Opposite-wound PUP

[mac639]

In a perfect world I suppose winding one coil CW and the other CCW on top of it would give zero output. I'm thinking of speakers pointing at each other and wired opposite polarity. Should be no sound but of course that doesn't happen but there will certainly be reduced output. I wish I could remember where I read something on the net a few months ago about hum cancelling. They were talking about putting a large coil with just a few turns all around the pickup case and the pots and other wiring close by. They also had a couple of low resistance resistors (pots?) in there and the whole thing was wired in series with the pickup. Since it had rather low DC resistance it didn't affect the overall performance of the pickup and was too far away from the magnets to be be influenced by them. BUt they claimed it intercepted the low frequency RF waves hanging around in the room and cancelled them (sucked them up) before they got to the pickup. I must try to find that article again if I can....it was interesting anyway.

[Bent]

Mac, this extra coil...how would you suggest it be wired up? It has to go to something, either ground, or hot, or one to both.
I have been using a wrap of copper foil around the coil and hooked it up to ground, with limited success.
Would this be the same or no?

[Dave-M]

Hi guys:
I posted this in another thread that no one responded to. Has anyone tried winding to a centertap using two reels of wire? It should take half the time of Bent's method. I, too, was wondering if this would cancel the audio as well as the hum.

For reference, two equal resistances in series double the ohms value of one resistance, and in parallel halve the ohms value.

If you know the DC resistance per foot of the wire you use, you can measure the length by an ohmmeter. Divide the total resistance by the resistance per foot. The smaller the gauge, the larger the resistance per foot, similar to a lane reduction on the freeway ... harder to get through.

The output of the pickup varies directly with the number of turns, so higher resistance means you have more turns, and therefore more gain.

DC resistance and AC impedance differ in magnitude for a coil. The impedance is the sum of the DC resistance and the AC reactance.

Inductive reactance varies directly with the frequency of the note struck on the guitar and the number of turns, and adds to the impedance.

The proximity of the pickup windings introduce a capacitance. Capacitive reactance varies directly with the number of turns, but inversely with frequency, and subtracts from the impedance.

So, lots of windings produce high gain, but your low frequencies are impeded by the capacitive reactance, and high frequencies are impeded by the inductive reactance. I think there is also an inherent capacitance between the coil and ground, which shorts out highs.

If I am wrong in any of this info, please let me know.

[Dave-M]

I just found this info.
Two pickup coils can be connected in four ways:

Code: Select all

Method Polarity  Windings  Output  Hum-Canceling
1)     Same      Same      Strong  No
2)     Opposite  Opposite  Strong  Yes
3)     Same      Opposite  Weak    Yes
4)     Opposite  Same      Weak    No

Courtesy http://www.1728.com/guitar1b.htm