Re: "by the dashboard light..."

[Wallace White <wallace@remdesign.com>]

LED's are definitely up to the task of dashboard lighting--at least HP
thinks so. They have a many-page application note on that topic. They're
a great choice (in my opinion too) because of their almost-monochromatic
light, so you don't end up filtering out most of your output; their
characteristic of not burning out but only dimming over time, meaning
that they probably won't ever need replacing; and their low heat output
and low current draw. All the same goes for LED stoplights (they've got
green now too) and tail lights, all of which HP and others are
promoting.

But, the Radio Shack-variety "high-output" LED's are junk, in my book.
They have fairly low output and really bad dispersion patterns. Places
like Jameco and Digikey list light output and dispersion angle in their
LED pages, so you can actually pick good ones. HP's best stuff is only
available in large lots, unfortunately, so no go there. (Did a project
requiring bright LED's a little while ago, and couldn't get them.) Just
be sure to pick a proper current-limiting resistor for them.

- Wallace
  '87 5kcstq 149k

Buchholz, Steven wrote:
> 
> > LED's for dash lighting...anyone considered this?  Would give a very pure
> > "red" look(ie, more like the newer cars) than the bulbs w/red filters(a la
> > 5k/200.)  I guess there's a fair amount of testing involved to find a LED
> > with the equivalent brightness.
> >
> ... well, IME those little incandescent bulbs put out quite a bit more
> light.  I tried LEDs in the memory seat switch on the 5kCSQA a while back
> and was seriously disappointed.  That said, there are quite a few new
> high-output LEDs that might do the trick ... and inside the dash you
> probably have room for the larger packages.  Around here they have been
> going absolutely nuts with LEDs ... a good many traffic signals have had the
> incandescent red signals replaced with groups of LEDs (which BTW are almost
> impossible to discern if they are on or off when the sun is direclty shining
> on them ): ... and I've noticed the tail lights on busses seem to have
> changed to LEDs as well.
> 
> I bought an "orange" high-output LED from Radio Schlock a while back.  It
> was nowhere near orange to me, but it was a shade of red that might look
> better in a dash than the normal LED red color ...
> 
> Steve Buchholz
> San Jose, CA (USA)