Difference between revisions of "CalcHowTo"

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</pre>
 
</pre>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML><HEAD><TITLE>Current Limiting Resistor Calculator</TITLE>
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 +
<SCRIPT language=JavaScript>
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 +
function Compute1(form) {
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with(Math) {
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var Precision= 0;
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var Vin= Number(form.Vin.value);
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var Vled= Number(form.Vled.value);
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var Iled= Number(form.Iled.value);
 +
 +
Rled= (Vin-Vled)/(Iled/1000);
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Wresistor= (Vin-Vled)*(Iled/1000);
 +
 +
if(Rled<0) {
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alert("the numbers you entered don't make sense!!!");
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}
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form.Rled.value= Rled.toFixed(Precision);
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Precision= 3;
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form.Wresistor.value= Wresistor.toFixed(Precision);
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}
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}
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 +
</SCRIPT>
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 +
<META name=GENERATOR content="MSHTML 8.00.6001.19154"></HEAD>
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 +
      <FORM method=post name=ParamForm action="">
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      <TABLE border=1>
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        <TBODY>
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<TR>
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          <TD colSpan=2>
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          <P align=center><FONT face=Arial><B>LED Current Limiting Resistor Calc</B></FONT></P></TD></TR>
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        <TR>
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          <TD><FONT size=3 face=Arial>Voltage Input</FONT></TD>
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          <TD><FONT face=Arial><INPUT value=5 size=17 name=Vin> (V)</FONT></TD></TR>
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        <TR>
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          <TD><FONT face=Arial>LED Voltage</FONT></TD>
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          <TD><FONT face=Arial><INPUT value=2.1 size=17 name=Vled> (V)</FONT></TD></TR>
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        <TR>
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          <TD><FONT face=Arial>LED Current</FONT></TD>
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          <TD><FONT face=Arial><INPUT value=20 size=17 name=Iled> (mA)</FONT></TD></TR>
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        <TR>
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          <TD colSpan=2>
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          <P align=center><FONT face=Arial><B>Results</B></FONT></P></TD></TR>
 +
        <TR>
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          <TD><FONT face=Arial>Current Limiting Resistor<BR><INPUT size=17 name=Rled>(Ohms)<BR><INPUT onclick=Compute1(document.ParamForm) value="Submit" type=button></FONT></TD>
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          <TD><FONT face=Arial>Resistor Power rating<BR><INPUT size=17 name=Wresistor>(Watts)<BR></FONT></TD>
 +
 +
</HTML>

Revision as of 15:48, 15 December 2011

Intro

As an electrial engineer I spent a lot of time using and creating excel based calculators. The problem I have is when I or other people make minor changes we rarely ever syncronize our updatse. Eventually we just redesign the calculators from scratch. To try and reduce time I wanted to create them in javascript on a webpage. That way I know I can access it anywhere and update it on any pc. 

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD><TITLE>Current Limiting Resistor Calculator</TITLE>

<SCRIPT language=JavaScript>

function Compute1(form) {
	with(Math) {
		var Precision= 0;
		var Vin= Number(form.Vin.value);
		var Vled= Number(form.Vled.value);
		var Iled= Number(form.Iled.value);
				
		Rled= (Vin-Vled)/(Iled/1000);
		Wresistor= (Vin-Vled)*(Iled/1000);
		
		if(Rled<0) {
			alert("the numbers you entered don't make sense!!!");
		}
		
		form.Rled.value= Rled.toFixed(Precision);
		Precision= 3;
		form.Wresistor.value= Wresistor.toFixed(Precision);
	}
}

</SCRIPT>

<META name=GENERATOR content="MSHTML 8.00.6001.19154"></HEAD>

      <FORM method=post name=ParamForm action="">
      <TABLE border=1>
        <TBODY>
		<TR>
           <TD colSpan=2>
           <P align=center><FONT face=Arial><B>LED Current Limiting Resistor Calc</B></FONT></P></TD></TR>
        <TR>
          <TD><FONT size=3 face=Arial>Voltage Input</FONT></TD>
          <TD><FONT face=Arial><INPUT value=5 size=17 name=Vin> (V)</FONT></TD></TR>
        <TR>
          <TD><FONT face=Arial>LED Voltage</FONT></TD>
          <TD><FONT face=Arial><INPUT value=2.1 size=17 name=Vled> (V)</FONT></TD></TR>
        <TR>
          <TD><FONT face=Arial>LED Current</FONT></TD>
          <TD><FONT face=Arial><INPUT value=20 size=17 name=Iled> (mA)</FONT></TD></TR>
        <TR>
          <TD colSpan=2>
          <P align=center><FONT face=Arial><B>Results</B></FONT></P></TD></TR>
        <TR>
          <TD><FONT face=Arial>Current Limiting Resistor<BR><INPUT size=17 name=Rled>(Ohms)<BR><INPUT onclick=Compute1(document.ParamForm) value="Submit" type=button></FONT></TD>
          <TD><FONT face=Arial>Resistor Power rating<BR><INPUT size=17 name=Wresistor>(Watts)<BR></FONT></TD>

</HTML>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE>Current Limiting Resistor Calculator</TITLE>

<SCRIPT language=JavaScript>

function Compute1(form) { with(Math) { var Precision= 0; var Vin= Number(form.Vin.value); var Vled= Number(form.Vled.value); var Iled= Number(form.Iled.value);

Rled= (Vin-Vled)/(Iled/1000); Wresistor= (Vin-Vled)*(Iled/1000);

if(Rled<0) { alert("the numbers you entered don't make sense!!!"); }

form.Rled.value= Rled.toFixed(Precision); Precision= 3; form.Wresistor.value= Wresistor.toFixed(Precision); } }

</SCRIPT>

<META name=GENERATOR content="MSHTML 8.00.6001.19154"></HEAD> 

     <FORM method=post name=ParamForm action="">
<TBODY> </HTML>

LED Current Limiting Resistor Calc

Voltage Input <INPUT value=5 size=17 name=Vin> (V)
LED Voltage <INPUT value=2.1 size=17 name=Vled> (V)
LED Current <INPUT value=20 size=17 name=Iled> (mA)

Results

Current Limiting Resistor
<INPUT size=17 name=Rled>(Ohms)
<INPUT onclick=Compute1(document.ParamForm) value="Submit" type=button>		 Resistor Power rating
<INPUT size=17 name=Wresistor>(Watts)
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