"James Wilkinson Sword" wrote in message
news
On Tue, 25 Apr 2017 21:01:37 +0100, Rod Speed
wrote:



"James Wilkinson Sword" wrote in message
news
On Tue, 25 Apr 2017 19:34:38 +0100, Rod Speed
wrote:

James Wilkinson Sword wrote
Graham. wrote
James Wilkinson Sword wrote

Yes, I've googled it, but there are many different approaches.
Which one is used in domestic LED bulbs?

Ultra-violet LED exciting a white phosphor,
much the same principle used in florescents.

That's what I would have assumed, but when you
look at a switched off white LED, it's not white.

All that means is that it isnt white when it doesn't have UV falling
on it and that the protective outer isnt the phosphor itself.

I would have expected it to have a white coating that
can be seen like on a switched off fluorescent tube.

The difference is that leds don't have glass as the protective outer.

Those adjustable-by-remote ones you have, just how many colours can you
make?

They claim 16M

Do they only have R G and B emitters,

Nope. The strips where the leds are visible have one big led and a couple
of smaller RGB ones. Not clear why there is more than one RGB one,
presumably because they arent anything like as bright as the white one.

Just discovered I can't actually take a photo of the strip with the leds
lit in the dark it completely ****s the exposure system in the phone.

Use a real camera

Don't have one anymore and wouldn't have any film for it even if I did.

and put it on manual exposure?

or could you make a spectrum similar to sunlight?