LEDS...

[Dark-Aries]

okay, I'm hoping somebody is really knowledgeable with leds here, basically white leds are just blue leds with yellow phospoher to make it white or whatever. To get true light can I mix seperate green,red,blue leds to create white light?If I use 5mm leds, will it still be easy to mix the light? what about 10mm? I'm working on a project right now and if this works it might help for LED modding screens (Even though what everybody is doing now is still perfectly fine...)

[jleemero]

I see no reason you can't use separate LEDs and mix the colors.

In fact, some white LEDs do just that, they emit all 3 colors (RGB) to produce white light.
Heck, if you wanted to, you could just use an RGB LED. (Though it'd be a good bit more expensive than a high-quality white LED)
Others do as you described, using phosphor of some sort and a Blue or UV base, to produce a very broad spectrum of white light.

[dragonhead]

tbh, a white LED is more "white" than trying to mix RGB leds. you might be able to pull it off with 1mm SMT leds

[Dark-Aries]

Thing is I might buy this old prjector for 80 bucks, but the lamp doesn't get power or whatever. After reading abit on the lumenlabs forum somebody did sucessfully use leds, but they used one expenisve led. If I can get regular elcheapo leds to produce and image with a matrix, I can get an ok to make my own DIY projector, I would ask this question over there but the lumenlabs forums are dead, updates only happen in rush hour and that's it.

[palmertech]

For a projector, you cannot use a matrix of small LEDs, you will need that one big expensive LED. Probably a Cree High Powered LED or something.

[bicostp]

I remember seeing an article on Instructables once where someone replaced a burnerd-out projector lamp with a halogen bulb meant to be a car headlamp. It would work, but might throw the color balance off due to the different color temperature of the bulbs. You could even use one of those Sylvania super-bright bulbs if you wanted to.

http://www.instructables.com/id/Head-Li ... -Mod-V1.2/

Who needs a "super-expensive" LED?

[Dark-Aries]

The reason behind all of this is because this

http://diy2005.aa.topzj.com/viewthread. ... ra=&page=1 (skim through the pages for all pics)

and

http://diy2005.aa.topzj.com/viewthread. ... 43&fpage=1 (the buddy's projector of the first link)

and this

http://www.allinbox.com/DARTG_BOX/DARTG_BOX.htm

all projectors using LED backlight. sure results might be even worse then MH lamps, but not needing to care ever about lamp life, and my room is always dark anyways so...and the soldering experience would be valuable when trying to make portables... also D.EX had RGB LEDS all in one, instead of using white leds, I can use those common anode RGB leds, will be much acurate colours..

[Kurt_]

They have LEDs that are sufficient for a projector on digikey for like, $25.

http://search.digikey.com/scripts/DkSea ... -2780-1-ND

They have way brighter ones, too. That one there is $10, and 75 candelas. (75000mcd)

[XCVG]

SparkFun has some super bright Luxeon LEDs, maybe those will work. It'll throw off colour balance though- white leds are way more 'cool' than an actual bulb.

[Dark-Aries]

I'm thinking about getting those super bright LEDSs, but they have to be RGB, somebody tried sperate colours and all they got was seperate blobs of colours. So if the seperate colours are formed together, I have a better chance of getting white light, even if there are visible lines. I'm also thinking of doing an RGB setup wih real small LEDS, Since the optimun ratio of LEDS to have is apparently RGGB, I would use the method on the third link, but have the top row only green leds, while the bottom row is red and blue. Since DealExtreme has this stuff for cheap I might splurge and start working on this soon. Breadboard is hopefully cheap from my local The source (Rat shack to americans...). Also ya, white LEDS give off a really blue picture unless they are RGB, I feel so knowledgeable after reading around 50 pages of this stuff over at lumenlabs, for only one thread. If I can get super bright LEDS that are RGB I won't have to solder so many LEDS, but they're uniformity is something that also must be considered...

[hailrazer]

The LED method of replacing the lamp in a commercial projector just will not work. Everyone who has tried it has got less than 20 lumens on the screen.

Even in a light controlled environment 20 lumens will keep you happy for about 10 seconds before you stop watching it.

And yes there are some nice pics floating around that look good with an led replacement, but I can make 5 lumens look good in a pic, but not in real life.

And if you're wondering I am a MOD at LumenLabs and yes the forum is quite dead.

[Dark-Aries]

ya, but the LED matrix projectors used small screens because of the sheer amount of soldering. If I use a 15.4" screen that means more LEDS, and since they would be RGB I would get better colours, for the off trade of brightness for sure compared to MH bulbs, but then again the bulb life would be so long it sort of balances out...

[hailrazer]

ya, but the LED matrix projectors used small screens because of the sheer amount of soldering. If I use a 15.4" screen that means more LEDS, and since they would be RGB I would get better colours, for the off trade of brightness for sure compared to MH bulbs, but then again the bulb life would be so long it sort of balances out...

No not really.

A 400 watt MH will net you about 200-250 lumens max and about 20,000 hours.

A led matrix will cost you 3 times as much and net you about 100 lumens max and around 50,000 hours life.

But the Led matrix will cost a lot more to replace. The 400 watt mh will cost less than $40 to replace.

The MH is better for now. In 3-4 years who knows.

[Dark-Aries]

Ya, but when it will get replaced technology will of hopefuly advanced enoughed to have even better leds, just trying to be optimistic...:)