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<DIV dir=ltr align=left><SPAN class=386432805-15112020><FONT color=#0000ff
size=2 face=Arial>After many years of building circuits, one acquires a basic
sense of where stability caps may be required. Often, I discover that an
opamp circuit is ringing a bit when I go probing around with the scope. I
tend to lay out the pads for stability caps on most inverting opamp circuits,
but often don't stuff them unless I find that I have to. I keep a big
stash of ceramic 101s for just that purpose.</FONT></SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Chris McDowell
[mailto:declareupdate@gmail.com] <BR><B>Sent:</B> Saturday, November 14, 2020
8:44 PM<BR><B>To:</B> David G Dixon<BR><B>Cc:</B> Bernard Arthur Hutchins, Jr;
synth-diy@synth-diy.org<BR><B>Subject:</B> Re: [sdiy] Voltage Feedback Resistors
and Circuit Stability<BR></FONT><BR></DIV>
<DIV></DIV><SPAN
style="BACKGROUND-COLOR: #ffecb3; COLOR: #000000; FONT-SIZE: 12px"><SPAN
style="BACKGROUND-COLOR: #ffecb3; COLOR: #000000; FONT-SIZE: 12px"><SPAN
style="PADDING-BOTTOM: 3px; LINE-HEIGHT: 1.6; BACKGROUND-COLOR: #ffecb3; FONT-STYLE: normal; PADDING-LEFT: 3px; PADDING-RIGHT: 3px; COLOR: #000000; FONT-SIZE: 12px; FONT-WEIGHT: normal; PADDING-TOP: 3px">[<STRONG>CAUTION:</STRONG>
Non-UBC Email]</SPAN></SPAN></SPAN>I'm happy you said this. I had written out a
post suggesting to build circuits before trying to optimize resistor noise
performance. started sounding like the responses that miss the point and don't
answer the op's question, so I deleted it hehe.
<DIV><BR></DIV>
<DIV>yours didn't feel this way David, there was context and previous responses.
I agree though, and I'm generally very happy when my hardware sounds "old"
(usually jusy means noisey heh) I also use whatever value I have the most of on
board, which often enough is 100k, with at least the option for caps in parallel
with feedback resistors. </DIV>
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<DIV dir=ltr>Chris </DIV>
<DIV dir=ltr><BR>
<BLOCKQUOTE type="cite">On Nov 14, 2020, at 7:13 PM, David G Dixon
<dixon@mail.ubc.ca> wrote:<BR><BR></BLOCKQUOTE></DIV>
<BLOCKQUOTE type="cite">
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<DIV dir=ltr align=left><SPAN class=910380901-15112020><FONT color=#0000ff
size=2 face=Arial>I've actually been accused of designing modules that sound
"too clean" and I use lots of 100k resistors all over the place. This is
one of those problems that probably isn't really a
problem.</FONT></SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Bernard Arthur
Hutchins, Jr<BR><B>Sent:</B> Saturday, November 14, 2020 11:36
AM<BR><B>To:</B> synth-diy@synth-diy.org<BR><B>Subject:</B> [sdiy] Voltage
Feedback Resistors and Circuit Stability<BR></FONT><BR></DIV>
<DIV></DIV><SPAN
style="BACKGROUND-COLOR: #ffecb3; COLOR: #000000; FONT-SIZE: 12px"><SPAN
style="BACKGROUND-COLOR: #ffecb3; COLOR: #000000; FONT-SIZE: 12px"><SPAN
style="PADDING-BOTTOM: 3px; LINE-HEIGHT: 1.6; BACKGROUND-COLOR: #ffecb3; FONT-STYLE: normal; PADDING-LEFT: 3px; PADDING-RIGHT: 3px; COLOR: #000000; FONT-SIZE: 12px; FONT-WEIGHT: normal; PADDING-TOP: 3px">[<STRONG>CAUTION:</STRONG>
Non-UBC Email]</SPAN></SPAN></SPAN>
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<P style="LINE-HEIGHT: 107%; MARGIN: 0in 0in 8pt; FONT-SIZE: 11pt"
class=MsoNormal><FONT face="Arial, sans-serif"> </FONT><SPAN
style="FONT-FAMILY: Arial, sans-serif">AWKWARD Questions </SPAN><O:P
style="FONT-FAMILY: Arial, sans-serif; font-variant-ligatures: inherit; font-variant-caps: inherit"> </O:P></P>
<P
style="LINE-HEIGHT: 107%; MARGIN: 0in 0in 8pt; FONT-FAMILY: Calibri, sans-serif; FONT-SIZE: 11pt"
class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial',sans-serif"><O:P></O:P></SPAN></P>
<P
style="LINE-HEIGHT: 107%; MARGIN: 0in 0in 8pt; FONT-FAMILY: Calibri, sans-serif; FONT-SIZE: 11pt"
class=MsoNormal><SPAN style="FONT-FAMILY: 'Arial',sans-serif">(1) <SPAN
style="mso-spacerun: yes"> </SPAN>In a synthesizer with standard
signal levels of +/- 5, has anyone even HEARD Johnson noises, let alone been
able to attribute it to a particular resistance?<SPAN
style="mso-spacerun: yes"> </SPAN><O:P> </O:P></SPAN></P>
<P
style="LINE-HEIGHT: 107%; MARGIN: 0in 0in 8pt; FONT-FAMILY: Calibri, sans-serif; FONT-SIZE: 11pt"
class=MsoNormal><SPAN style="FONT-FAMILY: 'Arial',sans-serif"><SPAN
style="mso-spacerun: yes"> </SPAN><O:P> </O:P></SPAN></P>
<P
style="LINE-HEIGHT: 107%; MARGIN: 0in 0in 8pt; FONT-FAMILY: Calibri, sans-serif; FONT-SIZE: 11pt"
class=MsoNormal><SPAN style="FONT-FAMILY: 'Arial',sans-serif">(2) <SPAN
style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-spacerun: yes"> </SPAN>Given a 100k resistor, how does one
(specific circuit/methodology please) observe/hear its Johnson noise as
compared to a 10k?<O:P> </O:P></SPAN></P>
<P
style="LINE-HEIGHT: 107%; MARGIN: 0in 0in 8pt; FONT-FAMILY: Calibri, sans-serif; FONT-SIZE: 11pt"
class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial',sans-serif"><O:P></O:P></SPAN></P><SPAN
style="LINE-HEIGHT: 107%; FONT-FAMILY: Arial, sans-serif; FONT-SIZE: 11pt">-Bernie
<SPAN style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-spacerun: yes"> </SPAN></SPAN><BR></DIV><SPAN>_______________________________________________</SPAN><BR><SPAN>Synth-diy
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