> I saw this sort of scheme yesterday, as I said.  The
> "trickery" that was used was simply only turning on one LED at a time.
> In the example I've seen, this is how it's done

You can of course do it the dump way, and have a rather low duty cycle,
but even with this circuit you can multiplex by row or collum, for a
much better duty cycle (better by a factor of N-1). Just take care that
the current depends somewaht on the number of LEDs that is on, so vary
the on-time accordingly.

Wouter van Ooijen

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Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products

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