On Tuesday, 13 December 2016 02:54:08 UTC, John Rumm wrote:
On 13/12/2016 00:23, Dave Plowman (News) wrote:
Got a set of Xmas lights. Gawd knows how they do them at the price.
Blue and White. PS/controller gives a variety of programmes. Including
flashing the blue and white alternately, or all on together. But only two
wires from the PS. I can see reversing the polarity could have one colour
or the other, but how both at once with no apparent flicker? Fast
switching?

Yup pretty much... Throw a bit of PWM into the mix as well, and you
should be able to get dimming and fading effects as well.

It's more than just PWM it's IC2 which uses atmel contollers to control each individual LED is possible .

https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1


https://www.amazon.co.uk/d/Indoor-Li...A38G67QEAA9E03


we have this sort of thing on our lab christmas tree it has a remote control I can set almost any colour and slow of fast transitions. Last time when two studetns were doing selfies with my tree I used teh remote to turn it off, they looked worried as they thought they'd broken the lights. :-)

So it might be that a dedicted xmas tree light setup uses the above and possibley even cheaper.