led taillight delima...help

[panic mode]

that should be ok in this case since it is the ratio we care about.
if you wanted to keep the frequency in the same range when R is 10x smaller, you would have to increase C 10x to make it up.
That would mean C4 to be 4.7uF which in this case shouldn't matter.
you don't care about frequency as long as it is high enough so you don't
see flickers.

 

[airbrush]

ahh...okay i see...good to know, thanks. So i can use anything really, but linear ones will be more to one end than a logarithmic which would be more spreadly evenly for dimming. And the ratings on them wont really matter for this application....1/8w,1/4w.

 

[panic mode]

there are formulas or 555 calculators that will tell you pretty close what
to expect but....why don't you simply try it out? it's valuable experience.

 

[airbrush]

yup..i'll give it a whirl when i have some time