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?

  • Why Friends Don’t Let Friends Run Windows

    Perhaps this is not nearly as motivational as it’s supposed to be:

    Win 10 Upgrade Popup
    Win 10 Upgrade Popup

    A friend sent that along after reading my efforts to squelch the Windows 10 nagware on an off-lease Dell Optiplex that will never, ever be updated.

    She just turned off automatic updates, which means she must examine all the updates and manually install ones that don’t download Win 10 (which she doesn’t want), forevermore. Unfortunately, that means she won’t automatically get all the security updates that help make current versions of Windows much less hazardous then in The Bad Old Days.

    Talk about a Hobson’s Choice: in practical terms, you must decide between automatic updates or not getting regular updates. OK, that’s actually a false dilemma, but you get the idea.

    If you run automatic updates the way Microsoft recommends, you’ll soon be running a free operating system that tracks and reports your every move, so as to deliver precisely targeted advertisements right on your desktop. What could possibly be better?

    Come the middle of next year, we may see an uptick in the number of people using Linux or running unpatched Windows boxes to cut down on nagware.

  • Hard Drive Platter Thicknesses

    It should come as no surprise that hard drive platters have different thicknesses:

    Hard Drive Platter Thickness
    Hard Drive Platter Thickness

    The thicker ones measure 1.25 mm, which is near enough to 50 mils to suggest they date back to the Good Old Days. The three thinner ones in the middle are 0.77 mm = 30 mil and could be slightly younger than dirt. There’s more where these came from and I expect more variation on the theme.

    The beveled edges make the platters look thinner than they really are; they’re firmly clamped together with no space between them.

    As nearly as I can tell, the IBM 350 Disk Storage Unit on the IBM 350 RAMAC had platters about 25 mil thick. Those were two feet in diameter, so they definitely don’t make ’em like they used to!

    The thickness wouldn’t matter, except that the OpenSCAD program producing the hub & spacer tabs for the Mood Lights needs to know.

  • Provincetown Pilgrim Memorial: Lighting Ticky-tacky

    This imposing memorial plaque stands in a small park in Provincetown MA, at the foot of the hill from which the Pilgrim Monument emerges:

    Provincetown Pilgrim Memorial
    Provincetown Pilgrim Memorial

    It’s one of those 1920-ish things with the impeccable stonework and bronze casting that you couldn’t possibly duplicate nowadays. But, at least twice between then and now, somebody thought it’d be a Good Idea to decorate it with what look to be Genuine Christmas Tree Lights:

    Provincetown Pilgrim Memorial - detail
    Provincetown Pilgrim Memorial – detail

    The most recent lamps and wires seem to be restrained by plastic clips glued onto the face of the stone:

    Provincetown Pilgrim Memorial - lamp detail
    Provincetown Pilgrim Memorial – lamp detail

    A previous generation drilled small holes and inserted metal pins that didn’t survive in a salt-spray environment, so I guess plastic seemed like the right answer.

    Words fail me…

  • New Countertop vs. Old Strut

    Spotted this in a restaurant near Lowell, MA on our road trip:

    Countertop trash cutout vs support strut
    Countertop trash cutout vs support strut

    Somehow, it’s very hard to coordinate sinks, supports, and plumbing these days…

  • Neopixel Current

    Adafruit’s Neopixels are RGB LEDs with a built-in current-limiting 400 Hz PWM controller and a serial data link. Successive Neopixels aren’t synchronized, so their PWM cycles can produce serious current spikes.

    Lighting up just the red LED in two Neopixels at PWM 16/255 produces this current waveform (at 10 mA/div):

    Neopixel current 10 mA - 16-0-0 0-1
    Neopixel current 10 mA – 16-0-0 0-1

    Each red LED draws about 20 mA, so when the two Neopixel PWM cycles coincide, you get a nasty 40 mA spike. When they don’t coincide, you get a pair of 20 mA pulses. Those pulses walk with respect to each other at a pretty good clip; the oscillators aren’t trimmed to precision.

    Lighting up three Neopixels with PWM 16/255 on the red does exactly what you’d expect. The horizontal scale  is now 100 µs/div, making the PWM pulses five times wider:

    Neopixel current 10 mA - 16-0-0 0-1-2
    Neopixel current 10 mA – 16-0-0 0-1-2

    The narrow spike comes from the brief shining instant when all three Neopixels were on at the same time. Now you have three PWM pulses, each with slightly different periods.

    Remember that these are PWM 16/255 pulses. When they’re at full brightness, PWM 255/255, there’s only a brief downtime between pulses that last nearly 2.5 ms and they’ll overlap like crazy.

    Obviously, the more Neopixels and the lower the average PWM setting, the more the average current will tend toward the, uh, average. However, it will have brutal spikes, so the correct way to size the power supply is to multiply the number of Neopixels in the string by the maximum possible 60 mA/Neopixel… which gets really big, really fast.

    A 1 meter strip of 144 knockoff Neopixels from the usual eBay supplier will draw 144 x 60 mA = 8.6 A when all the pulses coincide. Worse, the supply must be able to cope with full-scale transients and all the fractions in between. A husky filter cap would be your friend, but you need one with a low ESR and very high capacity to support the transients.

    No wonder people have trouble with their Neopixel strings; you really shouldn’t (try to) run more than one or two directly from an Arduino’s on-board regulator…

  • Label vs. Pictograph: Words Work

    Apparently, enough folks had enough trouble getting paper towels out of this dispenser to justify the emphatic English-only label:

    Towel dispenser - pictograph vs label
    Towel dispenser – pictograph vs label

    I’d lay money this is the second towel dispenser; the first got ripped apart while trying to extract the towels.

    At least the pictograph wasn’t the currently trendy black-on-black…

  • What Free Shipping Means

    It really is free:

    China Post postage label
    China Post postage label

    Yeah, I’m sure that’s not what it means, but, still…

    I don’t understand how the total cost of a nontrivial something shipped halfway around the planet can be less than the price I’d pay to return it. I’m certain it involves massive subsidies and mysterious cash flows that never break the surface of the eBay “Buy It Now!” pond.