Vacuum Tube LEDs: First Light!

2016-02-11

A test lashup to see how it all works, with an ersatz plate cap atop the IBM 21HB5A Beam Power tube on the far right end:

Vacuum Tube LEDs - test lashup — Vacuum Tube LEDs – test lashup

Those sockets must mount in a chassis, not flop around loose on the cable.

I hacked the code out of the Hard Drive Platter Mood Light; there’s a lot to not like about what’s left and I must rethink the overall structure. The colors now run an order of magnitude faster than the Platter Mood Light, with a 90° phase angle between successive Neopixels.

The mica spacers in the 12AT7 Dual Triode tube (second in the sequence, Noval socket) look cool & crystalline:

Vacuum Tube LEDs - Noval tube - blue phase — Vacuum Tube LEDs – Noval tube – blue phase

When the red phase comes around, it becomes a firebottle:

Vacuum Tube LEDs - Noval tube - red phase — Vacuum Tube LEDs – Noval tube – red phase

With a touch of fire in its hole, the IBM 21HB5A Beam Power tube looks just flat-out gorgeous, despite that translucent blue plate cap:

Vacuum Tube LEDs - IBM 21HB5A Beam Power Tube - violet amber phase — Vacuum Tube LEDs – IBM 21HB5A Beam Power Tube – violet amber phase

Cool green works pretty well:

Vacuum Tube LEDs - IBM 21HB5A Beam Power Tube - green violet phase — Vacuum Tube LEDs – IBM 21HB5A Beam Power Tube – green violet phase

If you wait long enough, it’ll probably turn True IBM Blue.

This worked out even better than I expected!

The Arduino source code as a GitHub gist:

	// Neopixel lighting for multiple vacuum tubes
	// Ed Nisley – KE4ANU – January 2015

	#include <Adafruit_NeoPixel.h>

	//———-
	// Pin assignments

	const byte PIN_NEO = A3; // DO – data out to first Neopixel

	const byte PIN_HEARTBEAT = 13; // DO – Arduino LED

	//———-
	// Constants

	#define UPDATEINTERVAL 25ul
	const unsigned long UpdateMS = UPDATEINTERVAL – 1ul; // update LEDs only this many ms apart minus loop() overhead

	// number of steps per cycle, before applying prime factors
	#define RESOLUTION 100

	// phase difference between tubes for slowest color
	#define BASEPHASE (PI/4.0)

	// number of LED strips around each tube
	#define LEDSTRIPCOUNT 1

	// number of LEDs per strip
	#define LEDSTRINGCOUNT 5

	// want to randomize the startup a little?
	#define RANDOMIZE true

	//———-
	// Globals

	// instantiate the Neopixel buffer array

	Adafruit_NeoPixel strip = Adafruit_NeoPixel(LEDSTRIPCOUNT * LEDSTRINGCOUNT, PIN_NEO, NEO_GRB + NEO_KHZ800);

	uint32_t FullWhite = strip.Color(255,255,255);
	uint32_t FullOff = strip.Color(0,0,0);

	struct pixcolor_t {
	byte Prime;
	unsigned int NumSteps;
	unsigned int Step;
	float StepSize;
	float TubePhase;
	byte MaxPWM;
	};

	// colors in each LED
	enum pixcolors {RED, GREEN, BLUE, PIXELSIZE};

	struct pixcolor_t Pixels[PIXELSIZE]; // all the data for each pixel color intensity

	byte Map[LEDSTRINGCOUNT][LEDSTRIPCOUNT] = {{0},{1},{2},{3},{4}}; // pixel IDs around each tube, bottom to top.

	unsigned long MillisNow;
	unsigned long MillisThen;

	//– Figure PWM based on current state

	byte StepColor(byte Color, float Phi) {

	byte Value;

	Value = (Pixels[Color].MaxPWM / 2.0) * (1.0 + sin(Pixels[Color].Step * Pixels[Color].StepSize + Phi));

	// Value = (Value) ? Value : Pixels[Color].MaxPWM; // flash at dimmest points
	// printf("C: %d Phi: %d Value: %d\r\n",Color,(int)(Phi*180.0/PI),Value);

	return Value;
	}


	//– 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("Multiple Vacuum Tube Mood Light with Neopixels\r\nEd Nisley – KE4ZNU – January 2016\r\n");

	/// set up Neopixels

	strip.begin();
	strip.show();

	// lamp test: run a brilliant white dot along the length of the strip

	printf("Lamp test: walking white\r\n");

	strip.setPixelColor(0,FullWhite);
	strip.show();
	delay(500);

	for (int i=1; i<strip.numPixels(); i++) {
	digitalWrite(PIN_HEARTBEAT,HIGH);
	strip.setPixelColor(i-1,FullOff);
	strip.setPixelColor(i,FullWhite);
	strip.show();
	digitalWrite(PIN_HEARTBEAT,LOW);
	delay(500);
	}

	strip.setPixelColor(strip.numPixels() – 1,FullOff);
	strip.show();
	delay(500);

	// fill the layers

	printf(" … fill using Map array\r\n");

	for (int i=0; i < LEDSTRINGCOUNT; i++) { // for each layer
	digitalWrite(PIN_HEARTBEAT,HIGH);
	for (int j=0; j < LEDSTRIPCOUNT; j++) { // spread color around the layer
	strip.setPixelColor(Map[i][j],FullWhite);
	strip.show();
	delay(250);
	}
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	// clear to black

	printf(" … clear\r\n");

	for (int i=0; i < LEDSTRINGCOUNT; i++) { // for each layer
	digitalWrite(PIN_HEARTBEAT,HIGH);
	for (int j=0; j < LEDSTRIPCOUNT; j++) { // spread color around the layer
	strip.setPixelColor(Map[i][j],FullOff);
	strip.show();
	delay(250);
	}
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	delay(1000);

	// set up the color generators

	MillisNow = MillisThen = millis();
	if (RANDOMIZE)
	randomSeed(MillisNow + analogRead(7));
	else
	printf("Start not randomized\r\n");
	printf("First random number: %ld\r\n",random(10));

	Pixels[RED].Prime = 7;
	Pixels[GREEN].Prime = 5;
	Pixels[BLUE].Prime = 3;
	printf("Primes: (%d,%d,%d)\r\n",Pixels[RED].Prime,Pixels[GREEN].Prime,Pixels[BLUE].Prime);

	unsigned int TubeSteps = (unsigned int) ((BASEPHASE / TWO_PI) *
	RESOLUTION * (unsigned int) max(max(Pixels[RED].Prime,Pixels[GREEN].Prime),Pixels[BLUE].Prime));
	printf("Tube phase offset: %d deg = %d steps\r\n",(int)(BASEPHASE*(360.0/TWO_PI)),TubeSteps);

	Pixels[RED].MaxPWM = 255;
	Pixels[GREEN].MaxPWM = 128;
	Pixels[BLUE].MaxPWM = 255;

	for (byte c=0; c < PIXELSIZE; c++) {
	Pixels[c].NumSteps = RESOLUTION * (unsigned int) Pixels[c].Prime;
	Pixels[c].Step = (RANDOMIZE) ? random(Pixels[c].NumSteps) : (3*Pixels[c].NumSteps)/4;
	Pixels[c].StepSize = TWO_PI / Pixels[c].NumSteps; // in radians per step
	Pixels[c].TubePhase = TubeSteps * Pixels[c].StepSize; // radians per tube

	printf("c: %d Steps: %d Init: %d",c,Pixels[c].NumSteps,Pixels[c].Step);
	printf(" PWM: %d Phi %d deg\r\n",Pixels[c].MaxPWM,(int)(Pixels[c].TubePhase*(360.0/TWO_PI)));
	}


	}

	//——————
	// Run the mood

	void loop() {

	MillisNow = millis();
	if ((MillisNow – MillisThen) > UpdateMS) {
	digitalWrite(PIN_HEARTBEAT,HIGH);

	for (byte c=0; c < PIXELSIZE; c++) { // step to next increment in each color
	if (++Pixels[c].Step >= Pixels[c].NumSteps) {
	Pixels[c].Step = 0;
	printf("Cycle %d steps %d at %8ld delta %ld ms\r\n",c,Pixels[c].NumSteps,MillisNow,(MillisNow – MillisThen));
	}
	}

	for (int i=0; i < LEDSTRINGCOUNT; i++) { // for each layer
	byte Value[PIXELSIZE];
	for (byte c=0; c < PIXELSIZE; c++) { // … for each color
	Value[c] = StepColor(c,-i*Pixels[c].TubePhase); // figure new PWM value
	// Value[c] = (c == RED && Value[c] == 0) ? Pixels[c].MaxPWM : Value[c]; // flash highlight for tracking
	}
	uint32_t UniColor = strip.Color(Value[RED],Value[GREEN],Value[BLUE]);
	if (false && (i == 0))
	printf("L: %d C: %08lx\r\n",i,UniColor);
	for (int j=0; j < LEDSTRIPCOUNT; j++) { // fill layer with color
	strip.setPixelColor(Map[i][j],UniColor);
	}
	}
	strip.show();

	MillisThen = MillisNow;
	digitalWrite(PIN_HEARTBEAT,LOW);
	}

	}

view raw MultiTube.ino hosted with ❤ by GitHub

Comments

6 responses to “Vacuum Tube LEDs: First Light!”

2016-02-11

madbodger

Pretty! I like that the bases are translucent too, but it would be interesting to see one in black so most of the light is coming from the tube.
1. 2016-02-11
  
  Ed
  
  I have both black and natural PETG in the drawer, cued behind the last of the cyan. I’ll start with natural (think “ceramic”) sockets, then drop a brass tube down the hole for directed light …
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