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<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>>>Howdy,</span></font><font size=2
color=black face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'><span style="mso-spacerun: yes">
</span>Is there an accurate way to measure capacitance? My Forrest Mims pocket</span></font><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>>book is the only place I have read how to test a
capacitor, but his method</span></font><font size=2 color=black
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>>doesn't measure it. I have a drawer full of
those assorted ceramic disc</span></font><font size=2 color=black
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>>capacitors that I have no idea what their values
are and would love to put</span></font><font size=2 color=black
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>>them to good use. Thanks a million.</span></font><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'><![if !supportEmptyParas]> <![endif]></span></font><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>>Jon Darby</span></font><font size=2 color=black
face="Courier New"><span style='font-size:10.0pt;font-family:"Courier New";
color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'><![if !supportEmptyParas]> <![endif]></span></font><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'><![if !supportEmptyParas]> <![endif]></span></font><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black;mso-color-alt:windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><font
size=2 color=black face="Courier New"><span style='font-size:10.0pt;font-family:
"Courier New";color:black'>I built a little potential divider using a variable
resistor as one side and the unknown cap as the other side. I then feed in a sine
wave of known amplitude across the ‘outer lugs’ and find a frequency and
resistance value where the output drops to a half of the input. IE the
reactance equals the resistance of the pot. It’s easiest with a dual trace
scope. Then you can use a frequency/reactance(in ohms)/capacitance table to
determine the value or better yet switch in a test cap of known value to
compare readings. This may seem a bit longwinded and it’s true it won’t measure
the smaller values because of stray capacitance error but if you build a jig
and have a whole box to do (and are very cheap like me) it will work fine down
to a few nanofarads.</span></font><font size=2 color=black face="Courier New"><span
style='font-size:10.0pt;font-family:"Courier New";color:black;mso-color-alt:
windowtext'><o:p></o:p></span></font></p>
<p class=MsoNormal><span class=EmailStyle16><font size=2 color=black
face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
Arial'><![if !supportEmptyParas]> <![endif]><o:p></o:p></span></font></span></p>
<p class=MsoNormal><span class=EmailStyle16><font size=2 color=black
face=Arial><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt;font-family:
Arial'>Lincoln<o:p></o:p></span></font></span></p>
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