[sdiy] Silvered mica caps in VCO core integrators

[Vinicius Brazil]

Precision & Stability. In RF we need precision, that´s the reason to the
use.
I also had no problems in AF circuits.

On Fri, Apr 15, 2016 at 1:29 PM, David G Dixon <dixon at mail.ubc.ca> wrote:

> That's what I wanted to know (but was afraid to ask).  Silvered mica caps
> are more or less insisted upon in RF circuits.  What becomes so bad in AF
> circuits?
>
> > -----Original Message-----
> > From: Synth-diy [mailto:synth-diy-bounces at dropmix.xs4all.nl]
> > On Behalf Of Simon Brouwer
> > Sent: Friday, April 15, 2016 3:57 AM
> > To: Ian Fritz; Sdiy
> > Subject: Re: [sdiy] Silvered mica caps in VCO core integrators
> >
> > Hi,
> >
> > Why is soakage an issue in VCO's?
> >
> > My impression is that the time constant of the soakage effect
> > is orders of magnitude longer than the period of audio range
> > signals. If that is correct, soakage would not significantly
> > affect the frequency stability of a VCO, or would it?
> >
> > Best regards
> > Simon
> >
> > > On 15 April 2016 at 03:56 Ian Fritz <ijfritz at comcast.net> wrote:
> > >
> > >
> > > Mica caps have too much dielectric soakage for serious use in VCOs.
> > > (See the famous Bob Pease writeups.)
> > >
> > > My super S/H project was started to compare soakage and
> > leakage in C0G
> > > ceramics vs plastics.  I found that C0G and polystyrene had nearly
> > > equivalent behavior.  Other plastics, including PPE, were inferior.
> > >
> > > I'll say it again: C0G is the way to go for high-performance synth
> > > circuits, especially given their small size and reasonable cost.
> > >
> > > Ian
> > >
> > >
> > > On 4/14/2016 4:33 PM, Pete Hartman wrote:
> > > > Film caps generally seem to be preferred, but I can't say
> > I've heard
> > > > any strong arguments for one type of film cap over
> > another for that purpose.
> > > >
> > > > Thanks
> > > >
> > > > Pete
> > > >
> > > > On Thu, Apr 14, 2016 at 4:25 PM, David G Dixon <dixon at mail.ubc.ca
> > > > <mailto:dixon at mail.ubc.ca>> wrote:
> > > >
> > > >     Yves suggests either polystyrene or silvered mica.  I
> > guess they're
> > > >     interchangeable...?  I think silvered mica are easier
> > to use (and to
> > > >     get).
> > > >
> > > >      > -----Original Message-----
> > > >      > From: Quincas Moreira [mailto:quincas at gmail.com
> > > >     <mailto:quincas at gmail.com>]
> > > >      > Sent: Thursday, April 14, 2016 2:15 PM
> > > >      > To: David G Dixon
> > > >      > Cc: Sdiy
> > > >      > Subject: Re: [sdiy] Silvered mica caps in VCO core
> > integrators
> > > >      >
> > > >      > I use polystyrene (as per Ray Wilson's
> > instructions)  but I'm
> > > >      > willing to bet Mica will be perfect as well.  In
> > fact I think
> > > >      > Yves Usson uses Mica for that in his VCO:
> > > >      > http://yusynth.net/Modular/EN/VCO/index.html
> > > >      >
> > > >      > On Thu, Apr 14, 2016 at 3:53 PM, David G Dixon
> > > >      > <dixon at mail.ubc.ca <mailto:dixon at mail.ubc.ca>> wrote:
> > > >      > > Hey team, what do we think about silvered mica
> > caps in VCO
> > > >      > core integrators?
> > > >      > > I've used them in filters, and they work great.
> > Any hidden
> > > >      > dangers I
> > > >      > > should be aware of?
> > > >      > >
> > > >      > > _______________________________________________
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> > > >      >
> > > >      >
> > > >      >
> > > >      > --
> > > >      > Quincas Moreira
> > > >      > Test Pilot at VBrazil Modular
> > > >
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