratio, I think they will become a better option than MH.
I don't think LEDs at this point are the end all answer, but I believe they will become a very good solution in the near future.
I just figured out that these LEDs will never be good enough, until they produce roughly 7,000 lumens each. Reason: I got my lux meter last night, and thought about it. On the back side of my lcd, towards the lens. I get 7,500 lumen average any given point on the lcd. At the hole for the lens, I get roughly 10,000 at any given point. These are averages, not the best. So, to bring an LED light up to where we have our Metal Halides, you have to be able to match the back side lux. At 133 lumen per given spot, you won't even be close. Even if you took all your LEDs and put them straight into the lens hole, there is still not 10,000 lumen at any given point. Sorry, I just feel I can close this case
I totally disagree (although I welcome your input ). I was talking about this on DIYPC. Look at it this way:
Say you get 300 lumens on the screen (which is what an average report for a DIY seems to be). Say you get 90% efficiency for each fresnel lens (2 of them) and each filter (IR and UV). Then you get 8% efficiency from the LCD. Going backwards from 300:
300 / 0.90 = 333.3 (field fresnel)
333.3 / 0.08 = 4166.6 (LCD)
4166.6 / 0.90 = 4629.6 (back fresnel)
4629.6 / 0.90 = 5144.0 (IR filter)
5144.0 / 0.90 = 5715.6 (UV filter)
and now we're back to the bulb. So out of 36,000 lumens, a little over 5700 lumens gets utilized. That's about 16% of the light from the bulb. That's horrible IMHO. If you could use 80% of the light from LEDs, you'd only need 7144.5 lumens spread over your entire LCD. That's about 63 LEDs at 113 lumens a piece.
). I was talking about this on DIYPC. Look at it this way:Say you get 300 lumens on the screen (which is what an average report for a DIY seems to be). Say you get 90% efficiency for each fresnel lens (2 of them) and each filter (IR and UV). Then you get 8% efficiency from the LCD. Going backwards from 300:
300 / 0.90 = 333.3 (field fresnel)
333.3 / 0.08 = 4166.6 (LCD)
4166.6 / 0.90 = 4629.6 (back fresnel)
4629.6 / 0.90 = 5144.0 (IR filter)
5144.0 / 0.90 = 5715.6 (UV filter)
and now we're back to the bulb. So out of 36,000 lumens, a little over 5700 lumens gets utilized. That's about 16% of the light from the bulb. That's horrible IMHO. If you could use 80% of the light from LEDs, you'd only need 7144.5 lumens spread over your entire LCD. That's about 63 LEDs at 113 lumens a piece.
Sorry, I humbly disagree with you. You are taking your readings from two different points. yes, at the screen you will get the 300-500 lumens. But remember, that is at any given spot, not total. you are taking a total output and what one led gives. It isn't the same. Take your leds, and aim them at the wall. You won't get 40 lumens at a 100" screen. Trust me, I am right.
You are taking your readings from two different points. yes, at the screen you will get the 300-500 lumens. But remember, that is at any given spot, not total. you are taking a total output and what one led gives. It isn't the same. Take your leds, and aim them at the wall. You won't get 40 lumens at a 100" screen. Trust me, I am right.Remember, this is not just 5700, I actually get 7500, per any place on the lcd, not total. remember, you are getting the average of 5700 lumens all over the lcd, not the 5700 total, which you are hoping to get from LED's. This is any place on the lcd, you can measure and get 5700 lumens average. With your LED's, you will get maybe Let's say 80%, 100 lumens at any given point.superdaveumo said:
Come one guys, somebody give me. Wow, I think he's got ya.
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