I found this article on the design of a guitar pickup interesting, because quite a few years ago a group of friends and I were trying to design a music writing guitar. This was unfortunately long before cheap high speed computers were available, so we were not able to market the idea, but we actually built a guitar and logic circuitry capable of doing the job.
From the linked article:
Pickups have been made with ceramic and Alnico magnets for decades, so it’s kind of an expected tradition that the pickups are so tall. That’s a design limitation of those magnets, not neodymium magnets. We’d like to see a guitar body without any pocket or hole cutout in it, with a pickup that’s super thin. One could make a pickup a little larger in area, but very thin so that it just sets on top of the body of the guitar. Imagine a guitar body with no pockets, and pickups that are less than 1/8" thick; that would be neat.
Part of what was needed was to unambiguously identify which string was vibrating and to pass this information along as a digital signal. Standard guitar pickups would not be able to do this, so I came up with the idea of using the plucked string as the moving coil, and small neodymium magnets were embedded and fit flush into the guitar body beneath each string where a pickup would normally be installed. The signal generated by the string moving through the magnetic field when plucked is amplified and generates an unambiguous output.
Each fret was sawed into six segments, and small wires were welded to the back of each and passed down the neck to the logic board. This enabled the logic scanning array to identify digitally which fret/string combination was being used. The ends of the steel guitar strings were wired into low impedance windings of tiny transformers, whose secondaries fed op amp differential amplifiers to get a CMOS level signal to drive Schmitt Triggers which provided the "plucked string" digital signal.
The guitar makers in the project did a beautiful job. It occurred to me that since we had individual signals from each string, we could output these as analog signals into a mixer and the guitarist could select the gain for each string separately. The idea worked very nicely, and although the music writing guitar never materialized (it's been done in the 21st century), the novel pickup idea seems to have generated a little interest in those guitar makers with whom I have shared the idea.
This innovation permits each string to be electronically processed individually for reverb, gain, fuzz etc. There need be no visible pickup since the magnets are either mounted flush or recessed and filled with epoxy and wood dust filler.
ETA: I have long been interested in rare earth magnets, and I found
Amazing Magnets to be a good source.
apparently the system misread a click or some such - it should have rejected the second????????? I obviously thought you meant this and the guitar one!!!!!
