Hi
White LEDs are excellent but pricey.  There are two types as I saw in
maplin, one with six leads (two blue, one red and one green LED) which can
be tuned to any colour and a two lead white one.  They are pure white and
work really well.


Tim Kerby


At 17:10 24/11/97 +0800, you wrote:
>I noticed a comment in another thread about so-called 'white' LEDS, and
>would like to contribute / ask for comments on experiences with these
>beasts.
>
>Experience.  (Kingbright RGB LED - 5mm clear and milky versions tested)
>
>As these are made from three separate LED die in a single epoxy 'LED'
>casing, there are some side effects that are not exactly desirable....  The
>most obvious is that the LEDs are only white when you are on a specific
>vector near-axis.  Moving away from this point the colour shifts towards
>the three primary colours and their combinations.  The actual usable white
>cone off the observed axis is VERY small.
>
>The blue chip is excellent, and creates a very pleasant blue colour - which
>is useful in itself to distinguish display states.
>
>The price becomes reasonable in very large quantities, but the colour
>prismatic effect renders it useless as a white led.  Imagine seeing a vivid
>RED indicator from an angle - when it is really 'white' (r+g+b) or 'yellow'
>(r+g)
>
>Over to you
>MC
>
>


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