I've been having quite a bit of fun with this ATTiny charlieplexing. Aside from the KITT Larson scanner thing, most recently have made a little EMF detector (originally showcased here for Arduino)
With apologies for the lame iPad photo quality, here's that one constructed, and another take on the 20 LEDs, arranged in a square which runs a sketch that loops around changing direction every 0.5 to 5sec.
Dave thanks again for the original inspiration.
Geoff
