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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>If matching is truly important, what I’d
do is solder on sockets so I could plug in different diodes. They probably
only need to be matched in pairs, I’m guessing, so you could just plug in two
and then try different other pairs until you like the results. I’m guessing
you will like the results after the first pair, because I’m betting there just
isn’t that much variation in 1N4148s.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Chris McDowell<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, April 10, 2020 2:49
PM<br>
<b><span style='font-weight:bold'>To:</span></b> Schwarz Raphael<br>
<b><span style='font-weight:bold'>Cc:</span></b> synth-diy@synth-diy.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [sdiy] Diode Matching</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>heresy perhaps, but have you tried -not- matching them? I'm curious how
poorly your ring mod performs with diodes just grabbed from the bag vs hand
matched. <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Chris<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
<br>
<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Apr 10, 2020, at 4:38 PM, Schwarz Raphael <<a
href="mailto:raphschwarz@gmail.com">raphschwarz@gmail.com</a>> wrote:<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<div style='word-wrap: break-word;-webkit-nbsp-mode: space;line-break:after-white-space'>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Seems to me like you have a crappy multimeter, <o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>temperature only plays out when when you want to match diodes up to a
few mV. On a 1n4148 there is about 150mV variation between 0°C and 90°C . At
room temperature lets say 15°C to 30°C there should be less than 5mV . If you
need 2mV matching I would tape them on a sheet of paper and let them rest a bit
before measuring<o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Recently I started to test replacing hand matched diodes by matched
transistor pairs in a single SMD package to avoid having to match SMD diodes.
It works well in simulation but I need to test that<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
<br>
<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Le 10 avr. 2020 à 20:19, ColinMuirDorward <<a
href="mailto:colindorward@gmail.com">colindorward@gmail.com</a>> a écrit :<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Others will have more informed feedback, but did you rule out
temperature changes as the cause of your measurement drifts?<o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Colin<o:p></o:p></span></font></p>
</div>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Fri, Apr 10, 2020 at 4:48 PM Didier Leplae via Synth-diy <<a
href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</a>> wrote:<o:p></o:p></span></font></p>
</div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;
margin-left:4.8pt;margin-right:0in'>
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<div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Does anyone have thoughts on the best way to do diode
matching? <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>I am building some ring modulators and need matched 4148
diodes, or similar.<o:p></o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>So far I have tried three different methods of testing and
find the results to be confusing and unreliable.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> The first method I tried was using
a <a
href="https://www.amazon.com/Transistor-DROK-Capacitor-Capacitance-Automatic/dp/B01MS1FOYM"
target="_blank">DROK transistor tester</a> (which also tests diodes).
I taped a strip of new 4148 diodes to a sheet of paper in a notebook and one by
one wrote down the results. I noticed that most of them had pretty similar
results, but there were a few outliers that had wildly higher readings (forward
voltage drop, I think). So, out of curiosity I went and tested those again and
found that the readings the second time were much more similar to the
others. <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> Then I started rechecking all of them and
found that I was getting a completely different set of readings. The
differences between readings on any one diode seemed to vary as much as
differences between diodes. And as I rechecked diodes I kept getting different
results.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> So, I concluded that my transistor tester
must not be very good.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> I then tried a the second method which is
the diode testing setting on <a href="https://www.etekcity.com/product/100111"
target="_blank">my Etekcity multimeter</a>. This time I found that all
the diodes read pretty much the same forward voltage drop. (They seem to
increase slightly the more diodes I tested but if I go back to the first diode,
for example, the reading will be at the same increased value). I came back
later and tested again, this time the results were similar in that they all
read the same value, except the value was 100mV or so lower. And again if I
came back the next day similar results. So, I concluded that my multimeter's
diode testing mode might be unreliable.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> I then tried the third method of using the
voltmeter, in mV setting, to test forward voltage drop. Since my voltmeter's mV
setting only goes to 2000mV, I used a 1.5V AA battery and a 10k resistor (to
give about 0.15mA) in series with my diode. The results were quite similar to
the readings I was getting using the diode testing mode on the multimeter. The
values in one set of tests would be virtually identical for all of the diodes,
but if I come back and test again they are quite different from the previous
value, but the same for all diodes.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>I'm pretty confused by all of this. Do I just have a
crappy multimeter? Or are my diodes all miraculously matched?<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Any thoughts would be helpful. <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Thanks,<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Didier<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'> <o:p></o:p></span></font></p>
</div>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>_______________________________________________<br>
Synth-diy mailing list<br>
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<a href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank">http://synth-diy.org/mailman/listinfo/synth-diy</a><o:p></o:p></span></font></p>
</blockquote>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br clear=all>
<br>
-- <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="https://www.instagram.com/colinmuirdorward/" target="_blank">https://www.instagram.com/colinmuirdorward/</a><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="https://www.instagram.com/colinmuirdorward/" target="_blank">-<br>
</a><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="https://www.instagram.com/ssdp_synthesis/" target="_blank">https://www.instagram.com/ssdp_synthesis/</a><o:p></o:p></span></font></p>
</div>
</div>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>_______________________________________________<br>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>_______________________________________________<br>
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http://synth-diy.org/mailman/listinfo/synth-diy<o:p></o:p></span></font></p>
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