Comments on: LED lighting, part 1

By: Tyler

Tyler — Sun, 16 May 2010 14:07:10 +0000

Oh forgot to mention to keep the work up, definitely nice

By: Tyler

Tyler — Sun, 16 May 2010 14:06:42 +0000

Very smart idea’s.. new to the whole soldering things but leds is where i started off..

By: joel

joel — Fri, 19 Mar 2010 20:04:14 +0000

Hi Rob- Yeah I’m starting to realize the shortfalls of an RGB system. The 2700K Luxeon Rebels look promising, next step is to mock them up in the intended environment and try them out.

I’ll check out Xicato. Do they manufacture their own LEDs or do they design and build fixtures? Or both?

By: Rob

Rob — Fri, 19 Mar 2010 16:52:24 +0000

If you want a decent warm white (<3000k) you should really avoid any RGB mixing – you will never get anything you are happy to sit and relax under.

Best off with the xicato LED but you may not be able to get hold of one very easily or cheaply. I've seen hundreds of LED products try and replicate warm white colour temperatures and the only successful product uses this xicato technology.

Good luck.

By: joel

joel — Fri, 19 Mar 2010 12:30:57 +0000

@Myndale- Woah, you’re kinda over my head there. It looks like I still have a lot to learn about color/illumination theory. Thanks for the links, I need to do some more studying!

By: RainboltArt

RainboltArt — Fri, 19 Mar 2010 03:42:49 +0000

Re:color, to get more yellow in your light reduce the ratio of blue to the other colors.
A format to consider is:
Less red = more cyan
Less green = more magenta
Less blue = more yellow

By: Guesat

Guesat — Fri, 19 Mar 2010 03:17:01 +0000

Cool Could post a more detail on how do this, or some links about it??? please

By: Myndale

Myndale — Fri, 19 Mar 2010 00:17:27 +0000

Do you have data sheets for the Rebels you’re using? Because they should specify CIE chromaticity and gamma values and from that you can calculate the exact voltages needed for any color you want including arbitrary white points on the black body curve line:

http://tinyurl.com/yl82htc

The LEDs you use (which can be anything, not just RGB) will form a convex hull on that chart indicating the total color range possible:

http://tinyurl.com/yg3enpp

If you want very fine control around the white point then you choose LEDs closer to the middle. I could whip up a spreadsheet to do these calculations for you if it’d help any.

By: joel

joel — Thu, 18 Mar 2010 20:41:37 +0000

Hi Stephen- Yes, all of those… My first requirement is for recessed lighting in a family room, but I would like to be ready to apply this anywhere/everywhere.

Generally I’m trying to create a “pleasing” light, and my starting point for that is incandescent, which is quite warm. That may be largely because we are so used to incandescent light, so it’s not to say that I can’t come up with something better.

By: Stephen

Stephen — Thu, 18 Mar 2010 19:46:47 +0000

This is a very interesting exercise, may I ask for what purpose are you choosing the warmth of the white? Are you replicating existing light devices like reading lights, back fill / wall wash or kitchen illumination? Or are you replacing different colours for different applications?