<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<p>I second toothed belts. This company is a great source for that
type of thing, or at least they will give you all the ideas you
could ever need.<br>
</p>
<p><a class="moz-txt-link-freetext" href="http://www.sdp-si.com/">http://www.sdp-si.com/</a><br>
</p>
<br>
<div class="moz-cite-prefix">On 10/24/2017 11:37 AM, Chromatest J.
Pantsmaker wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CADpm=3Er1uMpfqNO8h6yzrq-F4F861ADJ2QVKXWOp_cScUnOHw@mail.gmail.com">
<p dir="ltr">What about cog gear pulleys? You could maybe use
toothed belts and pulleys so you wouldn't have to worry about
slippage and what not.</p>
<p dir="ltr">Like this stuff: <a
href="http://www.mpja.com/mobile/Gears-and-Pulleys/products/528/"
moz-do-not-send="true">http://www.mpja.com/mobile/Gears-and-Pulleys/products/528/</a><br>
</p>
<div class="gmail_quote">On Oct 24, 2017 2:23 AM, "Rutger Vlek"
<<a href="mailto:rutgervlek@gmail.com" moz-do-not-send="true">rutgervlek@gmail.com</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">
<div>I thought about that. The gear ratio's are crucial to
the tuning of the tonewheel generator, and I feel that
varying belt diameter (tension related, temperature
dependant) could become an issue. Though, I have no way to
quantify this instinct.</div>
<div><br>
</div>
<div>As for 3D printing, this is really a nice case where
it's not perfect yet, as far as I can tell. I've asked
some experienced people, and what I heard was basically
that the composite nature of 3D printed objects results in
a not-so-homogene material, that has unpredictable wear
properties during applications with friction. Polishing
changes the surface a bit, but lack of internal homogenity
is supposedly a problem for gears, especially when running
at higher RPMs (more friction). From memory I recall the
drive shaft of the central AC motor in the Pari runs at
around 1200 RPM. It connects with a belt drive to the
first tonewheel drum shaft, which then connects with gears
towards the last (12th) tonewheel shaft, progressively
slowing down each drum such that identical drums given a
semi-tone tuning difference. The last drum connects with a
belt to the vibrato scanner.</div>
<div><br>
</div>
<div>As for PLL loop: I've never designed one, but it has my
interest. What amount of complexity am I looking at? Can
someone refer me to an example circuit schematic? Each
tonewheel drum contains several octaves, the highest
octave as (I believe) 16 dents on a single revolution. So
that would be the preferred source for PLL feedback, I
guess. The other octaves automatically align. The drums
are spring-coupled to the gear shafts by the way, so the
PLL loop may be affected by that (bouncing at startup?).</div>
<div><br>
</div>
<div>I do imagine this would be a HUGE step forward for the
Pari in becoming tunable and way more silent than it is.</div>
<div><br>
</div>
<div>Best,</div>
<div><br>
</div>
<div>Rutger</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2017-10-24 0:48 GMT+02:00 Sarah
Thompson <span dir="ltr"><<a
href="mailto:plodger@gmail.com" target="_blank"
moz-do-not-send="true">plodger@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Would belt drives work? They have huge
advantages over gears if you need smooth transfer with
no cogging or backlash.<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">
<div>
<div class="m_-6000375047331762992h5">On Mon, Oct
23, 2017 at 4:34 AM, <span dir="ltr"><<a
href="mailto:rburnett@richieburnett.co.uk"
target="_blank" moz-do-not-send="true">rburnett@richieburnett.co.uk</a>></span>
wrote:<br>
</div>
</div>
<blockquote class="gmail_quote" style="margin:0px
0px 0px
0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">
<div>
<div class="m_-6000375047331762992h5"><span>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">@roman
and Richie: thanks! From my limited
experience with bldc's I<br>
feel they would be costly, especially a
12-way driver system for them.<br>
Would they need hall sensor feedback to
get the tuning accurate<br>
enough?<br>
</blockquote>
<br>
</span>
Yes, probably not cheap. I don't think you'd
need hall sensors to detect the field, but you
would need to ramp the frequency up at a
controlled rate to allow the mechanical bits
time to accelerate up to operating speed.<span><br>
<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">The
pll sounds nice and classic. I'll look
into that. At present I'm<br>
not sure if the pick-up coils of the
generator could handle more<br>
loading, e.g. As required for closing the
loop. But a high impedance<br>
buffer would probably be ok.<br>
</blockquote>
<br>
</span>
Take the feedback for the PLL from the highest
frequency that you can. The loop filter in
the PLL has to filter out the ripple in the
compared reference and positional feedback
signals. The higher you can make the
reference and feedback signal frequencies, the
larger the bandwidth of the loop filter can
be, and the quicker the PLL speed controller
will settle. i.e. Don't use a reference
signal that is just one pulse per revolution,
as this can mean you end up with a very
sluggish control loop!<span
class="m_-6000375047331762992m_-6694011808400049865HOEnZb"><font
color="#888888"><br>
<br>
-Richie,</font></span></div>
</div>
<div
class="m_-6000375047331762992m_-6694011808400049865HOEnZb">
<div
class="m_-6000375047331762992m_-6694011808400049865h5"><br>
<span>
______________________________<wbr>_________________<br>
Synth-diy mailing list<br>
<a href="mailto:Synth-diy@synth-diy.org"
target="_blank" moz-do-not-send="true">Synth-diy@synth-diy.org</a><br>
<a
href="http://synth-diy.org/mailman/listinfo/synth-diy"
rel="noreferrer" target="_blank"
moz-do-not-send="true">http://synth-diy.org/mailman/l<wbr>istinfo/synth-diy</a><br>
</span></div>
</div>
</blockquote>
</div>
<span class="m_-6000375047331762992HOEnZb"><font
color="#888888"><br>
<br clear="all">
<br>
-- <br>
<div
class="m_-6000375047331762992m_-6694011808400049865gmail_signature"
data-smartmail="gmail_signature">[s]</div>
</font></span></div>
</blockquote>
</div>
<br>
</div>
<br>
______________________________<wbr>_________________<br>
Synth-diy mailing list<br>
<a href="mailto:Synth-diy@synth-diy.org"
moz-do-not-send="true">Synth-diy@synth-diy.org</a><br>
<a href="http://synth-diy.org/mailman/listinfo/synth-diy"
rel="noreferrer" target="_blank" moz-do-not-send="true">http://synth-diy.org/mailman/<wbr>listinfo/synth-diy</a><br>
<br>
</blockquote>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<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>
</pre>
</blockquote>
<br>
</body>
</html>