Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
So I picked up a cheap digital scale at Harbor Freight because it can count parts based on weight. After all the dust settled, it was on sale for about $8, which tells you just about all you need to know, and the “5 Year Warranty” looked generous on the box:
Harbor Freight 1 kg Scale
Alas, the fine print taketh away (clicky for more dots):
Warranty
Ah, well, all this stuff is disposable anyway, right? Nobody’d ever try to fix it…
The instructions for the Count function omit a step. In order to invoke the Count function, do this dance:
Turn it on
Count exactly 10 pieces on the scale, wait for stabilization
Press-and-hold PCS until the display shows 10
Release PCS
Press PCS briefly; the pcs annunciator turns on (they omitted that)
The display will still show 10, which is the number of pieces
Now you can weigh stuff and read off their counts
The scale resolution is 0.1 gram, so SMD resistors just aren’t going to count properly at all. It’s best if you add the entire group at one time, rather than trickle parts into the pan.
Well, it turns out that the DVD drive I stuffed into that case really does require a whole bunch of current. I tried playing a DVD and got erratic results, including weird keyboard (!) failures. Finally, I hitched a bench supply to the coaxial power jack on the case and caught it in the act:
Laptop DVD – current display
That jack normally connects to the power-only USB cable, which implies an upper limit of 100 mA. A bit of poking around inside shows that the coaxial power jack simply parallels the USB jack’s VCC line, so there’s no fancy negotiation or current sharing going on.
When the keyboard went nuts it was sharing an unpowered USB hub with this thing, which means that the overcurrent dragged down the hub’s supply. I was permuting all the choices to see if the failures suggested anything; eventually it did.
A bit of rummaging in the Basement Laboratory Warehouse Wing uncovered a 5.0 V 3.7 A wall wart switching power supply that is grossly in excess of the drive’s 1.5 A rating. Amazingly, it even had the correct coaxial power plug on the end of the cable, which never happens.
Alas, because the external supply back-powers the USB data cable, it lights up the Q150’s power button when the PC is turned off. I think I can insert an isolation diode into the USB power trace to isolate it from the jack, somewhat along the lines of that hack. However, that seems to require removing the USB connector to uncover a very well protected top trace. For now, I’ll just unplug the drive.
That tag should ensure any TSA agent will sideline me for an enhanced inspection sufficient to reset breakfast to last Tuesday. Or I get to ride in the cockpit. Maybe both.
Aitch is one of the very few people in the world who can use a business trip to the Atacama Desert as a cover story for his real activities, about which I know absolutely nothing because I’m Still Alive™. The fact that he returns with a camera full of gorgeous pix merely demonstrates the cover team’s finesse. The NSA schwag came from another trip. So he says, anyway.
Oh, that tag originally hung from the drawstring of a very nice black velveteen pouch containing an NSA-logo sippy cup along with the matching coaster. All made in China, of course: if irony were energy, we could saw off the entire Middle East and be done with it…
As part of sawing a kitchen countertop apart to fit it into the bathroom, this happened:
Sawed-off sawhorse
I’d very carefully checked the clearance for the first two cuts, but …
The sawhorse is polyethylene, which cannot be glued, so I drilled holes in the internal bulkheads, slobbered JB Industro-Weld epoxy through them, and filled the gaps with wood blocks:
Wood-epoxy PE repair
The goal being to not have metallic fasteners where the saw blade can find them.
This should work for a while:
Sawhorse cap repaired
If that’s never happened to you, I’d say you aren’t doing enough circular saw work…
I finally got around to replacing the sink in the front bathroom, which required a surprising number of tools:
Bathroom tool midden heap
As with the three other sinks I’ve replaced over the years, this one was a beautiful cast-iron monster made by the American Regulator & Standard Sanitary company, back before the name mushed into American Standard. This casting shows the original typography:
Bathroom sink by American Regulator and Standard Sanitary
A thin stainless steel trim ring and 16 (!) clamps held the sink in place on the countertop. Harsh experience taught me to support the sink while removing the clamps, because without the clamps there is nothing holding the sink up and I no longer enjoy stopping the tailpiece of a cast-iron sink with my chest…
Supporting the old sink
As it turned out, the sink required two pumps on the jack to break it free from the gunk gluing it in place; I was pleased to be wrong. I toted it to the end of the driveway, put a FREE sign on it, wherefrom it vanished within two hours. We’ll never know if it became someone’s precious antique or just a source of heavy brass fittings at the scrap metal recycler.
The original vanitory countertop had been recessed into the corner walls before the tiles went up, so I sawed out a chunk of the front edge and bent the plywood enough to tap it out without destroying anything. The countertop rotated around the left-front corner and the right-rear corner looked like this when the dust settled:
Extracted vanitory countertop
Half a century ago, the tile installers did a lovely mud job; the tiles adjoin and the grout is barely 1/16 inch wide. The vanitory case top was dead level, but the tiles weren’t quite aligned and my carefully applied and very neat 5 mm stripe of new caulk looks downright amateurish.
For what it’s worth, the new countertop started life as a stock kitchen countertop. I sawed off the backsplash, trimmed the length, cut a pair of notches to match the recesses, sawed a hole for the sink, rotated it into place, and screwed it down. You can go the custom-top route, but given that you only see about two square feet when you’re done, dropping $400 for 6 ft2 of fancy material with a gaping sink hole or over a kilobuck for a countertop with built-in recessed sink didn’t make enough sense to us.
And, no, vanitory is not a misspelling; I learned a new word during this project:
Vanitory job label
After we sell the house, the new owners will rip all this out without a second thought. After all, Dusky Rose went out of style a long time ago, a perfect hand-set array of 3/4 x 1-5/8 inch floor tiles isn’t attractive, and nobody cares about mud jobs. We’d rather keep that nice work around (even if we’re willing to put up with a simple countertop), but that’s just us; we’re the type of people who think keeping the original spring-loaded turned-wood dowel in the toilet paper holder is charming.
They’ll junk that space heater recessed into the wall, too: it has a long coily 120 V heating element strung inside, easily within the reach of questing little fingers. I added a GFI to that circuit, but I can’t imagine anybody else tolerating it. Times change.
I’ve carried all my stuff in a belt pack since long before such things were fashionable and, quite some years ago, a friend made me a custom-sized one that’s been in constant use ever since. Of late, one of the zippers got cranky and finally failed completely.
An autopsy showed the middle of the cross bar on the tab had worn completely through, the stubs had bent outward, and the remains no longer engage the zipper tooth lock.
Worn-through zipper tab
I replaced the tab with a short length of chain and a jump ring, but I fear the pack fabric is also reaching end of life.
The keyboard on my trusty HP 48GX calculator finally deteriorated to the point of unusability, so I tore the thing apart following the useful instructions there. The warning about applying force to the rivets that hold the case halves together gives you not the faintest concept of how much force is actually required to pry the mumble thing apart at the battery compartment; I finally invoked force majeure with a chisel scraper…
HP-48GX case rivets
I expected the calculator would not survive this operation and I wasn’t disappointed.
An HP 50g is now in hand. Here in late 2011 I’d expect HP’s top-of-the-line RPN calculator to sport a crisp high-resolution display, but noooo the low-contrast 131×80 LCD seems teleported directly from the latter part of the last millennium. The manuals are PDFs, which is OK, but their content is far inferior to the HP 48GX manuals. In particular, the editing / proofreading is terrible. I infer that the HP calculator division can barely fog a mirror and is on advanced life support; HP’s diverting all their money to, uh, executive buyouts or some other non-productive purpose.
The fact that HP sells new-manufacture HP 15C calculators doesn’t crank my tractor, even though I lived and died by one for many years. A one-line 7-segment display doesn’t cut it any more, even if the new machinery inside allegedly runs like a bat out of hell.
My HP 16C, now, that one you’ll pry out of my cold, dead hands. At one point in the dim past, I’d programmed the Mandelbrot iteration into it to provide bit-for-bit verification of the 8051 firmware for the Mandelbrot Engine array processor I did for Circuit Cellar: slow, but perfect. That calculator has a low duty cycle these days, but when I need it, I need it bad.
The Smell of Molten Projects in the Morning 