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: Electronics Workbench

Electrical & Electronic gadgets

  • Bafang Battery Charge Port: Whoopsie

    Bafang Battery Charge Port: Whoopsie

    The Bafang mid-drive e-bike kits I installed on Mary’s Tour Easy recumbent and a friend’s Terry Symmetry used the “Ultra-Slim Shark” lithium battery, a rectangular lump with a tapered snout:

    Bafang BBS02 - Terry Symmetry full assembly
    Bafang BBS02 – Terry Symmetry full assembly

    The battery has a key lock on its left side:

    Bafang battery - lock
    Bafang battery – lock

    The lock might deter casual thievery, but really prevents the battery from bouncing out of its mounting plate while riding.

    The right side has a charge port closed with a rubber plug:

    Bafang battery - charge port - closed
    Bafang battery – charge port – closed

    The cover protects a coaxial jack with a 5.5 mm OD and a 2.1 mm center pin:

    Bafang battery - charge port
    Bafang battery – charge port

    My friend in Raleigh generally removes the battery before hoisting the bike into the back of her car to haul it to a friend’s house for their companionable rides: not lifting an additional seven pounds is a Good Idea™.

    A momentary distraction in the middle of that process caused her to insert the brass key into the charging port, rather than the lock. The key put a very short circuit between the coaxial jack’s side contact and the center pin, melting the key tip and welding a brass nugget onto the side of the pin:

    Bafang battery - damaged charge port
    Bafang battery – damaged charge port

    The charger plug normally sits almost flush to the port’s surface:

    Bafang battery - charge plug
    Bafang battery – charge plug

    The nugget keeps the plug out the damaged port, preventing the plug from making electrical contact:

    Bafang battery - damaged port - plug
    Bafang battery – damaged port – plug

    She owned the problem and immediately bought another battery, which tells you the value she places on riding her e-bike.

    Verily it is written: let someone who is without whoopsie cast the first shade.

    Any takers? Yeah, the way I see it, someone who says they’ve never done anything quite like that is either not doing anything or not telling the complete truth. For sure, I’ve done plenty of inadvertent damage!

    Here’s the problem:

    • The damaged battery is the better part of 600 miles away from my shop
    • Civilians cannot ship 560 W·hr lithium batteries through any parcel delivery service
    • Civilians cannot fly or take the train with such a battery, either
    • Driving 1200 miles twice is out of the question for either of us

    How would you proceed?

    More to come …

    For reference:

    Basically, it is possible to ship lithium batteries up to 100 W·h.

  • Halogen Blinky Test

    Halogen Blinky Test

    Dropping the ordinary flashlight bulb into the drawer where it belonged revealed what I think is a halogen flashlight bulb, so I rebuilt the blinky test setup:

    Halogen flashlight bulb test setup
    Halogen flashlight bulb test setup

    This time I used a BUZ71A MOSFET (13 A, 100 mΩ RDS) driven with a 10 V gate pulse to make sure it acted like a switch instead of a current sink.

    The first attempt looked … odd:

    Halogen 3V - no cap - 4ms 1A-div
    Halogen 3V – no cap – 4ms 1A-div

    The gate pulse is yellow, the drain voltage is magenta, the bulb current is cyan at 1 A/div, and the timebase ticks along at 2 ms/div.

    Moving the magenta trace to the supply voltage on the other side of the bulb produces even more weirdness:

    Halogen 3V - no cap - Vsupply - 4ms 1A-div
    Halogen 3V – no cap – Vsupply – 4ms 1A-div

    Apparently, slugging a 3 A bench supply with a 3 A pulse lasting only 4 ms causes distress of the output tract.

    Kludging a hulking 22 mF (yes, 22000 µF) cap across the power supply provides enough local storage to make things work properly:

    Halogen 3V - 22000µF - Vsupply - 4ms 1A-div
    Halogen 3V – 22000µF – Vsupply – 4ms 1A-div

    With the cap in place, the drain terminal looks less unruly:

    Halogen 3V - 4ms 1A-div
    Halogen 3V – 4ms 1A-div

    The drain voltage starts at about 600 mV with the 3 A pulse, a bit more than you’d expect from the alleged 100 mΩ drain-source resistance, but those numbers are generally aspirational and the test setup leaves a lot to be desired.

    A 10 ms pulse produces a distinct flash, rather than a dull orange blip (timebase now at 10 ms/div):

    Halogen 3V - 22000µF - 10ms 1A-div
    Halogen 3V – 22000µF – 10ms 1A-div

    A 30 ms pulse reaches full brightness as the filament settles at normal operating temperature:

    Halogen 3V - 22000µF - 30ms 1A-div
    Halogen 3V – 22000µF – 30ms 1A-div

    A 20 ms flash might suffice for decorative purposes, in which case each pulse requires 90 mW·s = 3 V × 1.5 A × 20 ms of energy. Running it all day requires 7.8 kW·s = 2.2 W·h, so it’s even less appealing than that old skool tungsten bulb.

    Which is, of course, why LED flashlight bulbs are a thing.

  • Incandescent Blinky Test

    Incandescent Blinky Test

    A flashlight bulb emerged from the clutter, which prompted me to ask if it might make an interesting blinky. Spoiler: probably not.

    The bulb had “2.4 V 0.7 A” stamped on its shell, so the test setup looked like this:

    Flashlight bulb test setup
    Flashlight bulb test setup

    A list seems helpful:

    • Solder wires to bulb in lieu of a socket
    • Bench supply at 2.4 V
    • Grossly abused 2N3904 NPN transistor as a switch
    • Function generator pulsing the base
    • Scope voltage probes on base (yellow) and collector (magenta)
    • Tek current probe on bench supply lead (cyan, 500 mA/div)

    The function generator has a 50 Ω output, so depend on it to limit the base current just like it was a resistor. The output voltage is symmetric around 0 V, so apply an offset of half the peak-to-peak signal to get a positive-going pulse:

    Flashlight bulb test - function gen setup
    Flashlight bulb test – function gen setup

    A 150 ms pulse gives the bulb just barely enough energy to light as a little orange blip, with the collector voltage dropping as the filament heats up and its resistance increases:

    Tungsten 2.4V 700mA - 150ms
    Tungsten 2.4V 700mA – 150ms

    Given 350 ms to heat up, the bulb produces a nice white-hot flash:

    Tungsten 2.4V 700mA - 350ms
    Tungsten 2.4V 700mA – 350ms

    The poor transistor acts as a 600 mA constant current sink, which isn’t surprising given its 300 mA absolute maximum current rating.

    Homework: figure the base drive and current gain

    Protip: don’t do that to a cherished transistor

    The bulb resistance starts out at 0.5 Ω and rises to 2.5 Ω when the filament glows white-hot at the end of the pulse.

    Something like 250 ms produces a noticeable blink, requiring 360 mW·s = 2.4 V × 600 mA × 250 ms from the power supply. Blinking once every ten seconds all day means 8640 pulses for a total energy of 864 mW·hr; call it 1 W·hr.

    A pair of (fresh) AA alkaline cells provide 7.5 W·hr for maybe a week of blinkiness.

    A not-dead-yet 18650 lithium cell might offer 15 W·hr, but running the bulb from 3.7-ish V, rather than 3-ish V, increases the energy per pulse by 20% and decreases the run time correspondingly.

    Surely not worth the effort …

  • Incandescent Bulb Lifetime: Also Better Than Average

    Incandescent Bulb Lifetime: Also Better Than Average

    This bulb spent the last seven-plus years of its life lighting the front bathroom:

    Dead incandescent bulb - 7 years
    Dead incandescent bulb – 7 years

    The green corrosion around the tip seems strange, given that we don’t use the tub or shower in that bathroom, and I’m pretty sure it wasn’t the cause of the failure.

    My stock of incandescent bulbs will eventually run out; I must figure out how to light the deaders in an attractive manner.

  • Lyme Disease, Now With Bonus Babesiosis

    Lyme Disease, Now With Bonus Babesiosis

    Two weeks of doxycycline should kill off all the Borrelia bacteria responsible for Lyme disease, but a blood test shows the antibodies:

    Lyme test - 2021-11-10
    Lyme test – 2021-11-10

    Those antibodies will gradually disappear during the next few months and, unfortunately, a past Lyme infection does not prevent future infections.

    The tick also injected Babesia parasites which do not respond to antibiotic treatment:

    Babesia test - 2021-11-10
    Babesia test – 2021-11-10

    The “titer” refers to the dilution required to produce a negative test result, with the 1:64 reference titer representing six successive 50% dilutions. My blood required ten 50% dilutions to produce a negative result for the IgG antibodies and (presumably) six 50% dilutions from a 20% base for the IgM antibodies.

    As I understand the situation, IgM antibodies appear promptly upon infection and IgG antibodies follow along later, so my reaction to the Babesia infestation was ramping up after two weeks.

    In the Bad Old Days™, quinine was the go-to treatment for parasitic infections, but it has a host of horrific side effects at the dosage required for traction against actual diseases; tonic water ain’t gonna get you where you need to go.

    The new hotness is atovaquone, arriving as 100 ml of a yellow liquid with the consistency of latex paint, (allegedly) the taste of “tutti fruitti“, and a price (modulo your drug plan) making inkjet printer ink look downright affordable. You might expect to get a 5 ml measuring spoon along the the bottle, but suffice it to say it’s an exceedingly good thing I’m well stocked for printer cartridge refilling.

    All of the diseases and drugs list “fatigue” / “drowsiness” / “malaise” as symptoms / side effects and I’m here to tell you knocking off a couple of hours in the recliner during the day does nothing at all to disturb another nine hours in the sack overnight.

    A few weeks of low productivity in the Basement Shop™ will definitely count as a successful outcome.

    Protip: We need permethrin spray. Lots permethrin spray.

  • CFL Lifetime: Better Than Average

    CFL Lifetime: Better Than Average

    Although compact fluorescent lamps have fallen out of favor, I’m burning through a box of the things donated by a friend who upgraded to LEDs and figured I could put them to good use. In general, complex electronic doodads (like CFL or even LED lamps) used in hostile situations (like an ordinary downlight fixture) seem to fail too quickly to justify the power savings; searching for “cfl fail” will produce some evidence from around here.

    One of the downlights in the Basement Office just killed this specimen:

    Dead CFL - detail
    Dead CFL – detail

    Much to my surprise, however, it survived for more than five years:

    Dead CFL - over 5 years
    Dead CFL – over 5 years

    The previous CFL bulb in that fixture lasted only two years, so their average lifetime is entirely too short.

    A taller bulb does a better job of lighting up that corner, although it started with enough power-on hours to suggest it won’t survive for another five years:

    Dead CFL - replacement
    Dead CFL – replacement

    The ghostly humps above the overexposed glare are the long CFL tubes reflected inside the Pixel’s camera optics.

    I didn’t see much point in nailing a ceiling to too-low floor joists.

  • Alpha Geek Clock: Radome Update

    Alpha Geek Clock: Radome Update

    There being nothing like a new problem to take one’s mind off all one’s old problems:

    C-Max CMMR-60 WWVB receiver - D cell display holder
    C-Max CMMR-60 WWVB receiver – D cell display holder

    It’s a variation on the camera battery and AA alkaline holders for various blinky LEDs:

    Astable Multivibrator - D cell WWVB
    Astable Multivibrator – D cell WWVB

    The little flag holding the C-Max CMMR-60 receiver PCB gets glued to the copper upright to keep it from swiveling in the breeze.

    The conical caps on the ferrite bar antenna are glued to the uprights and the antenna, in the expectation this is a one-off build-only project.

    Rather than buy specialized D-cell contacts, I used 18650 lithium cell contacts and conjured the bridge by soldering two together:

    D cell bridge contact from 18650 contacts
    D cell bridge contact from 18650 contacts

    It sits on the windowsill, blinks quietly in the dark, and flickers invisibly during the daytime.

    Those D cells came from the same batch that powered the previous version for the last five years, so they probably won’t last that long, even with a Nov 2024 date code.

    C-Max is apparently out of the WWVB biz, but you can get a similar Canaduino AM WWVB receiver.

    The far more complex EverSet ES100-MOD WWVB receiver requires a microcontroller with an I²C interface and very careful power management.

    The OpenSCAD source code as a GitHub Gist:

    // Astable Multivibrator
    // Holder for Alkaline cells
    // Ed Nisley KE4ZNU August 2020
    // 2020-09 add LED radome
    // 2020-11 add radome trim
    // 2021-11 D cells and WWVB receiver
    /* [Layout options] */
    Layout = "Build"; // [Build,Show,Lid,Spider,AntCap,RecFlag]
    CellName = "AA"; // [AA, D]
    Struts = -1; // [0:None, -1:Dual, 1:Quad]
    WWVB = true;
    /* [Hidden] */
    NumCells = 2; // [2]
    // Extrusion parameters
    /* [Hidden] */
    ThreadThick = 0.25;
    ThreadWidth = 0.40;
    HoleWindage = 0.2;
    function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
    function IntegerLessMultiple(Size,Unit) = Unit * floor(Size / Unit);
    Protrusion = 0.1; // make holes end cleanly
    inch = 25.4;
    //- Basic dimensions
    WallThick = IntegerMultiple(3.0,ThreadWidth);
    CornerRadius = WallThick/2;
    FloorThick = IntegerMultiple(3.0,ThreadThick);
    TopThick = IntegerMultiple(2.0,ThreadThick);
    WireOD = 1.5; // battery & LED wiring
    WireOC = 8.0; // hole spacing in lid
    Gap = 5.0;
    // Cylindrical cell sizes
    // https://en.wikipedia.org/wiki/List_of_battery_sizes#Cylindrical_batteries
    CELL_NAME = 0;
    CELL_OD = 1;
    CELL_OAL = 2;
    // FIXME search() needs special-casing to properly find AAA and AAAA
    // Which is why CellName is limited to AA
    CellData = [
    ["AAAA",8.3,42.5],
    ["AAA",10.5,44.5],
    ["AA",14.5,50.5],
    ["C",26.2,50],
    ["D",34.2,61.5],
    ["A23",10.3,28.5],
    ["CR123A",17.0,34.5],
    ["18650",18.8,65.2], // bare 18650 with button end
    ["18650Prot",19.0,70.0], // protected 18650 = 19670 plus a bit
    ];
    CellIndex = search([CellName],CellData,1,0)[0];
    echo(str("Cell index: ",CellIndex," = ",CellData[CellIndex][CELL_NAME]));
    //- Contact dimensions
    CONTACT_NAME = 0;
    CONTACT_WIDE = 1;
    CONTACT_HIGH = 2;
    CONTACT_THICK = 3; // plate thickness
    CONTACT_TIP = 4; // tip to rear face
    CONTACT_TAB = 5; // solder tab width
    ContactData = [
    ["AA+",12.2,12.2,0.3,1.7,3.5], // pos bump
    ["AA-",12.2,12.2,0.3,5.0,3.5], // half-compressed neg spring
    ["AA+-",28.2,12.2,0.3,5.0,0], // pos-neg bridge
    ["D+",18.5,16.0,0.3,2.8,5.5],
    ["D-",18.5,16.0,0.3,6.0,5.5],
    ["D+-",50.0,19.0,0.3,7.0,0], // solder +/- tabs together
    ["Li+",18.5,16.0,0.3,2.8,5.5],
    ["Li-",18.5,16.0,0.3,6.0,5.5],
    ];
    function ConDat(name,dim) = ContactData[search([name],ContactData,1,0)[0]][dim];
    ContactRecess = 2*ConDat(str(CellName,"+"),CONTACT_THICK);
    ContactOC = CellData[CellIndex][CELL_OD];
    WireBay = 6.0; // room for wiring to contacts
    //- Wire struts
    StrutDia = 1.6; // AWG 14 = 1.6 mm
    StrutSides = 3*4;
    ID = 0;
    OD = 1;
    LENGTH = 2;
    StrutBase = [StrutDia,StrutDia + 2*5*ThreadWidth, // ID = wire, OD = buildable
    FloorThick + CellData[CellIndex][CELL_OD]]; // LENGTH = base is flush with cell top
    //- Holder dimensions
    BatterySize = [CellData[CellIndex][CELL_OAL] + // cell
    ConDat(str(CellName,"+"),CONTACT_TIP) + // pos contact
    ConDat(str(CellName,"-"),CONTACT_TIP) – // neg contact
    2*ContactRecess, // sink into wall
    NumCells*CellData[CellIndex][CELL_OD],
    CellData[CellIndex][CELL_OD]
    ];
    echo(str("Battery space: ",BatterySize));
    CaseSize = [3*WallThick + // end walls + wiring partition
    BatterySize.x + // cell
    WireBay, // wiring bay
    2*WallThick + BatterySize.y,
    FloorThick + BatterySize.z
    ];
    echo(str("CaseSize: ",CaseSize));
    BatteryOffset = (CaseSize.x – (2*WallThick +
    CellData[CellIndex][CELL_OAL] +
    ConDat(str(CellName,"-"),CONTACT_TIP))
    ) /2 ;
    ThumbRadius = 0.75 * CaseSize.z;
    StrutOC = [IntegerLessMultiple(CaseSize.x – 2*CornerRadius -2*StrutBase[OD],5.0),
    IntegerMultiple(CaseSize.y + StrutBase[OD],5.0)];
    StrutAngle = atan(StrutOC.y/StrutOC.x);
    echo(str("Strut OC: ",StrutOC));
    LidSize = [2*WallThick + WireBay + ConDat(str(CellName,"+"),CONTACT_THICK), CaseSize.y, FloorThick/2];
    LidScrew = [2.0,3.8,7.0]; // M2 pan head screw (LENGTH = threaded)
    LidScrewOC = CaseSize.y/2 – CornerRadius – LidScrew[OD]; // allow space around screw head
    //- Piranha LEDs
    PiranhaBody = [8.0,8.0,8.0]; // Z = heatsink fins + plastic body + lens
    PiranhaPin = 0.0; // trimmed pin length beyond heatsink
    PiranhaPinsOC = [5.0,5.0]; // pin XY distance
    PiranhaRecess = PiranhaBody.z + PiranhaPin/2; // minimum LED recess depth
    BallOD = 40.0; // radome sphere
    BallSides = 4*3*4; // nice smoothness
    PillarOD = norm([PiranhaBody.x,PiranhaBody.y]) + 2*WallThick;
    BallChordM = BallOD/2 – sqrt(pow(BallOD/2,2) – (pow(PillarOD,2))/4);
    echo(str("Ball chord depth: ",BallChordM));
    RadomePillar = [norm([PiranhaBody.x,PiranhaBody.y]), // ID = LED diagonal
    PillarOD,
    FloorThick + PiranhaRecess + BallChordM]; // height to top of ball chord
    echo(str("Pillar: ",RadomePillar));
    RadomeBar = [StrutBase[OD]*cos(180/StrutSides),StrutOC.y,StrutBase[OD]/2];
    Tape = [RadomePillar[ID],16.0,1.0]; // sticky tape disk, OD to match hole punch
    //- WWVB receiver hardware
    Antenna = [10.0 + 0.5,14.0,60.0 + 2.0]; // ferrite antenna bar with clearance
    AntCapSize = [Antenna[ID] + 1.0,Antenna[OD],5.0]; // LENGTH=insertion
    RecPCB = [24.0,16.0,5.0];
    //———————-
    // Useful routines
    module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes
    Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);
    FixDia = Dia / cos(180/Sides);
    cylinder(r=(FixDia + HoleWindage)/2,h=Height,$fn=Sides);
    }
    // Spider for single LED atop struts, with the ball
    module DualSpider() {
    difference() {
    union() {
    for (j=[-1,1]) {
    for (k=[-1,1])
    translate([0,j*StrutOC.y/2,k*RadomeBar.z])
    rotate(180/StrutSides)
    sphere(d=StrutBase[OD]/cos(180/StrutSides),$fn=StrutSides);
    translate([0,j*StrutOC.y/2,0])
    rotate(180/StrutSides)
    cylinder(d=StrutBase[OD],h=2*RadomeBar.z,center=true,$fn=StrutSides);
    }
    cube(RadomeBar,center=true); // connecting bar
    cylinder(d=RadomePillar[OD],h=RadomePillar[LENGTH],$fn=BallSides);
    translate([0,0,-RadomeBar.z/2])
    cylinder(d1=0.9*RadomePillar[OD],d2=RadomePillar[OD],h=RadomeBar.z/2,$fn=BallSides);
    }
    for (j=[-1,1]) // strut wires
    translate([0,j*StrutOC.y/2,-3*StrutBase[OD]/2])
    rotate(180/StrutSides)
    PolyCyl(StrutBase[ID],2*StrutBase[OD],StrutSides);
    for (k=[-1,1]) // LED wiring through bar
    translate([0,k*(StrutOC.x/2 – 2*RadomeBar.x),-RadomeBar.z])
    rotate(180/6)
    PolyCyl(StrutBase[ID],2*RadomeBar.z,6);
    translate([0,0,BallOD/2 + RadomePillar[LENGTH] – BallChordM]) // ball inset
    sphere(d=BallOD);
    translate([0,0,BallOD/2 + RadomePillar[LENGTH] – BallChordM – Tape[LENGTH]/2]) // tape inset
    intersection() {
    sphere(d=BallOD);
    cylinder(d=Tape[OD],h=2*BallOD,center=true);
    }
    translate([0,0,RadomePillar.z – PiranhaRecess + RadomePillar.z/2]) // LED inset
    cube(PiranhaBody + [HoleWindage,HoleWindage,RadomePillar.z],center=true); // XY clearance
    translate([0,0,StrutBase[OD]/4 + WireOD/2 + 0*Protrusion]) // wire channels
    cube([WireOD,RadomePillar[OD] + 2*WallThick,WireOD],center=true);
    }
    }
    //– WWVB antenna support cap
    module AntennaBar() {
    rotate([90,0,0])
    union() {
    cylinder(d=Antenna[ID],h=Antenna[LENGTH],$fn=BallSides,center=true);
    cylinder(d=2*Antenna[OD],h=Antenna[LENGTH] – 2*AntCapSize[LENGTH],$fn=BallSides,center=true);
    }
    }
    module AntennaCap() {
    rotate([90,0,0])
    intersection() {
    translate([0,-Antenna[LENGTH]/2 + AntCapSize[LENGTH],0])
    difference() {
    hull() {
    rotate([90,0,0])
    cylinder(d=AntCapSize[OD],h=Antenna[LENGTH],$fn=BallSides,center=true);
    for (j=[-1,1])
    translate([0,j*StrutOC.y/2,0])
    rotate(180/StrutSides)
    cylinder(d=StrutBase[OD],h=1*StrutBase[OD],$fn=StrutSides,center=true);
    }
    for (j=[-1,1])
    translate([0,j*StrutOC.y/2,-Antenna[OD]/2])
    rotate(180/StrutSides)
    PolyCyl(StrutBase[ID],Antenna[OD],StrutSides);
    AntennaBar();
    }
    rotate([-90,0,0])
    cylinder(d=Antenna[OD],h=Antenna[LENGTH],center=false);
    }
    }
    //– WWVB PCB support flag
    module RecFlag() {
    difference() {
    hull() {
    rotate(180/StrutSides)
    cylinder(d=StrutBase[OD],h=RecPCB.x,$fn=StrutSides);
    translate([0,RecPCB.y,0])
    rotate(180/StrutSides)
    cylinder(d=StrutBase[OD],h=RecPCB.x,$fn=StrutSides);
    }
    translate([0,0,-Protrusion])
    rotate(180/StrutSides)
    PolyCyl(StrutBase[ID],2*RecPCB.x,StrutSides);
    translate([0,StrutBase[OD]/2,-Protrusion])
    cube([StrutBase[OD],RecPCB.y,2*RecPCB.x],center=false);
    }
    }
    //– Overall case with origin at battery center
    module Case() {
    union() {
    difference() {
    union() {
    hull()
    for (i=[-1,1], j=[-1,1])
    translate([i*(CaseSize.x/2 – CornerRadius),
    j*(CaseSize.y/2 – CornerRadius),
    0])
    cylinder(r=CornerRadius/cos(180/8),h=CaseSize.z,$fn=8); // cos() fixes undersize spheres!
    if (Struts)
    for (i = (Struts == 1) ? [-1,1] : -1) { // strut bases
    hull()
    for (j=[-1,1])
    translate([i*StrutOC.x/2,j*StrutOC.y/2,0])
    rotate(180/StrutSides)
    cylinder(d=StrutBase[OD],h=StrutBase[LENGTH],$fn=StrutSides);
    translate([i*StrutOC.x/2,0,StrutBase[LENGTH]/2])
    cube([2*StrutBase[OD],StrutOC.y,StrutBase[LENGTH]],center=true); // blocks for fairing
    for (j=[-1,1]) // hemisphere caps
    translate([i*StrutOC.x/2,
    j*StrutOC.y/2,
    StrutBase[LENGTH]])
    rotate(180/StrutSides)
    sphere(d=StrutBase[OD]/cos(180/StrutSides),$fn=StrutSides);
    }
    }
    translate([BatteryOffset,0,BatterySize.z/2 + FloorThick]) // cells
    cube(BatterySize + [0,0,Protrusion],center=true);
    translate([BatterySize.x/2 + BatteryOffset + ContactRecess/2 – Protrusion/2, // contacts
    0,
    BatterySize.z/2 + FloorThick])
    cube([ContactRecess + Protrusion,
    ConDat(str(CellName,"+-"),CONTACT_WIDE),
    ConDat(str(CellName,"+-"),CONTACT_HIGH)
    ],center=true);
    translate([-(BatterySize.x/2 – BatteryOffset + ContactRecess/2 – Protrusion/2),
    ContactOC/2,
    BatterySize.z/2 + FloorThick])
    cube([ContactRecess + Protrusion,
    ConDat(str(CellName,"+"),CONTACT_WIDE),
    ConDat(str(CellName,"+"),CONTACT_HIGH)
    ],center=true);
    translate([-(BatterySize.x/2 – BatteryOffset + ContactRecess/2 – Protrusion/2),
    -ContactOC/2,
    BatterySize.z/2 + FloorThick])
    cube([ContactRecess + Protrusion,
    ConDat(str(CellName,"-"),CONTACT_WIDE),
    ConDat(str(CellName,"-"),CONTACT_HIGH)
    ],center=true);
    translate([-CaseSize.x/2 + WireBay/2 + WallThick, // wire bay with screw bosses
    0,
    BatterySize.z/2 + FloorThick + Protrusion/2])
    cube([WireBay,
    2*LidScrewOC – LidScrew[ID] – 2*4*ThreadWidth,
    BatterySize.z + Protrusion
    ],center=true);
    for (j=[-1,1]) // screw holes
    translate([-CaseSize.x/2 + WireBay/2 + WallThick,
    j*LidScrewOC,
    CaseSize.z – LidScrew[LENGTH] + Protrusion])
    PolyCyl(LidScrew[ID],LidScrew[LENGTH],6);
    for (j=[-1,1])
    translate([-(BatterySize.x/2 – BatteryOffset + WallThick/2), // contact tabs
    j*ContactOC/2,
    BatterySize.z + FloorThick – Protrusion])
    cube([2*WallThick,
    ConDat(str(CellName,"+"),CONTACT_TAB),
    (BatterySize.z – ConDat(str(CellName,"+"),CONTACT_HIGH))
    ],center=true);
    if (false)
    translate([0,0,CaseSize.z]) // finger cutout
    rotate([90,00,0])
    cylinder(r=ThumbRadius,h=2*CaseSize.y,center=true,$fn=22);
    if (Struts)
    for (i2 = (Struts == 1) ? [-1,1] : -1) { // strut wire holes and fairing
    for (j=[-1,1])
    translate([i2*StrutOC.x/2,j*StrutOC.y/2,FloorThick])
    rotate(180/StrutSides)
    PolyCyl(StrutBase[ID],2*StrutBase[LENGTH],StrutSides);
    for (i=[-1,1], j=[-1,1]) // fairing cutaways
    translate([i*StrutBase[OD] + (i2*StrutOC.x/2),
    j*StrutOC.y/2,
    -Protrusion])
    rotate(180/StrutSides)
    PolyCyl(StrutBase[OD],StrutBase[LENGTH] + 2*Protrusion,StrutSides);
    }
    translate([0,0,ThreadThick – Protrusion]) // recess around name
    cube([51.0,15,2*ThreadThick],center=true);
    }
    linear_extrude(height=2*ThreadThick + Protrusion,convexity=10) {
    translate([0,-3.5,0])
    mirror([0,1,0])
    text(text="softsolder",size=6,spacing=1.20,font="Arial:style:Bold",halign="center",valign="center");
    translate([0,3.5,0])
    mirror([0,1,0])
    text(text=".com",size=6,spacing=1.20,font="Arial:style:Bold",halign="center",valign="center");
    }
    }
    }
    module Lid() {
    difference() {
    hull()
    for (i=[-1,1], j=[-1,1], k=[-1,1])
    translate([i*(LidSize.x/2 – CornerRadius),
    j*(LidSize.y/2 – CornerRadius),
    k*(LidSize.z – CornerRadius)]) // double thickness for flat bottom
    sphere(r=CornerRadius/cos(180/8),$fn=8);
    translate([0,0,-LidSize.z]) // remove bottom
    cube([(LidSize.x + 2*Protrusion),(LidSize.y + 2*Protrusion),2*LidSize.z],center=true);
    for (j=[-1,1]) // wire holes
    translate([0,j*WireOC/2,-Protrusion])
    PolyCyl(WireOD,2*LidSize.z,6);
    for (j=[-1,1])
    translate([0,j*LidScrewOC,-Protrusion])
    PolyCyl(LidScrew[ID],2*LidSize.z,6);
    }
    }
    //——————-
    // Show & build stuff
    if (Layout == "Case")
    Case();
    if (Layout == "Lid")
    Lid();
    if (Layout == "AntCap")
    AntennaCap();
    if (Layout == "RecFlag")
    RecFlag();
    if (Layout == "Spider")
    if (Struts == -1)
    DualSpider();
    else
    cube(10,center=true);
    if (Layout == "Build") {
    rotate(90)
    Case();
    translate([0,-(CaseSize.x/2 + LidSize.x/2 + Gap),0])
    rotate(90)
    Lid();
    if (Struts == -1) {
    difference() {
    union() {
    translate([CaseSize.x/2 + RadomePillar[OD],0,0])
    DualSpider();
    translate([-(CaseSize.x/2 + RadomePillar[OD]),0,0])
    rotate([180,0,0])
    DualSpider();
    }
    translate([0,0,-2*CaseSize.z])
    rotate(90)
    cube(4*CaseSize,center=true);
    }
    }
    if (WWVB) {
    for (i=[-1,1])
    translate([i*(Antenna[LENGTH]/2 – AntCapSize[LENGTH]),CaseSize.x/2 + Antenna[OD],0])
    AntennaCap();
    translate([0,CaseSize.x/2 + Antenna[OD],0])
    RecFlag();
    }
    }
    if (Layout == "Show") {
    Case();
    for (j=[-1,1])
    color("Brown",0.3)
    translate([-StrutOC.x/2,j*StrutOC.y/2,Protrusion])
    cylinder(d=StrutDia[ID],h=3*CaseSize.z,$fn=StrutSides);
    translate([-(CaseSize.x/2 – LidSize.x/2),0,(CaseSize.z + Gap)])
    Lid();
    if (Struts == -1)
    translate([-StrutOC.x/2,0,3*CaseSize.z])
    DualSpider();
    if (WWVB) {
    for (j=[-1,1])
    translate([-StrutOC.x/2,,j*(Antenna[LENGTH]/2 – AntCapSize[LENGTH]),1.5*CaseSize.z])
    rotate([-j*90,0,0])
    AntennaCap();
    translate([-StrutOC.x/2,,-(StrutOC.y/2),2*CaseSize.z])
    RecFlag();
    }
    }
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