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.
Electrical & Electronic gadgets
Perhaps there’s something to redundancy after all:
The four light fixtures serve as both tail lights and brake lights. This was at an intersection, we were both stopped for the traffic signal, and all those LEDs should have been glowing brightly.
AFAICT, each light fixture has 20 LEDs with a third to a half either dead or dying.
I wonder if those are replacement fixtures, installed on the promise they’d last forever, when the original incandescent bulbs burned out …
A surprisingly competent AC power-line voltage / current / energy / power meter fits neatly into a mud ring atop a 4×4 inch square electrical box:
The inside view shows the wiring, such as it is:
The square black block is the split-core current transformer around the hot line wire, which sticks up just enough in any orientation to require an extension ring, thus a second trip to the Big Box store.
The mud ring has two tabs with threaded screw holes for the device (switch / GFCI / whatever): grab those with a Vise-Grip, flex until they break off, then file down the stub.
Generous globs of hot-melt glue secure the meter in the mud ring. I added a strip of duct tape under the connections in the hope it might avert disaster should either of the AC wires come loose, but my real hope is in the safety ground to the metal box.
The line cord comes from the Box o’ IEC cords, minus its IEC connector, plus the bright yellow USA-ian connector.
Yes, the three metal box pieces and the Leviton connector cost far more than the meter.
Not to code, but good enough for my purposes.
It turns out that keeping the garage door remote clipped to the starboard underseat pack on my Tour Easy attenuated its RF enough that even the directed receiver antenna couldn’t grab enough signal until I rolled onto the end of the driveway.
While contemplating what’s involved in making a 3D model of the remote’s curved backside, I realized the bike already had a perfect spot:
A few strips of good outdoor-rated foam tape later:
Believe it or not, the camera is looking through the year-old and unwashed fairing on my bike.
Stipulated: aligning the PCB antenna flat against a small aluminum plate atop a bunch of aluminum bars isn’t perfect. However, enough RF wriggles out to trigger our opener from four houses down the hill, giving it plenty of time to haul the door out of my way.
That was trivial …
A few weeks ago, the house seemed unusually warm when I crawled out of bed. Checking the heat pump thermostat woke me right up:
This, as they say, is not a nominal outcome.
A pair of AA alkaline cells powers the thermostat and, due to its wireless communication link to the heat pump’s air handler in the attic, it chews through two pairs a year. As you’d expect, it displays a “Battery Low” message for at least few days at the end of their lifetime, which was not the case for this failure.
After replacing the cells, the thermostat reported that, yes indeed, the house was much warmer than usual:
A temperature monitor showed the heat had jammed on in the deep of the night:
The heat pump exhaust temperature showed a similar event:
One of the AA cells showed about 1.3 V, but the other was around 0.25 V, suggesting an abrupt failure, rather than the normal gradual voltage decrease with plenty of time to replace the cells.
It’s reasonable to jam the heat on when the thermostat isn’t communicating, rather than let the house gradually freeze, but it did come as a surprise. I don’t know how the heat pump reacts to a battery failure during the cooling season; not refrigerating the house would be perfectly fine in most circumstances.
The Amazon Basics AA cells I’ve been using have worked as well as the Name Brand ones, so I was willing to write one off as happenstance.
However, during the recent Daylight Saving Time dance, I discovered the clock in Mary’s Long Arm Sewing Room had stopped, with an Amazon Basics AA alkaline cell from the same lot inside:
The date shows I’d replaced it in March, with the previous cell lasting an amazing 3-½ years. This one was completely dead, reading barely 0.1 V, after seven months. Mary hasn’t had a quilting project at the long-arm stage in recent months, so the clock may have been stopped for quite a while.
Perhaps something has gone badly wrong with Amazon’s battery supplier QC.
As the saying goes: Once is happenstance. Twice is coincidence. Three times is enemy action.
After about four years, the two well-aged 12 V 9 A·hr batteries in the Belkin F6C1500 UPS gave up after a few minutes without line power, whereupon I swapped the UPS out for a new one.
The old batteries don’t have much life left in them (the date in the title should be 2021):
That’s with a 1 A load, rather than the 2 A I used earlier, as they’ll never be used for heavy loads again.
The new 7 A·hr batteries can power a 300 W incandescent bulb for 10 minutes before sounding the Low Battery alert, then another three minutes before shutting down. That’s about 12 A at 24 V, call it 2.6 A·hr from grossly overstressed batteries.
Despite freezing the kitchen scraps going into the worm bin since the previous fruit fly infestation, a zillion flies are now in residence. Lacking the peppermint-stick tube of yesteryear, I conjured another fly trap from common household items:
The gap around the top got a strip of tape after I took the picture.
The gallon jug has cardboard stiffeners supporting a sheet of the sticky paper I used for the onion fly traps:
I was all set to 3D print a threaded adapter to join the two bottles when I realized they already had lids. A few minutes of lathe work added a passageway:
They’re held together by a generous ring of hot melt glue:
The LED strip provides enough light to simultaneously attract the flies and repel the worms.
The laser cuttery looks like this:
The white shape in the black block is a scan of the cut-open jug, with the other shapes in that row being rectangularized versions. The two tiny notches in the Top and Bottom shapes hold the sticky paper.
The two rings at the top adapt the LED-wrapped bottle to the existing fitting on the worm bin from the previous episode. They’re visible as shadows near the bottom of the bottle.
The circle is a laser-cut hole in the gallon jug bottom for the screened plug made for the pepermint-stick tube; the less said about that operation the better.
So far, so good, although previous experience suggests the flies will be breeding ahead of their (considerable) losses for the next few weeks.
Mary reported a problem unplugging the USB charger powering the light pad (the successor to the pad I repaired) she uses for quilting layouts:
Yes, that blade is sticking out of the hot (“Line”) side of the outlet.
The only way into the charger was through its other end:
Because I had no intention of returning it to service, I tried pushing the errant blade back in place, only to have it overshoot the mark and bulldoze various parts aside:
The two upright shapes contact the blades, but do not lock them in place. The PCB pulled easily out of the case, with no objection from the remaining (“Neutral”) blade.
The blades are simple steel bars press-fit into the plastic case, without holes / dimples / notches to lock them into the plastic. As far as I could tell, they were not molded in place.
I tossed the corpse into the e-waste box, extracted another USB charger from the Box o’ USB Chargers and returned the light pad to service.
I do have a few Genuine UL Listed USB chargers, but these are not among them.
The Smell of Molten Projects in the Morning 