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Posts Tagged Improvements

M20 Camera Operation

A reader asked how the M20 camera mount on my bike works with respect to the camera’s clock; this description explains a few things missing from the original writeup.

SJCAM M20 Mount - Tour Easy side view
SJCAM M20 Mount – Tour Easy side view

Do you have to set the time & date at start of every ride?

The internal clock shuts down about ten seconds after you pull the battery. If-and-only-if you swap batteries fast enough, it’ll keep time forever. Screw up once and it snaps back to Epoch Zero.

“Car mode” automagically begins recording when USB power goes on, but the manual advises:

TIP: When using your camera as a dashcam, use a car charger cable and remove the internal battery to make sure it does not die out while you travel.

That’s because the M20 continues to run from its internal battery when USB power drops. After recording an hour of a parking lot or your garage wall, the battery dies and so does the clock.

Of course, without the internal battery, the clock dies ten seconds after you turn off the car.

The internal battery has many days of capacity with the camera turned off (whew!), so I conjured the case & PowerCore battery tray to handle our normal rides. The internal battery keeps the clock alive overnight and during the rain we’ve had for the last week, the PowerCore supplies juice during the ride, and I recharge the PowerCore every few weeks.

The M20 doesn’t draw charging current when I turn it on, but poking the PowerCore’s status button also turns on its outputs, whereupon the M20 decides it should begin charging and, bonus, draw power from the PowerCore during the entire ride. The M20 finishes charging while we ride, but the PowerCore continues supplying power and, when I turn the M20 off, the PowerCore sees no current draw and shuts itself off.

Only a geek could love a lashup like that, but it works around the M20’s broken clock and removes its battery maintenance hassle.

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Pedal Spindle Wrench Flat Tweakage

A new-old-stock pair of pedals for Mary’s bike had wrench flats just slightly too narrow for my 15 mm wrench:

Titanium pedal spindle - as built
Titanium pedal spindle – as built

Well, that’s easy to fix:

Titanium pedal spindle - filed to flats
Titanium pedal spindle – filed to flats

For reasons lost in the mists of time, those are titanium spindles. They file just like steel; I’m not fussy.

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Monthly Science: Weight

Progress is our most important product:

Weight Chart 2019-04 - Ed
Weight Chart 2019-04 – Ed

Now that we’ve begun bicycling more regularly, Winter Bloat is transmogrifying into thigh muscle.

The hills around here become noticeably steeper during winter; we attribute the additional elevation to frost heaves …

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Hiatus

We’ll be tackling several long-delayed household projects during the next month. As a consequence, I won’t be doing my usual techie tinkering and will post shop notes only occasionally.

There’s not much to say about scraping, priming, and repainting, other than that it’s an ugly job which must get done!

Turkey on patio rail
Turkey on patio rail

If only we could train the turkeys to scrape the rail …

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Xiaomi Dafang Hacks: Hostname for OSD and Filename

The config/hostname.conf file (found under /system/sdcard/when the camera is running) file defines the camera’s name:

Cam4

That file overrides the contents of the usual etc/hostname.conf file, somewhat to my surprise, which remains the default Ingenic-uc1_1.

The bin/hostname utility returns the hostname:

[root@Cam4 ~]# which hostname
/bin/hostname
[root@Cam4 ~]# hostname
Cam4

You can automagically get the hostname in the on-screen display by modifying the OSD formatting variable in config/osd.conf:

OSD="$(/bin/hostname) %Y-%m-%d %H:%M:%S"

Which works because the main OSD script sources the config file to set the variable:

Xiaomi Dafang - 15-04-2019_13.26.18
Xiaomi Dafang – 15-04-2019_13.26.18

It’s also helpful (at least for my purposes) to add the hostname to the image filenames. A one-line tweak in the scripts/detectionOn.sh script does the trick:

snapshot_filename=$(/bin/hostname)_$(date "$snapshot_pattern")

Which produces names along these lines:

-rwxr-xr-x  1 ed   root 246K Apr 23  2019 Cam4_2019-04-23_17.51.02.jpg*

Having source code makes simple changes like this … simple!

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Fluorescent Ballast Caps: FAIL

After converting another fluorescent shoplight into an LED fixture, I tested its capacitors:

Fluorescent ballast capacitors - one failed
Fluorescent ballast capacitors – one failed

The ESR02 reports one as a 4.8 µF capacitor, the other as a “defective part” with a 4 kΩ resistance. Having a cap fail by turning into a resistor is surprising; I’m more surprised it didn’t simply burn up.

They’re visually indistinguishable, of course.

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Samsung EVO Pro 32 GB MicroSD Cards

Installing the Xiaomi Dafang Hacks firmware requires an MicroSD card in each camera and, my previous stock having run low, four more just arrived:

Samsung EVO Plus - 32 GB MicroSD
Samsung EVO Plus – 32 GB MicroSD

Prices have collapsed to the point where known-good (all four passed f3probe testing) cards direct from Samsung (as opposed to Amazon’s “commingled inventory” counterfeit situation) now cost $12-ish each with free shipping.

After I finish fiddling with the first camera, I’ll copy its card onto these four, unique-ify the IP addresses / hostnames /suchlike, and bring ’em all online.

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