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.

Category: Oddities

Who’d’a thunk it?

The Value of Closeout Pictures

With the Bafang BBS02 and all its gimcrackery on the Terry Symmetry buttoned up and ready to go, I took a few closeout pictures for future reference.

The motor has a sheaf of wires sticking out of the bottom crying out for a protective covering:

Bafang BBS02 – wire bundle cover

Although cameras tell only the truth they’re allowed to see and can be made to lie by omission, sometimes their latent truth was completely invisible to eyewitnesses in real time.

I only noticed the mis-routed shift cable when I looked through the last set of pictures.

It should pass through the plastic channel under the metal tab holding the cable guide to the bottom bracket shell:

Bafang BBS02 – wire bundle vs shift cable

Normally, aiming the cable into the channel is no big deal. In this case, I had to undo the shift cable, remove the left crank, loosen the motor and rotate it out of the way, nudge the cable with a small screwdriver, then reinstall in reverse order.

Dang, that was close …

2021-07-13
Power Outage

A gusty thunderstorm knocked out power across Dutchess County, including half the service to our house. Being glad the refrigerator and freezer were on the live phase, I shut off the affected breakers on the dead phase, as well as all the 240 V breakers, and, with the living room darkened, we skipped our evening storytime.

By the next morning, a quick lamp test showed the recloser out on the pole had worked its magic, so I flipped all the breakers back on. The living room remained dark, prompting an investigation of the fuse box feeding the original house wiring:

Blown 20 A glass fuse

Yup, another blown fuse.

Given what happens while wind and falling branches knock power lines askew, anything is possible. I have no idea where the fault current went, but replacing the fuse brought the living room back to normal.

None of the various UPS / lamps / phones seem damaged; I admit not peering inside the outlets to check for arc damage.

2021-07-10
Vacuum Tube Lights: Urethane Coated Plate Cap

With a generous dollop of JB Plastic Bonder left over from a set of Bafang brake sensor magnets, I tried coating the ersatz plate cap of a triode tube:

Triode – urethane coated plate cap

That’s the result after leaving it hanging upside-down while it cured to push all the drips to the top.

For comparison, the uncoated cap back in the day:

Triode – plate cap plug

Seeing as how the urethane is an adhesive, not a coating, I’d say it looks about as bad as expected.

As with all 3D printed things, one must embrace imperfections and striations, rather than endlessly strive for perfection.

Now, if I had a resin printer …

2021-07-09
Tour Easy: Amber DRL Internal Resistor

Plotting current against voltage for the amber truck side marker lights produces the expected straight-ish line:

Side Marker I vs V plot – with fuse

The slope suggests a 330 Ω resistor, but the internal PCB sports a pair of 150 Ω SMD resistors.

I don’t believe the X-axis intercept for a moment, but 1.5 V seems about right for an amber LED.

Oh, and the DMM fuse doesn’t have a ceramic body. You’re seeing the vaporized remains of a 315 mA fuse neatly deposited over the inside of the glass tube after being shorted across a 3 A bench supply.

I hate it when that happens. Replacing it emptied the little bag of those meter fuses; next time it’ll get a half amp fuse.

2021-07-07
Carolina Wren Construction

A great musical interlude on the patio announced an airlift of construction materials eventually producing this pile inside the top cover of the propane tank:

Carolina Wren – nest started atop propane tank

The male Carolina Wren switched from the Tweedle of Great Nestbuilding to the less musical Mighty Chirr of Disapproval, presumably because he noticed a mouse (or, perhaps, chipmunk) occupying the lower ring of the tank. Rodents and birds do not coexist well at all; I have no doubt a mouse would climb right up the tank for a supply of breakfast eggs.

I must blow the crud off the tank before the next fill.

2021-07-03
Homebrew Mint Extract

I clearcut a stand of spearmint and turned it into three jars of what should become mint extract:

Homebrew mint extract – start 2021-06-17

The left jar has 3 ounces of mint mostly covered with 80 proof vodka and the other two jars each have 5 ounces submerged in 180 proof grain alcohol.

Nine days later:

Homebrew mint extract – 2021-06-26

The vodka is now on the right and shows a weird layering caused by the leaves extending above the light yellow liquid; I’ve been inverting the jars every few days. The grain alcohol looks more like the previous iteration, with uniformly decolored leaves in dark green liquid.

A closer look:

Homebrew mint extract – vodka vs grain alcohol – 2021-06-26

What’s happening in the vodka jar does not look like a nominal outcome …

2021-06-27
Discrete LM3909: Green and Blue vs. Dead Alkalines

These two discrete LM3909 circuits recently stopped blinking:

LM3909 AA alkaline – Green and Blue

The green LED (on the left) took six months to wear its pair of not-dead-yet AA alkalines from 2.7 V down to nearly zero.

The blue LED in the radome took two months to go from 1.0 V (!) to nearly zero. It didn’t start very bright and went decidedly dim along the way, but the LM3909 circuitry still managed to jam a few microamps through the LED.

In both cases, one of the cells was reverse-charged by a few hundred millivolts, although neither leaked.

Both got another set of not-quite-dead AA cells and they’re back in action.

2021-06-26