On Thu, 21 Nov 2002, Olin Lathrop wrote:

*>A piece of #12 wire will be easier to deal with, and the much smaller
*>outer diameter will make it easier to compute the expected resistance.
*>Computing the resistance of a hollow tube between two point connections to
*>the outside of the tube is not a trivial matter.

It is trivial for a shunt because the tube with uniform axial current flow
forms equipotential rings on it and the load (meter) impedance is very
high wrt the shunt.

You only want the resistance by length of the tube to be able to take a
long enough piece. That can be computed from ohms/sq and the weight of the
tube per unit length (easier than fumbling with wall thickness etc). All
you need is a kitchen scale and a resistivity table.

Me, I'd take a 1kW heater band from some appliance (toaster ?) and fold it
over N times. That's the proper material for shunts too (manganin or
constantan). Connection is best made by crimping. By the time you need to
reproduce this there will likely be other options.

Peter

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