All online and my tables stop at 50 SWG. I don't know if the standard copper resistivity formula breaks down over/less than 50 SWG. Wire in question , measured optically to about 0.05 mm diameter as too fine to mike up. About
I presume that the sizing conventions still hold, where the gauge value is logarithmically related to the nominal resistance. 50 gauge should be about 10 ohms/foot, 60 about 100 ohms/foot, etc.
19.7/meter is about 6 ohms/foot, so that should be about 48 gauge?There is a free downloadable calculator that goes to 60 gauge (and that has other capabilities as well) over at
As a last resort, you could try drawing a graph of diameter or diameter-squared against SWG, AWG or resistance. If you can find a straight-line relationship, you can extrapolate to any value you need.
I think you can still buy graph paper, rulers and pencils in shops - if you can find any shops. :-)
On Mon, 15 Aug 2011 15:12:37 +0100, "N_Cook" put finger to keyboard and composed:
Resistivity is calculated according to the following formula:
rho = R x A / L
where ...
rho = resistivity = 1.68e-8 ohms/metre for copper R = resistance A = cross-sectional area L = length of material
Therefore ...
A = rho / (R/L) = 1.68e-8 / 19.7
A = pi x r^2 = pi x (dia/2)^2
dia = 2 x sqrt(A / pi) = 2 x sqrt(1.68 x 10^-8 / 19.7 / pi) = 0.03295 mm
According to the tables, your wire size appears to be 49 SWG.
- Franc Zabkar
"Nutcase Kook"
** Last time I dealt with fine enamelled wire like, that it was from the high impedance (output end ) transducer of an Accutronics reverb unit.But the finest I have seen is on the coil of an AKG D19 ( 200 ohms) mic capsule - about 0.03 mm.
The D19 diaphragm was sold as a spare part and used in other mics, like the original D12.
..... Phil
copper
About
Thanks for that, a useful little suite of apps
Have something to add? Share your thoughts — no account required.
Ask the community — no account required