[sdiy] varactor/varicaps?

Harry Bissell harrybissell at wowway.com
Fri Nov 19 14:46:56 CET 2010

seems that such a filter would have problems with CV feed-through
(like so many other diode-like technologies) unless you were willing
to make some form of balanced circuit.  Their limited range is
uhhhh.... "limited"   :^P

H^) harry

----- Original Message -----
From: David G. Dixon <dixon at interchange.ubc.ca>
To: 'dan snazelle' <subjectivity at hotmail.com>, 'synth-diy DIY' <synth-diy at dropmix.xs4all.nl>
Sent: Thu, 18 Nov 2010 17:00:02 -0500 (EST)
Subject: Re: [sdiy] varactor/varicaps?

> anybody know much about varicaps? they sound too good to be true...voltage
> variable capacitance up to 200pf?

Well, the value is right, because I use 205pF silvered mica caps in all of
my own filter designs.

However, the big problem I can see right off the bat is that this would give
linear control of filter cutoff, when what you really want is exponential
control.  It might be an interesting way to introduce linear FM to a filter,
but probably not worth it.

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Harry Bissell & Nora Abdullah 4eva

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