I sure like the idea of a shift register or two, or three, maybe four?
And one 555 for each output on a shift register.  That is, if
the shift register has eight output pins, 1,2...8 then there would
be one 555 sourcing current for all led's attached to pin 1 of all
the shift registers.

There could also be a shift register controlling the 555's.  By shifting a
one into the 555's control shift register and then shifting the one down
the line at some rate, you accomplish two things.  First you multiplex
the led's by only enabling each group (all pin 1's, all pin 2's ...all pin
8's)
for a short time.  And also you have insured that each shift register only
has one pin driving led's at a time.  (so they won't burn any fool that
sticks his finger on it to see if it is running hot) (getting your finger
branded with the numbers 555 could only be worse if it have been
a 666 chip)

I leave the method of getting diferent brightness for the led's as a
exercise for the reader.  (I have ideas, but this is a tough crowd)

Bill C.    bill@cornutt.com

>      Hmm...
>        I just thought, why bother with the PIC if you need to feed the
>output into a load of shift registers.  Just use a bit of discreet logic
and
>clock it all with a 555.  There, knew I could get one in there somehow :)
>
>        Mike Rigby-Jones
>        mrjones@nortel.co.uk
>