MISC/ResistorDivider.html at master · FireyProtons/MISC · GitHub

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<HTML>
<HEAD>
<TITLE>Bennet's Resistor Ratio Calculator</TITLE>
<META http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<META name="Author" content="Bennet Blake">
<META name="keywords" content="resistor, ratio, calculator, JavaScript">
<META name="GENERATOR" Content="CodeWright 7.0 - It Rocks!">
<link rel="SHORTCUT ICON" href="../SL_grid.ico">
<SCRIPT LANGUAGE="JavaScript">
<!--
  res10per = new Array( 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2 )
  res05per = new Array( 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0,
                        3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1 )
  res01per = new Array( 1.00, 1.02, 1.05, 1.07, 1.10, 1.13, 1.15, 1.18, 1.21, 1.24,
                        1.27, 1.30, 1.33, 1.37, 1.40, 1.43, 1.47, 1.50, 1.54, 1.58,
                        1.62, 1.65, 1.69, 1.74, 1.78, 1.82, 1.87, 1.91, 1.96, 2.00,
                        2.05, 2.10, 2.15, 2.21, 2.26, 2.32, 2.37, 2.43, 2.49, 2.55,
                        2.61, 2.67, 2.74, 2.80, 2.87, 2.94, 3.01, 3.09, 3.16, 3.24,
                        3.32, 3.40, 3.48, 3.57, 3.65, 3.74, 3.83, 3.92, 4.02, 4.12,
                        4.22, 4.32, 4.42, 4.53, 4.64, 4.75, 4.87, 4.99, 5.11, 5.23,
                        5.36, 5.49, 5.62, 5.76, 5.90, 6.04, 6.19, 6.34, 6.49, 6.65,
                        6.81, 6.98, 7.15, 7.32, 7.50, 7.68, 7.87, 8.06, 8.25, 8.45,
                        8.66, 8.87, 9.09, 9.31, 9.53, 9.76 )

  var desired_ratio, test_ratio
  var best_first_res, best_second_res, first_res, second_res, test_error, least_error
  var scale_factor, R1, R2, dec_precision

  // print out the full resistor tables in a second pop up window
  function print_table()
  {
    var ii
    win2 = open("text/html")
    win2.document.open("text/html")
    win2.document.write("<H1>Resistor Table</H1><BR><H3>10% Resistor Values</H3>")
    for( ii = 0; ii< res10per.length; ii++ ) win2.document.write( res10per[ii],", " )
    win2.document.write("<BR><H3>5% Resistor Values</H3>")
    for( ii = 0; ii< res05per.length; ii++ ) win2.document.write( res05per[ii],", " )
    win2.document.write("<BR><H3>1% Resistor Values</H3>")
    for( ii = 0; ii< res01per.length; ii++ ) win2.document.write( res01per[ii],", " )
  }

  //////////////////////////////////////////////////////////////////
  // scale the desired ratio to be 1.0 <= ratio < 10.0
  // scale factor will be what the results need to multiplied by
  // to get back to the origional order of magnitude
  //////////////////////////////////////////////////////////////////
  function scale_ratio()
  {
    dec_precision = 4  // four digits of precision after decimal point
    scale_factor = 1.0
    if( desired_ratio < 1.0 )
    do
    {
      dec_precision += 1    // keep adding precision as we get smaller
      desired_ratio *= 10.0
      scale_factor /= 10.0
    } while( desired_ratio < 1.0 )
    else
    {
      if( desired_ratio >= 10.0 )
      do
      {
        desired_ratio /= 10.0
        scale_factor *= 10.0
      } while( desired_ratio >= 10.0  )
    }
	}

  ///////////////////////////////////
  // calculate the 10% values
  ///////////////////////////////////
  function calc_10_percent()
  {
    var ii, jj

    least_error = 100.0
    for( ii=0; ii<12; ii++ )
    {
      first_res = res10per[ii]
      for( jj=0; jj<12; jj++ )
      {
        second_res = res10per[jj]
        if( first_res < second_res ) first_res *= 10.0
        test_ratio = first_res / second_res
        test_error = ( test_ratio - desired_ratio ) / desired_ratio
        if( Math.abs(test_error) < Math.abs(least_error) )
        {
          least_error = test_error
          if( scale_factor >= 10.0 )
            best_first_res = first_res * scale_factor
          else
            best_first_res = first_res
          if( scale_factor < 1.0 )
            best_second_res = second_res / scale_factor
          else
            best_second_res = second_res
        }
      }
    }

    // now write out the results
	  document.rr_calc.b10_R1.value = best_first_res
    document.rr_calc.b10_R2.value = best_second_res
    document.rr_calc.b10_error.value = (least_error * 100.0).toFixed(2)
    document.rr_calc.b10_ratio.value = (best_first_res / best_second_res).toFixed(dec_precision)

    // now do the error calculations

    // first the 10% high side
    R1 = 1.10 * best_first_res
    R2 = 0.9 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcp10_R1.value = R1.toFixed(2)
    document.rr_calc.wcp10_R2.value = R2.toFixed(2)
    document.rr_calc.wcp10_error.value = test_error.toFixed(1)
    document.rr_calc.wcp10_ratio.value = (R1/R2).toFixed(dec_precision)

    // now the 10% low side
    R1 = 0.9 * best_first_res
    R2 = 1.10 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcn10_R1.value = R1.toFixed(2)
    document.rr_calc.wcn10_R2.value = R2.toFixed(2)
    document.rr_calc.wcn10_error.value = test_error.toFixed(1)
    document.rr_calc.wcn10_ratio.value = (R1/R2).toFixed(dec_precision)

    // then the 5% high side
    R1 = 1.05 * best_first_res
    R2 = 0.95 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcp105_R1.value = R1.toFixed(2)
    document.rr_calc.wcp105_R2.value = R2.toFixed(2)
    document.rr_calc.wcp105_error.value = test_error.toFixed(1)
    document.rr_calc.wcp105_ratio.value = (R1/R2).toFixed(dec_precision)

    // and the 5% low side
    R1 = 0.95 * best_first_res
    R2 = 1.05 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcn105_R1.value = R1.toFixed(2)
    document.rr_calc.wcn105_R2.value = R2.toFixed(2)
    document.rr_calc.wcn105_error.value = test_error.toFixed(1)
    document.rr_calc.wcn105_ratio.value = (R1/R2).toFixed(dec_precision)

  }

  /////////////////////////////////
  // calculate the 5% table
  /////////////////////////////////
  function calc_5_percent()
  {
    var ii, jj

    least_error = 100.0
    for( ii=0; ii<24; ii++ )
    {
      first_res = res05per[ii]
      for( jj=0; jj<24; jj++ )
      {
        second_res = res05per[jj]
        if( first_res < second_res ) first_res *= 10.0
        test_ratio = first_res / second_res
        test_error = ( test_ratio - desired_ratio ) / desired_ratio
        if( Math.abs(test_error) < Math.abs(least_error) )
        {
          least_error = test_error
          if( scale_factor >= 10.0 )
            best_first_res = first_res * scale_factor
          else
            best_first_res = first_res
          if( scale_factor < 1.0 )
            best_second_res = second_res / scale_factor
          else
            best_second_res = second_res
        }
      }
    }

    // now write out the results
	  document.rr_calc.b5_R1.value = best_first_res
    document.rr_calc.b5_R2.value = best_second_res
    document.rr_calc.b5_error.value = (least_error * 100.0).toFixed(2)
    document.rr_calc.b5_ratio.value = (best_first_res / best_second_res).toFixed(dec_precision)

    // now do the error calculations

    // first the 5% high side
    R1 = 1.05 * best_first_res
    R2 = 0.95 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcp5_R1.value = R1.toFixed(2)
    document.rr_calc.wcp5_R2.value = R2.toFixed(2)
    document.rr_calc.wcp5_error.value = test_error.toFixed(2)
    document.rr_calc.wcp5_ratio.value = (R1/R2).toFixed(dec_precision)

    // now the 5% low side
    R1 = 0.95 * best_first_res
    R2 = 1.05 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcn5_R1.value = R1.toFixed(2)
    document.rr_calc.wcn5_R2.value = R2.toFixed(2)
    document.rr_calc.wcn5_error.value = test_error.toFixed(2)
    document.rr_calc.wcn5_ratio.value = (R1/R2).toFixed(dec_precision)

    // then the 3% high side
    R1 = 1.03 * best_first_res
    R2 = 0.97 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcp3_R1.value = R1.toFixed(2)
    document.rr_calc.wcp3_R2.value = R2.toFixed(2)
    document.rr_calc.wcp3_error.value = test_error.toFixed(2)
    document.rr_calc.wcp3_ratio.value = (R1/R2).toFixed(dec_precision)

    // and the 3% low side
    R1 = 0.97 * best_first_res
    R2 = 1.03 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcn3_R1.value = R1.toFixed(2)
    document.rr_calc.wcn3_R2.value = R2.toFixed(2)
    document.rr_calc.wcn3_error.value = test_error.toFixed(2)
    document.rr_calc.wcn3_ratio.value = (R1/R2).toFixed(dec_precision)
  }


  /////////////////////////////////
  // calculate the 1% table
  /////////////////////////////////
  function calc_1_percent()
  {
    var ii, jj

    least_error = 100.0
    for( ii=0; ii<96; ii++ )
    {
      first_res = res01per[ii]
      for( jj=0; jj<96; jj++ )
      {
        second_res = res01per[jj]
        if( first_res < second_res ) first_res *= 10.0
        test_ratio = first_res / second_res
        test_error = ( test_ratio - desired_ratio ) / desired_ratio
        if( Math.abs(test_error) < Math.abs(least_error) )
        {
          least_error = test_error
          if( scale_factor >= 10.0 )
            best_first_res = first_res * scale_factor
          else
            best_first_res = first_res
          if( scale_factor < 1.0 )
            best_second_res = second_res / scale_factor
          else
            best_second_res = second_res
        }
      }
    }

    // now write out the results
	  document.rr_calc.b1_R1.value = best_first_res
    document.rr_calc.b1_R2.value = best_second_res
    document.rr_calc.b1_error.value = (least_error * 100.0).toFixed(4)
    document.rr_calc.b1_ratio.value = (best_first_res / best_second_res).toFixed(dec_precision)

    // now do the error calculations

    // first the 1% high side
    R1 = 1.01 * best_first_res
    R2 = 0.99 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcp1_R1.value = R1.toFixed(3)
    document.rr_calc.wcp1_R2.value = R2.toFixed(3)
    document.rr_calc.wcp1_error.value = test_error.toFixed(3)
    document.rr_calc.wcp1_ratio.value = (R1/R2).toFixed(dec_precision+2)

    // now the 1% low side
    R1 = 0.99 * best_first_res
    R2 = 1.01 * best_second_res
    test_error = ((R1/R2)-(desired_ratio*scale_factor)) / (desired_ratio*scale_factor)
    test_error *= 100

    document.rr_calc.wcn1_R1.value = R1.toFixed(3)
    document.rr_calc.wcn1_R2.value = R2.toFixed(3)
    document.rr_calc.wcn1_error.value = test_error.toFixed(3)
    document.rr_calc.wcn1_ratio.value = (R1/R2).toFixed(dec_precision+2)

  }

  ////////////////////////////////////////////////////////
  // calcualte the whole table based on the input ratio
  ////////////////////////////////////////////////////////
  function calc_table()
  {
    desired_ratio =  parseFloat(document.rr_calc.des_RATIO.value)
    scale_ratio()
    calc_10_percent()
    calc_5_percent()
    calc_1_percent()
    document.rr_calc.des_RATIO.focus()  // put the cursor back in the entry box
  }

// -->
</SCRIPT>
</HEAD>
<BODY background="../links/graph_paper.gif" bgcolor=abbfe0 text=000080 link=0000ff vlink=4040c0>

  <H1>Resistor Ratio Calculator</H1>
  <FORM NAME="rr_calc">
  <TABLE BORDER="1" ALIGN="CENTER" WIDTH="100%">
  <TR>
    <TD WIDTH="20%"><B>Desired Ratio (R1/R2):</B></TD>
    <TD COLSPAN="2"><INPUT TYPE="TEXT" NAME="des_RATIO" VALUE="1.0"></TD>
	<TD><INPUT TYPE="BUTTON" NAME="Calc" VALUE="Calculate"  ONCLICK="calc_table()"></TD>
	<TD><INPUT TYPE="BUTTON" NAME="pop_tab" VALUE="Pop Resistor Table"  ONCLICK="print_table()"></TD>
  </TR>
  <TR>
    <TD >&nbsp;</TD>
    <TD ><B>R1</B></TD>
    <TD ><B>R2</B></TD>
    <TD ><B>Error %</B></TD>
    <TD ><B>R1/R2</B></TD>
  </TR>
  <TR>
    <TD ><B>Best 10%</B></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b10_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b10_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b10_error"  ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b10_ratio"  ></TD>
  </TR>
  <TR>
    <TD >Worst Case +10%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp10_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp10_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp10_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp10_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case -10%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn10_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn10_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn10_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn10_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case +5%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp105_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp105_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp105_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp105_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case -5%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn105_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn105_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn105_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn105_ratio" ></TD>
  </TR>
  <TR>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
  </TR>
  <TR>
    <TD ><B>Best 5%</B></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b5_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b5_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b5_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b5_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case +5%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp5_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp5_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp5_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp5_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case -5%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn5_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn5_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn5_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn5_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case +3%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp3_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp3_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp3_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp3_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case -3%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn3_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn3_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn3_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn3_ratio" ></TD>
  </TR>
  <TR>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
    <TD >&nbsp;</TD>
  </TR>
  <TR>
    <TD ><B>Best 1%</B></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b1_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b1_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b1_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="b1_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case +1%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp1_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp1_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp1_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcp1_ratio" ></TD>
  </TR>
  <TR>
    <TD >Worst Case -1%</TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn1_R1" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn1_R2" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn1_error" ></TD>
    <TD ><INPUT TYPE="TEXT" NAME="wcn1_ratio" ></TD>
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