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Re: graphical analysis menagerie (was: Need Ideas)



At 19:21 1/2/00 -0800, John M. wrote:

Allen Bradley carbon composition resistors decrease in resistance with
temperature. So the scaling constant k is evidently negative.

Taking a sample A-B 0.27ohm resistor:
Temp (K) Res (ohms)
0.3 10^6
1 10^2
3 3
10 1
30 0.7
100 0.3 (from a graph of Rose-Innes's)

I don't have a curve fitting package here. Can someone else
fit this?

Make that Resistance = r*exp(k*sqrt(temperature))

Assuming that your data is good and that John's statement in true, then
your data does not all lie within the "large range" that John refers to.
I can get a tolerable, but far from excellent fit to no more than three of
these data points--not an impresssive feat for a two parameter fitting
function.

John Mallinckrodt

Reading intermediate points off a log-log graph by eye is certainly
far from exact. But Rose-Innes cautions about the form of the curve
to be expected - and its repeatability.


brian whatcott <inet@intellisys.net>
Altus OK