Saturday, February 26, 2011  Shopping List - Feb 26      Project
18 - Dual 8-Bit Binary Counters  Looks like I'll be paying a
visit to my local electronics store on Monday... I believe that
one of my 595 chips is damaged. Let me explain.  I wired up the
circuit as shown in Figure 6-4... it's a fairly logical layout
if you understand Project 17. When I fired it up, I could get
the LEDs on the left (sorry, I had to use all red LEDs) to start
counting down from 255... but the LEDs on the right (connected
to new 595 chip) weren't lighting up.  I tried quite a few
things:  1. I switched out the LEDs with a few random ones
(green, yellow, red mix) but no luck. 2. I switched out the LEDs
on the left (that I knew worked) with the ones on the right...
no luck. 3. I reversed the two 595 chips and the LEDs on left
stopped working but ones on right did work.   Then I went back
to my wiring... just in case. The wiring was fine, but given
that swapping the 2 chips also reversed the LEDs lighting up,
I'm fairly certain I've