Tag: Improvements

Making the world a better place, one piece at a time

Auvon TENS/EMS: Pulse Waveforms

The Auvon AS8016 TENS/EMS unit produces bipolar pulses with no net DC offset, so the UI controls the negative and positive amplitudes equally. The range has 20 steps, with the screen shots here set to 10 units. The actual output voltage depends on the mode, with some modes producing a peak voltage well above the others at the same UI setting.

It’s worth noting the effect comes from current passed through skin and muscle, rather than voltage applied to it. The test setup uses a 500 Ω resistance to make the current vary linearly with the voltage (which is definitely not the case with human bodies): a 20 V pulse passes 40 mA through the resistor:

Auvon AS8016 – test setup

The simplest bipolar pulses always start with the negative phase. The shortest pulse width is 100 µs:

Auvon M02 Pulse

And 150 µs:

Auvon M03 Pulse

And 200 µs:

Auvon M01 Pulse

Up to 250 µs:

Auvon M06 Pulse

Some modes have a short zero-voltage pause between the negative and positive phases:

Auvon M17 Pulse

The pause can be the same duration as the negative and positive phases:

Auvon M14 Pulse

Some modes have pulses starting with the positive phase, others switch the leading phase during the course of the output modulation.

My casual survey of the consumer-grade field suggests the pulse waveform has less to do with well-tested effects and more to do with marketing or straight-up woo, but I admit to being a cynic.

2021-12-29
Auvon TENS/EMS: Lead Identification

One of Santa’s myriad helpers recently handed me an Auvon AS8016 TENS/EMS Unit. The manual is, shall we say, light on tech details, but some casual searching turns up the general specs for medical-grade units found in physical therapy offices, plus adjacent Rule 34 compliant (i.e. NSFW) offerings.

Being that type of guy, I had to look at the electricity. Somewhat to my surprise, the reference load turns out to be a pure 500 Ω resistance, which is easy enough to cobble up from a pair of 1 kΩ resistors:

Auvon AS8016 – test setup

The alligator clips crunched around the 2 mm pins are not appropriate for even a brutal e-stim session; they’re from the Small Drawer of Test Connectors, to which they shall return unblooded.

The red Sharpie highlight around one pin identifies the center conductor of the two-wire cable, as determined by simple continuity testing:

Auvon AS8016 – marked cable

The 22 mil = 0.5 mm wire (from the Little Tin o’ Snippets) fits snugly into the coaxial connector’s center contact; one could probably slip a rounded shim between the shell and the outer contact, perhaps to debug an intermittent connection. Note that the connectors on both ends of the wires are not standardized among various TENS/EMS manufacturers.

The AS8016 has two pairs of connectors:

Auvon AS8016 – wire jacks

The A1 and A2 jacks are wired in parallel, as are the B1 and B2 jacks, with the A pair galvanically isolated from the B pair. You can set the modes / programs / pulse parameters differently for A and B. Although the manual doesn’t mention it, using the A and B channels (perhaps with the same settings) prevents a galvanic connection (and thus any current) from flowing between the A and B electrodes; this seems important for electrode pairs placed on opposite sides of your body to prevent current through your heart.

The pulses have no DC component, so the actual wire polarity doesn’t really matter, but a foolish consistency definitely simplifies going back to re-measure things. Subsequent waveforms show the voltage with respect to the unmarked (outer) conductor.

Suppressing the DC bias prevents ionic migration between / under the electrode pads. The classic RC-equivalent output circuit uses a series capacitor, resulting in an asymmetric pulse waveform with zero net DC voltage:

Capacitor Coupled Pulse

There’s no DC path between the center and outer conductors, but in this day and age the circuitry could be a completely isolated bipolar FET driver:

Auvon M01 Pulse

With all that sorted out, I can make measurements!

2021-12-28
Walker Leg Shortening

While looking for something else, Mary came across a walker in the attic and mentioned that, if she ever had to use it, the shortest position of the adjustable legs would put the hand grips too high for comfort. Maybe they

Well, I can fix that:

Walker shortening – hole indexing

The holes are an inch apart, so I clamped the V blocks parallel to the X axis on the drill press, zeroed the X axis knob, slid the leg to get the drill bit into the last hole, clamp in place, crank the table an inch, then use a step drill to start the hole:

Walker shortening – hole drilling

The holes are just slightly larger than the 1/4 inch step on the drill, so the twist drill cuts them to size.

A tubing cutter sliced an inch off all four legs and all four frame tubes:

Walker shortening – latch relocation

The white plastic fitting in the frame tube prevents the legs from rattling, but I had to drill another hole to move the latch button, too.

With a bit of luck, we’ll never need the thing.

2021-12-02
Simple Pliers Rack

A Round Tuit™ finished this trivial project:

Long-handle pliers rack

Yeah, it’s just seven pairs of holes drilled with a 5/8 inch Forstner bit in a scrap 2×4, which was then introduced to Mr Belt Sander to peel off the dust of ages.

There’s a spare set of holes in front because I’m absolutely certain that, without them, another pair of pliers would suddenly pop into existence on the bench.

2021-12-01
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

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

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.

2021-11-24

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

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 + 25ThreadWidth, // 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 – 2CornerRadius -2StrutBase[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 = 434; // 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,jStrutOC.y/2,kRadomeBar.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,jStrutOC.y/2,-3StrutBase[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 – 2RadomeBar.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],$fn=BallSides,center=true);
	cylinder(d=2Antenna[OD],h=Antenna[LENGTH] – 2AntCapSize[LENGTH],$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([iStrutOC.x/2,jStrutOC.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,
	2LidScrewOC – LidScrew[ID] – 24*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([i2StrutOC.x/2,jStrutOC.y/2,FloorThick])
	rotate(180/StrutSides)
	PolyCyl(StrutBase[ID],2*StrutBase[LENGTH],StrutSides);

	for (i=[-1,1], j=[-1,1]) // fairing cutaways
	translate([iStrutBase[OD] + (i2StrutOC.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 + 2Protrusion),(LidSize.y + 2Protrusion),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]),1.5CaseSize.z])
	rotate([-j*90,0,0])
	AntennaCap();
	translate([-StrutOC.x/2,,-(StrutOC.y/2),2*CaseSize.z])
	RecFlag();
	}
	}

view raw Astable Multivibrator – Alkaline Batteries.scad hosted with ❤ by GitHub

2021-11-17

LED-ified Halogen Desk Lamp: DC LED Driver

Feeding half-wave rectified 12 V AC into the 4 W LED lamp I hung on the end of the halogen desk lamp worked at human scale, but produced dark bars across images made with my Pixel phones. Having solved that problem for the LED lighting on Mary’s sewing machines, I replaced the OEM transformer with a 12 VDC power supply:

LED Desk Lamp – Driver installed

The steel lump inside the base is the OEM weight that, in addition to two pounds of transformer, kept the whole affair from toppling over.

The transformer inside the DC supply weighs basically nothing:

LED Desk Lamp – Driver PCB

The original 12 VAC transformer powered a 50 W halogen bulb and loafed along at 14.7 VAC (yes, RMS) into the 4 W LED. The light is somewhat dimmer at 12 VDC, but not enough to worry about.

Aaaaand the photo bars are gone!

2021-11-16