[sdiy] Magnetic String Actuation

[Spiros Makris]

Hello, list,
I am interested in experimenting with magnetic string actuation. That is,
use an electromagnet to induce vibration to metallic(?) strings; the
opposite of what a guitar pickup does typically. I have seen this concept
realised in a couple of different applications:
1. Magnetic Resonator Piano <http://instrumentslab.org/research/mrp.html> is
an electronically augmented piano that can do cool stuff such as real
crescendos, electromagnetically dump strings, produce overtones etc. Every
sound produced comes from the strings themselves.

2. Ebow <https://www.thomann.de/gr/ebow_ebow.htm> is an electromagnetic
actuator for the electric guitar. Place it close to the strings and they
will start vibrating, similar to the way they do when using a bow.

3. Moog Guitar <https://www.soundonsound.com/reviews/moog-guitar> contains
some sort of actuator and suitable circuitry to make it infinitely sustain
notes, apply active damping and more.

I bet there are more if we start digging, but these are some examples I can
think of off the top of my head. Unfortunately, I don't have enough to go
on here and decide on what kind of hardware I need to produce this effect.
The magnetic resonator piano researchers have published a couple of papers
that go over the fundamental equations involved. Still, unless you can
really wrap your head around them (I can't) it's not enough to get you
going.
I obviously need some electromagnet, either off the shelf or custom wound.
Then I need an amplifier that can drive enough power into it, in the
correct frequency range.
Aliexpress is full of various electromagnets. How could I decide on a
couple that might be promising and give them a try?
What about output amplifiers? I know the basics of driving speaker coils,
but my guess is a strongly inductive load like an electromagnet is going to
be a different story.

I've been thinking about this for the past 10 years and still didn't manage
to figure it out. Any kind of info or advice you could share is invaluable!
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