>   Also, you can consider "pre-emptive" filament warming of lamps at
> least 1 second *before* they are switched to full brilliance, using
> about 10% of full PWM time.  In other words, perform your animation one
> second in advance!

It is possible to pre-warm all the lamps in a subvisible temperature, it
means that lamps never turn off. I think this could also stretch somehow
lamps life, and improve a fast turn on.

>  In case it's not obvious, this is a full-fledged PWM application and
> also, if the micro "hangs" in mid-multiplex there's going to be
> considerable smoke released unless you put in place a few protective
> measures.  The WDT at *no* prescale is an obvious one to start, as is
> using pull-ups to default to lamp drivers *off*.

I have a pulsed pwm high energy driver connected to a microcontroller,
the way to ensure it will never smoke in case of the uC hangs was using
a high pass filter, a simple RC filter with a timming bigger than the
largest pulse, so in case of uC hangs with active level output, the
driver will receive just one large pulse (around 120% of power) and turn
off, nothing else.

> > There are some seriously dangerous voltages and high insantaneous
> > currents present so beware. (Standard warning for newbies who might
> > not fully understand the dangers involved).  Kids... dont try this at
> > home.

Why not use low voltage lamps? there are plenty of them in outdoors and
stores decoration where the codes doesn't allow higher voltages... as 12
or 24Vdc...  It would allow to use power FETs to drive the matrix.