Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!sdd.hp.com!hplabs!hpfcso!hpfcdj!myers
From: myers@hpfcdj.HP.COM (Bob Myers)
Newsgroups: sci.electronics
Subject: Re: RE Descrambler
Message-ID: <17660151@hpfcdj.HP.COM>
Date: 11 Feb 91 18:04:31 GMT
References: <1991Feb9.233031.25283@sactoh0.sac.ca.us>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 19

>I've finally decided to build the descrambler and have a quick
>question.  What does NPO stand for on capacitors?  Is there
>anything I should know before I start building this thing?

"NPO" stands for "Negative-Positive-Zero" (if it stands for anything), and
basically means a ceramic capacitor whose value changes very little with
temperature.  (I believe that "C5G" or something like that is the present
designation for this.)  Other ceramic dielectrics have other designators which
signify their behavior vs. temperature; two common ones are X7R and Z5U, which
are worse than NP0 vs. temperature. (Z5U is the worst - I think it's something
like -20%/+80% or thereabouts over a 0-85 deg. C range.  Z5U tends to be seen
a lot on what are basically cheap, low-quality caps - as in lots of voids and
other defects in the dielectric.  I'd avoid them like the plague even if you
can handle the lousy temp. coefficient.)


Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers@fc.hp.com                          |  sentient life-form on this planet.