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?

  • Monthly Science: Cheap WS2812 LED Failures

    The two knockoff Neopixel test fixtures went dark while their USB charger accompanied me on a trip, so they spent a few days at ambient basement conditions. When I plugged them back into the charger, pretty much the entire array lit up in pinball panic mode:

    WS2812 LED - test fixture multiple failures
    WS2812 LED – test fixture multiple failures

    Turns out three more WS2812 chips failed in quick succession. I’ve hotwired around the deaders (output disconnected, next chip input in parallel) and, as with the other zombies, they sometimes work and sometimes flicker. That’s five failures in 28 LEDs over four months, a bit under 3000 operating hours.

    For lack of a better explanation: the cool chips pulled relatively moist air through their failed silicone encapsulation, quietly rotted out in the dark, then failed when reheated. After they spend enough time flailing around, the more-or-less normal operating temperatures drives out the moisture and they (sometimes) resume working.

    Remember, all of them passed the Josh Sharpie Test, so you can’t identify weak ones ahead of time.

  • Ersatz Yellow Pages Scam

    These mailings generally carry a “trash before reading” interest level, but this one stands out:

    Biz Directory Scam - the deal
    Biz Directory Scam – the deal

    The Terms and Conditions feature some gems:

    Biz Directory Scam - Terms and Conditions
    Biz Directory Scam – Terms and Conditions

    The first few sections suggest their past behavior has required some … admissions … to avoid future issues.

    Section 9 says the laws of Florida apply and the “agreement is performable” (whatever that means) “at United Directories’ address located in Jacksonville Beach, Florida”. They’re so afraid of their customers that the only address appearing on the mailer is in Atlanta, Georgia, but a bit of poking around suggests their HQ is inside what looks like a beachfront house across from Joe’s Crab Shack or a biz building up the street.

    Section 11 says your “listing” will be renewed every six months at $396, so you pay nigh onto 800 bucks a year for a “customizable web page” nobody visits.

    Section 12 tells you “Unpaid accounts will incur a 10% late charge” and “Any credits will be applied to the next subscription period.”

    This will come as no surprise:

    http://www.cbsnews.com/news/phony-phone-directory-fla-firm-guilty-of-425-million-fraud-trading-on-yellow-pages-name-say-prosecutors/

    Searching for obvious keywords + scam won’t turn up any surprises, either.

    Sad fact: they actually have some listings.

    I wish no ill will on anyone, but if somebody’s gotta be under the next meteor strike, I have a short list of candidates …

  • Arduino Joystick: Button Pullup FAIL

    I wired a resistive joystick to the knockoff Nano controlling the crystal tester and connected the button to an analog input because I have a lot of those left over and why not. Unfortunately, the ADC returned a sequence of random-ish numbers indicating the button didn’t have a pullup to +5 V.

    One might be forgiven for assuming the pads marked R5 would hold such a pullup resistor, had the joystick not been relentlessly cost-reduced:

    Keyes resistive joystick - R5 location
    Keyes resistive joystick – R5 location

    One would, of course, be completely wrong.

    Having been around this block several times, I measured the pad-to-pin resistances and found R5 firmly affixed to the GND and +5V pins, with the SW (a.k.a. button) pin floating free. Pressing the joystick hat closes the switch next to R5, thereby connecting the SW pin to GND.

    Baffles me. Maybe a fresh intern did the PCB layout and just misplaced the resistor?

    So I soldered an ordinary resistor (*) between the +5 V and SW pins:

    Keyes resistive joystick - button pullup
    Keyes resistive joystick – button pullup

    Now it works just as it should.

    (*) For long-lost reasons, I have a zillion 12.4 kΩ 1% resistors appearing in place of simple 10 kΩ resistors.

     

  • Why Electricity Won

    Spotted this impressive array at an apartment building:

    Gas meter array
    Gas meter array

    That’s just for one wing; the other end of the building has a similar installation. Each apartment has an electric stove and gas heat / AC.

    The plumbing!

  • Yellowbook Do-Not-Deliver Delivery Option

    Last summer I followed the procedure that should turn off (one of) the ersatz “Yellow Pages” directories littering our driveway.

    This just arrived:

    YellowBook Do-Not-Deliver Delivery
    YellowBook Do-Not-Deliver Delivery

    Seeing as how they have the wrong town in my address, there’s still another excuse available.

    My guess: they’re paid by tonnage of books delivered and have a powerful incentive to continue delivering all of them, no matter what gets in the way.

    You absolutely cannot make this stuff up.

  • Amazon Packaging

    The ample padding around this bag of fragile pecans leaves nothing to be desired:

    Amazon - well-packed pecans
    Amazon – well-packed pecans

    They’re firmly held in place on all sides, well protected from injury, and survived their shipping ordeal unscathed: not a bruise or break to be found. Well done!

    That’s not always the case. A padded envelope recently arrived with an obvious wound:

    Amazon - envelope perforations
    Amazon – envelope perforations

    Which came from its completely unprotected contents:

    Amazon - unprotected PCB pins
    Amazon – unprotected PCB pins

    Fortunately, the fragile glass front plate of that OLED managed to put itself flat against a small box inside the otherwise empty bag. it wasn’t broken, but due only to good fortune.

    “Static sensitive parts enclosed”, indeed …

  • Generic I²C 128×64 OLED Displays: Beware Swapped VCC and GND

    A batch of 1.3 inch white I²C OLED displays arrived from halfway around the planet, so I figured I could run a quick acceptance test by popping them into the socket on the crystal tester proto board:

    White 1.3 inch OLED on crystal tester
    White 1.3 inch OLED on crystal tester

    The first one flat-out didn’t work, as in not at all. The original display continued to work fine, so I compared the old & new displays:

    OLED Modules - pinout difference
    OLED Modules – pinout difference

    Yup, swapped VCC and GND pins. I should be used to that by now.

    I rewired the socket, tried the new displays, undid the change, popped the original display in place, and all is right with the world. Somewhat to my surprise, all five new displays worked, including the one I’d insulted with reversed power.