On Tuesday, July 12, 2016 at 9:29:24 AM UTC-5, wrote:
I bought several Color Changing Solar LED sidewalk lights at Walmart. Of
the four I bought, three of them changed color, the 4th one stayed red
all the time. Since I was going to Walmart, I took the defective one and
exchanged it yesterday for one that works properly.

I'm only posting this because I opened it up before I returned it, and I
could not see any circuit board, chips or other parts. Just the LED and
some wires going to the battery and solar panel. This makes me wonder
how they change color???? Apparently the whole circuit is built right
into the LED itself. Anyone know anything about them?

Your cellphone has more computing power than a mainframe computer used by NASA to control the Moon landings. 10 years ago, I was using LED's that had control chips built in to the LED body which caused them to go from on to blink when voltage was applied to one of the 3 leads. I could see a tiny black speck under the emitter in the translucent body of the LED. I imagine that the tiny chip inside newer LED's is much more complicated after a decade.. ^_^

[8~{} Uncle LED Monster