[sdiy] really basic question .. tolerance

[Grant Richter]

One tip for calculating tolerances. Excel makes a great tool for calculating
all the possible variations of resistor tolerances. You can set a variable
cell for tolerance and have max and min voltages calculated for you by the
spreadsheet. Very handy.

> From: Peter Grenader <petergrenader at mksound.com>
> Date: Sat, 18 Jan 2003 14:14:56 -0700
> To: John L Marshall <john.l.marshall at gte.net>, Tim Ressel
> <madhun2001 at yahoo.com>, diysynth <diy_list at analog-synth.de>,
> <synth-diy at dropmix.xs4all.nl>
> Subject: Re: [sdiy] really basic question .. tolerance
> 
> 
> <<> tolerance are connected in series that the result will be out of
> tolerance?>>
> 
> <<Please show me an example of two 1% resistors in series or parallel where
>> the tolerance exceeds 1%. I heard this rule many times but I can't see it.>>
> 
> I haven't read all the replies in this string, so I can only respond to what
> I said originally:
> 
> Be careful of accumulative tolerances.
> 
> Meaning: the amount from the nominal value of each resistor will be summed
> as well. I didn't mention anything about them suddenly being out of
> tolerance.
> 
> I guess if you needed 1% and one of the two you used in series was a 20%,
> depending on the summed value you could be headed for trouble.
> 
> P
> 
> 
> 
> 
>> 
>> 
>> Tim or Harry or Peter,
>> 
>> Please show me an example of two 1% resistors in series or parallel where
>> the tolerance exceeds 1%. I heard this rule many times but I can't see it.
>> 
>> Complex circuits are another story. I can see how errors accumulate through
>> gain stages.
>> 
>> I need empirical evidence to be convinced.
>> 
>> Take care,
>> John
>> www.sound-photo.com
>> ---------------------------------------------------------------------------
>> 
>> ----- Original Message -----
>> From: "Tim Ressel" <madhun2001 at yahoo.com>
>> To: "diysynth" <diy_list at analog-synth.de>; <synth-diy at dropmix.xs4all.nl>
>> Sent: Saturday, January 18, 2003 1:32 PM
>> Subject: Re: [sdiy] really basic question .. tolerance
>> 
>> 
>>> Joerg,
>>> 
>>> That is an optimistic way of looking at it. However
>>> the worse-case is still the sum. If I'm worrying about
>>> tolerances, I always look at worse-case.
>>> 
>>> --tim
>>> 
>>> 
>>> 
>>> --- diysynth <diy_list at analog-synth.de> wrote:
>>>> Hi all
>>>> 
>>>>> tolerance are connected in series that the result
>>>> will be out of
>>>> tolerance?
>>>>> 
>>>>> Add two 100k resistors 101k + 101k = 202k still 1%
>>>> 
>>>> Sure ? I allways thought, the resulting tolerance
>>>> gets better with the
>>>> factor t_res=t_single/sqrt(n), where n is the number
>>>> of used resistors, and
>>>> t_single is the tolerance of the single resistor ?
>>>> 
>>>> Joerg
>>>> 
>>>> 
>>> 
>>> 
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>> 
>> 
> 
> 
>