Dale Botkin <dale@BOTKIN.ORG> wrote...

>But what point would there be to limiting the current to 2A or more?  I =
know
>that would produce little black craters where LEDs used to be.  The
>objections I'm hearing raised are of the "what happens when your crystal
>stops oscillating and one column of LEDs gets stuck on?" variety.

And for those objections, Brent Brown's solution is a very elegant
one.

What I've been talking about is a separate problem: in normal
operation, you are relying on maximum transistor beta to limit current
and protect your circuit.  In my experience this is not reliable, and
unless you provide some sort of current limiting- whether on an
individual basis for each LED, or by row, or by column or for the
array as a whole- you are inviting trouble down the line when your
design goes into production.

Dave

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