This is a guest post by
Olger Groen . If you would like to write for ExtremeCircuits, then drop
us an email via contact form or simply comment. A long time ago when a
parallel printer port was the standard, i was thinking how to get the
most led’s on a 8 bit interface. And came up with a simpel way to
demultiplex. It can be used with dip-switches or any other 8 bit
interface like a usb i/o interface. I made a 256 run light using two
74hct193 and a 74hct132. The resistor can/need to be matched by what
type of led’s and power you use. Parts are still available in Europe,
for the usa don’t know , but i think no problem. I made a compact disign
by using 2 standard PCB’s, 16 BC557AP and two 74154N ‘s.
have fun with it……..
Author: Olger Groen – olger.groen at telfort.nl