On 09/16/2012 04:54 PM, J. L. Trantham wrote: > Pete, > > Thanks for the reply. > > I was just looking at the properties of the wire. I guess I don't > understand the 'resistivity' of 43-48 uOhmcm for the wire that is about the > same size as what the resistor is made of.
Example: 45 uOhmCm * L / A = Ohms L = length of wire in Cm A = Area of wire in Cm^2 > It lists a tempco of .00001 per K. Hmmm - 10 ppm / C? Not great. I assume that the resistors are empirically matched in pairs during manufacturing. > As best I can tell, the 5903 ohm resistor is about 15.5 mm long, on a 1 inch > flat form about 1 mm thick (about 2 inches per turn) and about 14 turns per > mm as best I can tell. I measured the wire at .05 mm thickness. That would > put it at about 217 turns, 434 inches, and about 13.6 ohms per inch. My > original calculation appears to be wrong. Using 45 uOhmCm: 45E-6 * 434 in * (2.54 Cm / in) / (pi * (.005 cm / 2)^2) = 2.52 KOhm At the risk of stating the obvious, have you considered Vishay resistors for the rebuild? Best regards, -- Bob Smither, Ph.D. smit...@c-c-i.com ========================================================================== "I'm sorry I ever invented the Electoral College." - Al Gore 11/08/00 ==========================================================================
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