Incubator build: Part 3 – build something

With the particularly sketchy parts of both the hardware and software “figured out”, I was now ready to actually build something that might some day hold eggs. Mostly this consisted of leaning together some spare materials I found, with just enough tape and fasteners to keep it from falling over. The BOM for this is:

  • an old single pane window
  • a 2×10 cut into 6 pieces such that it makes a rectangle (4 sides) and a bottom (2 pieces)
  • a piece of scrap vapor barrier
  • a NodeMCU ESP32 dev board
  • a 12V computer fan
  • a breadboard
  • two DHT22 sensors
  • a lightbulb (with fixture)
  • a loaf pan (for water)
  • an unused computer power supply (never to be used again after this…)
  • a smattering of Wago connectors and wires
  • a transistor
  • a bunch of screws and some tape
  • some literal garbage, to “mount” things (an empty cardboard box for some staples or something, and a broken off piece of wood?)
  • an extension cord with the female end cut off

I wish I had taken more pictures, because I was super proud at the time, but this is the only one I could find.

It’s not pretty, but it sure is a box!

As you can see, this is an electrical hazard, it’s filthy, and barely held together. It was also among the coolest things I’d ever built at that point. It seemed to work half decently – as long as the water was kept topped up, the humidity seemed pretty stable. With no real thermal mass except for the air and the small amount of water, the temperature fluctuated quite a bit. By virtue of the temperature fluctuating, the relative humidity also fluctuated significantly. Either way, it was a bit hard to tell exactly how it was performing because I was just dumping the readings out into the terminal and publishing them as MQTT messages (nothing was subscribed).

Automatic egg turner

At the same time as I reached the limits of my very basic understanding of electrical components, I was struggling to come up with a way to make an egg turner. I knew I wanted to automatic egg turner to be a part of this build, but I couldn’t figure it out. There are a bunch of recommendations on the internet (e.g. use the old style car antenna motor), but they were not particularly accessible (in terms of availability or price point). Sure, it’s a great tip to use an old antenna motor from the scrap heap, but it’s not that great a tip if you don’t have old antenna motors sitting around. Intentionally ordering something that’s only recommended because it’s cheap/accessible would be like buying used pallets to make woodworking product. It just misses the point.

Embarrassingly, this is about as close as I got. The idea was to mount a little wooden sled on the drawer pull, and have that push back and forth. It “worked” with some very generous interpretations of the word…

It’s not pretty, but it… also doesn’t really work that well

Assembling robust mechanisms that do even simple things is also hard! This is well outside my domain, so I don’t even know where you go on the Internet to look up “DIY convert rotational movement into oscillating linear movement”. Ironically, searching that exact phrase leads to some pretty great resources. At the time I didn’t realize that’s what I wanted though. Even if you DO find something, you have to build it in a way that doesn’t suck.

And this is where the whole project truly became hideously sidetracked…

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