Turtle Teleportation: Vassar Road

As always, we knew this wouldn’t end well for the small lump just in front of the car’s rear wheel (clicky for more, albeit fuzzy, dots):

Turtle 0134 - Vassar Rd - 2018-05-20

Turtle 0134 – Vassar Rd – 2018-05-20

So I stopped to lend a hand:

Turtle 1280 - Vassar Rd - 2018-05-20

Turtle 1280 – Vassar Rd – 2018-05-20

A fumbling hand, as it turned out, on the turtle’s slippery shell:

Turtle 1364 - Vassar Rd - 2018-05-20

Turtle 1364 – Vassar Rd – 2018-05-20

A belly-up turtle in the middle of the road knows the solution to the Halting Problem.

I hoped a secluded spot under a pine tree was closer to its destination:

Turtle 1724 - Vassar Rd - 2018-05-20

Turtle 1724 – Vassar Rd – 2018-05-20

However, if the turtle is a female in search of an egg-laying site, then she and all her progeny must cross Vassar Road in the other direction to reach the Mighty Wappinger Creek.

We’ll teleport them if we see them, too …



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SJCAM M20 Date/Time vs. Battery Change

A recent ride reminded me to do something about this:

M20 - Date-Time Reset - detail - 2018-05-18

M20 – Date-Time Reset – detail – 2018-05-18

So I wrote up a support ticket on the SJCAM site:

The time-of-day clock in my M20 often resets when I change the battery in the middle of a bike ride.

I turn the camera off, wait for the status light to go out, remove the battery, install the new battery, turn it on, and the time-of-day displayed on the screen has reset to 2016-01-01 00:00:00.

I’m using firmware 1.3.1 (the latest), genuine and fully charged SJCAM batteries, and swap the batteries as fast as I can. Sometimes it works, but maybe half of my bike rides end years before they start! [grin]

It seems my turned-off M20 is extremely sensitive to the power fluctuations occurring during a battery change.

What do you recommend?

Thanks …

Their reply:

The capacity of internal memory battery on main board is very small due to hardware limitation so it can save date and setting for about 10 seconds after pulling out battery.

Would you please check it again ?

I’d call that a design screwup, not a “hardware limitation”. Perhaps I don’t understand how putting a slightly larger capacitor on the PCB, in place of the one that’s already there, would pose a problem.

They also recommend checking with my “re-seller”, but, seeing as how I bought it directly from their nominally official Amazon store, so:

In case they are not able to offer help, SJCAM Technical Department offers a maintenance service. The steps of such service are:
1. You ship the camera directly to our Technical Department address at your own cost (it is located in Shenzhen, China).
2. We check and repair the camera. The repair process usually takes about 3-5 working days.
3. We ship the camera back to you.
Note: The whole process usually takes about 20-30 days, and if your camera doesn’t have damage on the main-board, screen or lens, the maintenance will be free, but we charge 15$ as return shipping cost.

As usual, round trip shipping to Shenzen costs half the price of the M20 camera package, a fact I’m sure they’re well aware of. I did a warranty return to Australia with the Cycliq Fly6, before replacing the battery myself, and (re)learned valuable lessons about warranties and batteries.

I turned SJCam’s offer down, which prompted a curious proposal:

You can send back your camera to SJCAM factory and then we can replace internal memory battery for you.

So the “hardware limitation” has morphed into a (presumably inadequate) internal battery that, when replaced, will resolve the problem. Huh.

Note: you can’t use the M20’s “Car mode” with the timestamp function, because you must remove the battery to let the camera start when the USB power goes on. Unlike basically all other cameras-with-clocks, the M20 wasn’t designed to run its internal clock without a battery.

Improving my battery change speed definitely has the best ROI. Alas, my dexterity has a definite upper limit …

AFAICT, the M2 has a glued-together / assemble-only shell, so cracking the case and hacking a cap isn’t happening.


Littelfuse Automotive Fuse Tester

Fuses came up during the Second Squidwrench Electronics Workshop, so I’ll bring a handful along to the next session. Conveniently, the doomed Sienna’s rear storage compartment disgorged a new-old-stock box of fuses, along with a fuse puller/tester containing a pair of feeble vintage 164 / LR60 / AG1 alkaline cells:

Littelfuse Mini Auto Fuse Puller-tester - as opened

Littelfuse Mini Auto Fuse Puller-tester – as opened

Somewhat to my surprise, the other side of the PCB has components:

Littelfuse Mini Auto Fuse Puller-tester - circuitry

Littelfuse Mini Auto Fuse Puller-tester – circuitry

It looks like transistor switch to minimize the current through the fuse and protect the LED from over / reverse voltage, should you apply it to a live circuit.

A pair of new cells had it working just fine, not that I expect to need it in real life.

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Kenmore 158: First Needle LED Failure

The first white LED fixture built to illuminate one of Mary’s Kenmore 158 sewing machines has been in regular use for the last four years:

Kenmore 158 Sewing Machine - mixed LED lighting

Kenmore 158 Sewing Machine – mixed LED lighting

We never found a good time to rip-and-replace the “prototype” with brighter SMD LEDs and one of the LEDs finally gave up.

They’re 10 mm white LEDs with five chips wired in parallel, which is obvious when you look into the remaining LED running at 1 mA:

10 mm white LED - chips

10 mm white LED – chips

The center chip is just dimmer than the others, which means their QC doesn’t tightly control the forward voltage spec.

The wire bonds on the anode terminal of the failed LED look a bit sketchy:

10 mm white LED - wire bonds

10 mm white LED – wire bonds

Fortunately, I hadn’t removed the 120 VAC wiring for the original bulb and I have two OEM bulbs from other machines, so I just removed my LED gimcrackery, installed a good old incandescent bulb, and she’s back to sewing with a pleasantly warm machine.

The fixture holding the LEDs broke apart as I extracted it, but it’ll never be used again:

10 mm white LED - fixture

10 mm white LED – fixture

The LEDs are rated at 3.5 V and 200 mA (!), but were reasonably bright in series from a 6 V unregulated supply. Perhaps a power glitch killed the poor thing? We’ll never know.

LEDs are reputed to have lifetimes in the multiple tens of thousands of hours, but I’ve seen plenty of failed automotive LEDs and fancy new LED streetlights out there, not to mention many dead and dying traffic signals. Seeing as how they’re in (presumably) well-engineered fixtures with good power supplies and are at most only a few years old, there shouldn’t be any failures yet.




Silicone Insulated Wire

Quite unlike the non-standard ribbon cable in the WWVB loop antenna, these 10 foot hanks of 24 AWG silicone insulated wire were exactly as described:

24 AWG Silicone Wire

24 AWG Silicone Wire

The probes report a resistance of 270 mΩ (net of the 50 mΩ probe-to-probe resistance), as close as one could ask to the nominal 26 Ω/1000 ft spec for 24 AWG wire at the current Basement Laboratory temperature.

They are exceedingly limp and flexy, due to many teensy conductors; not at all like PVC hookup wire.

If you’re willing to buy 500 feet of each color, the cost-per-foot from a reputable supplier gets downright competitive, but I’m not in that market.

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QRPme Pocket Pal II

A QRPme Pocket Pal II could be a suitable project for a Squidwrench “advanced soldering” class:

QRPme Pocket Pal II - front

QRPme Pocket Pal II – front

Yes, it comes with a tin case:

QRPme Pocket Pal II - tin case

QRPme Pocket Pal II – tin case

You must fit your own insulating sheet under the PCB; polypropylene snipped from a retail package works fine.

It’s intended as a “mint tin sized tester for all kinds of hamfest goodies”, but it seems like a nice source of small currents, voltages, and signals suitable for stimulating all manner of circuitry one might encounter in later sessions of a beginning electronics class.

Before using it, of course, one must solder a handful of small through-hole parts into the PCB, a skill none of us were born with.

For completeness, the back side, hot from the soldering iron:

QRPme Pocket Pal II - rear

QRPme Pocket Pal II – rear

The kits (always buy two of anything like this) arrived minus a few parts, which I suspect was due to an avalanche of orders brought on by a favorable QST review. Fortunately, I (still) have a sufficient Heap o’ Parts to finish it off without resupply, although a hank of 9 V battery snaps will arrive in short order.


Multicolored Chicken Eggs

This cheerful assortment came from a friend with an assortment of happy chickens:

Multicolored chicken eggs

Multicolored chicken eggs

The lonely Medium white egg, obviously strictly from commercial, serves as a size and color reference. Most of the others weighed in the Large to Extra-Large range.

Even though none of the chickens had the digital upgrade, the morning omelet tasted just fine!

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