MOTM

--- In motm@yahoogroups.com, "Paul Schreiber" <synth1@a...> wrote:
> 
> Personally, I can't *stand* blue LEDs but I'm a fruitcake.

Hmm - to be a fruitcake, wouldn't you actually need to *like* blue 
LEDs to the point of replacing every LED in every piece of equipment 
you own with blue ones?  Blue LEDs are still fairly new and, therefor, 
somewhat trendy.  In a few years I'm sure this blue LED craze will be 
over ... maybe.

If you don't like blue LEDs, I would think that makes you conservative 
- or something.  Besides, legend has it that you despise LEDs in 
general (or at least electrically) - now that might make you a 
fruitcake!  :)


I will admit, one thing that can be annoying about blue LEDs...  If 
you wear glasses, you know something first hand about optics: the 
refraction of a lens is not uniform for all wavelengths of light!  As 
the human eye picks up "detail" through red and green, glasses are 
"tuned" to focus these frequencies best.  As a result, if you view 
some piece of equipment with a blue indicator straight on it looks 
fine.  But the more you view from off axis, the more the blue shifts 
out of place in the image.  (Best I can describe it - so if you wear 
glasses, could be another annoying thing about blue LEDs.)


Paul is right about the cone angle - for panel indicators, it would be 
nice to have wide cone angles.  My favorite blue LEDs (and also proper 
primary green LEDs) are manufactured by Nichia.  (Where Shuji Nakamura 
invented the gallium nitride (GaN) LED technology.)

The Nichia part numbers (for blue) are the NSPB320BS (3mm round) and 
NSPB520S (5mm round) - these are not the highest output (these are 
"only" 700mcd) but that's already way too much for a panel indicator!  
The cone angle is 45 degrees - something like 80 degrees would really 
be preferred.  The green parts are NSPG320BS and NSPG520S.  Also 45 
degrees but be careful with these ones at 2300mcd ... your eyes are 
*real* sensitive to green light too!  (If for some strange reason you 
think this isn't good enough, they make the narrow beam models at like 
11,600mcd, ouch!!!)

They also have a really neat product, the NSTM515AS - this is a "full 
spectrum" LED with three separate elements for the light primaries.  
(Red, Green, and Blue)  It is a 5mm round diffused package with a 80 
degree cone angle.  By changing the current into each element you can 
basically mix any color of light you want.  Build a big enough array 
of these, with appropriate driving circuits, and you could watch 
television on LEDs.


Now, you may have bought some of those Kingbright RGB LEDs (or, for 
that matter, the Kingbright blue LEDs) that are sold in the Mouser 
catalog and found them, uh, underwhelming.  (I did!)  The Nicha parts 
work much better.

Nichia has a Thomas register storefront where you can order small 
quantities of any of this stuff...

https://trorderonline.thomasregister.com/TrooFrame.tpl?Origin=VURL&AZN
umber=73223398


I think Dave has the right idea about putting blue LEDs into the Lumex 
lenses - a diffused white lens would solve the cone angle problem.



--- In motm@yahoogroups.com, "osthelder" <osthelder@n...> wrote:
>
> Blue LED's should be outlawed!  I have a client that loves bright
> LED status indicators [...]  I had this thing right in front of my
> face-maybe a foot from my bespectacled eyes-when I put the plug in
> for the battery power test.  Saw a blue spot for a day!

The Andromeda has one of those on the back panel - probably a 
Panasonic LED judging by the color and the relatively narrow beam.  It 
makes about a 5" diameter blue spot on the wall when switched on.  One 
day I'm sure I will switch the thing off and find that blue spot has 
been permanently burned into the wall.  :)



Seth