From: "Tom Wild"
Subject: Re: what is 100R mean in a schematics?
Date: Sat, 11 Jan 2003 18:04:21 -0500
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+80 -20 refers to the variation over the specified temperature range of the
"Spehro Pefhany" wrote in message
> On Sat, 4 Jan 2003 16:22:12 -0000, the renowned "Zefram Cochrane"
> >"John Woodgate" wrote in message > >Now,
> >of them was a tiny
> >> That is 22 000 pF = 22 nF = 0.022 uF. The 'Z' describes the tolerance,
> >> which is +80/-20%
> >I've always wondered this: why are capacitor tolerances asymmetric.
> >+80/-20% means a range of 17.6nF to 39.6nF. Why don't they just call
> >it, say, a 28.6nF capacitor, with a tolerance of 39% or something ?
> Those tolerances usually apply to electrolytic capacitors and some of
> the nastier lot of semiconductor ceramic caps. In essence, they can't
> make the cap that accurate and we don't really care that much about
> the maximum capacitance that it might have, more about the minimum.
> For example, for filter caps, if a 1000uF is actually 1500uF, no big
> deal, but if it was 500uF it might cause problems. Same issue with the
> bypass capacitors that are often ceramic types.
> Best regards,
> Spehro Pefhany
> "it's the network..." "The Journey is the reward"
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