Online Resistor Calculator Cloud App Free Software

Abhishek Ghosh

By Abhishek Ghosh July 20, 2015 8:02 pm Updated on July 20, 2015

Online Resistor Calculator Cloud App Free Software

Here is an Online Resistor Calculator Cloud App Free Software to Calculate Resistance of the 4 Band Color Coded Registers. It Can Run on OpenStack Based CDN, OpenShift PaaS, Anywhere and on localhost. We found the Javascript on a website with no proper licensing.

This app is required to calculate the resistance of the registers used in electronics work without a multimeter. It is tough work to calculate using the reference table :

Color	Digit value	Multiplier	Multiplied Out	Tolerance
Black	0	10⁰	1
Brown	1	10¹	10
Red	2	10²	100
Orange	3	10³	1,000
Yellow	4	10⁴	10000
Green	5	10⁵	100,000
Blue	6	10⁶	1,000,000
Violet	7	10⁷	10,000,000
Gray	8	10⁸	100,000,000
White	9	10⁹	1,000,000,000
Gold				±5%
Silver				±10%

We only released it for educational purpose. You can download and use it with GNU GPL 3.0 License.

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Online Resistor Calculator Cloud App Free Software

You can see the demo of Online Resistor Calculator running on HP Cloud CDN. Obviously we have a GitHub Repo of this web application. Usage is very easy :

Explaining the Online Resistor Calculator Cloud App

The main Javascript is this :

<script language="JavaScript">
function calcResistance(input) {
    msv = document.colorSelect.band1.value;
    lsv = document.colorSelect.band2.value;
    mult = document.colorSelect.band3.value;
    tol = document.colorSelect.band4.value;
    var bgColors = new Array("black", "#583030", "red", "orange", "yellow", "green", "blue", "purple", "gray", "white", "gold", "silver");
    var fgColors = new Array("white", "white", "white", "black", "black", "white", "white", "white", "black", "black", "black", "black");
    resistText = msv + lsv;
    for (var i=0; i<mult; i++) {
        resistText += "0";
    }
    resistText = addCommas(resistText); // Insert commas
    resistText += " \u2126 \u00B1"; // Add ohm, space, plus/minus sign
    if (tol == "10")
        resistText += "5%";
    else if (tol == "11")
        resistText += "10%";
    
    document.colorSelect.band1.style.background = bgColors[parseInt(msv)];
    document.colorSelect.band1.style.color = fgColors[parseInt(msv)];
    document.colorSelect.band2.style.background = bgColors[parseInt(lsv)];
    document.colorSelect.band2.style.color = fgColors[parseInt(lsv)];
    document.colorSelect.band3.style.background = bgColors[parseInt(mult)];
    document.colorSelect.band3.style.color = fgColors[parseInt(mult)];
    document.colorSelect.band4.style.background = bgColors[parseInt(tol)];
    document.colorSelect.band4.style.color = fgColors[parseInt(tol)];
    document.getElementById("resistorValue").innerHTML=resistText;
}

function addCommas(x) {
    return x.replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}
</script>

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function calcResistance(input) {

msv = document.colorSelect.band1.value;

lsv = document.colorSelect.band2.value;

mult = document.colorSelect.band3.value;

tol = document.colorSelect.band4.value;

var bgColors = new Array("black", "#583030", "red", "orange", "yellow", "green", "blue", "purple", "gray", "white", "gold", "silver");

var fgColors = new Array("white", "white", "white", "black", "black", "white", "white", "white", "black", "black", "black", "black");

resistText = msv + lsv;

for (var i=0; i<mult; i++) {

resistText += "0";

}

resistText = addCommas(resistText); // Insert commas

resistText += " \u2126 \u00B1"; // Add ohm, space, plus/minus sign

if (tol == "10")

resistText += "5%";

else if (tol == "11")

resistText += "10%";

document.colorSelect.band1.style.background = bgColors[parseInt(msv)];

document.colorSelect.band1.style.color = fgColors[parseInt(msv)];

document.colorSelect.band2.style.background = bgColors[parseInt(lsv)];

document.colorSelect.band2.style.color = fgColors[parseInt(lsv)];

document.colorSelect.band3.style.background = bgColors[parseInt(mult)];

document.colorSelect.band3.style.color = fgColors[parseInt(mult)];

document.colorSelect.band4.style.background = bgColors[parseInt(tol)];

document.colorSelect.band4.style.color = fgColors[parseInt(tol)];

document.getElementById("resistorValue").innerHTML=resistText;

}

function addCommas(x) {

return x.replace(/\B(?=(\d{3})+(?!\d))/g, ",");

}

</script>

This must be rendered with this HTML code :

<table>
<tr align="center"><td>Band 1</td><td>Band 2</td><td>Band 3</td><td></td><td>Band 4</td></tr>
<tr align="center"><td>Value 1 (MSV)</td><td>Value 2</td><td>Weight</td><td></td><td>Tolerance</td></tr>
<tr>
<form name="colorSelect" method="" action="">
<td><select name="band1" value="1" onChange="calcResistance(this)" style="width: 150px; color: white; background: #583030;">
<option value="0" style="color: white; background: black;">Black (0)</option>
<option value="1" style="color: white; background: #583030;" selected>Brown (1)</option>
<option value="2" style="color: white; background: red;">Red (2)</option>
<option value="3" style="color: black; background: orange;">Orange (3)</option>
<option value="4" style="color: black; background: yellow;">Yellow (4)</option>
<option value="5" style="color: white; background: green;">Green (5)</option>
<option value="6" style="color: white; background: blue;">Blue (6)</option>
<option value="7" style="color: white; background: purple;">Violet (7)</option>
<option value="8" style="color: white; background: gray;">Gray (8)</option>
<option value="9" style="color: black; background: white;">White (9)</option>
</select></td>
<td><select name="band2" value="0" onChange="calcResistance(this)" style="width: 150px; color: white; background: black;">
<option value="0" style="color: white; background: black;" selected>Black (0)</option>
<option value="1" style="color: white; background: #583030;">Brown (1)</option>
<option value="2" style="color: white; background: red;">Red (2)</option>
<option value="3" style="color: black; background: orange;">Orange (3)</option>
<option value="4" style="color: black; background: yellow;">Yellow (4)</option>
<option value="5" style="color: white; background: green;">Green (5)</option>
<option value="6" style="color: white; background: blue;">Blue (6)</option>
<option value="7" style="color: white; background: purple;">Violet (7)</option>
<option value="8" style="color: white; background: gray;">Gray (8)</option>
<option value="9" style="color: black; background: white;">White (9)</option>
</select></td>
<td><select name="band3" value="2" onChange="calcResistance(this)" style="width: 150px; color: white; background: red;">
<option value="0" style="color: white; background: black;" selected>Black (1)</option>
<option value="1" style="color: white; background: #583030;">Brown (10)</option>
<option value="2" style="color: white; background: red;" selected>Red (100)</option>
<option value="3" style="color: black; background: orange;">Orange (1k)</option>
<option value="4" style="color: black; background: yellow;">Yellow (10k)</option>
<option value="5" style="color: white; background: green;">Green (100k)</option>
<option value="6" style="color: white; background: blue;">Blue (1M)</option>
<option value="7" style="color: white; background: purple;">Violet (10M)</option>
<option value="8" style="color: white; background: gray;">Gray (100M)</option>
<option value="9" style="color: black; background: white;">White (1G)</option>
</select></td>
<td>&nbsp;&nbsp;&nbsp;</td>
<td><select name="band4" value="0" onChange="calcResistance(this)" style="width: 150px; color: black; background: gold; size:5;">
<option value="10" style="color: black; background: gold;">Gold (&plusmn; 5%)</option>
<option value="11" style="color: black; background: silver;">Silver (&plusmn; 10%)</option>
</select></td></tr>
<tr><font size="24"><center><td colspan="2" align="right"><h4>Resistance:&nbsp;&nbsp;</h4></td><td colspan="3" align="left"><h4><text id="resistorValue">1,000 &ohm; &plusmn;5%</text></h4></td></center></font></tr>
</form>
</table>

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<table>

<tr align="center"><td>Value 1 (MSV)</td><td>Value 2</td><td>Weight</td><td></td><td>Tolerance</td></tr>

<tr>

<option value="0" style="color: white; background: black;">Black (0)</option>

<option value="1" style="color: white; background: #583030;" selected>Brown (1)</option>

<option value="3" style="color: black; background: orange;">Orange (3)</option>

<option value="4" style="color: black; background: yellow;">Yellow (4)</option>

<option value="5" style="color: white; background: green;">Green (5)</option>

<option value="7" style="color: white; background: purple;">Violet (7)</option>

<option value="9" style="color: black; background: white;">White (9)</option>

</select></td>

<option value="0" style="color: white; background: black;" selected>Black (0)</option>

<option value="1" style="color: white; background: #583030;">Brown (1)</option>

<option value="3" style="color: black; background: orange;">Orange (3)</option>

<option value="4" style="color: black; background: yellow;">Yellow (4)</option>

<option value="5" style="color: white; background: green;">Green (5)</option>

<option value="7" style="color: white; background: purple;">Violet (7)</option>

<option value="9" style="color: black; background: white;">White (9)</option>

</select></td>

<option value="0" style="color: white; background: black;" selected>Black (1)</option>

<option value="1" style="color: white; background: #583030;">Brown (10)</option>

<option value="3" style="color: black; background: orange;">Orange (1k)</option>

<option value="4" style="color: black; background: yellow;">Yellow (10k)</option>

<option value="5" style="color: white; background: green;">Green (100k)</option>

<option value="7" style="color: white; background: purple;">Violet (10M)</option>

<option value="9" style="color: black; background: white;">White (1G)</option>

</select></td>

<option value="11" style="color: black; background: silver;">Silver (± 10%)</option>

</select></td></tr>

<tr><font size="24"><center><td colspan="2" align="right"><h4>Resistance:  </h4></td><td colspan="3" align="left"><h4><text id="resistorValue">1,000 &ohm; ±5%</text></h4></td></center></font></tr>

</form>

</table>

You can play here on CodePen.

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