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Pete's Log: August Staycation, Day 1

Entry #1982, Mon, August 16, 2021, 16:50 CDT (Life in General, Smokepacking)
(posted when I was 43 years old.)

I have some vacation to burn and also I've been feeling a little burned out and also also I had a few projects around the house I wanted to do get done, so a few weeks ago I put in a vacation request and now the time has come. My motivation level to work on those projects, however, has vanished. Two reasons:

  • I still have a lingering tail end of my cold
  • The world has conspired to make us no longer wish to host a party, making the house projects feel less urgent

Sigh. But all is not lost. In the mail today, I received my second PCB design! Real nice of it to show up on a day that I have time to play with it.

No alt text found for this picture. Please email prijks@esgeroth.org to complain.

So let's do some bullets. I made this for a couple of reasons:

  • As fun as the XOR Gate is, and as much as I did learn things making it, I felt like I needed more PCB design practice before attempting something more serious.
  • Also, playing with KiCad is just fun.
  • If I'm going to develop a 74HC165 component for ESPHome, I should have a variety of test platforms.
  • I think I have a propensity to double down on absurdity.

So, in addition to owning at least 16 74HC165s in DIP16 format, I now also own 10 74HC165s in SOIC format. I paid $8 for them at digikey. Bringing the total cost of my 74HC165 habit above $20.


So here were my goals for this PCB:

  • Make it compact. This is one reason why I chose the SOIC package instead of using some of the DIP16 chips I already had, check this size comparison:
    No alt text found for this picture. Please email prijks@esgeroth.org to complain.
  • Use components that are less forgiving than in the XOR Gate. In the XOR Gate if I got any size wrong, I could basically just bend the leads a bit to make up for it. I wanted footprints to really matter. So basically this meant using surface-mount components (the other reason I chose the SOIC package)
  • Learn some new PCB things, like vias and copper pours

I think I succeeded on all my goals. The board itself is less than an inch square, meaning it cost less than $5 for three of them (and probably would've been even less if wasn't trying to get them American-made). That's including shipping, which still blows my mind.

So time for some soldering.

No alt text found for this picture. Please email prijks@esgeroth.org to complain. No alt text found for this picture. Please email prijks@esgeroth.org to complain.

One done, time to test. My debouncing tests had started to yield some fruit, so I tested this with a 555-based debouncing circuit. I didn't want to take my debouncing test apart, so this monstrosity was used for testing:

No alt text found for this picture. Please email prijks@esgeroth.org to complain.

It works! Since unlike the XOR Gate I have reason to use more than one of these, let's assemble them all.

No alt text found for this picture. Please email prijks@esgeroth.org to complain.

And give them a test. One thing I've come to realize is testing things with lots of inputs can get tedious. Three of these means 24 inputs. But here we go.

No alt text found for this picture. Please email prijks@esgeroth.org to complain.

And it works!

Guess I have no excuses now to not write that 74HC165 component for ESPHome...


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