<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">It's an interesting read, this patent! And I wasn't even aware Moog was actively filing new patents in recent years.<div><br></div><div>@David: I didn't know that about the Dixie. And I'm not sure if I understand you correctly. You mean the Dixie runs on a triangle core, and the implementation of the tri-core requires a comparator that provides you a pulse output of which you can modulate the duty cycle? How can that change rise and fall time of the triangle, then? It would have to be combined with a change in the expo CV right to achieve that? Or am I missing something?</div><div><br></div><div>Regards,</div><div><br></div><div>Rutger</div><div><div><br></div><div><br><div><br><div><div>On 10 apr 2018, at 19:59, David G Dixon wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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<div dir="ltr" align="left"><span class="732225517-10042018"><font color="#0000ff" size="2" face="Arial">All I could see of the patent were the figures, but based on
that, it looks a lot like what happens in the Dixie. All of the "modes"
shown in the final figure could be obtained simply by duty-cycle control of
the driving square waves in a tri-square oscillator.</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>Rutger
Vlek<br><b>Sent:</b> Tuesday, April 10, 2018 6:34 AM<br><b>To:</b> Tim
Parkhurst<br><b>Cc:</b> synth-diy@synth-diy org<br><b>Subject:</b> Re: [sdiy]
Continuously variable waveshaping (was Behringer Neutron)<br></font><br></div>
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<div>I recently stumbled on this recent patent by Moog: <a href="https://patents.google.com/patent/US20160335998A1/un">https://patents.google.com/patent/US20160335998A1/un</a></div>
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<div>It concerns continuously variable waveforms, but implements it at the
core of a VCO rather than by crossfading the outputs (waveshapers) of
one. The idea is awesome, but I have my reservations about the real-world
feasibility of the method (given component tolerances and accuracies).</div>
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<div>Rutger</div>
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<div class="gmail_quote">2018-04-08 21:09 GMT+02:00 Tim Parkhurst <span dir="ltr"><<a href="mailto:tim.parkhurst@gmail.com" target="_blank">tim.parkhurst@gmail.com</a>></span>:<br>
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<div dir="ltr"><span style="TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-STYLE: normal; TEXT-INDENT: 0px; DISPLAY: inline; FONT-FAMILY: arial,sans-serif; WHITE-SPACE: normal; FLOAT: none; LETTER-SPACING: normal; COLOR: rgb(34,34,34); FONT-SIZE: 12px; FONT-WEIGHT: 400; WORD-SPACING: 0px; font-variant-caps: normal; font-variant-ligatures: normal; text-decoration-style: initial; text-decoration-color: initial">"
'High </span><span style="TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-STYLE: normal; TEXT-INDENT: 0px; DISPLAY: inline; FONT-FAMILY: arial,sans-serif; WHITE-SPACE: normal; FLOAT: none; LETTER-SPACING: normal; COLOR: rgb(34,34,34); FONT-SIZE: 12px; FONT-WEIGHT: 400; WORD-SPACING: 0px; font-variant-caps: normal; font-variant-ligatures: normal; text-decoration-style: initial; text-decoration-color: initial">frequency
hash' is a direct quote from Ken Stone's description of that</span><br style="TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-STYLE: normal; TEXT-INDENT: 0px; FONT-FAMILY: arial,sans-serif; WHITE-SPACE: normal; LETTER-SPACING: normal; COLOR: rgb(34,34,34); FONT-SIZE: 12px; FONT-WEIGHT: 400; WORD-SPACING: 0px; font-variant-caps: normal; font-variant-ligatures: normal; text-decoration-style: initial; text-decoration-color: initial"><span style="TEXT-TRANSFORM: none; BACKGROUND-COLOR: rgb(255,255,255); FONT-STYLE: normal; TEXT-INDENT: 0px; DISPLAY: inline; FONT-FAMILY: arial,sans-serif; WHITE-SPACE: normal; FLOAT: none; LETTER-SPACING: normal; COLOR: rgb(34,34,34); FONT-SIZE: 12px; FONT-WEIGHT: 400; WORD-SPACING: 0px; font-variant-caps: normal; font-variant-ligatures: normal; text-decoration-style: initial; text-decoration-color: initial">circuit,
by the way."</span>
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and the band name for my new EDM / free jazz group. </span></div>
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<div dir="ltr">Tim (add in some corned beef and you've got a tasty breakfast)
Servo<br>---<br>"Imagination is more important than knowledge." - Albert
Einstein<br><br><br><br></div></div></div></div></div>
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<div class="gmail_quote">On Sun, Apr 8, 2018 at 11:36 AM, Guy McCusker <span dir="ltr"><<a href="mailto:guy.mccusker@gmail.com" target="_blank">guy.mccusker@gmail.com</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: rgb(204,204,204) 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote"><span>On Sun, Apr 8, 2018 at 6:54 PM, David G Dixon
<<a href="mailto:dixon@mail.ubc.ca" target="_blank">dixon@mail.ubc.ca</a>> wrote:<br>> My wavefolder (as
found in the Intellijel uFold) uses TL072, and doesn't<br>> generate
"high-frequency hash". Also, I've achieved what looks a lot like
a<br>> resonant filter output with a sawtooth wave, without a
filter. Given the<br>> way that this folder works (with diode
"turnaround" circuits) I'm not sure<br>> that slew rate is a
significant factor. The opamp outputs in the folder<br>> chain
are confined to relatively small voltages -- the first one to about
3V<br>> or less, and the subsequent ones much less. Other folders
may have<br>> significantly different modes of operation where slew
rate is important, but<br>> not the ones based on diode
turnarounds.<br><br></span>There's a bit of talking at cross-purposes here
I think. The wave<br>folder in the CGS29 and also the Serge wave
multiplier (middle<br>section) also does not generate "high frequency
hash" and works fine<br>with a fast op amp. Their design is also similar
to your "turnaround"<br>idea, as it happens.<br><br>The "high frequency
hash" business concerns a different part of the<br>CGS29, the Grinder
section, which exploits op amp overshoot and<br>ringing. It makes sense
that slew rate is a factor there. ("High<br>frequency hash" is a direct
quote from Ken Stone's description of that<br>circuit, by the way.)<br>
<div class="m_6681943215784096788HOEnZb">
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