The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
If you measure something often enough, it becomes science
After pausing to recover from construction, Ms Robin laid four eggs in four days:
She’s surprisingly tolerant of our comings and goings, as well as garage door openings and closings:
We’re trying to stay out of her way as much as possible.
The gallery pix come from my phone, held against the soffit over the nest, and aimed entirely by feel, while standing on the Greater Ladder. If I had access to the top of the soffit, I’d drill a webcam hole, but …
Having some interest in my Sony HDR-AS30 helmet camera’s NP-BX1 battery runtime, I’ve been measuring and plotting recharge versus runtime after each ride:
The vertical axis is the total charge in mA·h, the horizontal axis is the discharge time = recorded video duration. Because 1 A = 1 coulomb/s, 1 mA·h = 3.6 C.
The data points fall neatly on two lines corresponding to a pair of cheap USB testers:
When you have one tester, you know the USB current. When you have two testers, you’re … uncertain.
The upper tester is completely anonymous, helpfully displaying USB Tester while starting up. The lower one is labeled “Keweisi” to distinguish it from the myriad others on eBay with identical hardware; its display doesn’t provide any identifying information.
The back sides reveal the current sense resistors:
Even the 25 mΩ resistor drops enough voltage that the charger’s blue LED dims appreciably during each current pulse. The 50 mΩ resistor seems somewhat worse in that regard, but eyeballs are notoriously uncalibrated optical sensors.
The upper line (from the anonymous tester) has a slope of 11.8 mA·h/minute of discharge time, the lower (from the Keweisi tester) works out to 8.5 mA·h/minute. There’s no way to reconcile the difference, so at some point I should measure the actual current and compare it with their displays.
Earlier testing suggested the camera uses 2.2 W = 600 mA at 3.7 V. Each minute of runtime consumes 10 mA·h of charge:
10 mA·h = 600 mA × 60 s / (3600 s/hour)Which is in pretty good agreement with neither of the testers, but at least it’s in the right ballpark. If you boldly average the two slopes, it’s dead on at 10.1 mA·h/min; numerology can produce any answer you need if you try hard enough.
Actually, I’d believe the anonymous meter’s results are closer to the truth, because recharging a lithium battery requires 10% to 20% more energy than the battery delivered to the device, so 11.8 mA·h/min sounds about right.
Memo to Self: Trust, but verify.
Team Beaver continues to add logs, branches, and mud to their dam beside the Dutchess Rail Trail:
Apparently they’re now busy raising a bunch of little beavers inside the lodge. Next year we expect the water will begin rising in other marshes along the rail trail.
Go, beavers, go!
A shed snakeskin appeared when I opened the garage door:
The skin sits atop the retaining wall next to the door, on a stone(-like) background with poor contrast: even an empty snake has good camouflage!
The exterior looks like genuine snakeskin:
I didn’t know the interior has an entirely different pattern:
As far as I can tell, the snake was going about its business elsewhere in the yard.
To be fair, there’s some luck involved.
Update: After Mitch nudged me, I found the (somewhat the worse for wear) snakeskin again. The head end was split, much as I described, but the tail end was intact (the snake having pulled out like a finger from a glove) and what I though was the inside of the top was the outside of the bottom, just pushed inward to form a very thin double layer.
Today I Learned … to always look closer!
The Dutchess Rail Trail has gotten far more use in recent months than ever before, with entire families walking along the path:
Almost by definition, though, goslings don’t practice social distancing …
The empty Organ Pipe Mud Dauber Wasp nest popped off the wall with relatively little damage:
The open cells on the back side show the wasps don’t waste any effort on putting mud where it’s not needed:
Cracking it in half shows the rugged walls between the cell columns:
Several cells contained three or four (thoroughly dead!) spiders apiece, evidently the result of un-hatched eggs:
Each successful cell contained a brittle capsule wrapped in a thin cocoon, surrounded by fragments of what used to be spiders, with an exit hole chewed in the side:
I regret not weighing the whole affair, as all that mud represents an astonishing amount of heavy hauling and careful work by one or two little wasps!
A pileated woodpecker devoted considerable attention to debugging the remains of a stump in our front yard:
It’s surely a descendant of this one, eleven years ago:
If you’re willing to wait a decade or so, a stump pretty much falls apart on its own, meanwhile providing habitat for critters both great and small.
Update: By popular demand, a slightly pixelated pileated woodpecker:
The Smell of Molten Projects in the Morning 