Tri-color Leds and poor results mixing colors

[snoopy]

I've been mucking around with bi-color and tri-color leds and have found that mixing colors with two or more of the leds activated doesn't produce the mixed color very well because the actual led dies are not co-located and the separation between the dies means you more or less see the different colored leds rather than the mixed colors. Probably ok if you are standing way back from them but up close it is not to good. Even the diffused ones are not much better than the clear ones. Anyone had any experience or can suggest better alternatives to the cheapies ?

cheers

[ataradov]

Depends on your price range. I've used this one https://www.digikey.com/product-detail/en/cree-inc/CLV1L-FKB-CHMMQEHBB7673673/CLV1L-FKB-CHMMQEHBB7673673TR-ND/4794071 (type, not specific LED) and they are great. But they are quite expensive. But if you only need a few for a project, I would definitely use them.

[snoopy]

Thanks for that Alex.

I have specced in the Thru-hole 5mm types because I need to bend the leads over on a 90 degree angle. Do you know of any in that footprint ?

cheers
david

[JS]

Maybe use smd and put a light pipe to the place it needs to be seen, so it has all that optic channel to blend. But it's true that they don't blend nicely, I had a phone with a small multi color LED to show different notifications and depending on the view angle the colors look quite different, and if you reflected the thing in the dark you could see 3 circles as in Venn diagrams.

JS

[TerraHertz]

This might be relevant: https://www.eevblog.com/forum/chat/$-blue-leds-on-equipment/msg291409/#msg291409

To get an even mix of the light from RGB LEDS, use at least three diffuser films, with gaps between. In some kind of internally reflective tube.
Using ordinary 5mm RGB LEDs with clear plastic, I ground the front of the LED flat with a rough surface (1st diffuser), then a few mm gap, 2nd diffuser consisting of some LCD panel diffuser film (or just a bit of tissue paper), another gap, then the  translucent white glass bezel (which has a ground rear surface, for 3rd diffuser.

[ataradov]

I have specced in the Thru-hole 5mm types because I need to bend the leads over on a 90 degree angle. Do you know of any in that footprint ?

Not that I could find, but I was probably looking at the same sources (ebay, aliexpress). I have not tried any from more reputable manufacturers. But I would definitely go to DigiKey and order a variety of less budget LEDs and see how they perform.

[Bendba]

A cheap trick I use is to dip the RGB LEDs in white nail polish that has this glitter like flakes. You lose a fair bit of the brightness but it does a half decent job at mixing the colours.

The funny part is to explain to your wife why you have some nail polish :-P

[Kjelt]

It is indeed all about diffusers and the optical path.
Professional multicolored lightbulbs even use seperate leds in distances of 5mm or more and can get a good uniform colormix.
I usually use some thin milky plastick sheet, but there are many many different types of diffusers, example:
https://www.pyrasied.nl/product-categorie/lichtdiffusers/

The problem is getting those in small quantities for hobby use, but if you go to a local plasticks shop they usually have small samples of 15x15cm you can take for free