[V8] Elegant mechanisms [WAS RE: Heater Vent Bulb Change WriteUp?]

[urq]

I gave it some consideration ... there are two inherent problems with trying
to use LEDs in this application.  The first is that LED's don't take to
dimming with potentiometers as incandescents do.  Dimming LEDs is usually
done by varying duty cycle on the drive signal.  When you look at the
internals of the vent illumination there are 4 "light pipes" which go to the
various points to be illuminated.  I suspect you would have a difficult time
finding an LED with a sufficiently wide dispersion angle to get good
illumination to all the points.  Of course you could get 4 LEDS and have one
point to each port ... but I doubt there'd be an off the shelf unit that
would do this.  Of course if you decided that the vent illumination doesn't
need to be dimmed (as I would be willing to allow) that would make the
problem easier to solve.  A bulb is likely to last many years and is not
that difficult to replace when you know how ... and we all know how reliable
the LEDs in the window switches are ... ;-)

I'm also considering using some of that reflective metal sealing tape used
for air ducts to cover the hole I machined in the side of the vent housing.
This would tend to reflect more of the light toward the pipes ... something
that might make LEDs work better too.  

Steve B
San Jose, CA (USA)

-----Original Message-----

Has anyone experimented with replacing dash/instrument/switch bulbs with
LEDs?