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Making yellow from bi-color (red/green) LEDs

Just curious... if you're trying to use a bi-color (red/green) LED to make yellow, how well does it work using an LED with a clear "lens" along with a (clear) light-pipe (mounted above the PCB, going through the case)? I've used diffused LEDs in the past to do this with no problem, but I'm thinking that with a clear lens there won't be enough mixing of the red and green and the user will just perceive the two distinct colors rather than yellow as intended. Thoughts?

Given a choice of packages (e.g., 1210 vs. 0605), presumably I'd want the smallest one available so that the red and green LED chips are as close together as possible, right?

Thanks,

---Joel

Reply to
Joel Kolstad
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As long as the viewer does not have a clear image of the two die in the LED, the light will appear to be a single color. The only problem with not diffused sources like this is that the apparent hue may vary a bit with viewing angle.

Reply to
John Popelish

Just wait till they decide to build cheaper traffic lights by using a single light housing, with bi-color LEDs to get Red, Green and Yellow.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

Thanks John; I'm ordering a few to play with and see how it does. In an 0605 package I suspect that unless you're within inches of the LED you wouldn't be able to discern the colors individually. (Harkening back to the time as a kid you put your face up to the glass and realize that there are actually three different colors there, all arranged in nice little triads...)

---Joel

Reply to
Joel Kolstad

its called pixel convergence ;)

followed by image convergence (when there are more than one pixel).

Cheers Terry

Reply to
Terry Given

On Feb 14, 5:07 pm, "Michael A. Terrell"

...snip...

I recall reading someplace that the multi-position lights are necessary because of both color blind people and high sunlight conditions where even people with normal vision cannot distinguish the light color due to the ambient brightness.

- mkaras

Reply to
mkaras

That won't stop some greedy politician from trying to have them installed, so he can pocket the difference.

--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
Reply to
Michael A. Terrell

I was absolutely astonished when I did this the first time - I could resolve the individual dots, but I still saw the overall picture in my peripheral vision, as if it were superimposed over the little dots.

Kinda boggled my mind, but when you're 8 or 10, that's not hard. ;-)

Cheers! Rich

Reply to
Rich Grise

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