​

let voltageSlider, voltageDropSlider, currentSlider;

let resistorValue, resistorBands;

let voltage, voltageDrop, current;

​

function setup() {

  const canvas = createCanvas(500, 250);

  var mainElement = document.querySelector('main');

  canvas.parent(mainElement);

  textSize(16);

  // Sliders

  // Typical voltage is between 3 and 12 volts

  voltageSlider = createSlider(3, 12, 5, 0.1);

  voltageSlider.size(270);

  voltageSlider.position(200, 20);

  // Typical LED voltage drops

  voltageDropSlider = createSlider(1.7, 3.3, 1.9, 0.1);

  voltageDropSlider.size(270);

  voltageDropSlider.position(200, 60);

  // Desired current in milliamps

  currentSlider = createSlider(2, 20, 10, 1);

  currentSlider.size(270);

  currentSlider.position(200, 100);

}

​

function draw() {

  background(235);

  // Read slider values

  voltage = voltageSlider.value();

  voltageDrop = voltageDropSlider.value();

  current = currentSlider.value();

​

  // Calculate resistor value

  idealResistorValue = (voltage - voltageDrop) / (current / 1000); // Ohm's Law, I in Amps

  resistorValue = findClosestStandardResistor(idealResistorValue);

  // Display circuit information

​

  fill(0);

  textSize(16);

  text("Input Voltage: " + voltage + "V", 10, 35);

  text("LED Voltage Drop: " + voltageDrop + "V", 10, 75);

  text("LED Current: " + current + "mA", 10, 115);

  // Calculate and display resistor value

  textSize(16);

  text("Ideal Resistor Value: " + idealResistorValue.toFixed(0) + " Ω", 20, 140);

  text("Nearest Resistor: " + resistorValue.toFixed(0) + " Ω", 20, 160);

  // Resistor Colors

  textSize(12);

  text('red          yellow         green          blue/white', 220,57);

  // Current Brightness

  text('very dim,       dim,      medium,      bright,      max', 210, 97);

  // Calculate resistor bands

  resistorBands = calculateResistorBands(resistorValue.toFixed(0));

  text("Band 1 Color: " + resistorBands[0], 120, 190);

  text("Band 2 Color: " + resistorBands[1], 120, 210);

  text("Multiplier: " + resistorBands[2], 120, 230);

​

​

  // Display resistor bands

  drawResistor(280, 160, 150, 50, resistorBands);

}

​

function calculateResistorBands(resistorValue) {

  // Resistor color coding logic

  let colors = ["black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white"];

  let bands = [];

  if (resistorValue < 1) {

    bands = ["black", "black", "black"]; // For values less than 1 Ohm

  } else {

    rString = str(resistorValue)

    let firstBand = int(rString[0]);

    text("First Band: " + firstBand, 20, 190);

    let secondBand = int(rString[1]);

    text("Second Band: " + secondBand, 20, 210);

    let multiplier = rString.length - 2;

    text("Multiplier: " + multiplier, 20, 230);

    // Ensure the indices are within the colors array range

    firstBand = ensureIndexInRange(firstBand, colors);

    secondBand = ensureIndexInRange(secondBand, colors);

    multiplier = ensureIndexInRange(multiplier, colors);

​

    bands.push(colors[firstBand], colors[secondBand], colors[multiplier]);

  }

​

  return bands;

}

​

function ensureIndexInRange(index, array) {

  // Check if index is within the array range

  if (index >= 0 && index < array.length) {

    return index;

  } else {

    return 0; // Default to the first color if out of range

  }

}

​

function drawResistor(x, y, w, h, bands) {

  // Draw the wire below

  fill('black');

  rect(x-30, y+20, w+60, 10);

  // Draw the resistor body - the 5th parameter is corner roundness

  fill("tan");

  rect(x, y, w, h, 10);

​

  // Draw the bands

  for (let i = 0; i < bands.length; i++) {

    fill(bands[i]);

    rect(x + 20 + i * 30, y, 20, h);

  }

}

​

function findClosestStandardResistor(inputOhms) {

  const e12 = [1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2];

​

  let standardValues = [];

  for (let factor = 0.1; factor <= 1000000; factor *= 10) {

    e12.forEach(value => {

      standardValues.push(value * factor);

    });

  }

​

  let closest = standardValues[0];

  let minDiff = Math.abs(inputOhms - closest);

​

  for (let i = 1; i < standardValues.length; i++) {

    let diff = Math.abs(inputOhms - standardValues[i]);

    if (diff < minDiff) {

      minDiff = diff;

      closest = standardValues[i];

    }

  }

​

  return closest;

}

​