This is a small experiment motivated by the Magnetic Resonator Piano. The audio features harmonics of the E-string.

I’ve hooked up a more or less random electromagnetic coil to an old cassette player amp. The coil is positioned between the 1st and second fret (got a lot of good sounds there). There’s a lot of recording noise due to low levels (have to find a better amp for the coil)
The recording is produced by putting a sine signal on the coil, starting at around 82Hz and then slowly rising frequency up to an octave higher. I played with the harmonics when I found them and then continued up to the next resonance.
The coils frequency can be heard at 2:30 an other positions where there is little resonance from the guitar.