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 it used to work, it can work again
It seems I do more typing than the good folks at Kinesis expected:
In round numbers, the keyboard is all of two years old and that little ridge is pretty much history.
The ultimate fix will likely involve a dab of epoxy, but a duct tape snippet should show me how much of a bump my fingers need to find the home keys without conscious thought:
Early returns suggest one layer isn’t quite prominent enough; some iteration will be in order.
And, yeah, I should yank the keycaps for some deep cleaning.
Spotted this in a mall built just before the 2008 financial implosion:
Maybe the original catalog items went obsolete by the time they signed up enough tenants in that section to justify any lighting at all?
In related news, a facelift some years ago at the motel next to the decaying Red Oaks Mill dam installed square lamp posts on the existing square concrete pedestals, but replaced the original metal conduit with a plastic sheath:
The cable may sit low enough in the recess to survive, but I wouldn’t bet my life on it.
A reasonably good silicone-wire multimeter probe set arrived last spring and has worked well enough (I thought, anyhow) for the usual voltage measurements, but recently failed while measuring a small current. We all know how this will turn out, but the details may be of some interest.
Measuring the resistance from tip to plug located the fault to the black probe, after which I poked a pin through the insulation near the plug:
The two leads near the bottom go to my shiny Siglent bench multimeter. Despite their similarity to the failed probes, I’m pretty sure Siglent has better QC (well, mostly).
The probe’s resistance was near zero from the tip (offscreen to the left) to the pin and megohms from pin to plug (on the right). Figuring the wire worked loose, I pulled it away from the plug:
Huh.
Although I wouldn’t have trusted those probes anywhere near their alleged 1 kV rating, seeing that exposed copper-like substance was disconcerting.
Hacking off the strain relief bushing around the wire got closer to the fault:
And, finally, the problem becomes obvious:
Yet Another Cold Solder Joint:
Pulling a black banana plug from the heap, I decided to drill a proper hole to anchor the wire:
Which looked like this afterward:
And produced a strongly mismatched pair:
Ain’t it amazing how much fun you can have for a few bucks, all delivered by eBay? [sigh]
This seemed appropriate for a day involving toys of all descriptions…
A cast iron stove (most likely a mid-last-century reproduction rather than a Genuine Antique™) emerged from a living room recess:
The line across the lid lifter handle shows where it broke, long ago, likely while being played with. Back then, I’d done a static-display-grade fix with a dab of clear epoxy, but a better repair seemed called for; my repair-fu has grown stronger.
I expected the handle to be pot metal, so drilling a hole in both ends for a music-wire stiffener seemed reasonable:
Much to my surprise, the carbide bit skittered off the surface, leaving fine swarf standing on the end. Turns out the lid lifter is cast iron, just like the rest of the stove!
Given that much of a clue, I aligned the pieces in a pair of machinist’s vises:
Slide apart (the vises stand on a smooth glass sheet; the nubbly side is down), dab silver solder flux on the ends, capture a snippet of 40% silver solder in the gap:
Hit it ever so gently with a propane torch and slide together:
The solder flows at 1200 °F = 650 °C, roughly corresponding to the blue-gray color near the joint. The nice purple (540 °C) on the left shows where I held the flame to start, with yellows (400 °C) on both sides. Good enough, sez I, it’s going to be a static-display exhibit.
Most of the solder went to the back side, so I filed it smooth and buffed off most of the heat coloration with a stainless-steel wire wheel in the Dremel:
A little more wire-brush action left the front side looking good:
As with most of the repairs around here, it simply makes me feel better …
Now, go play with your toys!
The front fender on Mary’s bike snapped loose while we were on our way for groceries, but my repair kit now once again includes a few feet of duct tape and we continued the mission:
The final fracture seems to be just the little gray section amid the older fractures, so the Planet Bike clip was hanging on by a thread:
Our bikes being equipped as alike as I can make them, another copy of the bracket I used on my bike sufficed:
Stipulated: duct tape is déclassé, but it works better than anything else I’ve tried.
The defunct 18650 lithium cell I used for the DSO150 power supplyprompted me to crack open a battery from a long-gone Dell laptop to see if any of its cells were in better condition:
Yup, gently crushing it in a vise splits the case enough to work the Designated Prydriver around the joint, a process considerably simplified by the knowledge the case isn’t going back together again.
Prying the top off reveals the cells and their connections:
One of the cells had corroded, accounting for the pack’s failure:
The others were undamaged, but had self-discharged down to about 1.5 V over the course of several years and refused to charge.
The moral may be to tear the pack apart as soon as it fails, a point always easier to recognize in retrospect.
So I taped the packs to prevent shorts and tossed them into the recycle box.
After a bit over five years, the NiMH cells in my ancient Philips Sonicare Essence toothbrush finally gave out:
Down near the end, the poor thing barely gave one brushing after an overnight charge.
While I was dismantling the case, I charged the last two new-old-stock NiMH cells:
They arrived the same five years ago as the deaders in the toothbrush, but haven’t been used in the interim and charged well enough. The NiteCore D4 charger arrived after they did and isn’t really intended for 2/3 AA cells, so I used short brass tubes to make up the difference. I should have used the 300 mA low-current charging option (press-and-hold the Mode button for a second), although it didn’t overcook them at 750 mA.
The process went pretty much as before, with the new cells soldered in place atop the PCB:
And the PCB tucked back into the case:
I applied a solder bridge to the BLINKY pads, which seemed to disable the blinking and turn the LED on full with the toothbrush in the charger. Without waiting for a full charge cycle, I sucked the solder off the pads and restored the previous blinkiness.
A few strips of Kapton tape and it’s back in operation:
The first charge lasted for two weeks, so things are looking good again. When the stock of knockoff replacement brush heads wears out, it’ll be time to get a whole new toothbrush … even if the batteries aren’t completely dead yet.
The Smell of Molten Projects in the Morning 