On Tue, 11 May 2010 17:07:56 +0000, Cydrome Leader wrote:

Meat Plow wrote:
On Fri, 07 May 2010 22:47:07 +0000, Cydrome Leader wrote:

Meat Plow wrote:
On Thu, 06 May 2010 15:21:52 +0000, Cydrome Leader wrote:

Meat Plow wrote:
On Thu, 06 May 2010 01:20:36 -0500,
rote:

I keep seeing these little solar power sidewalk lights. Last year
they were all white (blueish white). Lately I see them where they
change color. Yet, they only have one LED. How can a LED change
color? I thought the color was determined by dopeing it with a
metal. So how can they change? This has me puzzled.

Bi-color LED have two LED inside with a common cathode. Change the
polarity and you switch on the other LED.

this probably has nothing to do with bicolor LEDs. Who the hell
would make a red/green sidewalk light anyways?

Anyways, white LEDs are sort of like flourescent lights. They
junction makes bright blue light and there is a phosphor that then
converts this into "white". Quite a bit of the blue leaks out.

The quality of white can vary (and does so more with cheap LEDs) in
addition to the phosphor actually aging.

so a visible color change from a cheap white LED isn't all that
surprising.

The OP asked how an LED can change color and I gave an answer. You
got a problem with that? And most white light LEDs are made from
yellow and purple junctions and are not in the least like a ****ing
fluorescent light.

yeah, that's it. taking one color and using it to excite a phosphor to
emit another color is nothing like a flourescent light at all.

you called me, cree and nichia on our conspiracy.

So tell me, what's the forward drop on an LED with "yellow" and
"purple" junctions again, and how are the wired again?

You're one of those newsgroup assholes who will argue with anyone about
anything, ****k off.

Maybe[SLAP]

Maybe you should learn what the words **** off mean?