Decreasing Resistance in Strat PUP

[RockHound]

Hey all!

New to the board. Thanks for having me.

I recently started winding strat pickups as a hobby/experiment. I'm finding that immediately after winding my pickups I measure my resistance and I'm happy with the result. However, reading always slowly decrease for a couple of days after my winds. The total decrease is typically about .5k total. For example, I wound a Texas Special style pickup to 7k, then a couple of days later its down to 6.5k.

Any thoughts? Thanks in advance!

[nosaj]

Temperature maybe?

nosaj

[Helmholtz]

The DCR of any PU depends on its temperature, because the resistance of copper increases by 3.9% per 10°C.
Your measured DCR drop of 0.5k corresponds to a temperature decrease of 18°C.

[kayakerca]

Hey all!

New to the board. Thanks for having me.

I recently started winding strat pickups as a hobby/experiment. I'm finding that immediately after winding my pickups I measure my resistance and I'm happy with the result. However, reading always slowly decrease for a couple of days after my winds. The total decrease is typically about .5k total. For example, I wound a Texas Special style pickup to 7k, then a couple of days later its down to 6.5k.

Any thoughts? Thanks in advance!

I have found that my Strat winds are close to 1kΩ hotter right after the wind is finished and the leads are soldered on. I always attributed it to the coil being a little warmer after the wind and when it cools, the temperature drop produces the resultant decrease in the in the DCR. Right or wrong, I always think of the process of winding as a lot like a tire on a car going round and round as you travel down the road where the tire compresses under the weight of the vehicle flexes the rubber causing it to heat up. Probably way wrong on this and why the coil temperature drops after the coil cools a bit after the wind, but you are right, it does.

[RockHound]

That makes sense. I usually measure right after soldering the leads. Probably adds a good amount of heat on the coil. Thank you!

[eschertron]

The process of winding does a lot of work on the wire. Bending a piece of 42awg doesn't seem as intense a workout as a strongman bending a crowbar, but repeat 15 thousand times...

[max oersted]

The DCR of any PU depends on its temperature, because the resistance of copper increases by 3.9% per 10°C.
Your measured DCR drop of 0.5k corresponds to a temperature decrease of 18°C.

I hope this info will be as helpful to all of you as it has been for me. Thanks.

58F (-2.17%)
59F (-1.95%)
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72F (0.87%)
73F (1.08%)
74F (1.30%)
75F (1.52%)
76F (1.73%)
77F (1.95%)
78F (2.17%)

[Helmholtz]

I hope this info will be as helpful to all of you as it has been for me. Thanks.

Sorry, not for me.
I just can't handle Fahrenheit. All thermometers over here and most of the world show Celsius.
And that medieval () Fahrenheit scale just doesn't fit with the formulae of science.

[big_teee]

I hope this info will be as helpful to all of you as it has been for me. Thanks.

Works for me!
Thanks,
T