> So, a big question I have now is, how many individual LEDs
> can you multiplex so that the display is bright enough?  What
> is the minimum number of components needed to drive 100's
> multiplexed LEDs?

A couple of after-thoughts -

"minimum number" might not be the best way to go. As I noted
in my previous post, corners had been cut on commercial units
for minimal cost savings, resulting in the premature demise and
necessary repair of the display. There's no real way to get round
the repetitive circuits needed. And the end result is supposed
to be a readable functioning display isn't it ?

When expanding the display to many 100s of LEDs or characters,
a point will be reached when the best possible refresh rate just
won't cut it with a simple 1-micro solution (although the strobing
could be handled by a separate IC in synch with the micro) and
the display will become either slow or dim. In this situation it
would be better to share the workload between several micros,
and they each look after their own section of display, ie several
small efficient displays joined together. A supervisory micro
looks after message loading, synch timing, and farming out
display data to the section micros. Large commercial systems
do it this way

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