Colour changing LED's

[The Medway Handyman]

Hi Been looking at these

does an LED light change colour? Would each fitting have LED's of each colour, or do the LED's themselves change colour?

[Grunff]

The lights will either contain 3 different LEDs, a red, green and blue, or they will contain a single multi-colour LED, which contains 3 elements within the same LED package.

[Graham]

No, they would be two or more LEDs in the same package. You can have a two colour LED with only two wires but internally it's two back-to back LED's with steering diodes so the colour depends on the polarity.

[The Medway Handyman]

Thanks. That makes sense now.

Super-bright LED torches

've just ordered one of those :-)

[Dave Plowman (News)]

Usually three colours so the same in principle as a CRT TV screen. If you have the three sources close enough together they give the impression of a single colour.

You obviously don't visit discos much these days. ;-)

[:Jerry:]

AIUI the LEDs, within the common housing, do the 'steering', depending on which tail is ve+. Also there are tri-colour LEDs which emit their third colour when supplied with an AC supply rather than DC.

[Peter Parry]

Lights that shine upwards are pretty awful. If you don't mind some fairly simple construction work a packet of 100 each high intensity LEDS in red green and blue from one of the many Chinese suppliers on eBay plus the rather cunning controller from Big Clive (of this group) at

will allow you to do some much better effects at a fraction of the price.

I used this kit plus a length of plastic trunking and a pile of red green and blue LEDS mounted in triads on a REMAP project

to make a 6ft long ceiling light for a child with severe brain damage who found slowly changing lights to be very calming but the standard disco lighting kits supplied were too bright and to hot running to be left on overnight.

[John Rumm]

The most useful torch I ever bought was a head torch a bit like:

(except my one is just on or off - one brightness)

It is amazing how much easier many jobs are when you have a light that looks where you do and does not need a hand to hold. I find I can rewire a whole house on about one set of AAA batteries on mine.

[John Rumm]

No, that is still a bi-colour - the AC just flashes each "side" in quick alternation allowing the eye to integrate the colours. A true tri-colour LED has three leads allowing both sides to be lit in parallel.

[:Jerry:]

With respect, that sounds like dancing on the head of a pin...

[Dave Plowman (News)]

Not really - a true bi-colour will allow any colour between the two primaries. Or fade between them, etc

[John Rumm]

What, cramped?

Hardly - they are fundamentally different devices, and require different control logic. There is no requirement to reverse polarity with a tri-colour for example, and the light output is continuous rather than pulsed when displaying colours other than the two native ones.

You need quite clever PWM control circuits to get a bi-colour to do what can be done easily with a tri-colour.

Bi-colour are more use for positive two state indicators like power / standby lights etc.

[Red]

Disco's!!!! Not been called that for a decade or 2. Pot and kettle there, me thinks ;o)

R.

[The Medway Handyman]

I have a similar thing from Argos, 2 , 4 or 8 LEDS. Wish I'd seen that one earlier, better spec cheaper!

Very useful for wiring as you say, also plumbing - when you are laying on your back under a sink! LED torches are great for plumbing, the smallest drip seems to sparkle - great for spotting that leak.

[mike]

John Rumm wrote in news:4690f905$0$8729 $ [e-mail]:

Seconded, except I got one of these

's the mutts; 3 brightness levels and the lowest is much brighter than any other torch I have - the brightest is scary!

I've had multi led ones before, but this one is _much_ brighter.

mike