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: Science

If you measure something often enough, it becomes science

  • Mint Extract: The Beginning

    Mary harvested a great bunch of spearmint from a place where it wouldn’t be missed and, after rinsing, plucking, and chopping, we now have a liter of Mint Extract in the making:

    Mint Extract - start - 2018-05-29
    Mint Extract – start – 2018-05-29

    The big jars got 3 oz of coarse-chopped leaves apiece, the smaller jar 1 oz, and the (removed) stems added up to 3.5 oz, so call it 1/3 waste. Not that this is an exact science, but I’d say 3/4 pound of just-picked mint, packed slightly tighter than those jars, would produce a liter of extract.

    Because we started with fresh-picked leaves, a liter of 190 proof = 95% ethanol Everclear (*) will extract the oil better than the 80 proof = 40% ethanol vodka I used for dried vanilla beans.

    A day later, the leaves definitely look dehydrated:

    Mint Extract - browning leaves - 2018-05-30
    Mint Extract – browning leaves – 2018-05-30

    Those bottles are lying on their sides with the camera above, looking through the air bubble to the leaves. Unlike commercial mint extract, this stuff is green!

    It’ll be finished after a month of daily agitation, but surely it’s an exponential process: a few hundred μl already pep up a mug o’ cocoa just fine.

    In very round numbers, I get 10 drops / 0.1 ml, so 1 drop = 10 μl.

    Bonus: the cutting board smells wonderful.

    (*) It may be Olde White Guy Privilege, but clerks don’t even blink when I stagger up to the counter clutching a bottle of high-octane hooch; they don’t even card my age!

  • Monthly Science: Water Bottle Refill Stations

    The O’Neill Center at WCSU has two sets of drinking fountains:

    Water bottle refill stations
    Water bottle refill stations

    The bottle shape on the back of each fountain marks the sensor for its water bottle refill spout. The small rectangular block above and right of the sensor is a virtue signalling display giving the number of disposable bottles allegedly not consigned to a landfill.

    The left fountain:

    Water bottle refill station - left
    Water bottle refill station – left

    The center fountain:

    Water bottle refill station - center
    Water bottle refill station – center

    The right fountain:

    Water bottle refill station - right
    Water bottle refill station – right

    Which looked exactly like either a test pattern or a failed display, until I waved my hand over the senor and watched it increment to 00008889. Timing is everything!

    The other trio of fountains had the same progression, so it must be a chirality thing.

    I can’t say whether you should use the left fountain to avoid some germs or the right fountain for the freshest water. Not having to maneuver our bottle under the usual arch from a drinking nozzle was a big win, though, so mad props to ’em.

  • Kenmore 158: First Needle LED Failure

    The first white LED fixture built to illuminate one of Mary’s Kenmore 158 sewing machines has been in regular use for the last four years:

    Kenmore 158 Sewing Machine - mixed LED lighting
    Kenmore 158 Sewing Machine – mixed LED lighting

    We never found a good time to rip-and-replace the “prototype” with brighter SMD LEDs and one of the LEDs finally gave up.

    They’re 10 mm white LEDs with five chips wired in parallel, which is obvious when you look into the remaining LED running at 1 mA:

    10 mm white LED - chips
    10 mm white LED – chips

    The center chip is just dimmer than the others, which means their QC doesn’t tightly control the forward voltage spec.

    The wire bonds on the anode terminal of the failed LED look a bit sketchy:

    10 mm white LED - wire bonds
    10 mm white LED – wire bonds

    Fortunately, I hadn’t removed the 120 VAC wiring for the original bulb and I have two OEM bulbs from other machines, so I just removed my LED gimcrackery, installed a good old incandescent bulb, and she’s back to sewing with a pleasantly warm machine.

    The fixture holding the LEDs broke apart as I extracted it, but it’ll never be used again:

    10 mm white LED - fixture
    10 mm white LED – fixture

    The LEDs are rated at 3.5 V and 200 mA (!), but were reasonably bright in series from a 6 V unregulated supply. Perhaps a power glitch killed the poor thing? We’ll never know.

    LEDs are reputed to have lifetimes in the multiple tens of thousands of hours, but I’ve seen plenty of failed automotive LEDs and fancy new LED streetlights out there, not to mention many dead and dying traffic signals. Seeing as how they’re in (presumably) well-engineered fixtures with good power supplies and are at most only a few years old, there shouldn’t be any failures yet.

     

  • Corroded Concrete

    Nothing lasts forever, not even concrete:

    Downspout Splash Block - Corroded Concrete
    Downspout Splash Block – Corroded Concrete

    The downspouts are obviously more recent than the splash blocks, but the whole shopping center wasn’t more than a few decades old. Rain isn’t nearly as acid as it used to be, but it still eats away at concrete.

    After about two decades, though, even high-quality concrete goes bad:

    Rt 376 bridge deterioration - marker 1102 - 2018-05-07
    Rt 376 bridge deterioration – marker 1102 – 2018-05-07

    That’s the upper surface of the Rt 376 bridge at Red Oaks Mill, with a fragment of the corroded lower edge still dangling over the Wappinger Creek:

    Red Oaks Mill bridge - dangling concrete
    Red Oaks Mill bridge – dangling concrete

    Mostly, we manage to bike around the decayed infrastructure.

  • Squidwrench Electronics Workshop: Session 2

    Some ex post facto notes from the second SquidWrench Electronics Workshop. This turned out much more intense than the first session, with plenty of hands-on measurement and extemporized explanations.

    Measure voltage across and current through 4.7 kΩ 5 W resistor from 0.5 V to 30 V. Note importance of writing down what you intend to measure, voltage values, units. Plot data, find slope, calculate 1/slope.

    Introduce parallel resistors: 1/R = 1/R1 + 1/R2. Derive by adding branch currents, compute overall resistance, factor & reciprocal.

    Review metric prefixes and units!

    Introduce power equation (P = E I) and variations (P = I² R, P = E²/R)

    Measure voltage across  and current through incandescent bulb (6 V flashlight) at 0.1 through 6 V, note difference between voltage at power supply and voltage across bulb. Plot data, find slopes at 1 V and 5 V, calculate 1/slopes.

    Measure voltage across ammeter with bulb at 6 V, compute meter internal resistance, measure meter resistance. Note on ammeter resistance trimming.

    Measure voltage across and current through hulking power diode from 50 mV – 850 mV. Note large difference between power supply voltage and diode voltage above 750-ish mV. Note power supply current limit at 3 A. Plot, find slopes at 100 mV and 800 mV, calculate 1/slopes. Compare diode resistance with ammeter resistance.

    Review prefixes and units!

    The final whiteboard:

    Whiteboard - Session 2
    Whiteboard – Session 2

    Hand-measured data & crude plots FTW!

  • Squidwrench Electronics Workshop: Session 1

    Some ex post facto notes from the first SquidWrench Electronics Workshop, in the expectation we’ll run the series from the start in a while. I should have taken pictures of my scribbles on the whiteboard.

    Define:

    • Voltage – symbol E (Electromotive Force or some French phrase), unit V = volt
    • Current – symbol I (French “intensity” or some such), unit A = ampere
    • Resistance – symbol R (“resistance”), unit Ω (capital Greek Omega) = ohm

    Introduce Ohm’s Law & permutations, postpone calculations.

    Measure the actual voltage of assorted cells & batteries. Identify chemistry, internal wiring:

    • 1.2 = nickel-cadmium or nickel-metal-hydride
    • 1.5 = carbon-zinc or alkaline
    • 2 V = lead-acid
    • 3.0 = primary lithium
    • 3.6 – 3.7 = rechargeable lithium, several variations
    • 4.8 = 4 x 1.2 V
    • 7.2 = 6 x 1.2 V
    • 7.4 = 2 x 3.6 V
    • 9.6 = 8 x 1.2 V
    • 10.8 = 3 x 3.6 V
    • 12 = 6 x 2 V

    Measure various resistors, favoring hulking finger-friendly sandstone blocks.

    Introduce metric prefixes:

    • Engineering notation uses only multiple-of-three exponents
    • μ = micro = 10-6
    • m = milli = 10-3
    • k = kilo = 103
    • M = mega = 106

    Discuss resistor power dissipation vs. size vs. location, postpone power formula.

    Clip-lead various resistors to various batteries, measure voltage & current.

    Introduce fixed & variable power supplies, repeat resistor measurements.

    Now compute permutations of Ohm’s Law using actual data!

  • Monthly Science: As Seen On Radio

    This showed up when I looked at our APRS tracks after a recent ride:

    Balloon chase - KJ5HY-9
    Balloon chase – KJ5HY-9

    Poking around a bit showed the target:

    Balloon chase - W2KGY-12
    Balloon chase – W2KGY-12

    Contrary to what I thought, it didn’t come up the Hudson River from West Point:

    Balloon chase - W2KGY-12 track - 2018-04-21 to 2018-04-24
    Balloon chase – W2KGY-12 track – 2018-04-21 to 2018-04-24

    Knowledge of the Universal Law of the Conservation of Perversity informs you a balloon will never land in the middle of a putting green:

    Balloon chase - W2KGY-12 landing site
    Balloon chase – W2KGY-12 landing site

    Apparently the launch is part of a regular class project at West Point. Good clean fun!