Month: April 2020

Electronics Workbench, Oddities, Photography & Images

Halogen H3 Bulb

Peering into the bulb salvaged from the Nissan fog light suggests the scuff on the lens corresponds to an impact mighty enough to disarrange the filament:

Halogen H3 bulb - 1.5 A - light
Halogen H3 bulb – 1.5 A – light

No surprise, as the car completely shattered the utility pole.

The glow draws 1.5 A from a bench supply at 1 V, just to show the filament isn’t lighting up evenly across those gaps. The bulb runs at 55 W from 12 V and would be, I’m sure, blindingly bright, although the heat concentrated in those few coils suggests it’d burn out fairly quickly.

By LED standards, though, you don’t get much light for your 1.5 W …

An underexposed version highlights the filament, just for pretty:

Halogen H3 bulb - 1.5 A - dark
Halogen H3 bulb – 1.5 A – dark

Cropped to 9:16, it’s now a desktop background.

Electronics Workbench

HP 10526T Logic Pulser Checkout

When I re-capped the HP 10525T Logic Probe, I expected the matching HP 10526T Logic Pulser would require the same treatment. Having finally gotten a Round Tuit, I preemptively pulled it apart to see what was going on inside:

HP 10526T Logic Pulser - PCB detail
HP 10526T Logic Pulser – PCB detail

The manual includes the schematic, of course:

HP 10526T Logic Pulser - schematic
HP 10526T Logic Pulser – schematic

The IC is a Motorola SN7404 Hex Inverter sporting an HP house number in a ceramic flatpack: pin 1 in the upper right, VCC on pin 4, and common on pin 11. The 7716 datecode suggests the chip first saw daylight shortly after single-chip microcontrollers became a nontrivial thing.

The pushbutton switch triggers the expected pulses at pins 10 (purple) and 12 (yellow), with timings controlled by the RC networks:

U1.12 U1.10
U1.12 U1.10

The collector output of Q2 is a robust 73 mA pulse through its 62 Ω resistor:

Q2.c
Q2.c

Q1 dumps 15 mA into its 300 Ω resistor:

Q1.C
Q1.C

The push-pull output at the emitter of Q3 and the collector of Q4 looks similar (albeit with some delay cranked in to show the tidy exponential tail):

Q3.e - Q4.c
Q3.e – Q4.c

The manual specifies a 3.0 Ω resistor to ground for Test A, thusly:

HP 10526T Logic Pulser - Test A setup
HP 10526T Logic Pulser – Test A setup

The output peaks at nearly 3 V to drive a robust 1 A (!) pulse:

Test A pulse
Test A pulse

Test B requires a 6.2 Ω resistor driven from 5 V, but a 6.8 Ω resistor came to hand:

HP 10526T Logic Pulser - Test B setup
HP 10526T Logic Pulser – Test B setup

The downward pulse doesn’t quite reach 0 V (because saturation voltage, etc), so it’s a mere 725 mA:

Test B pulse
Test B pulse

HP’s formal setup for Test C requires a totalizing counter to show the pulser produces exactly one pulse for each button push. I just wired up a 47 Ω resistor and eyeballed a few pulses:

Test C pulse - 47 ohm
Test C pulse – 47 ohm

The lighter 85 mA load through the resistor allows a more rectangular pulse than the 3 Ω resistor. Yup, looks clean to me.

Because the pulser drives its output both low and high with great authority, it doesn’t care what state the external net wants. Here’s what happens with the 47 Ω resistor connected to a 2.5 V supply:

Bipolar pulse - 47 ohm 2.5 V
Bipolar pulse – 47 ohm 2.5 V

No matter where the logic family’s threshold might be, the net will experience one downward and one upward transition through it: with the pulser delivering nigh onto an amp, the net’s driver doesn’t stand a chance.

However, the pulser was designed for TTL and DTL (remember DTL?) circuitry, so hammering a 3.3 V microcontroller pin probably isn’t a Good Idea. The notion of keeping a pulser around Just In Case may have reached its end times.

Oh, and about the re-capping. Turns out HP used solid tantalum capacitors and they’re still doing fine after four decades, thankyouverymuch. I put it back together and expect it will continue working forevermore.

Home Ec, Machine Shop

Magnifying Desk Lamp Pivot Clamp: One More

For reasons not relevant here, I made another clamp for a magnifying desk lamp and mailed it off in a small box. A few measurements suggested all such lamps share a common design and similar parts, so I duplicated my previous attempt, with some improvements.

On the upside, the same scrap of aluminum plate I used for the previous clamp emerged from the stockpile and, after a session with Mr Disk Sander, sported two square & reasonably perpendicular sides:

Magnifying Lamp Clamp - squaring stock
Magnifying Lamp Clamp – squaring stock

Rather than rely on my original dimension scribble, I transfer-punched the hole location from my as-built clamp to the stock:

Magnifying Lamp Clamp - locating stem hole
Magnifying Lamp Clamp – locating stem hole

That’s a reenactment based on a true story: the actual punching happened on the bench vise’s anvil surface, with too many moving pieces supported & aligned by an insufficient number of hands.

Drilling the 5/16 inch hole required mounting the Greater Chuck on an MT1 taper adapter for the Sherline:

Magnifying Lamp Clamp - drilling stem clamp
Magnifying Lamp Clamp – drilling stem clamp

It’s normally on an MT2 adapter for the mini-lathe tailstock, where it handles drills up to 3/8 inch. For the record, the Sherline’s Lesser Check tops out at 1/4 inch and the Least Chuck at 5/32 inch.

Punch & drill the 4 mm cross hole for the clamping screw:

Magnifying Lamp Clamp - drill cross hole
Magnifying Lamp Clamp – drill cross hole

Grab the plate in a toolmaker’s vise, set up some casual guidance, and bandsaw right down the middle:

Magnifying Lamp Clamp - sawing clamp halves
Magnifying Lamp Clamp – sawing clamp halves

Bandsaw the outline to free the two halves from the stock, then clean up their perimeter:

Magnifying Lamp Clamp - rounded
Magnifying Lamp Clamp – rounded

Saw the clamp clearance almost all the way through to leave a protrusion, then file the scarred kerf more-or-less flat:

Magnifying Lamp Clamp - filing interior
Magnifying Lamp Clamp – filing interior

Do a trial fit in my lamp, which lacks the fancy brushed-metal finish of the remote one:

Magnifying Lamp Clamp - trial fit
Magnifying Lamp Clamp – trial fit

It holds tight and rotates well, so break the edges and shine up the outside to a used-car finish (“high polish over deep scratches”):

Magnifying Lamp Clamp - surface finish
Magnifying Lamp Clamp – surface finish

The inside remains gritty to improve traction on the lamp stem:

Magnifying Lamp Clamp - interior
Magnifying Lamp Clamp – interior

Declare victory, box it up, and away it goes!

Electronics Workbench, Machine Shop, Software

Nissan Fog Lamp: Arduino Firmware

The upcycled Nissan fog lamp now has a desk stand:

Nissan Fog Lamp - table mount
Nissan Fog Lamp – table mount

A knockoff Arduino Pro Mini atop a strip of foam tape drives the WS2812 RGB LEDs:

Nissan Fog Lamp - table mount interior
Nissan Fog Lamp – table mount interior

Next time, I’ll cut the wires another inch longer.

The firmware is a tidied-up version of the vacuum tube code, minus cruft, plus fixes, and generally better at doing what it does. The Pro Mini lacks a USB output, so this came from the same code running on a Nano:

14:44:04.169 -> Algorithmic Art
14:44:04.169 ->  RGB WS2812
14:44:04.169 -> Ed Nisley - KE4ZNU - April 2020
14:44:04.169 -> Lamp test: flash full-on colors
14:44:04.169 ->  color: 00ff0000
14:44:05.165 ->  color: 0000ff00
14:44:06.160 ->  color: 000000ff
14:44:07.155 ->  color: 00ffffff
14:44:08.151 ->  color: 00000000
14:44:09.180 -> Random seed: da98f7f6
14:44:09.180 -> Primes: 7 19 3
14:44:09.180 ->  Super cycle length: 199500 steps
14:44:09.180 -> Inter-pixel phase: 1 deg = 26 steps
14:44:09.180 ->  c: 0 Steps:  3500 Init:  1538 Phase:   2 deg PWM: 255
14:44:09.180 ->  c: 1 Steps:  9500 Init:  7623 Phase:   0 deg PWM: 255
14:44:09.213 ->  c: 2 Steps:  1500 Init:  1299 Phase:   6 deg PWM: 255
14:44:19.265 -> Color 2     steps 1500  at 15101    ms 50       TS 201     
14:45:34.293 -> Color 2     steps 1500  at 90136    ms 50       TS 1701    
14:45:43.085 -> Color 1     steps 9500  at 98940    ms 50       TS 1877    
14:45:47.332 -> Color 0     steps 3500  at 103192   ms 50       TS 1962    
14:46:49.324 -> Color 2     steps 1500  at 165170   ms 50       TS 3201  
… much snippage …
17:26:52.896 -> Color 2     steps 1500  at 9769584  ms 50       TS 195201  
17:28:07.926 -> Color 2     steps 1500  at 9844618  ms 50       TS 196701  
17:29:11.000 -> Color 0     steps 3500  at 9907697  ms 50       TS 197962  
17:29:22.974 -> Color 2     steps 1500  at 9919653  ms 50       TS 198201  
17:30:27.941 -> Supercycle end, setting new color values
17:30:27.941 -> Primes: 17 7 3
17:30:27.941 ->  Super cycle length: 178500 steps
17:30:27.941 -> Inter-pixel phase: 1 deg = 23 steps
17:30:27.941 ->  c: 0 Steps:  8500 Init:  5415 Phase:   0 deg PWM: 255
17:30:27.974 ->  c: 1 Steps:  3500 Init:  3131 Phase:   2 deg PWM: 255
17:30:27.974 ->  c: 2 Steps:  1500 Init:   420 Phase:   5 deg PWM: 255
17:30:46.394 -> Color 1     steps 3500  at 10003091 ms 50       TS 369     
17:31:21.964 -> Color 2     steps 1500  at 10038658 ms 50       TS 1080

The “Super cycle length” is the number of 50 ms steps until the colors start repeating, something over an hour in that sample. When the code reaches the end of the supercycle, it picks another set of three prime numbers, reinitializes the color settings, and away it goes.

The fog light looks pretty in action:

Nissan Fog Lamp - blue phase
Nissan Fog Lamp – blue phase

The four LEDs don’t produce the same light pattern as the halogen filament and they’re distinctly visible when you squint against the glare:

Nissan Fog Lamp - reflector LED detail
Nissan Fog Lamp – reflector LED detail

The shadow on the right comes from the larger hood support strut, the shadow on the left is the narrower strut, and the two other gaps show the beam angle gaps between the LEDs.

You’ll see plenty of residual sandpaper scratches on the lens: my surface (re)finishing hand is weak.

The LED beamwidth is so broad the “bulb” position inside the reflector doesn’t make much difference, particularly as it must, at most, wash a wall and ceiling at close range:

Nissan Fog Lamp - wall wash light
Nissan Fog Lamp – wall wash light

All in all, a much-needed dose of Quality Shop Time.

The Arduino source code as a GitHub Gist:

// Neopixel Algorithmic Art
// W2812 RGB Neopixel version
// Ed Nisley - KE4ZNU
#include <Adafruit_NeoPixel.h>
#include <Entropy.h>
//----------
// Pin assignments
const byte PIN_NEO = A3; // DO - data out to first Neopixel
const byte PIN_HEARTBEAT = 13; // DO - Arduino LED
#define PIN_MORSE 12
//----------
// Constants
// number of pixels
#define PIXELS 4
// lag between adjacent pixels in degrees of slowest period
#define PIXELPHASE 1
// update LEDs only this many ms apart (minus loop() overhead)
#define UPDATEINTERVAL 50ul
#define UPDATEMS (UPDATEINTERVAL - 0ul)
// number of steps per cycle, before applying prime factors
#define RESOLUTION 500
//----------
// Globals
Adafruit_NeoPixel strip = Adafruit_NeoPixel(PIXELS, PIN_NEO, NEO_GRB + NEO_KHZ800);
uint32_t FullWhite = strip.Color(255,255,255);
uint32_t FullOff = strip.Color(0,0,0);
uint32_t MorseColor;
struct pixcolor_t {
unsigned int Prime;
unsigned int NumSteps;
unsigned int Step;
float StepSize;
float Phase;
byte MaxPWM;
};
unsigned long int TotalSteps;
unsigned long int SuperCycleSteps;
byte PrimeList[] = {3,5,7,11,13,17,19,29}; // small primes = faster changes
// colors in each LED and their count
enum pixcolors {RED, GREEN, BLUE, PIXELSIZE};
struct pixcolor_t Pixel[PIXELSIZE]; // all the data for each pixel color intensity
uint32_t UniColor;
unsigned long int MillisNow;
unsigned long int MillisThen;
//-- Select three unique primes for the color generator function
// Then compute all the step parameters based on those values
void SetColorGenerators(void) {
Pixel[RED].Prime = PrimeList[random(sizeof(PrimeList))];
do {
Pixel[GREEN].Prime = PrimeList[random(sizeof(PrimeList))];
} while (Pixel[RED].Prime == Pixel[GREEN].Prime);
do {
Pixel[BLUE].Prime = PrimeList[random(sizeof(PrimeList))];
} while (Pixel[BLUE].Prime == Pixel[RED].Prime ||
Pixel[BLUE].Prime == Pixel[GREEN].Prime);
if (false) {
Pixel[RED].Prime = 1;
Pixel[GREEN].Prime = 3;
Pixel[BLUE].Prime = 5;
}
printf("Primes: %d %d %d\r\n",Pixel[RED].Prime,Pixel[GREEN].Prime,Pixel[BLUE].Prime);
TotalSteps = 0;
SuperCycleSteps = RESOLUTION;
for (byte c = 0; c < PIXELSIZE; c++) {
SuperCycleSteps *= Pixel[c].Prime;
}
printf(" Super cycle length: %lu steps\r\n",SuperCycleSteps);
Pixel[RED].MaxPWM = 255;
Pixel[GREEN].MaxPWM = 255;
Pixel[BLUE].MaxPWM = 255;
unsigned int PhaseSteps = (unsigned int) ((PIXELPHASE / 360.0) *
RESOLUTION * (unsigned int) max(max(Pixel[RED].Prime,Pixel[GREEN].Prime),Pixel[BLUE].Prime));
printf("Inter-pixel phase: %d deg = %d steps\r\n",(int)PIXELPHASE,PhaseSteps);
for (byte c = 0; c < PIXELSIZE; c++) {
Pixel[c].NumSteps = RESOLUTION * Pixel[c].Prime; // steps per cycle
Pixel[c].StepSize = TWO_PI / Pixel[c].NumSteps; // radians per step
Pixel[c].Step = random(Pixel[c].NumSteps); // current step
Pixel[c].Phase = PhaseSteps * Pixel[c].StepSize; // phase in radians for this color
printf(" c: %d Steps: %5d Init: %5d Phase: %3d deg",c,Pixel[c].NumSteps,Pixel[c].Step,(int)(Pixel[c].Phase * 360.0 / TWO_PI));
printf(" PWM: %d\r\n",Pixel[c].MaxPWM);
}
}
//-- Helper routine for printf()
int s_putc(char c, FILE *t) {
Serial.write(c);
}
//------------------
// Set the mood
void setup() {
pinMode(PIN_HEARTBEAT,OUTPUT);
digitalWrite(PIN_HEARTBEAT,LOW); // show we arrived
Serial.begin(57600);
fdevopen(&s_putc,0); // set up serial output for printf()
printf("Algorithmic Art\r\n RGB WS2812\r\nEd Nisley - KE4ZNU - April 2020\r\n");
Entropy.initialize(); // start up entropy collector
// set up pixels
strip.begin();
strip.show();
// lamp test: a brilliant white flash
printf("Lamp test: flash full-on colors\r\n");
uint32_t FullRGB = strip.Color(255,255,255);
uint32_t FullR = strip.Color(255,0,0);
uint32_t FullG = strip.Color(0,255,0);
uint32_t FullB = strip.Color(0,0,255);
uint32_t FullOff = strip.Color(0,0,0);
uint32_t TestColors[] = {FullR,FullG,FullB,FullRGB,FullOff};
for (byte i = 0; i < sizeof(TestColors)/sizeof(uint32_t) ; i++) {
printf(" color: %08lx\r\n",TestColors[i]);
for (int p=0; p < strip.numPixels(); p++) {
strip.setPixelColor(p,TestColors[i]);
}
strip.show();
delay(1000);
}
// get an actual random number
uint32_t rn = Entropy.random();
printf("Random seed: %08lx\r\n",rn);
randomSeed(rn);
// set up the color generators
SetColorGenerators();
MillisNow = MillisThen = millis();
}
//------------------
// Run the mood
void loop() {
MillisNow = millis();
if ((MillisNow - MillisThen) >= UPDATEMS) { // time for another step?
digitalWrite(PIN_HEARTBEAT,HIGH);
TotalSteps++;
strip.show(); // send out precomputed colors
for (byte c = 0; c < PIXELSIZE; c++) { // compute next increment for each color
if (++Pixel[c].Step >= Pixel[c].NumSteps) {
Pixel[c].Step = 0;
printf("Color %-5d steps %-5d at %-8ld ms %-8ld TS %-8lu\r\n",
c,Pixel[c].NumSteps,MillisNow,(MillisNow - MillisThen),TotalSteps);
}
}
// If all cycles have completed, reset the color generators
if (TotalSteps >= SuperCycleSteps) {
printf("Supercycle end, setting new color values\r\n");
SetColorGenerators();
}
for (int p = 0; p < strip.numPixels(); p++) { // for each pixel
byte Value[PIXELSIZE];
for (byte c=0; c < PIXELSIZE; c++) { // compute new colors
Value[c] = (Pixel[c].MaxPWM / 2.0) * (1.0 + sin(Pixel[c].Step * Pixel[c].StepSize - p*Pixel[c].Phase));
}
UniColor = strip.Color(Value[RED],Value[GREEN],Value[BLUE]);
strip.setPixelColor(p,UniColor);
}
MillisThen = MillisNow;
digitalWrite(PIN_HEARTBEAT,LOW);
}
}
view raw AlgoArt-RGB.ino hosted with ❤ by GitHub
Home Ec

Groundhog Activity

The groundhog responsible for trimming the lawn greenery in our area has discovered the long-disused driveway salt barrel:

Groundhog - in salt barrel
Groundhog – in salt barrel

There’s always another appointment on the calendar, though:

Groundhog - trotting on driveway
Groundhog – trotting on driveway

A busy critter with no time to waste!

Oddities, Photography & Images, Science

Pileated Woodpecker vs. Stump

A pileated woodpecker devoted considerable attention to debugging the remains of a stump in our front yard:

Pileated Woodpecker - front yard stump
Pileated Woodpecker – front yard stump

It’s surely a descendant of this one, eleven years ago:

Pileated Woodpecker
Pileated woodpecker

If you’re willing to wait a decade or so, a stump pretty much falls apart on its own, meanwhile providing habitat for critters both great and small.

Update: By popular demand, a slightly pixelated pileated woodpecker:

Pileated Woodpecker - front yard stump - pixelated
Pileated Woodpecker – front yard stump – pixelated
Electronics Workbench, Machine Shop, Software

Nissan Fog Lamp: Desk Stand

The Nissan fog lamp looks pretty good pointing at the ceiling:

Nissan Fog Lamp - table mount
Nissan Fog Lamp – table mount

I briefly considered sandblasting the shell to knock back the corrosion, but came to my senses: this is art!

The shell has a bayonet mount intended for the cable connector, but a bout of solid modeling produced a matching twist-lock desk stand:

Nissan Fog Light Base - Slic3r preview
Nissan Fog Light Base – Slic3r preview

The locking dogs overhang little enough, relative to their diameter, to let the thing build without internal supports. Took about three hours without any intervention at all.

The little hole matches up with the slot on the bottom holding a USB cable bringing power from a wall charger:

Nissan Fog Lamp - table mount interior
Nissan Fog Lamp – table mount interior

It’s a knockoff Arduino Pro Mini without the USB interface found on a Nano, so the USB data wires don’t connect to anything.

The base might look better under a layer of (black?) epoxy, although I’m definitely a fan of those brutalist 3D printed striations.

The OpenSCAD source code as a GitHub Gist:

// Nissan Fog Light Base
// Ed Nisley KE4ZNU 2020-04-20
/* [Hidden] */
ThreadThick = 0.25;
ThreadWidth = 0.40;
HoleWindage = 0.2;
function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
Protrusion = 0.1; // make holes end cleanly
//----------------------
// Dimensions
ID = 0;
OD = 1;
LENGTH = 2;
/* [Fog Light] */
ShellBase = [49.0,55.0,10.0];
Dog = [55.0,60.0,7.0];
DogWidth = 21.0;
DogAngle = atan(DogWidth / ShellBase[ID]);
echo(str("Dog angle: ",DogAngle));
ReflectorOD = 90.0;
LensOD = 110.0;
LensAngle = -90; // peak relative to dogs
WallThick = 4.0;
BaseThick = 2*WallThick;
CableOD = 3.5;
$fn = 3*4*5;
//-------------------
// Useful shapes
module Dogs(h=Dog[LENGTH]) {
translate([0,0,h/2])
intersection() {
cube([Dog[OD],DogWidth,h],center=true);
cylinder(d=Dog[OD],h=h,center=true);
}
}
//-------------------
// Build it
difference() {
union() {
cylinder(d=(Dog[OD] + 2*WallThick),h=(BaseThick + ShellBase[LENGTH]));
intersection() {
resize([0,0,2*BaseThick])
sphere(d=LensOD);
translate([0,0,BaseThick/2])
cube([2*LensOD,2*ReflectorOD,BaseThick],center=true);
}
}
translate([0,0,BaseThick])
cylinder(d=ShellBase[OD],h=ShellBase[LENGTH] + Protrusion);
translate([0,0,BaseThick]) {
Dogs();
rotate(1.5*DogAngle)
Dogs();
rotate(2*DogAngle)
Dogs(2*ShellBase[LENGTH]);
}
rotate(LensAngle)
translate([0.75*ShellBase[ID]/2,0,-Protrusion]) {
cylinder(d=CableOD,h=2*BaseThick,$fn=8);
translate([LensOD/2,0,CableOD/2])
cube([LensOD,CableOD,CableOD + Protrusion],center=true);
}
translate([31,0,ThreadThick-Protrusion])
cube([23.0,55.0,2*ThreadThick],center=true);
}
linear_extrude(height=2*ThreadWidth + Protrusion) {
translate([32,0,-Protrusion])
rotate(-90) mirror([1,0,0])
text(text="Ed Nisley",size=6,font="Arial:style:Bold",halign="center");
translate([23,0,-Protrusion])
rotate(-90) mirror([1,0,0])
text(text="softsolder.com",size=5,font="Arial:style:Bold",halign="center");
}
view raw Nissan Fog Light - Desk Base.scad hosted with ❤ by GitHub