​

// This began as...

// Spring

// by REAS <http://www.groupc.net>

// and became...

// testMOD99

// mangled by oz

// Updated 03 NOV 03

​

​

// Re-written 18 July 2024 to P5J ver 1.9.4   (without applets)

// to become a demonstration of secondary emission of electrons

// from an electrically floating element.

// Background history for The RCA Selectron digital memory tube

// Click and drag the storage eyelet to change its potential

// Spring drawing constants for eyelet

​

let max = 250; // Maximum Y value

let min = 150; // Minimum Y value

let over0 = false; // If mouse over clear

let over1 = false; // If mouse over set

let move = false; // If mouse down and over

let charge = 20; // Initial charge on eyelet

let size = 5; // Width of the shape

let ypos; // Position of electrons

let ringer; // Position of the electron which can succeed

let yspeed = 10; // Speed of the electrons

let ydirection = 1; // Top to Bottom

let ringerdir = 1; // Top to Bottom of the lone electron

let drift = 0; // Deflected electron lateral movement

let level = 0; // Top of the heap

let twins = 1; // secondary electron display enable

let dl = 0; //drift * level

let dlt = 0; // drift * level * twins

// Spring simulation constants

let M = 0.8; // Mass

let K = 0.2; // Spring constant

let D = 0.07; // Damping

let R = 200; // Rest position

​

// Spring simulation variables

let ps = 200.0; // Position

let vs = 0.0; // Velocity

let as = 0; // Acceleration

let f = 0; // Force

​

//BFont metaItalic;

// The font "Meta-Italic.vlw.gz" must be located in the

// current sketch's "data" directory to load successfully

​

function setup() {

  createCanvas(500, 380);

  rectMode(CORNERS);

  noStroke();

  colorMode(RGB);

  frameRate(20);

  //  metaItalic = loadFont("Meta-Italic.vlw.gz");

​

  // Set the starting position of the electron beam

​

  ypos = 40;

  ringer = 40;

  //  textFont(metaItalic, 20);

}

​

function draw() {

  background(102);

  updateEyelet();

  drawEyelet();

​

  // border

​

  fill(0);

  rect(0, 0, 2, 380);

  rect(0, 0, 500, 2);

  rect(500, 380, 0, 378);

  rect(500, 380, 498, 0);

​

  // buttons...........................................................

  if (over0) {

    fill(255);

    ps=150

  }

  rect(400, 240, 420, 260);

​

  fill(0);

  if (over1) {

    fill(255);

    ps=250

  }

  rect(400, 300, 420, 320);

​

  // Cathodes are red

  fill(200, 75, 30);

  rect(180, 44, 122, 36);

​

  // Collectors are gray

  fill(70, 70, 70);

  rect(195, 45, 440, 35);

​

  fill(255, 255, 255);

  text("region where electrons are repelled", 205, 140);

  text("region where electrons are collected", 205, 170);

  text("region where electrons are ejected", 205, 200);

  text("cathode", 125, 30);

  text("phosphor", 120, 345);

  text("Secondary Electron Emission", 250, 373);

  text("collector", 278, 30);

  text("pulse eyelet low", 290, 255);

  text("pulse eyelet high", 287, 315);

​

  // Electrons are blue...right?

  fill(20, 200, 200);

​

  // Above this level, lower potential, electrons are repelled

  rect(205, 150, 215, 151);

​

  // Below this level, higher potential, secondary electrons are ejected

  rect(205, 180, 215, 181);

​

  // Update the position of the electron beam

​

  ypos = ypos + yspeed * ydirection;

  ringer = ringer + yspeed * ringerdir;

  level = ps + 5 - charge - ypos;

​

  //  Blast out secondaries if charge is low (delta potential high)

  if (ps - charge > 180 && ypos > ps - 5 - charge) {

    ydirection = -1;

    ringerdir = -1;

    charge = charge - 9;

    yspeed = 15;

    drift = -1;

    twins = 0.5;

  }

​

  //  Let the lone electron pass

  if (charge < 2 && ypos > 180) {

    ringerdir = 1;

  }

​

  //  Hey, this ain't a Van de Graaff -- leakage exists

  if (charge < 0) {

    charge = 0;

  }

​

  // repel if fully charged

  //  (charge) && (touch: where repelled)

  if (ps - charge < 155 && ypos > ps - 15 - charge) {

    ydirection = -1;

    ringerdir = -1;

    charge = charge - 3;

    drift = -1;

    yspeed = 15;

  }

​

  //emit some electrons from the cathode, if none in play

  if (ypos > ps + 5 - charge || ypos < 30) {

    ypos = 37;

    ringer = 37;

    drift = 0;

    yspeed = 10;

    twins = 1;

    ydirection = 1;

    ringerdir = 1;

    charge = charge + 3;

  }

​

  //  Let the lone electron pass

  if (charge < 2 && ypos > 180) {

    ringerdir = 1;

  }

​

  // Draw the primary electrons

​

  dl = drift * level;

  dlt = dl * twins;

​

  ellipse(130 - dl * 1.3, ypos, 5, 5);

  ellipse(170 - dl * 1.3, ypos, 5, 5);

  ellipse(140 - dl, ypos, 5, 5);

  ellipse(160 - dl, ypos, 5, 5);

​

  // And draw the secondaries -- coincident if they don't exist

​

  ellipse(130 - dlt * 1.3, ypos, 5, 5);

  ellipse(170 - dlt * 1.3, ypos, 5, 5);

  ellipse(140 - dlt, ypos, 5, 5);

  ellipse(160 - dlt, ypos, 5, 5);

​

  // Draw our lone secondary electron

​

  ellipse(150 + dl * 0.3 * (ringerdir - 1), ringer, 5, 5);

​

  //  Draw a phosphor grain.

​

  fill(20, 250 - 2 * (ringer - 305), 20);

​

  if (ringer < 305) {

    fill(20, 100, 20);

  }

​

  ellipse(150, 300, 20, 20);

}

//  Hey, this ain't FORTRAN ... there's no GOTO

​

function drawEyelet() {

  // Set color and draw eyelet and electrons

  if (

    ((over0 || over1) && move) ||

    (key == "n" && keyPressed == true) ||

    (key == "p" && keyPressed == true)

  ) {

    fill(255);

  } else {

    fill(0);

  }

  rect(100, ps, 146, ps + 10);

  rect(156, ps, 200, ps + 10);

  rect(100, ps - 50, 105, ps);

  rect(200, ps - 50, 195, ps);

  fill(20, 200, 200);

  rect(105, ps, 195, ps - charge);

​

  fill(255, 255, 255);

​

  text("eyelet", 53, ps - 25);

​

  // Draw voltage divider

​

  stroke(255);

  // line(100,  ps -10, 35, ps - 10 );

​

  // line(60,  ps, 35, ps );

​

  line(100, ps - 10, 50, ps - 10);

  line(45, ps - 10, 35, ps - 10);

​

  line(45, ps - 4, 45, ps - 16);

  line(50, ps - 4, 50, ps - 16);

​

  line(38, ps - 7, 35, ps - 10);

  line(38, ps - 13, 35, ps - 10);

​

  line(32, 40, 122, 40);

  line(135, 325, 33, 325);

  line(33, 350, 33, 280);

  point(140, 325);

  point(144, 325);

  point(148, 325);

  point(152, 325);

  point(156, 325);

  point(160, 325);

​

  beginShape();

  vertex(32, 30);

  vertex(32, 73);

  vertex(30, 75);

  vertex(35, 80);

  vertex(30, 85);

  vertex(35, 90);

  vertex(30, 95);

  vertex(35, 100);

  vertex(32, 103);

​

  vertex(32, 110);

  vertex(32, 137);

  vertex(30, 140);

  vertex(35, 145);

  vertex(30, 150);

  vertex(35, 155);

  vertex(30, 160);

  vertex(35, 165);

  vertex(30, 170);

  vertex(35, 175);

  vertex(30, 180);

  vertex(35, 185);

  vertex(30, 190);

  vertex(35, 195);

​

  vertex(30, 200);

  vertex(35, 205);

  vertex(30, 210);

  vertex(35, 215);

  vertex(30, 220);

  vertex(35, 225);

  vertex(30, 230);

  vertex(35, 235);

  vertex(30, 240);

  vertex(35, 245);

  vertex(33, 247);

  vertex(33, 280);

  endShape();

​

  text("+V", 25, 370);

  text("-V", 25, 15);

​

  noStroke();

}

​

function updateEyelet() {

  // Update the eyelet position

  if (!move) {

    f = -K * (ps - R); // f=-ky

    as = f / M; // Set the acceleration, f=ma == a=f/m

    vs = D * (vs + as); // Set the velocity

    ps = ps + vs; // Updated position

  }

  if (abs(vs) < 0.1) {

    vs = 0.0;

  }

​

  // Test if mouse is over

  if (mouseY > 300 && mouseY < 320 && mouseX > 400 && mouseX < 420) {

    over1 = true;

  } else {

    over1 = false;

  }

​

  if (mouseY > 240 && mouseY < 260 && mouseX > 400 && mouseX < 420) {

    over0 = true;

  } else {

    over0 = false;

  }

//  text(mouseY, 50, 250);

​

}

​