HQ Pickup winding wire from AndryPickupParts team

[Joe Gwinn]

The temperature coefficient of resistance of pure copper

The temperature coefficient of DC resistance of pure copper is 0.0039 per degree centigrade. The 0.0039 is dimensionless, being a pure ratio.

For example, assume a coil wound with copper that is 10,000 ohms at 20 C. At 25 C, this same coil will read (10000)(1+0.0039*(25-20))=10,195 ohms, a ~2% rise.

This is true regardless of the winding details of the coil, at least to the first order. The resistance of the wire will increase as the wire is stretched, because the wire becomes longer and of smaller cross-sectional area. If one tests a coil too soon after winding, thermal effects and mechanical relaxation effects will both be operating, making measurements hard to understand.

Electrical resistivity and conductivity - Wikipedia

[David Schwab]

I bought several rolls of wire from MWS, the SPN was Essex, the PE was Elektrisola.
Not sure what brand the HFV was, it came from Mojo.
It's a good quality, and tough as nails.
I guess MWS just sells whatever they can get a good deal on at the time.
B_T

I buy my wire from BAE, and they mostly sell Elektrisola, but every now and then it's something else.

[MrCandy]

This is true regardless of the winding details of the coil, at least to the first order. The resistance of the wire will increase as the wire is stretched, because the wire becomes longer and of smaller cross-sectional area. If one tests a coil too soon after winding, thermal effects and mechanical relaxation effects will both be operating, making measurements hard to understand.

Yes we confirm the impact factor. You can see it on coil №1. It was the firs coil that day and stoper of tensioner was not warmed.
In the end wire lay not so tightly, the result you can see looking at RP index.

Also about temperature coefficient of copper: its linearity changes with time, normalization of copper temperature characteristics takes about 3-5 years.
Our chief really learned it very well when he worked at precision deep sensors and apparatus in Private Development Institute.
But this effect has very indirect relationship with guitar pickups. Caliber stability is what really matters.

[big_teee]

The first time I took a pickup out of the wax pot, and read the DCR.
The DCR was so high it scared me.
It's amazing how much temp. effects everything.
B_T

[copperheadroads]

[QUOTE=MrCandy;223413]

So is this test ACTUALLY 5 different brand of bobbins or identical bobbins with different tension

[Joe Gwinn]

Also about temperature coefficient of copper: its linearity changes with time, normalization of copper temperature characteristics takes about 3-5 years.
Our chief really learned it very well when he worked at precision deep sensors and apparatus in Private Development Institute. But this effect has very indirect relationship with guitar pickups. Caliber [diameter] stability is what really matters.

Yes. Which is why resistance standards and precision resistance thermometers are not made of copper.

[MrCandy]

So is this test ACTUALLY 5 different brand of bobbins or identical bobbins with different tension

The bobbins are identical. As for the first bobbin, mecanical breaker of tensioner was not warmed and this has affected the frequency characteristics.
You can see it on attached screens above.