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interactive_impedance.html
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interactive_impedance.html
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<!DOCTYPE html>
<!--
Interactive impedance simulation, copyright 2021, James Cumby
Adapted from examples found at https://physics.weber.edu/schroeder/html5/default.html
Previous license:
Chaotic pendulum simulation, copyright 2013-2014, Daniel V. Schroeder
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated data and documentation (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
Except as contained in this notice, the name of the author shall not be used in
advertising or otherwise to promote the sale, use or other dealings in this
Software without prior written authorization.
-->
<head>
<meta charset="utf-8">
<title>Impedance Spectroscopy</title>
<style>
input[type="range"] {
width: 140px;
padding: 0px; /* remove extra space in IE */
-webkit-user-select: none;
-moz-user-select: -moz-none;
-ms-user-select: none;
user-select: none;
}
input[type="range"]::-ms-tooltip {
display: none; /* hide automatic readout in IE */
}
input[type="range"]::-ms-track {
color: transparent; /* hide tick marks in IE */
}
</style>
</head>
<body style="background-color:#c0c0c0; font:15px sans-serif;">
<div style="width:810px; margin-left:auto; margin-right:auto;">
<h1 style="font-size:24px; text-align:center;">Interactive Impedance Spectroscopy</h1>
<div style="width:200px; float:left; text-align:center;">
<input id="startButton" type="button" value="Start" onclick="startStop();" style="width:90px; font-size:16px; text-align:center;">
<input id="resetButton" type="button" value="Reset" onclick="init();" style="width:90px; font-size:16px; text-align:center;">
<span style="padding:0 30px 0 30px;">
Frequency (Hz) = <span id="freqReadout">0.50</span>
<input id="freqSlider" type="range" min="0.1" max="2.0" step="0.01" value="0.5" oninput="sliderChange()" onchange="sliderChange()">
</span>
<span style="padding:0 30px 0 30px;">
Resistance (Ω) = <span id="resistanceReadout">5.0</span>
<input id="resistanceSlider" type="range" min="1" max="20" step="0.1" value="5" oninput="sliderChange()" onchange="sliderChange()">
</span>
<span style="padding:0 30px 0 30px;">
Capacitance (F) = <span id="capacitanceReadout">0.100</span>
<input id="capacitanceSlider" type="range" min="0.001" max="0.3" step="0.001" value="0.1" oninput="sliderChange()" onchange="sliderChange()">
</span>
<span style="text-align:left;">
<div>
<input type="radio" id="radioR" value="R" name="radiogroup" checked onclick="init()">
<label for="radioR">Resistor</label>
</div>
<div>
<input type="radio" id="radioC" value="C" name="radiogroup" onclick="init()">
<label for="radioC">Capacitor</label>
</div>
<div>
<input type="radio" id="radioRC" value="RC" name="radiogroup" onclick="init()">
<label for="radioRC">Parallel RC</label>
</div>
</span>
</div>
<canvas id="imageCanvas" width="600" height="200" style="float:right; border:1px solid black;"></canvas>
<canvas id="bodeCanvas" width="250" height="300" style="margin-left:6px; border:1px solid black;"></canvas>
<canvas id="freqCanvas" width="250" height="300" style="margin-left:6px; border:1px solid black;"></canvas>
<canvas id="nyquistCanvas" width="250" height="300" style="margin-left:6px; border:1px solid black;"></canvas>
<div style="width:250px; margin-left: 7px; float:left; text-align:center;">
<input type="button" value="Clear Bode" onclick="drawBodePlot()" style="width:200px; font-size:16px;">
</div>
<div style="width:250px; margin-left: 7px; float:left; text-align:center;">
<input type="button" value="Clear Signals" onclick="clearFreqPlot()" style="width:200px; font-size:16px;">
</div>
<div style="width:250px; margin-left: 7px; float:left; text-align:center;">
<input type="button" value="Clear Nyquist" onclick="drawNyquistPlot()" style="width:200px; font-size:16px;">
</div>
</div>
<script type="text/javascript" src="./math.js"></script>
<script>
// Global variables:
var imageCanvas = document.getElementById("imageCanvas");
var imageContext = imageCanvas.getContext("2d");
var bodeCanvas = document.getElementById("bodeCanvas");
var bodeContext = bodeCanvas.getContext("2d");
var freqCanvas = document.getElementById("freqCanvas");
var freqContext = freqCanvas.getContext("2d");
var nyquistCanvas = document.getElementById("nyquistCanvas");
var nyquistContext = nyquistCanvas.getContext("2d");
var startButton = document.getElementById("startButton");
var freqSlider = document.getElementById("freqSlider");
var freqReadout = document.getElementById("freqReadout");
var resistanceSlider = document.getElementById("resistanceSlider");
var resistanceReadout = document.getElementById("resistanceReadout");
var capacitanceSlider = document.getElementById("capacitanceSlider");
var capacitanceReadout = document.getElementById("capacitanceReadout");
var buttonR = document.getElementById("radioR");
var buttonC = document.getElementById("radioC");
var buttonRC = document.getElementById("radioRC");
var inputList = new Array(freqCanvas.height + 10 );
var outputList = new Array(freqCanvas.height + 10 );
var phase;
var impedance = math.complex(0,0)
var pistonIn;
var pistonOut;
var pistonMin;
var pistonMax;
var forceIn;
var forceOut;
var shiftScale;
var capacitorPos;
var starttime;
var runtime = 0;
var animReference;
var input = 1; // max input force
var outputScale = 30;
var running = false;
var freqXScale, freqYScale;
var bodeXScale, bodeYScale;
var nyquistXScale, nyquistYScale;
var ratio; // scaling ratio for high-resolution (retina) displays
window.onload = init; // initialize when ready!
// Initialize the graphics and reset variables to initial values:
function init() {
inputList = new Array(freqCanvas.height + 10 );
outputList = new Array(freqCanvas.height + 10 );
phase;
impedance = math.complex(0,0)
forceIn = 0;
forceOut = 0;
shiftScale = 3;
capacitorPos = 0;
runtime = 0;
freqXScale = freqCanvas.width/2; // pixels per unit
freqYScale = freqCanvas.height / 7; // pixels per unit
bodeXScale = bodeCanvas.width / 5; // pixels per unit
bodeYScale = bodeCanvas.height / 7; // pixels per unit
nyquistXScale = nyquistCanvas.width / 5; // pixels per unit
nyquistYScale = nyquistCanvas.height / 7; // pixels per unit
calculateImpedance();
var omega = 2*Math.PI*freqSlider.value;
pistonIn = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
pistonOut = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
capacitorPos = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
sliderChange();
if (buttonR.checked == true) {
//pistonIn = 0;
//pistonOut = 0;
//drawResistor();
resistanceSlider.disabled = false;
capacitanceSlider.disabled = true;
capacitanceReadout.innerHTML = 'NA';
} else if (buttonC.checked == true) {
// Set initial positions at t=0
//capacitorPos = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
//pistonIn = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
//pistonOut = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
//capacitorPos = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega);
//drawCapacitor();
resistanceSlider.disabled = true;
resistanceReadout.innerHTML = 'NA';
capacitanceSlider.disabled = false;
} else if (buttonRC.checked == true) {
//drawRC();
resistanceSlider.disabled = false;
capacitanceSlider.disabled = false;
}
drawRC();
drawFreqPlot();
drawBodePlot();
drawNyquistPlot();
if (running == true) {
startStop();
}
startButton.value = "Start";
}
function calculateImpedance() {
// Determine overall impedance from sliders
var omega = 2*Math.PI*freqSlider.value;
var complexR = math.complex(resistanceSlider.value,0);
var complexC = math.complex(0,1.0/(omega*capacitanceSlider.value));
// in parallel, Z_tot = Z_1Z_2 / (Z_1 + Z_2)
var complexRC = math.divide(math.multiply(complexR, complexC), math.add(complexR, complexC));
if (buttonR.checked == true) {
impedance = complexR;
} else if (buttonC.checked == true) {
impedance = complexC;
} else if (buttonRC.checked == true) {
impedance = complexRC;
}
}
// Update with time
function run(timestamp) {
//if browser doesn't support requestAnimationFrame, generate our own timestamp using Date:
var timestamp = timestamp || new Date().getTime()
runtime = timestamp - starttime
// Generate input cosine (used instead of sin to make animation start in the middle)
var omega = 2*Math.PI*freqSlider.value
forceIn = input * Math.cos( runtime/1000 * omega );
//var forceIn = math.multiply(input, math.exp( math.multiply(math.complex(0,1), omega, runtime/1000) ));
// Calculate impedance
calculateImpedance();
// Calculate output current
//var forceOut = math.divide(forceIn, impedance);
forceOut = input * Math.cos( runtime/1000 * omega + impedance.toPolar().phi) / impedance.toPolar().r
inputList.unshift(forceIn);
if (inputList.length > (freqCanvas.height + 10) ) {
inputList.pop()
}
outputList.unshift(forceOut);
if (outputList.length > (freqCanvas.height + 10) ) {
outputList.pop()
}
// Update global position variables if needed, and update plots
capacitorPos = Math.sin(impedance.toPolar().phi) * outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega)
pistonIn = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega)
pistonOut = outputScale*input * Math.sin( runtime/1000 * omega + impedance.toPolar().phi) / (impedance.toPolar().r*omega)
if (buttonR.checked == true) {
//drawResistor();
} else if (buttonC.checked == true) {
//drawCapacitor();
} else if (buttonRC.checked == true) {
//drawRC();
}
drawRC();
freqPoints();
bodePoints();
nyquistPoints();
animReference = requestAnimationFrame(function(timestamp){
run(timestamp)
});
}
// Function to implement start/stop button click:
function startStop() {
running = !running;
if (running) {
requestAnimationFrame(function(timestamp){
starttime = timestamp - runtime || new Date().getTime() - runtime; //if browser doesn't support requestAnimationFrame, generate our own timestamp using Date
run(timestamp);
});
startButton.value = "Pause";
} else {
cancelAnimationFrame(animReference);
startButton.value = "Resume";
}
}
// Function to update drive amplitude readout:
function sliderChange() {
freqReadout.innerHTML = Number(freqSlider.value).toFixed(2);
resistanceReadout.innerHTML = Number(resistanceSlider.value).toFixed(1);
capacitanceReadout.innerHTML = Number(capacitanceSlider.value).toFixed(3);
if (buttonR.checked == true) {
//drawResistor();
} else if (buttonC.checked == true) {
//drawCapacitor();
} else if (buttonRC.checked == true) {
//drawRC();
}
drawRC();
}
function drawPistons() {
// Draw pistons
imageContext.beginPath();
imageContext.moveTo(shiftScale*pistonIn+0.2*imageCanvas.width, imageCanvas.height*0.1);
imageContext.lineTo(shiftScale*pistonIn+0.2*imageCanvas.width, imageCanvas.height*0.9);
imageContext.moveTo(shiftScale*pistonOut + 0.8*imageCanvas.width, imageCanvas.height*0.1);
imageContext.lineTo(shiftScale*pistonOut + 0.8*imageCanvas.width,imageCanvas.height*0.9);
imageContext.strokeStyle = "black";
imageContext.lineWidth = 5;
imageContext.stroke();
// Input force
imageContext.beginPath();
imageContext.moveTo(shiftScale*pistonIn+0.2*imageCanvas.width - 100*inputList[0], imageCanvas.height*0.5);
imageContext.lineTo(shiftScale*pistonIn+0.2*imageCanvas.width, imageCanvas.height*0.5);
imageContext.lineTo(shiftScale*pistonIn+0.2*imageCanvas.width - imageCanvas.width*0.02*Math.sign(inputList[0]), imageCanvas.height*0.53);
imageContext.moveTo(shiftScale*pistonIn+0.2*imageCanvas.width, imageCanvas.height*0.5);
imageContext.lineTo(shiftScale*pistonIn+0.2*imageCanvas.width - imageCanvas.width*0.02*Math.sign(inputList[0]), imageCanvas.height*0.47);
imageContext.strokeStyle = "rgba(128,0,255,0.95)";
imageContext.lineWidth = 5;
imageContext.stroke();
// Output force
imageContext.beginPath();
imageContext.moveTo(shiftScale*pistonOut+0.8*imageCanvas.width, imageCanvas.height*0.5);
imageContext.lineTo(shiftScale*pistonOut+0.8*imageCanvas.width+100*outputList[0], imageCanvas.height*0.5);
imageContext.lineTo(shiftScale*pistonOut+0.8*imageCanvas.width+100*outputList[0] - imageCanvas.width*0.02*Math.sign(outputList[0]), imageCanvas.height*0.53);
imageContext.moveTo(shiftScale*pistonOut+0.8*imageCanvas.width+100*outputList[0], imageCanvas.height*0.5);
imageContext.lineTo(shiftScale*pistonOut+0.8*imageCanvas.width+100*outputList[0] - imageCanvas.width*0.02*Math.sign(outputList[0]), imageCanvas.height*0.47);
imageContext.strokeStyle = "rgba(255,0,128,0.95)";
imageContext.lineWidth = 5;
imageContext.stroke();
}
function drawRC() {
// Draw a mixture of resitor/capacitor components
imageContext.fillStyle="white";
imageContext.fillRect(0, 0, imageCanvas.width, imageCanvas.height);
imageContext.fillStyle="lightblue";
// Draw fluid to fit pipework shape
imageContext.beginPath();
imageContext.moveTo(shiftScale*pistonIn+0.2*imageCanvas.width, imageCanvas.height*0.1);
imageContext.lineTo(shiftScale*pistonOut + 0.8*imageCanvas.width, imageCanvas.height*0.1);
imageContext.lineTo(shiftScale*pistonOut + 0.8*imageCanvas.width,imageCanvas.height*0.9);
imageContext.lineTo(shiftScale*pistonIn+0.2*imageCanvas.width, imageCanvas.height*0.9);
imageContext.closePath();
imageContext.fill();
drawPistons();
// Draw pipe outline to match capacitor shape
imageContext.strokeStyle = "black";
imageContext.lineWidth = 5;
imageContext.beginPath();
imageContext.moveTo(imageCanvas.width*0.00, imageCanvas.height*0.1);
imageContext.lineTo(imageCanvas.width*1, imageCanvas.height*0.1);
imageContext.moveTo(imageCanvas.width*0.00,imageCanvas.height*0.9);
imageContext.lineTo(imageCanvas.width*1, imageCanvas.height*0.9);
imageContext.stroke();
if (capacitanceSlider.disabled == false) {
// 'springs'
imageContext.beginPath();
imageContext.moveTo(imageCanvas.width*0.5, imageCanvas.height*0.1);
imageContext.lineTo(imageCanvas.width*0.5 + shiftScale*capacitorPos, imageCanvas.height*0.1);
imageContext.moveTo(imageCanvas.width*0.5, imageCanvas.height*0.9);
imageContext.lineTo(imageCanvas.width*0.5 + shiftScale*capacitorPos, imageCanvas.height*0.9);
imageContext.strokeStyle = "gray";
imageContext.lineWidth = parseInt(30-capacitanceSlider.value*100);
imageContext.stroke();
// 'spring' attachment
imageContext.beginPath();
imageContext.arc(imageCanvas.width*0.5, imageCanvas.height*0.1, 6, 0, 2*Math.PI);
imageContext.fillStyle="gray";
imageContext.fill();
imageContext.strokeStyle = "black";
imageContext.lineWidth = 3;
imageContext.stroke();
imageContext.beginPath();
imageContext.arc(imageCanvas.width*0.5, imageCanvas.height*0.9, 6, 0, 2*Math.PI);
imageContext.fillStyle="gray";
imageContext.fill();
imageContext.strokeStyle = "black";
imageContext.stroke();
}
// Add barrier
imageContext.lineWidth = 16;
// remove hole if pure capacitor
if (resistanceSlider.disabled == false) {
var holeOffset = (resistanceSlider.value/resistanceSlider.max)*imageCanvas.height*0.35;}
else {
var holeOffset = imageCanvas.height*0.5
}
imageContext.beginPath();
imageContext.moveTo( imageCanvas.width*0.5 + shiftScale*capacitorPos , imageCanvas.height*0.1);
imageContext.lineTo( imageCanvas.width*0.5 + shiftScale*capacitorPos , imageCanvas.height*0.1+holeOffset);
imageContext.moveTo( imageCanvas.width*0.5 + shiftScale*capacitorPos , imageCanvas.height*0.9);
imageContext.lineTo( imageCanvas.width*0.5 + shiftScale*capacitorPos , imageCanvas.height*0.9-holeOffset);
imageContext.stroke();
}
// Initialize the plot canvas:
function drawFreqPlot() {
// First erase the plot with white:
freqContext.fillStyle = "white";
freqContext.fillRect(0, 0, freqCanvas.width, freqCanvas.height);
// Next draw gridlines:
freqContext.strokeStyle = "lightgray";
freqContext.lineWidth = 1;
for (var x=0; x<=freqCanvas.width; x+=freqXScale/2) {
freqContext.beginPath();
freqContext.moveTo(x, 0);
freqContext.lineTo(x, freqCanvas.height);
freqContext.stroke();
}
//for (var y=(freqCanvas.height/2 - freqYScale*3 + freqYScale*(runtime%1000)/1000); y<freqCanvas.height; y+=freqYScale) {
// freqContext.beginPath();
// freqContext.moveTo(0, y);
// freqContext.lineTo(freqCanvas.width, y);
// freqContext.stroke();
//}
// Finally draw labels:
freqContext.font = "12px sans-serif";
freqContext.fillStyle = "black";
freqContext.textAlign = "center";
freqContext.textBaseline = "bottom";
freqContext.fillText("Force", freqCanvas.width/2, freqCanvas.height-2);
freqContext.textAlign = "left";
freqContext.textBaseline = "top";
freqContext.fillText("Time", 4, 3);
}
function clearFreqPlot() {
// Reset arrays except for most recent entry
var oldIn = inputList[0];
var oldOut = outputList[0];
inputList = new Array(freqCanvas.height + 10 );
outputList = new Array(freqCanvas.height + 10 );
inputList[0] = oldIn;
outputList[0] = oldOut;
drawFreqPlot();
}
function freqPoints() {
drawFreqPlot();
freqContext.fillStyle = "rgba(128,0,255,0.95)";
inputList.forEach(function (item, index) {
freqContext.fillRect(freqCanvas.width/2 + freqXScale*item, index, 5, 5);
});
freqContext.fillStyle = "rgba(255,0,128,0.95)";
outputList.forEach(function (item, index) {
freqContext.fillRect(freqCanvas.width/2 + freqXScale*item, index, 5, 5);
});
}
// Set up the Bode plot initially
function drawBodePlot() {
// First erase the plot with white:
bodeContext.fillStyle = "white";
bodeContext.fillRect(0, 0, bodeCanvas.width, bodeCanvas.height);
// Next draw gridlines:
bodeContext.strokeStyle = "lightgray";
bodeContext.lineWidth = 1;
for (var x=0; x<=bodeCanvas.width; x+=bodeXScale) {
bodeContext.beginPath();
bodeContext.moveTo(x, 0);
bodeContext.lineTo(x, bodeCanvas.height);
bodeContext.stroke();
}
for (var y=0; y<bodeCanvas.height; y+=bodeYScale) {
bodeContext.beginPath();
bodeContext.moveTo(0, y);
bodeContext.lineTo(bodeCanvas.width, y);
bodeContext.stroke();
}
// Finally draw labels:
// x-label
bodeContext.font = "12px sans-serif";
bodeContext.fillStyle = "black";
bodeContext.textAlign = "center";
bodeContext.textBaseline = "bottom";
bodeContext.fillText("Frequency", bodeCanvas.width/2, bodeCanvas.height-2);
// 1st y-label
bodeContext.textBaseline = "top";
bodeContext.textAlign = "left";
bodeContext.fillText('|Z|', 4, 4);
// 2nd y-label
bodeContext.textAlign = "right";
bodeContext.fillText('Phase', bodeCanvas.width-4, 4);
bodeContext.textAlign = "left";
}
// Add points to Bode plot
function bodePoints() {
bodeContext.fillStyle = "rgba(128,0,255,0.95)";
bodeContext.fillRect(freqSlider.value/freqSlider.max*bodeCanvas.width*0.9 + bodeCanvas.width*0.05, bodeCanvas.height - (0.9*bodeCanvas.height * impedance.toPolar().r / (resistanceSlider.max)) + 0.05*bodeCanvas.height, 5, 5);
bodeContext.fillStyle = "rgba(255,0,128,0.95)";
bodeContext.fillRect(freqSlider.value/freqSlider.max*bodeCanvas.width*0.9 + bodeCanvas.width*0.05, bodeCanvas.height - (0.9*bodeCanvas.height * impedance.toPolar().phi*2/math.PI) - 0.05*bodeCanvas.height, 5, 5);
}
// Set up the Nyquist plot initially
function drawNyquistPlot() {
// First erase the plot with white:
nyquistContext.fillStyle = "white";
nyquistContext.fillRect(0, 0, nyquistCanvas.width, nyquistCanvas.height);
// Next draw gridlines:
nyquistContext.strokeStyle = "lightgray";
nyquistContext.lineWidth = 1;
for (var x=0; x<=nyquistCanvas.width; x+=nyquistXScale) {
nyquistContext.beginPath();
nyquistContext.moveTo(x, 0);
nyquistContext.lineTo(x, nyquistCanvas.height);
nyquistContext.stroke();
}
for (var y=0; y<nyquistCanvas.height; y+=nyquistYScale) {
nyquistContext.beginPath();
nyquistContext.moveTo(0, y);
nyquistContext.lineTo(nyquistCanvas.width, y);
nyquistContext.stroke();
}
// Finally draw labels:
// x-label
nyquistContext.font = "12px sans-serif";
nyquistContext.fillStyle = "black";
nyquistContext.textAlign = "center";
nyquistContext.textBaseline = "bottom";
nyquistContext.fillText("Z'", nyquistCanvas.width/2, nyquistCanvas.height-2);
// 1st y-label
nyquistContext.textBaseline = "top";
nyquistContext.textAlign = "left";
nyquistContext.fillText("-Z''", 4, 4);
}
// Add points to Bode plot
function nyquistPoints() {
nyquistContext.fillStyle = "rgba(128,0,255,0.95)";
nyquistContext.fillRect(impedance.re/(resistanceSlider.max)*nyquistCanvas.width*0.9 + nyquistCanvas.width*0.05, nyquistCanvas.height - (0.9*nyquistCanvas.height * impedance.im / (resistanceSlider.max)) - 0.05*nyquistCanvas.height, 5, 5);
}
// Improve accessibility with keyboard shortcuts
document.onkeydown = function(e) {
if(e.keyCode === 32) { // The spacebar
startStop();
}
else if (e.keyCode === 27) {// Esc key
init();
}
else if (e.keyCode === 70) {// f key
document.getElementById('freqSlider').focus();
}
else if (e.keyCode === 82) {//r key
document.getElementById('resistanceSlider').focus();
}
else if (e.keyCode === 67) {// c key
document.getElementById('capacitanceSlider').focus();
}
else if (e.keyCode === 66) {// b key
drawBodePlot();
}
else if (e.keyCode === 78) {//n key
drawNyquistPlot();
}
else if (e.keyCode === 83) {// s key
clearFreqPlot();
}
};
</script>
</body>
</html>