Since it is not evident in the linked diagram, and my ACSII diagram got botched up, I should probably point out that the guitar strings are grounded.
I think the only thing Seymour Duncan designs is electromagnetic pickups. I believe the basic circuit design was designed 40+ years ago by the...
I've got a circuit depicted below. Another, more colorful diagram can be found at http://www.seymourduncan.com/support/schematics/S_1singlecoil_1vol_1tone.html . The circuit has a grounded guitar string that vibrates over an inductor in a magnetic field. The inductor is actually a composite...