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<DIV dir=ltr align=left><SPAN class=823451008-30052021><FONT face=Calibri>I
added VC to Morphlag with the 2164 VCA -- it was pretty
straightforward.</FONT></SPAN></DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>ackolonges fds via
Synth-diy<BR><B>Sent:</B> Saturday, May 29, 2021 5:15 PM<BR><B>To:</B> Quincas
Moreira<BR><B>Cc:</B> Synth-Diy mailing list<BR><B>Subject:</B> Re: [sdiy] VC
Glide Circuit<BR></FONT><BR></DIV>
<DIV></DIV>
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Non-UBC Email]</FONT></TD></TR></TBODY></TABLE>
<DIV
style="FONT-FAMILY: Calibri, Helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">Thanks
a lot to David and Quincas for recommending alternative designs.</DIV>
<DIV
style="FONT-FAMILY: Calibri, Helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri, Helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">I
found the Morphlag and DUSG schematics, and they look great, though for my
application I was hoping to make 8 of them to try to get that nice polyphonic
portamento sound out of my synth, and these designs with separate up and down
rates, and exponential/linear control seem a little bit overboard for this...
Also, for the Morphlag, I'd still have to add in VC control, which for me would
look like the OTA section of the Unipole that I linked, and I'd worry that I'd
be stuck with the same issue if I don't understand what the problem is with my
current circuit. <BR></DIV>
<DIV
style="FONT-FAMILY: Calibri, Helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri, Helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">Thanks
again for the comments - much appreciated, and if anyone has any idea why my
built circuits aren't able to achieve the fast glide times of the simulation,
I'd love to hear it.<BR></DIV>
<DIV>
<DIV id=appendonsend></DIV>
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style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<HR style="WIDTH: 98%; DISPLAY: inline-block" tabIndex=-1>
<DIV dir=ltr id=divRplyFwdMsg><FONT style="FONT-SIZE: 11pt"
face="Calibri, sans-serif"><B>From:</B> Quincas Moreira
<quincas@gmail.com><BR><B>Sent:</B> Saturday, May 29, 2021 9:13
PM<BR><B>To:</B> ackolonges fds <ackolonges@hotmail.com><BR><B>Cc:</B>
Synth-Diy mailing list <synth-diy@synth-diy.org><BR><B>Subject:</B> Re:
[sdiy] VC Glide Circuit</FONT>
<DIV> </DIV></DIV>
<DIV dir=auto>Can’t beat the Serge DUSG
<DIV><BR></DIV>
<DIV><A
href="https://www.elby-designs.com/webtek/cgs/serge/cgs75/cgs75_vcs.html">https://www.elby-designs.com/webtek/cgs/serge/cgs75/cgs75_vcs.html</A><BR><BR>
<DIV dir=ltr>Sent from my iPhone</DIV>
<DIV dir=ltr><BR>
<BLOCKQUOTE type="cite">On 29 May 2021, at 3:37, ackolonges fds via Synth-diy
<synth-diy@synth-diy.org> wrote:<BR><BR></BLOCKQUOTE></DIV>
<BLOCKQUOTE type="cite">
<DIV dir=ltr>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">Hi
All,</DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">I
wanted some VC slew for keyboard-style playing from my modular, so I searched
for a circuit, and decided to try and build one called 'Unopole', - circuit
diagram at <A id=LPlnk
href="https://thonk.co.uk/documents/stroh/Wiring/Unopole.jpg">https://thonk.co.uk/documents/stroh/Wiring/Unopole.jpg</A><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">The
graph on the bottom right of the diagram shows a 0V to 10V signal slewing in
10ms, and I simulated the circuit in Falstad Circuit Simulator (text for
circuit pasted at end), and it is slewing even faster. However, when I build
the real circuit the glide is much slower.</DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">I've
tried putting maximum current (2ma) to the OTA control pin, bringing down the
value of the charging cap C1 to 10nF, and the fastest I'm able to get it to
glide (at fastest pot setting and CV input together) is about 32ms from 0V to
1V, which is about 300ms over 10V.<BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">Below
about 10nF for C1, the tuning of the 1V/Oct signal starts faltering. I'm using
a ceramic C0G cap for this. Should I be using a different type of cap? If so,
which would you recommend? <BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">Alternatively,
does anyone have any ideas as to why I'm having trouble getting fast enough
glides with this circuit? I've built it a few times with the same results. Or,
has anybody on here built a different VC glide circuit that is more
suitable?</DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">Thanks
so much for any advice any of you may have.</DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">FALSTAD
CIRCUIT</DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">------------------------<BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt">$
1 0.000005 11.086722712598126 17 5 50 5e-11
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3</SPAN><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
style="FONT-FAMILY: Calibri,Helvetica,sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 12pt"><BR></DIV>
<DIV
class="x__Entity x__EType_OWALinkPreview x__EId_OWALinkPreview x__EReadonly_0"><IMG
style="MAX-WIDTH: 100%"
src="https://thonk.co.uk/documents/stroh/Wiring/Unopole.jpg"
NOSEND="1"></DIV><BR><SPAN>_______________________________________________</SPAN><BR><SPAN>Synth-diy
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