Could you replace the discrete darlingtons with an array? Might be
easier if you didn't have to solder each individual transistor.

Josh
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Jinx wrote:
>
> > I have built an 8 x 128 leds designs as a matrix display,
> > the rows [8] goes to rb0  to rb7 then the columns goes to the
> > ra0 to ra3 through a cascade demultiplexer
>
> It sounds very similar to mine, except I use transistors for
> drive. Without them it would be very dim. I have to disagree
> slightly with others' comments about the required power.
> Although this uses normal 3mm LEDs it is quite bright and
> uses only 40mA (surprised me !!)  For 5mm ultrabrights, I
> agree, the power consumed will be higher, but what I found
> illustrates that it can be done at lower power (battery supply
> was a requirement). This one is strobing at 200Hz, based
> on a timer IRQ. It's a work in progress (displays messages
> but the s/w is unrefined), so can't help much further
>
>

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