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.
Who’d’a thunk it?
Our Compact Edition of the OED doesn’t get much use these days, but Mary needed a magnifier for a class on quilt judging and the OED has one that seemed just about right:
The magnifier comes in a removable box fitted neatly into the drawer, revealing a surprise underneath:
A detail view:
It’s a plastic ant from a bag in the Kiddie Surplus box my Shop Assistant grew up with and a pleasant reminder of long-ago days, carefully placed where only I’d ever see it.
Of course, it’s still there …
Being a sucker for infrastructure and numbers, the fire sprinkler system pressure gauges in the motel stairwell proved irresistible.
The first floor gauge shows a nice round 100 psi:
Up on the second floor, it’s 90 psi:
With a different brand of gauge, it’s also 90 psi on the third floor:
Maybe 85 psi on the fourth:
Squinting at the parallax, call it 80 psi on the fifth:
At the top of the vertical pipe on the fifth, on the other side of a valve, we return to the original valve company at 78 psi:
Water weighs just over 62 lb/ft³ at room temperature, which works out to 0.43 lb/in² per vertical foot. Not having packed my laser distance widget, I’ll guesstimate 12 feet and 5 psi per floor.
A quick graph with an eyeballometric straight-line fit:
Call it 0.42 psi/ft, which is pretty close to the right answer.
Hitching a charged, albeit worn, NP-BX1 lithium battery to the astable multivibrator produces a blinding flash:
The current pulse shows the wearable LED really takes a beating:
The current trace is at 100 mA/div: the pulse starts at 400 mA, which seems excessive even to me, and tapers down to 200 mA. It’s still an order of magnitude too high at the end of the pulse.
On the other paw, maybe a 14% duty cycle helps:
The top trace shows the base drive voltage dropping slightly, although I suspect the poor little transistor can’t take the strain.
The LED really does need a ballast resistor …
Around 1960, somebody my father knew at the Harrisburg AMP factory gave me a chunk of plugboard bandsawed from a scrapped computer or industrial controller, because he knew I’d enjoy it:
He was right.
I spent months rearranging those little cubes (some with cryptic legends!) into meaningful (to me) patterns, plugging cables between vital spots, and imagining how the whole thing worked:
Long springs ran through the notches under the top of the blocks to connect the plug shells to circuit ground. The ends of the steel rails (still!) have raw bandsaw cuts, some of the blocks were sliced in two, the tip contact array behind the panel wasn’t included, and none of that mattered in the least.
Only a fraction of the original treasure trove survives. It was absolutely my favorite “toy” ever.
Quite some years ago, our Larval Engineer assembled the pattern you see; the hardware still had some attraction.
I’ve asked Mary to toss it in the hole with whatever’s left of me, when that day arrives …
An obsolete Intuit / Roam Data credit card reader emerged from the heap:
“Turn up the volume” suggested where the power comes from:
They drive a LOUD, probably square-ish, audio signal through both “earphone”channels, rectify and regulate the output, and have plenty of power for the reader. The card data returns through the “mic” as another audio signal; I assume they choose an encoding well-suited for a dab of DSP decoding.
Nowadays, of course, 3.5 mm jacks are obsolete, audio data travels by Bluetooth, and you must keep a myriad batteries charged at all times.
The Wzye Pan camera overlooking the bird feeders attracted the attention of a Downy Woodpecker:
The camera sits on a “guest” branch of the house network, fenced off from the rest of the devices, because Pi-Hole showed it relentlessly nattering with its Chinese servers:
In round numbers, the Pan camera tried to reach those (blocked) iotcplatform domains every 30 seconds around the clock, using a (permitted) google.com lookup to check Internet connectivity. Pi-Hole supplied the latter from its cache and squelched the former, but enough is enough.
I haven’t tested for traffic to hardcoded dotted-quad IP addresses not requiring DNS lookups through the Pi-Hole. Scuttlebutt suggests the camera firmware includes binary blobs from the baseline Xaiomi/Dafang cameras, so there’s no telling what’s going on in there.
The Xiaomi-Dafang Hacks firmware doesn’t phone home to anybody, but requires router port forwarding and a compatible RTSP client on the remote end. Isolating it from the rest of the LAN must suffice until I can work out that mess; I assume the camera has already made my WiFi passwords public knowledge.
We’re riding home with groceries along Raymond Avenue, approaching the Vassar Main Gate roundabout, and, as is my custom, I’ve been pointing to the middle of the lane for maybe five seconds as I move leftward to take the lane:
The driver of HCX-1297 is having none of it:
The mirror passed maybe a foot away from my shoulder; I’d reeled my arm in as the front fender passed by.
All three traffic circles / roundabouts on Raymond neck the lane down and angle it rightward into the circle, which is supposed to “calm” traffic:
The design doesn’t allow much flinch room for cyclists and certainly isn’t calming for us.
The NYS engineer who designed the Raymond roundabouts said the whole thing was “standards compliant”, refused to go on a check ride with me to experience what it was like, and told me to detour through the Vassar campus if I felt endangered while sharing the road.
Obviously, NYS DOT personnel do not dogfood their “share the road” bicycle standards by riding bicycles.
The Smell of Molten Projects in the Morning 