Archive for November, 2018
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 …
Nowadays, SMT pogo pins produce a much more compact holder, so I figured I could put all those batteries to good use:
Obviously, the battery holder should grow ears to anchor the 14 AWG copper posts and would look better in black PETG:
The battery lead wires get soldered to the ends of the pogo pins and are recessed into the slot in the end of the fixture. I used clear epoxy to anchor everything in place.
Fits perfectly and works fine!
The OpenSCAD source code as a GitHub Gist:
That was ten months ago. This is now:
The camera sees the nozzle in a mirror laid flat on the platform, making the image less crisp than a direct view.
So the silicone seems a bit worn around the tip, has acquired a few firmly adhered globs, and definitely isn’t as shiny.
Rather than (try to) peel it off and reapply a new coating, I picked off the globs, cleaned around the nozzle, and slobbered a thin layer atop the existing silicone:
Extruding a few millimeters of filament pushed the film off the nozzle opening and it now works as well as it ever did.
The ancient (Came With The House™) Electrolux canister vacuum cleaner long ago lost the plastic bushing around the opening passing its retractable cord, which I’d long sworn to replace. A recent trip around the Basement Laboratory paused near the recently relocated Box o’ Wire Loom & Braid, whereupon I snipped off a few inches of split loom and tucked it in place:
Looks and works better than before, anyhow.
The blue flap dangling off the back should latch over the exhaust port, but failed long ago when the latch tab eroded. I attempted a repair, which never worked quite right, and won’t get around to attempting another for quite a while.
Being a bear of unbearable consistency, I save edited picture files with a description following the original camera-assigned sequence number:
IMG_20181108_190041 - Kindle Fire Picture Frame - Another Test Image.jpg
Yup, spaces and all.
I store my general-interest pix chronologically by year, in subdirectories for interesting categories, so copying all the edited (a.k.a. “interesting”) pictures to the Kindle Fire becomes a one-liner:
cd /mnt/bulkdata/Cameras find 20?? -iname \*\ \*jpg -print0 | xargs -0 cp --parents -t /mnt/part/Pictures
--parents parameter tells
cp to recreate the directory structure holding the picture in the target directory, thereby keeping the pix neatly sorted in their places, rather than creating one heap o’ pictures.
Come to find out I’ve edited slightly over 7 k general-interest pictures in the eighteen years I’ve been using digital cameras, of maybe 27 k total pictures. Call it a 25% hit ratio; obviously I’m not nearly fussy enough.
Then there’s another 16 k project-related pictures, of which 10 k were edited into something useful. With an emphasis on utility, rather than aesthetics, a 60% hit ratio seems OK.
Which works out to half a dozen pictures a day, every day, for eighteen years. I loves me some good digital camera action!
Unlike ordinary bike tubes, Michelin ProTek tubes have a square-ish cross section:
As with the cork version, they fit fine:
The picture is slightly fuzzy, because zooming a Pixel photo doesn’t magically create any new mmmm pixels.
I tested the washer with 45 psi air (the recommended maximum) and it holds the pressure fine. Better than a fouled ProTek valve, anyway.
Flushed with success, I preemptively replaced both OEM cork washers, an action which will surely come back to haunt me.
Cutting it open reveals the perfectly good greenish-yellow sealant:
The sealant also carries black rubbery grit / shavings / dust, perhaps intended to jam inside larger gashes while the sealant coagulates and binds it together.
There’s a lot of rubber floating around in there:
Dismantling the Presta valve stem show the rubbery crud on and around the valve seal and seat:
Whenever I pumped up the tires, I finger-tightened the nut to ensure a good seal, as you do with all Presta valves. Obviously, finger-tight can’t handle that much crud between the sealing surfaces.
I’m sorry to say I was right about the leaky valve stem, because I think all the ProTek tubes will fail in exactly the same way.
The valve has small wrench flats making it easy to remove, so I can at least attempt to de-gunk them when they develop slow leaks.
Color me unimpressed.