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.

Author: Ed

60 kHz Tuning Fork Resonator: Maximum Overdrive

Datasheets loosely associated with the tuning fork resonators in hand suggest 1 μW maximum drive power, which works out to maybe 100 mVrms = 150 mVpk at about 10 kΩ ESR. If you inadvertently apply 500 mVpk = 375 mVrms, the resulting 14 μW does this:

Broken 60 kHz Tuning Fork Resonator – overview

I was applying a precisely tuned 60 kHz sine wave to the first pass at a crystal filter grafted onto the loop antenna preamp and wasn’t paying attention to the amplitude. For all I know, though, the poor thing died from a power-on transient. I’m pretty sure I didn’t break it during extraction, because it stopped being a resonator while in the circuit.

The missing tine fell out of the can:

Broken 60 kHz Tuning Fork Resonator – tine detail

Laser trim scars form a triangle near the tip, a T a bit further down, a slot just above the nicely etched gap.

A closer look at the fractured base:

Broken 60 kHz Tuning Fork Resonator – detail

The metalization appears black here and gold in person.

So, yeah, one down and 49 to go …

2017-09-20
Sharing the Road on Raymond Avenue: Passing into the Roundabout

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.

So it goes.

2017-09-19
Amazon Packaging: PAR30 LED Bulb

The second incandescent bulb over the kitchen sink popped and a replacement LED bulb arrived with the by-now-familiar homeopathic Amazon padding:

Amazon Packaging – Satco LED bulb

Turns out the new bulb is slightly brighter than the old one:

Satco S9415 LED PAR30 bulbs

Oh, and it’s three bucks cheaper, too.

Eyeballometrically, 5% makes no difference whatsoever, even in a side-by-side comparison.

Life is good.

2017-09-18
Eyeglasses: New Nose Pads

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.

This was significantly easier than the Silhouette frame repair!

2017-09-17
American Standard Kitchen Faucet: Cleaning and O-Rings

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.

2017-09-16
Monthly Image: Orb-Weaving Spider
Once again, the season of orb-weaving spiders 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
```
2017-09-15
LF Crystal Tester: 60 kHz Resonator Frequency Distribution

Histogramming all 50-ish resonator frequencies shows reasonably good distributions:

Notably, there’s no obvious suckout in the middle, as with those eBay Hall-effect sensors.

60 kHz Resonant Frequencies – CX 24 pF – histogram

I don’t know what to make of the difference between the ~~parallel~~ series-capacitor and basic serial resonant frequencies for each tuning fork:

60 kHz Resonant Frequencies – CX 24 pF – delta histogram

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?

For reference, the resonators look like this:

Quartz resonator – detail

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.]

2017-09-14