So I finished wiring up the other two 4026 chips... still careful about grounding myself before touching them.
As you can see from the pictures, my breadboard isn't nearly as pretty as the author's version (see page 178). Doing this exercise really makes you appreciate the author's hard work with trimming all those wires to make it look pretty - and trimming... and trimming... and cutting... and trimming.
On the positive side, I'm done with most of the wiring... on the negative side (get it - positive, negative) I'm almost out of green wire! Next time I visit ACK I'm going to invest in blue, yellow, and any other colors they may have... red, black, and green are fine, but I wouldn't have minded wiring up the 2nd 4026 chip with yellow and the third 4026 with blue... just to keep everything easy to find.
Anyway, here's a video showing the circuit working... press S3 and it zeroes out the LED. Press S2, and it increments by 1 (most of the time)... holding down S1 locks the LED and any further presses of S2 while holding down s1 don't add to the increment.
One somewhat tricky part of the schematic on page 174 (Figure 4-37) is the jumping of pin 15 on all three 4026 chips and then throwing in a 1k resistor and pushbutton (for S2). I did it on the first try, but you really have to examine the schematics to see how best to make things work.
I'm almost done - now I need to wire in some 555 timer chips and some capacitors to create the reflex tester game. When done, I'll have completed 50% of the book's experiments. Have a great weekend, everyone!