On 11/17/2012 4:26 AM, Brett Nordgren wrote:
> Geoff,
>
> The formulas were derived.  I just assumed a simple linear relation
> between resistance and temperature, which is a decent approximation at
> normal temperatures.  My formula came from  (RT2-RT1)=0.00393*(T2-T1).
> At very low (cryogenic) temperatures, you need a more complex formula.
> I should have mentioned that the temperatures are Celsius or Kelvin.  As
> you point out, since you are taking a difference, which one you use
> doesn't matter.
>
> You can find more than you'd ever want to know if you do a Google search
> on     copper temperature coefficient.  That's what I did.
>
> Regards,
> Brett
>
> At 10:41 PM 11/16/2012, you wrote:
>
>> mucho gracious, yes, carbon has a reverse coeff.
>> too bad they are not identical or you might somehow
>> get a hybrid resistor which will stay the same
>> as temp changes. i shall assume T = kelvin or rankin
>> which are absolute but then as deltas that may not be
>> important.
>> are these formulas within the crc handbook ?
>> geoff
>
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+0.393 percent per degree C

It gotta be Centegrade or Kelvin or it wont work.
just like me, it gotta be electronics or i dont work :-)

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