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multimeter in need of calibration
Saturday, July 25 2026
location: 940 feet west of Woodworth Lake, Fulton County, NY
This morning when I went to look at the stool I'd spent so much time carving yesterday, I saw it had developed a prominent crack in its shelf, that platform I'd included to stabilize the legs about half way down from the top (or seat). The wood was probably still quite green when I collected it even though it had broken away from its parent tree and had received no further nutrients or water in at least a year (and maybe as much as three years). The lesson here is to not carve stools out of wood containing too much moisture; such cracking did not happen to the two other stools I'd made using blocks of significantly drier wood. Still, the crack doesn't affect the function of the stool and it mostly gives it a look of having had experiences (much like Jimi Hendrix in his 20s). It's sort of like the crack in the Liberty Bell.
I spent a couple hours this morning rasping and sanding away the rough patches on the stool, gradually giving in the smooth curving organic appearance of a muscular animal. It is easy to see why a sculptor, even a non-gay one, would want to carve muscly men from marble and other solid materials.
I'd yet to track down mysterious problems with the ESP8266 that works as a cellular hotspot watchdog and indoor weather condition sensor. That device has only worked intermittently for nearly a month now, but occasionally it transmits weather data. By now it was becoming clear that the problem was probably its power supply, which is a 13 volt wall wart that is connected in parallel to a 12v marine battery that provides plenty of backup power should there be a power failure. The twelve or thirteen volts then goes through a DC-to-DC converter to get it down to 5v before going to a regulator on the NodeMCU board to get it down to 3.3v for the ESP8266. Last night I'd checked these voltages with my old trusty blue multimeter and saw that the wall wart was producing something like 23 volts and what should be 3.3v on the ESP8266 power pins was closer to 5v. This seemed weird, and my first instinct was to believe the multimeter and think something had gone very wrong with the electronics I was testing. But I have another multimeter, and when I used that to do some testing, the voltages in the circuit was what they should be (13v from the wall wart and 3.3v on the ESP8266). Clearly my multimeter needed calibration, but I could find nothing about doing that on my particularly model.
So I took it apart. Inside I found four surface-mount potentiometers that I tweaked slightly and then somewhat more. But no combination of tweaks were able to correct the full 40 to 45 percent that the the multimeter was off. But I was able t reduce the error to about 10%, which gets the multimeter back to usable (at least for most applications, which tend to be more qualitative than quantitative and where accurate readings are unnecessary). I asked ChatGPT what the problem might be, and it suggested looking for a cracked solder joint, which I have yet to do.
I then proceeded to upgrade my hotspot watchdog device so that the NodeMCU is plugged into a carrier card to which the actual support circuits connect. This would allow me to swap out individual NodeMCUs (and their ESP8266s) when they seem to become unreliable. I've yet to actually have one become unreliable (the only change I've seen is that they die when I misapply voltages), though I was now suspicious of the ESP8266 that had been working as a hotspot watchdog, so I swapped in a new one, and at first it seemed to work great even with the existing marine battery and wall wart power supply. This lead me to draw a big red T on the old NodeMCU, indicating it is only good for testing. But later the new NodeMCU started misbehaving, and the only way to fix it was by disconnecting the marine battery from the wall wart and NodeMCU. This suggested that the problem was actually with the battery, which is now about five years old. ChatGPT suggested that allowing it to deplete in the fall and overwinter in this state might've been bad for its internal plates.
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This evening after I'd finished all the things I'd wanted to do for the day, I grabbed the big Kobalt chainsaw and walked down to the dock via the old dock trail, which Gretchen said was now blocked by a massive tree that had fallen. But when I went to cut the fallen tree, it turned out my battery was almost dead. So I left the saw there at the fallen tree and continued with my plans to drink a beer while floating around on an innertube. As I was doing that, I could see some kid actually playing in the lake over by Pyotr's dock. They were even paddling around in a kayak, but never ventured more than about 50 feet into the lake. (I have a feeling that if this were the 1970s, they wouldn't've been kept on such a short leash.)
I recharged the chainsaw battery at the cabin for only about an hour or so and returned to the fallen tree and easily cut it into two pieces. Because the wood was so rotten, I could just push one of the massive pieces out of the way human power without even resorting to levers, as it had the density of paper maché.
Returning to the cabin, I then went to that fallen black cherry in the woods to the west that I'd used as raw materials for making my latest stool. I cut up another couple pieces of it and carried it home, an effort that gave me a delightful burst of exercise. (I'd taken 120mg of pseudoephedrine this morning, and it feels good to carry heavy weights while under its influence.)
Later this evening at around dusk, I was up on the highest deck doing some sweeping when I saw a single fat bat flitting about over the cabin grounds. I told Gretchen about him, referring to him as a "fledermaus." She came up to watch him with me, and he kept flying around in a circuit in the cabin clearing for at least a half hour. At one point as he flew, he actually stopped flapping for a second or two and glided, something I've never seen any bat do. Gretchen decided his name was Flynn. She then went on to wonder why our cabins always seemed to collect so many single males of various animal species around it (though we had no idea what gender Flynn really was). I asked what other males besides Flynn and Throckmorton (a loon who, in our mythology, relocated from Twenty Ninth Pond to Woodworth Lake at around the time we bought our cabin). She then mentioned "Robert." I didn't remember Robert, so Gretchen explained that Robert was a male toad who followed us from Twenty Ninth Pond to Woodworth Lake like Throckmorton, though she'd never actually seen Robert, she'd only heard him. (It's possible that Gretchen is misremembering Robert's species and he is actually a bullfrog.)
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The new Liberty-Bell-style crack in the new stool and the results of much sanding. Click to enlarge.
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