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?

  • Garage Door Openers: Pity the Color Blind

    The small garage door opener I tote around in the Tour Easy’s underseat bag failed after many years of exposure to the elements, so I paid a few bucks more for a cheap replacement in order to get fast delivery from a (US!) eBay supplier:

    Garage door opener remote controls
    Garage door opener remote controls

    For whatever it’s worth, before buying the replacement I tried:

    • Cleaning the battery contacts
    • Installing a new CR2032 battery
    • Programming the hitherto-unused buttons to open the door

    The remote control would occasionally work, but none of the “repairs” made much difference; I suspect corrosion hidden under the components or cracked solder joints.

    The eBay item description clearly, if inarticulately, specifies the compatibility requirement:

    key chain remote control
    compatible for purple learn button

    So I trotted out to the garage and inspected the button:

    Sears Garage Door Opener - purple button
    Sears Garage Door Opener – purple button

    Looks purple to me, but, being that type of guy, I also read the adjacent instruction sticker:

    Sears Garage Door Opener - instructions
    Sears Garage Door Opener – instructions

    Nobody, nobody, maintains the documentation. [sigh]

    I figured if they went to all the trouble of ordering a bazillion switches with purple caps, then the PCB surely holds the corresponding RF filters & firmware & whatever else that button signifies.

    Seeing as how we have exactly one garage door opener and no lights or other doodads, I told the opener to obey both the 1 and 2 buttons, thereby dramatically reducing the dexterity required to open the door while pedaling up the driveway. The opener can remember an unspecified number of transmitters, so I didn’t go for all four buttons.

  • Monthly Science: CR2023 Lithium Cells vs. Wearable LEDs

    Those wearable LEDs spent the last five months sitting on the kitchen window sash, quietly discharging their CR2032 lithium cells:

    Wearable LED with CR2023 cell
    Wearable LED with CR2023 cell

    Occasional voltage measurements produced an interesting graph:

    CR2032 vs Wearable LEDs
    CR2032 vs Wearable LEDs

    CR2023 primary lithium cells start out around 3.3 V, so these were pretty much dead (from their previous lives in dataloggers) when I slipped them into their holders. The LEDs seem to be blue LEDs, with threshold voltages around 3.6 V, with colored phosphors / filters, so they started out dim and got dimmer. The green(-ish) LED obviously fell over a cliff and went dark in late January; I have no way to measure long-term microamp currents, alas.

    The reddish LED is still going, mmm, strong.

    If you need a rather dim light for a surprisingly long time, these things will do the trick.

    I should gimmick up another astable multivibrator to blink one LED.

    The original data:

    CR2032 vs Wearable LEDs - data
    CR2032 vs Wearable LEDs – data

  • The Perils of PDF

    The Dodge Ram ProMaster cargo van we rented to haul our bikes to Glens Falls (and bring some furniture back) sat on their 2500 truck chassis, thus weaponizing an obvious phishing email waiting for me on our return:

    Subject: About the Dodge ram 2500
    Kindly review full details of your order.
    Methner

    The From and To addresses were identical, which is always a tipoff, as was the fact neither were any of my addresses. The email had an attached PDF, of course, although the context suggested handling it with the same nonchalance I’d use with any lump of high-level radioactive waste.

    That brief text tripped my junk filters, but, somewhat to my surprise, all the scanners at VirusTotal passed Order 372.PDF without complaint (since then, one scanner woke up, smelled the scam, and tagged the file as “PDF/Phishing.A.Gen”).

    Converting the PDF to plain text with pdftotext produced an empty file, so the PDF payload isn’t a script.

    Passing the PDF through strings revealed a URL for a (probably compromised) server unrelated to the (obviously bogus) email address, wrapped with layout verbiage suggesting a clickable link:

    <</Subtype/Link/Rect[ 205.25 467.11 369.91 499.51] /BS<</W 0>>/F 4/A<</Type/Action/S/URI/URI(http://bogus-domain-here.com/wp-settings/bloglist/hh/index.php) >>>>

    Passing the PDF through pdftoppm produced this comforting image:

    Bogus Order Form - Image
    Bogus Order Form – Image

    The “100% SECURE” padlock logo, with a green check for added confidence, is a nice touch.

    At this point, if a product involves The Cloud, you can deal me out.

  • Gas Pump UI: FAIL

    During our most recent trip, I stopped at a new-to-me gas station, managed to figure out the pump’s UI enough to swipe my card and fill the tank, then utterly failed at the Print Receipt? prompt:

    Gas Pump Keypad Abrasion
    Gas Pump Keypad Abrasion

    A quick hike to the adjacent pump suggested pressing the illegible key above Enter, but the UI timed out before I got back and the promised “moment” never ended. The attendant generated a receipt showing I’d paid for the gas and told me to jiggle the pump nozzle, which didn’t improve the situation. We eventually agreed he’d handle it later and I drove away, never to return, hoping that the next customer didn’t get a free fill on my dime dollar C-note.

    Surely I’d know what to do, were I a regular customer …

  • Some Things Last: 100 W Incandescent Bulb

    The light switch for our attic turns on a single ceramic socket at the top of the stairs. The bulb burned out a few days ago:

    Long-lasting 100 W Incandescent Bulb
    Long-lasting 100 W Incandescent Bulb

    To the best of my knowledge, that bulb has been in service since we moved in almost two decades ago. Most likely, it was installed when the house was built in 1955, because it matches several new-old-stock bulbs in a battered box that Came With The House™.

    To be fair, the attic light doesn’t see much service, but … it’s been a great cost-performer!

    The attic temperatures range from well below 0 °F in the winter to well above 120 °F in the summer, so it’s no place for CFL or LED bulbs. I swapped in a 60 W bulb from my heap, although I doubt it’ll be good for another half-century.

  • Patient Sign-In FAIL

    We must announce our arrival at the dentist by signing in through a web-based iPad app:

    Dentist iPad sign-in - network fail
    Dentist iPad sign-in – network fail

    You’ll note the signal strength indicator in the upper left shows as much RF as one might reasonably expect from a router within line-of-sight across the room.

    FWIW, I’m getting really tired of the hipster dark-gray on light-gray design ethos.

  • Caution 480 V Power

    This seemed rather … casual:

    Caution 480 Volt Power
    Caution 480 Volt Power

    The armored cable draped over the fence probably came from the gland at the top of the box, which now sports a blocking plate that might actually be weatherproof. It had taped-over ends and I assume it fed something downstream that’s now disconnected; the far end of a large loop to the right burrows underground along the sidewalk.