Odp: Odp: [sdiy] really basic question .. tolerance

[Roman Sowa]

carbon have tempco in range of 200-1000ppm, sometimes not even
specified. They age faster, meaning they change it's value with time
and that's also why they are usually not better than 2%.
And there's also noise factor, but I wouldn't like to go there again ;)

Metal film have tempco 15-200ppm and most of the time they can
be found in 1%, but recently 0.25% and better are easily available.

Roman

----- Original Message ----- 
From: Tim Curtis <sexsymbol at execpc.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, January 19, 2003 12:25 PM
Subject: Re: Odp: [sdiy] really basic question .. tolerance


> On a related topic...
> 
> I've never really been all that up on what the actual differences are 
> between metal film and carbon film resistors.  Can anyone give me some 
> insight?
> 
> I'm assuming that there's more to it than just the tolerance.
> 
> I've got a board that I'm populating here that specifically calls for 1% 
> metal film resistors, but I've got a really good stash of 5% carbon 
> films here.  I'm planning to order about 10 different values of the 
> 1%'s, but is there a reason that I can't just select 5% carbons that are 
> actually within the 1% spec?
> 
> Thanks!
> 
> Tim
> 
> 
> 
> Roman Sowa wrote:
> 
> >Some resistor manufacturers claim that every resistor going onto
> >the reel is measured. This way it's easy to guarantee that all
> >resistors on that reel fit within given tolerance.
> >This way they probably select 1% and 0.5% from the same
> >production run I guess.
> >OTOH if others don't measure every resistors before packing
> >they can only guarantee some statistical parameter like "2-sigma
> >or whatever" depending on stability of manufacturing process.
> >
> >I never worked in resistor fab, I just assume that reading
> >datasheets.
> >Yeah, I'm so geekily twisted I even read resistor's datasheet
> >
> >Roman
> >
> >----- Original Message -----
> >From: Ian Fritz <ijfritz at earthlink.net>
> >To: harrybissell <harrybissell at prodigy.net>; John L Marshall
> ><john.l.marshall at gte.net>
> >Cc: diysynth <diy_list at analog-synth.de>; <synth-diy at dropmix.xs4all.nl>
> >Sent: Sunday, January 19, 2003 12:59 AM
> >Subject: Re: [sdiy] really basic question .. tolerance
> >
> >
> >  
> >
> >>Um ... I still have a question.
> >>
> >>When I buy a 1% resistor is its value guaranteed to be within 1%, or is it
> >>just that some point on the statistical distribution ( the 2-sigma point or
> >>whatever) is at 1%?
> >>
> >>I've always assumed the former, but is
> >>this correct?
> >>
> >>   Ian
> >>
> >>
> >>At 04:34 PM 1/18/2003, harrybissell wrote:
> >>    
> >>
> >>>Yep... I'm in
> >>>
> >>>H^) harry
> >>>
> >>>John L Marshall wrote:
> >>>
> >>>      
> >>>
> >>>>We all agree. I think.
> >>>>
> >>>>Take care,
> >>>>John
> >>>>www.sound-photo.com
> >>>>        
> >>>>
> >
> >
> >
> >  
> >
> 
>