cap question

[Arthur Harrison]

FWIW, several years ago, I heard exactly the same explanation
re: unobtainability of polystyrene film.

As far as the 2nF goes, if you can obtain a 1.8nF or 2.2nF part,
perhaps you can use it instead of 2nF, and trim the value of the
potentiometer accordingly.

BTW, a seldom considered, but superb dielectric for these
applications is mica, although a 2nF mica cap is quite expensive
(and perhaps too large for some layouts).  Cornell Dubilier makes
a 2nF, +/-5% mica job, their part number CD19FD202J03, and it's
in the Newark catalog as stock number 15F1259 for $2.42 each.
(See: http://www.newark.com/)

-Art
-----Original Message-----
From: Bill Layer <b.layer at vikingelectronics.com>
To: List, Christopher <Chris.List at sc.siemens.com>; synth-diy at mailhost.bpa.nl
<synth-diy at mailhost.bpa.nl>
Date: Tuesday, December 29, 1998 11:55 AM
Subject: RE: cap question


>Hi Chris, All,
>
>>This cap is the integrator for the VCO. Best bet for a VCO is
>>Poly"styrene" - can be found in the Mouser catalog, and they only come
>>in small values (I keep hearing rumors that they aren't being made
>>anymore - why is that?).
>
>The rumors stem from the closing of a major manufacturer of PS film in
>Germany. Perhaps some of our German (or is that Deutsch?) friends know more
>about the defunct firm.
>
>I heard this info from the folks at Reliable Capacitor, who gave it as the
>reason that they were unable to continue supplying their *very* excellent
>PS part that we used heavily at Atma-Sphere. We (now they) bought the
>remaining stock on hand.
>
>So my question is: Why the hell can't 3M make a decent PS film? Apparently,
>microscopic pinholes are the enemy...
>
>
>Bill Layer
>Sales Technician
><b.layer at vikingelectronics.com>
>
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