I ordered the entire breadboard CPU kit and am working through it, slowly. I'm trying to build the circuits without necessarily aping what Ben did in the videos, but by trying to arrive at the same goal.

So far, I've just built the clock module. Here are my observations so far.

About what's provided:

  • I know that nowhere does he say that the way I'm approaching it is even a suggested way, but it would be nice if there were stated goal points:

    • Use a 555 to build a frequency-adjustable pulse signal
    • Use a 555 to build a single-pulse generator triggered by a debounced button
    • Use a 555 to build a switched on/off signal triggered by a debounced switch (use the 555 in a different manner than before)
    • Use LS logic NOT, AND, OR circuits with the previous circuits to use the switch circuit to select between generated pulse and manual pulse. Provide signal and inverted signal. Also provide a facility for an external signal to disable the output

    The last one was the biggest one for me. I provided the switched signal, then realized that he also wanted the halt input. Then I realized that he also wanted the inverse signal.

  • I didn't receive the stated number of 1kΩ resistors. I got 4 (or maybe 5 and I lost one somewhere), but the booklet says 10. I had to steal one from my stash.

  • The switch and pot that were provided are not well suited for solderless-breadboard use. They wobble quite a bit. The switch is worse because the pushbutton that Ben uses in the videos is replaced with a sliding switch, and the pushing sideways on that unstable component feels very fraught. The pot is not as bad, especially after I trimmed off the little feet on its plastic case, which had been interacting with the breadboard's divots weirdly, but it still wants to lift.

  • That said, all the components feel like quality components.

  • The blue LEDs are remarkably bright in comparison to the yellow ones, and none of the provided resistor values bring it down to match the intensity of the yellow ones. I ended up using only the yellow ones.

  • I'd rather have gotten a set of "dupont" pin jumpers than the little box of preformed jumper wires for doing initial trial connections. If I'm going to make my own to-length jumpers with the included wire spools, the preformed jumpers just feel like an irritating inbetween.

  • The provided breadboards really are way better than other breadboards I've used. They're not perfect — I still occasionally have a hard time inserting a wire for no apparent reason — but they hold different size leads without any problem and don't seem to lose their clamping force.

  • The power supply cable is just too short. You have to be working right at a power outlet for it to be long enough. I suppose that's not an issue for someone at an electronics bench, but someone at an electronics bench also probably already has a bench power supply.

  • There were some components that I'm unsure why they were included. Maybe I should look back at the videos.

  • The booklet has a final schematic at the end, but the logic section is just a logic diagram. This is mostly fine — it should be obvious that I need to hook up power and ground, but, for the incoming halt signal: should I have a pull-up/down resistor for the input to the logic circuit? Seems likely.

About my build process:

  • If I had it to do over again, I would wire it so that the tall components (the LEDs and electrolytic caps) sit flush on the breadboard rather than spanning multiple rows. When they sit flush, they're pretty stable, but when they sit on top of their legs, they like to wobble. I don't feel like it's unstable, really, or likely to detach, but there are knobs and buttons and switches to manipulate here. This likely means "wasting" some rows, but that's probably not too relevant on this circuit. It might become a bigger deal on the more complex circuits to come.
  • I wish I'd come up with a better idea for the meanings of the different colors of wire earlier on. But also I don't know how I'd be able to come up with that without doing it once first or just having someone just give me a paradigm.
  • Almost everything ended up on the lower half of the breadboard, which resulted in more wire overlap than I'd have liked. With the 555s, that's kind of dictated, since the output is going to be on the lower half (unless you orient the chip the other way), but that also means all of the outputs to your logic circuits are on the lower half. If I had it to do over again, would I plan the whole layout ahead of time to see if there's a better way?
  • The breadboards supplied are marked in such a way that it's clear which way is "up", and, if you use that way, and put pin 1 to the left, the Vcc rail is the one further from the Vcc pins, and the ground rail is the one further from the ground pins. Slightly annoying. I feel like I probably should have planned ahead for that better.
  • An oscilloscope is really helpful in seeing the debouncing that you're doing, and also the signal improvements afforded by the capacitors and tying the various 555 pins as suggested by Ben in the videos. Obviously, you can just trust that it's going on, but it's nice to see. (I have a "cheap" handheld oscilloscope that I got for $200 and it worked fine for this.)
  • I should have paid more attention to the leads I connected to on the pot. It came out such that counterclockwise is faster and clockwise is slower, which feels backwards. It's an easy fix, but annoying. (I placed it so that it sits on the gap between the rows and the rails, so I can't just flip it.)
  • I once spent an awfully long time debugging why the pulse wasn't working any more after coming back to it after a few days before I finally realized that the pot was set to the circuit's fastest setting and it just appeared to be solid-on. Since then, I made sure to leave it visibly pulsing.