Re: Blue LEDs? when did that happen?

From: John Larkin (jjlarkin_at_highlandSNIPtechTHISnologyPLEASE.com)
Date: 09/29/04 

Date: Wed, 29 Sep 2004 08:28:32 -0700

On Wed, 29 Sep 2004 05:38:23 GMT, Don Bruder <dakidd@sonic.net> wrote:

>In article <jq7kl0tn106j1cgllt87f1tkgrlpubmekp@4ax.com>,
> John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:
>
>> On Wed, 29 Sep 2004 00:19:48 +0100, "Adam Aglionby"
>> <nws@capersville.co.uk> wrote:
>>
>> >
>> >"guy-jin" <guyvf@usa.net> wrote in message
>> >news:774e24ad.0409281409.260b5f16@posting.google.com...
>> >> I ran across an old electronics book, the beginning chapters of which
>> >> deal with light emitting diodes. it described the problem of blue
>> >> LEDs; IIRC, the distance between the poles determines the color, but
>> >> when you get them far enough apart to make blue light, current no
>> >> longer flows between the poles.
>> >>
>> >> Am I remembering correctly, and how was the problem solved?
>>
>> It's the semiconductor bandgap, not the physical dimensions, that
>> determines the color.
>>
>> >
>> >By one man Shuji Nakamura
>> >
>> >http://www.businessweek.com/1999/99_24/b3633068.htm
>> >
>> >Adam
>> >
>> >
>>
>> I think the Cree SiC blue led's predated these, but they were
>> horrendously inefficient: they needed something like 3 volts, 50 mA to
>> be a decent panel indicator. Paralleled 74S38s + 27 ohms from 5 volts!
>>
>> But where do they use blue traffic lights?
>>
>> John
>>
>
>Blue plus yellow equals green...

Is that somehow better than using green?

John