Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
We’re approaching the Vassar Main gate roundabout on Raymond Avenue. I’m signaling for the middle of the lane, which involves extending my left arm straight out and pointing downward:
Raymond Avenue – Passing at Main Gate 1 rear – 2017-08-31
Evidently, the driver figures he can get past us into the roundabout, missing my hand by maybe a foot:
Raymond Avenue – Passing at Main Gate 2 – 2017-08-31
Six seconds later, we’re all stopped, because the planter in the middle of the roundabout is designed to hide the oncoming traffic and make you slow down:
Raymond Avenue – Passing at Main Gate 1 – 2017-08-31
I’m getting more assertive about moving leftward before we enter the approach, but obviously I’m not quite far enough over.
A stray nose pad appeared on the kitchen floor and, after some investigation, it corresponded with the stub in Mary’s oldest reading glasses. Some rummaging in the Bag o’ Eyeglass Stuff produced a similar pair of pads:
Glasses – missing nose pad
Although the lenses have become somewhat scuffed over the years, masking the optics with Parafilm is always Good Practice:
Glasses – new nose pads – masked
The split boxes clamped around the pad stems required a bit of delicate opening-up with a utility knife blade before the new ones pressed firmly into place.
The O-rings on the spout of our American Standard kitchen faucet wore out again; having described that repair many times, there’s no need to say much more about it. I didn’t want to get into this repair while thinking about the hot limit problem, but I did check to make sure the box under the sink had some O-ring replacement kits.
A bench vise with soft jaws holds the spout while you remove the escutcheon ring retainer:
Kitchen faucet spout – in vise
Basically, just tap around the ring with a long drift punch and it’ll eventually fall out onto the reasonably clean rag below it.
The interior of the spout before cleaning shows why you should never look into your plumbing:
Kitchen faucet spout interior – before
After a few hours in a white vinegar bath and a few minutes of scrubbing with a ScotchBrite pad:
Kitchen faucet spout interior – after – 1
Another view:
Kitchen faucet spout interior – after – 2
Obviously, you could do better, but it’s hard to get excited about the last few nodules. For whatever it’s worth, the nodules grow despite our water softener; I have no clue what’s going on in there.
A few wipes of silicone grease, reassemble in reverse order, apply a firm shove, and it’s leakless again. For a while, anyhow.
Once again, the season of orb-weavingspiders has arrived, with this one building her web across a living room window:
Orb Weaving Spider – with insect
I set the Sony HDR-AS30V atop a tripod, told it to take photos at 5 second intervals, then stitched the images into a Youtube video. It won’t go viral, but watching the spider construct her web over the course of two hours was fascinating.
She finishes the spiral at about 1 m video = 1.25 h real time, settles down for what might be a nap (it’s hard to tell with spiders), and has an insect join her for supper at 1:28, half an hour later. Spiders go from “inert” to “death incoming” almost instantly, even in real time running.
Another orb weaver set up shop in the adjacent window, but moved out the next day. Perhaps there’s a minimum spacing requirement?
Two more orb weavers guard windows in the kitchen and laundry room. We sometimes leave the lights on for them.
YouTube has other web-building videos with far more detail, of course.
The magic incantation to create the video from a directory of images in the form DSC01234.JPG:
sn=1 ; for f in *JPG ; do printf -v dn 'dsc%04d.jpg' "$(( sn++ ))" ; mv $f $dn ; done
ffmpeg -r 15 -i /mnt/video/2017-09-03/100MSDCF/dsc%04d.jpg -q 1 Orb-Weaving-2017-09-03.mp4
Perhaps each resonator’s frequency depends on its (laser-trimmed) tine mass and follows a more-or-less normal distribution, but the parallel-serial difference series capacitor changes the frequency based on (well-controlled) etched dimensions producing quantized results from three different masks / wafers / lots, with the motional inductance and capacitance incompletely modeling the physics?
Producing the histograms uses the LibreOffice frequency() array function, which requires remembering to whack Ctrl-Shift Enter to activate the function’s array-ness.
[Update: Faceplant about “parallel” resonance, which is actually the shifted resonant peak due to the 24 pF series cap. Apparently I typo-ed the second histogram subheading and ran with the error; the figures are now correct.]
The usual model for a quartz resonator apportions half the measured both-leads-to-case capacitance to each lead:
AT26 crystal capacitance fixture – Cpar detail
These AT26 / TF26 cases run around 0.6 pF, so each parasitic capacitor is 300 fF:
60 kHz Quartz Resonator – model
For ordinary quartz crystals, you solder the case to the ground plane to get rid of the sneak path around the central capacitor (normally C0, but labeling it properly in LTSpice just isn’t happening), but those little aluminum cans aren’t solderable. One could blob some Wire Glue over them, but …
So I just wrapped a wire around the case and soldered it to a convenient ground point under the board:
Solid lines = case ungrounded. Dotties = case grounded.
Grounding the case knocks the off-peak response down by less than 1 dB. The on-peak response remains about the same, so eliminating the series capacitance does reduce the blowthrough.
With the case grounded and CX = 6 pF in the circuit, the peaks over on the right seem ever so slightly lower in frequency, which suggests a slightly higher motional capacitance. There’s not much to write home about, though, so I’d say there’s very little effect, even on this scale.
The Smell of Molten Projects in the Morning 