<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<div class="moz-cite-prefix">On 30.05.2021 02:15, ackolonges fds via
Synth-diy wrote:<br>
</div>
<blockquote type="cite"
cite="mid:SY3PR01MB1787B0AA601C9C4B00D58A3CD5209@SY3PR01MB1787.ausprd01.prod.outlook.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<style type="text/css" style="display:none;">P {margin-top:0;margin-bottom:0;}</style>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
Thanks a lot to David and Quincas for recommending alternative
designs.</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
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;
font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
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 style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
</div>
</blockquote>
<p><br>
</p>
<p><br>
</p>
<p>It's just a wild guess, but R3 does delimit the maximum current
that flows into the Iabc pin. Maybe go a bit lower 6.8k or so.<br>
</p>
<p>Are you running it on 15V as well? As a change in supply voltage
will bring the maximum control current down also.</p>
<p>However these effects should not account for the big difference
you see.</p>
<p><br>
</p>
<p>Have you measured the control current properly, i.e. with a meter
in series to confirm the current source is working as expected? <br>
</p>
<p><br>
</p>
<p>Your current source maybe is oscillating. You should check that
with a scope. To dampen, I would place a 1k resistor between the
cap C2 and diode D1.</p>
<p><br>
</p>
<p><br>
</p>
<p>Best,<br>
René<br>
</p>
<p><br>
</p>
<p><br>
</p>
<blockquote type="cite"
cite="mid:SY3PR01MB1787B0AA601C9C4B00D58A3CD5209@SY3PR01MB1787.ausprd01.prod.outlook.com">
<div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
</div>
<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt"
face="Calibri, sans-serif" color="#000000"><b>From:</b>
Quincas Moreira <a class="moz-txt-link-rfc2396E" href="mailto:quincas@gmail.com"><quincas@gmail.com></a><br>
<b>Sent:</b> Saturday, May 29, 2021 9:13 PM<br>
<b>To:</b> ackolonges fds <a class="moz-txt-link-rfc2396E" href="mailto:ackolonges@hotmail.com"><ackolonges@hotmail.com></a><br>
<b>Cc:</b> Synth-Diy mailing list
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a><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"
moz-do-not-send="true">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
<a class="moz-txt-link-rfc2396E" href="mailto:synth-diy@synth-diy.org"><synth-diy@synth-diy.org></a> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
Hi All,</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
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
href="https://thonk.co.uk/documents/stroh/Wiring/Unopole.jpg"
id="LPlnk" moz-do-not-send="true">https://thonk.co.uk/documents/stroh/Wiring/Unopole.jpg</a><br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
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;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
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;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
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;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
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;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
Thanks so much for any advice any of you may have.</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
FALSTAD CIRCUIT</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
------------------------<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
$ 1 0.000005 11.086722712598126 17 5 50 5e-11
<div>174 48 128 48 208 1 100000 0.48020000000000007
Resistance</div>
<div>g 48 224 48 240 0 0</div>
<div>R 48 128 48 96 0 0 40 12 0 0 0.5</div>
<div>w 64 176 96 176 0</div>
<div>r 96 176 176 176 0 15000</div>
<div>r 96 240 176 240 0 10000</div>
<div>w 176 176 176 240 0</div>
<div>a 240 192 320 192 8 12 -12 1000000
0.000005472331080331692 0 100000</div>
<div>g 240 208 240 240 0 0</div>
<div>w 176 176 240 176 0</div>
<div>c 336 192 336 256 0 1e-10 -0.5472385803642495
0.001</div>
<div>w 320 192 336 192 0</div>
<div>d 400 192 400 256 2 default</div>
<div>w 336 192 400 192 0</div>
<div>w 176 240 176 272 0</div>
<div>w 176 272 304 272 0</div>
<div>w 304 272 304 256 0</div>
<div>w 304 256 336 256 0</div>
<div>w 336 256 400 256 0</div>
<div>w 400 256 464 256 0</div>
<div>t 432 224 464 224 1 -1 5.814783631368241
-0.5472385803642495 100 default</div>
<div>w 464 256 464 240 0</div>
<div>w 432 224 432 192 0</div>
<div>w 432 192 400 192 0</div>
<div>w 464 208 464 144 0</div>
<div>r 464 144 464 80 0 10000</div>
<div>402 656 352 768 352 1 0\s0\s40\s-9\s0\s0\s0.5
0\s0\s40\s9\s0\s0\s0.5
0\s1\s-12.343529771373202\s0.5472335109924158\s100\sdefault
0\s1\s-0.5472335109924158\s0.5469786835162118\s100\sdefault
0\s1\s0\s0.5469786835162118\s100\sdefault
0\s1\s-8.547498288201437\s-4.257672077077218\s100\sdefault
0\s1\s-2.9215945571340436\s0.5469761486367535\s100\sdefault
0\s-1\s0.12505886554275492\s-0.14737295745119638\s100\sdefault
0\s-1\s0\s-0.14737295745119638\s100\sdefault
0\s-1\s17.405000677164992\s-0.12505886554275492\s100\sdefault
0\s-1\s0.5469710782877009\s-0.5467162500596725\s100\sdefault
0\s-1\s0\s-0.5467162500596725\s100\sdefault
0\s-1\s7.72624111758356\s-0.5469710782877009\s100\sdefault
0\s1\s0\s0.1634519859667556\s100\sdefault
0\s1\s-0.159115513874303\s0.1634519859667556\s100\sdefault
0\s1\s-8.857504054228007\s0.159115513874303\s100\sdefault
0\s1\s0\s0.10015101242435948\s100\sdefault
0\s1\s0\s-4.704497213289612\s100\sdefault</div>
<div>r 656 320 560 320 0 10000</div>
<div>R 560 320 512 320 0 2 100 5 0 0 0.5</div>
<div>w 464 80 752 80 0</div>
<div>w 752 80 752 320 0</div>
<div>w 768 352 800 352 0</div>
<div>c 800 352 800 416 0 8.2e-8 0.18007155406906683
0.001</div>
<div>g 800 416 800 432 0 0</div>
<div>w 800 352 848 352 0</div>
<div>r 672 496 752 496 0 10000</div>
<div>w 656 384 656 496 0</div>
<div>w 656 496 672 496 0</div>
<div>a 912 336 992 336 8 15 -15 1000000
0.1800697533715331 0.18007155406906683 100000</div>
<div>w 752 496 864 496 0</div>
<div>w 848 352 912 352 0</div>
<div>w 864 496 864 320 0</div>
<div>w 864 320 912 320 0</div>
<div>w 864 320 864 272 0</div>
<div>w 864 272 992 272 0</div>
<div>w 992 272 992 336 0</div>
<div>r 992 336 1072 336 0 330</div>
<div>g 96 240 96 272 0 0</div>
<div>o 28 64 0 4098 10 0.1 0 2 28 3</div>
<span>o 45 64 0 4098 10 0.1 1 2 45 3</span><br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;
font-size:12pt; color:rgb(0,0,0)">
<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"
moz-do-not-send="true"></div>
<br>
<span>_______________________________________________</span><br>
<span>Synth-diy mailing list</span><br>
<span><a class="moz-txt-link-abbreviated" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a></span><br>
<span><a class="moz-txt-link-freetext" href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a></span><br>
<span>Selling or trading? Use <a class="moz-txt-link-abbreviated" href="mailto:marketplace@synth-diy.org">marketplace@synth-diy.org</a></span><br>
</div>
</blockquote>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
Synth-diy mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a>
<a class="moz-txt-link-freetext" href="http://synth-diy.org/mailman/listinfo/synth-diy">http://synth-diy.org/mailman/listinfo/synth-diy</a>
Selling or trading? Use <a class="moz-txt-link-abbreviated" href="mailto:marketplace@synth-diy.org">marketplace@synth-diy.org</a>
</pre>
</blockquote>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
--
<a class="moz-txt-link-abbreviated" href="mailto:synth@schmitzbits.de">synth@schmitzbits.de</a>
<a class="moz-txt-link-freetext" href="http://schmitzbits.de">http://schmitzbits.de</a></pre>
</body>
</html>