"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
Bob Engelhardt fired this volley in
:

Yes. Do you know how much current they use? How many are there? Run
on 12v, I assume.

Not well, though. It won't be nearly linear over the spin of the dial,
because of the tremendous "knee" in the avalanche current characteristics
of LEDs.

The best (but more complex) way to vary an LED's brightness is with pulse
width modulation. A 555 timer set up as an adjustable one-shot will
build you a fairly effective PWM source for this sort of application.

Keep the fundamental frequency above 100Hz to reduce visible flicker
artifacts (like when you move your eyes, and it seems to make a dotted
line instead of a streak).

LLoyd

I was never any good at electronics. What would I buy at Radio Shack?

Steve