Aerosol Can Corrosion

An odd smell in the Basement Laboratory Chemical Warehouse led to this discovery:

Leaking aerosol can
Leaking aerosol can

It’s a can of spray-on topical anesthetic That Came With The House™, so it’s almost certainly four decades old and, other than being moved to that shelf, hasn’t been touched in the last quarter century.

Surprisingly, the orange-brown goo wiped off the shelf almost completely. The similarly old box of stain remover on the left was a dead loss.

MOSFET Astable: NP-BX1 Rundown

After eight months from a full charge, an old NP-BX1 lithium battery has come to this:

Astable green - NP-BX1 - 2.31 V
Astable green – NP-BX1 – 2.31 V

The astable still ticks along at 1.4 seconds per blink, but the green LED barely lights up from a 2.1 V battery:

Astable green - NP-BX1 - 12 mV 100 ohm
Astable green – NP-BX1 – 12 mV 100 ohm

A pulse of 12 mV across the 100 Ω resistor puts the LED current at a mere 120 µA: no wonder the poor thing wasn’t visible in ordinary room light.

Another full charge restored its vigor for another couple of seasons.

Privacy Preferences: Broken As Intended

The Chase website seems to be fine, except:

Chase Privacy Settings - not working
Chase Privacy Settings – not working

Huh.

Follow the money: being a bank / credit card / fintech company, it’s safe to assume they sell your sensitive bits and have zero incentive to let you limit their actions in any way.

A week later, that part of their site remains broken, presumably as intended.

Huion H610Pro (V2) Tablet vs. USB 3.0

For reasons that surely made sense at the time, the Huion H610Pro (V2) tablet can recognize when it’s connected to an Android device’s USB port and enter a special mode where the stylus only responds in a phone-shaped portrait rectangle over on the left side:

Huion H610Pro (V2) Tablet - Android layout
Huion H610Pro (V2) Tablet – Android layout

There’s a Vulcan Nerve Pinch button push to force the tablet into Android mode if it doesn’t automagically get there on its own, but AFAICT there’s no way to force it out of Android mode.

It’s a USB 2.0 device, but I had plugged it into a USB 3.0 port on my desktop box, whereupon it would enter Android mode on pretty nearly every boot. The only way to coerce it back into normal mode was to unplug it, replug it, then manually run the xsetwacom incantation to restrict the coordinates to the portrait monitor.

I just discovered it works perfectly when plugged into one of the few USB 2.0 ports on the box.

Apparently, USB 3.0 ports keep the thing powered all the time, whereupon it doesn’t see the proper sequence of events (or, perhaps, sees the Android sequence) during the next boot. USB 2.0 ports don’t do that and it works fine all the time.

Much better!

Monthly Science: Chestnut Weevil Damage

The dried chestnuts looked undamaged in their husk, but three groups of weevil grubs surely left some damage behind:

Chestnut husk - dried
Chestnut husk – dried

Gingerly prying the seeds out revealed holes in all three:

Chestnut weevil damage - exterior
Chestnut weevil damage – exterior

The weevils converted the nut meat into what looks like solid frass:

Chestnut weevil damage - interior
Chestnut weevil damage – interior

Having eaten themselves out of house and home, they moved on to the next plane of existence.

For most of them, that would be bird food.

Craftsman Garage Door Opener: Rogue Remote

Just before midnight, the garage door opened, but, being early-to-bed folks, it wasn’t either of us. I pulled my fingernails out of the ceiling, padded out to the garage, verified there was nobody (not even a critter more substantial than a spider) inside, closed the door with the hardwired control button on the wall, and went back to bed. An hour later, the door opened again, then tried to take a bite out of me when I walked under it.

I pulled the opener’s plug, yanked its emergency release latch, lowered the door, and returned to bed; it was not a restful night.

The key to the diagnosis came from the little yellow LED on the back of the opener, just above the purple LEARN button:

Craftsman Garage Opener - indicator LED
Craftsman Garage Opener – indicator LED

In addition to indicating various programming states, it also lights when the opener’s radio receives a transmission from one of the remote controls. The LED was flickering continuously, showing that something was hosing the receiver with RF.

We have three remotes: one in the car, one on my bike, and one in the back room overlooking the garage. None of them worked reliably, suggesting the RF interference was clobbering their transmissions.

Disabling the remotes by removing their batteries (which were all good) also stopped the interference. Reinstalling the batteries one-by-one identified the rogue opener:

Craftsman Garage Opener - remote innards
Craftsman Garage Opener – remote innards

The slip of paper let me isolate the battery terminal and stick a milliammeter in the circuit, which showed the remote was drawing about 1.5 mA continuously. I thought one of the pushbutton switches had gone flaky, but swapping an unused one for the main door switch had no effect.

I lost track of which remote it was, but it lived in the car or the back room for all its life, so it hasn’t suffered extreme environmental stress. I have no idea why it would fail late one night, although I admit to not monitoring the LED on a regular basis. For whatever it’s worth, in the weeks leading up to the failure, activating the opener sometimes required two pokes at the remote, but nothing bad enough to prompt any further investigation.

A new cheap knockoff remote arrived in few days and it’s all good.

Protip: different openers, even from the same company, use different RF frequencies. For Craftsman openers, the color of the LEARN button is the key to the frequency; purple = 139.53753 MHz.