>I just did some tests with medium bright LEDs at 100 mA (goal
>is bright LEDs at 200 mA), and 5Hz is too low, 20 Hz seems to
>be a good compromise. So the 1 degree equivalence is 125 usec.
>Even with this "low" current and medium bright LEDs, 10us
>pulses (for the weakest stars) seems to be just bright enough.

You are going to need to have a counterbalance anyway, so why not have it as
another set of leds strung along it. You will get twice the pulse rate of
the leds at a given rotation speed then, and could even make the star
twinkle by lighting only one string.

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