Combination of colored LEDs to get white

I thought about getting a more efficient light by combining different coloured LED's (e.g. red+green+blue or red+cyan) instead of white LED's. If a ARC-AAA turquoise, and if I combine this with a red LED, thats already "almost" white. And the turqouise LED is much brighter than a comparable white one!
You would also save some power due to the reduced Vf of the red LED's.

best regards,

Peter

i dont think that would look good...not very white i mean...a bit of colour here and there...

Once the proper combo is found the biggest problem would be some sort of diffuser or whatever to thoroughly mix the colors so there wouldn't be color fringes. I have two units here (commercial) tha use R-G-B LEDs to get a range of colors, including white (a WallWasher and their little 1AA lightstick).

They actually give a decent white, but there are fringes because of the distance between sources (LRDs). The lightstick is closest to a clean color because of a "frosted" diffuser.

A lot of people have tried. I think you can find some info on the web. The eye is more sensitive to some colors. I think you need more red than blue. Or is it the other way around? One problem is the beam angle of various LED's. That might be hard to match.

I wonder if anyone has tried covering the lens with Writerite, or whatever that film is called, to blend the
colors.

I'm not too fussy about color, so if you get one that's not too ugly, I might buy one. It's got to be rugged though, and brighter than Mr. Bulk's. /ubbthreads/images/graemlins/grin.gif

take a look at this thread where I took photos of a light pen with red, green and blue LEDs -

LED Colors and Vision (pics)

[ QUOTE ]
Tomas said:
I have two units here (commercial) tha use R-G-B LEDs to get a range of colors, including white (a WallWasher and their little 1AA lightstick).

[/ QUOTE ]

Tomas -

You have a RGB LED single AA flashlight?

That's just what I was looking for -
can you please give a reference or url for this?

Thanks,

Tomas is very likely talking about the Sauce products. /ubbthreads/images/graemlins/wink.gif

They are fun lights! /ubbthreads/images/graemlins/grin.gif

[ QUOTE ]
B@rt said:
Tomas is very likely talking about the Sauce products. /ubbthreads/images/graemlins/wink.gif
<snip>
They are fun lights! /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

many thanks for the url -
I also found them by a roundabout way via froogle.com

Do these use 3 separate discreet LEDs?
- or is it a single RGB LED?

There are
LightWands (1x AA);
MiniLightWands (1x N) and
MicroLightWands (4x LR44)

I really like the looks of the MicroLightWand:


But the MiniLightWand:

using one N size battery is all of $5.29 with FREE shipping from Amazon.com
http://www.amazon.com/exec/obidos/tg/detail/-/B00005NPY6/ref=pd_sim_toys_1/002-6325558-3109658?v=glance&s=toys

They use separate LEDs for the different colors... /ubbthreads/images/graemlins/icon23.gif

Craig has some nice RGB LEDs on his site. /ubbthreads/images/graemlins/wink.gif

Gee! I was out having a spot of tea with friends and when I got back there had been questions asked and already answered. /ubbthreads/images/graemlins/grin.gif

Everything Bart said was correct (as usual /ubbthreads/images/graemlins/smile.gif ).

I got mine at Target - the WallWasher was in with the nightlights and the wand was in the toy section.

They both use descrete red, green, and blue LEDs, and are interesting to play with (and the wall wash works great lighting the wall behind a huge potted plant - nice effect).

If you're thinking of doing this with Luxeons, the green is the weak link. Mixing Luxeons to get white

One of Don Klipstein's web pages might help here.
http://members.misty.com/don/ledrgb2w.html
I don't think he has data on Luxeons though.

We once made a TriLight using Red, Green and Blue - and it made the normal three-circle pattern on the wall, the center was sort-of white; you would need some type of diffusor

Yeah. I've been looking around for sheets of frosted Plexiglas or somesuch. It seems this isn't something that's typically offered in Lexan.

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highlandsun said:
Yeah. I've been looking around for sheets of frosted Plexiglas or somesuch. It seems this isn't something that's typically offered in Lexan.

[/ QUOTE ]

Sandpaper+Lexan. Alternately, drafting Mylar makes a good diffuser. The sandpaper method gives you control over the amount of diffusion.

Having the same curiosity, I made a RGB cluster last year and in addition to the appropriate dropping resistors for each bank of 3 LED's, I added a variable POT:



I added a sheet of POC's LSD film which aided considerably in mixing the light. Due to the variations in beam angles of the LED's the corona was not the same color as the center beam. It was an interesting project and I learned that I was in no position to control the pallet as I had hoped. Variations in Vin would likely effect the Vf of the LED's in my simple circuit and the resulting change in current through the LED's would shift.

- Don

Sandpaper - duh... Thanks for the suggestion. I don't know what drafting mylar is, but I'll presume it's very thin and translucent. The mylar I'm familiar with is extremely thin and transparent.

re: doing a cluster with 5mm LEDs - I would have scrambled the array so no same colors were adjacent. For my Luxeon project I'm just going to put 3 stars adjacent, in a triangular layout, and hope for the best. The hex bases keep the emitters relatively far from each other, so I definitely need a diffuser to blend the output...

For a diffuser, you might try a piece of one of these bottle types:

Tums (side of the bottle is textured)
Rolaids
alcohol

I used to have a cut-off Tums bottle bottom placed over my eternaLight for a diffuser for reading at night. It works well.

*Tomas* I bought a Light Washer after your mention of it in another thread (a gift for a 7 year old girl's birthday). It is so groovy. She likes it, but doesn't rave about it like I do. I will be getting one for myself.

re: LightWasher - I don't rave about it much either, but my friend (I bought it for her) loves it. When I cannibalize it and hook up its outputs to drive my Luxeon array, then I might have something to rave about.

I've seen professional/commercial color wash arrays selling for hundreds to thousands of dollars. Looking at the $300 or so I dropped just buying these Luxeons, I'm beginning to see where the costs add up...

just had my MiniLightWand delivered, and it is a fun thing.


Cost all of $5.66 (free shipping, but +tax) from Amazon
http://www.amazon.com/exec/obidos/tg/detail/-/B00005NPY7/qid=1055274920/sr=8-2/ref=sr_8_2/102-2918979-7978520?v=glance&s=toys&n=507846

I know that N sized batteries are harder to find and probably more expensive - but the price was so low the difference is likely to way offset any increase in battery costs for my usage.

The one button accesses a lot of functions and one can control the color mixing. But being a single button and dependent on hold timing - although the mixing balance is continuous - the exact balance one wants may be hard to obtain consistently (but, hey do you want for $5! /ubbthreads/images/graemlins/grin.gif )

Being 3 separate discreet LEDs the mixing is fair with the diffuser cone - but it's not much better than that 3 color LED pen I used - photos in this thread:

LED Colors and Vision (pics)