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<DIV dir=ltr align=left><SPAN class=194105801-16022022>I use back-to-back
electrolytics to block DC in my four-quadrant multiplier circuits. I'm
paying exactly $0.02 for 47uF electrolytic caps from Tayda, so it is an absolute
no-brainer.</SPAN></DIV>
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<DIV dir=ltr align=left><SPAN class=194105801-16022022></SPAN> </DIV>
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<DIV dir=ltr align=left><FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Mattias
Rickardsson<BR><B>Sent:</B> Tuesday, February 15, 2022 12:31 PM<BR><B>To:</B>
Barry Klein<BR><B>Cc:</B> Synth DIY<BR><B>Subject:</B> Re: [sdiy] emulating
bi-polar capacitors<BR></FONT><BR></DIV>
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<DIV dir=auto>Hej Danjel and others,
<DIV dir=auto><BR></DIV>
<DIV dir=auto>I don't recall seeing any hard facts about non-polarized
electrolytics performing better than ordinary polarized in audio circuits, but
still they occasionally turn up in designs. Would be interesting to hear why
they sometimes are preferred by audio designers, though! :-)</DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>I searched for "non-polarized" in Douglas Self's reference book
"Small Signal Audio Design" and found a couple of applications where they
actually do make sense - but it's a practical reason rather than an audio
performance reason:</DIV>
<DIV dir=auto>DC blocking in inputs & outputs, where it's possible that the
connected gear pulls the voltage way off ground level, and you never know in
what direction.</DIV>
<DIV dir=auto>Douglas Self writes:</DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>"C2 is a DC-blocking capacitor to prevent voltages from
ill-conceived source equipment getting into the circuitry. It is a non-polarized
type as voltages from the outside world are of unpredictable polarity, and it is
rated at not less than 35 V so that even if it gets connected to defective
direct-coupled equipment with an op-amp output jammed hard against one of the
supply rails, no harm will result."</DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>Any other good reasons for using them?</DIV>
<DIV dir=auto>And sorry, no - I don't have any better advice than what has
already been said. :-)</DIV>
<DIV dir=auto><BR></DIV>
<DIV dir=auto>/mr</DIV>
<DIV dir=auto><BR></DIV></DIV><BR>
<DIV class=gmail_quote>
<DIV dir=ltr class=gmail_attr>Den tis 15 feb. 2022 20:43Barry Klein via
Synth-diy <<A
href="mailto:synth-diy@synth-diy.org">synth-diy@synth-diy.org</A>>
skrev:<BR></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>I used one in a typical dual op amp triangle oscillator on
the phaser in a Music Man amp design. It made a difference in extremely slow
sweep symmetry and also I had a function where you pull the knob out and could
fix the sweep wherever you wanted it. After I left the whole thing was
redesigned. Maybe I didn’t know what I was doing…. 45 years ago…
Self-taught by Electronotes. What a fun job before work politics F’d it all
up.<BR><BR>Barry<BR><BR><BR>> On Feb 15, 2022, at 11:32 AM, Mike Bryant
<<A href="mailto:mbryant@futurehorizons.com" rel=noreferrer
target=_blank>mbryant@futurehorizons.com</A>> wrote:<BR>> <BR>>
<BR>>> I've never bothered, I've never noticed a difference in just
using a 47μ instead of playing about with back-to-back capacitors even after
the thick end of 40 years the earliest stuff I built that way still has
capacitors that capacitate just fine.<BR>> <BR>> --<BR>>>
Gordonjcp<BR>> <BR>> <BR>> Agreed. Unless you actually have a
reverse DC bias voltage (in which case rotate the capacitor) I've never
understood any need for the non-polarised capacitors. Most mixing
consoles are full of thousands of them either feeding the input or fed from
the output of an opamp via a resistor to ground.<BR>> <BR>> <BR>>
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