Product: Musical Instrument: Guitar
Visual Magnetic Field Guitar   (+5)  [vote for, against]
A visual display that corresponds to your performance!

This is my first post, so please no biting off my head. I searched past posts for related ideas and found none, so here goes...

Most electric guitars have a pickgaurd - the piece of plastic that lies underneath the strings to protect the body of the guitar from becoming all scratched up (from misguided and/or overzealous strumming). If you were to construct one that had a thin cavity in it, which was filled with iron filings and a suitable liquid to suspend the filings against the force of gravity, I believe you would have an automatic visual display to go with your music.

The pickguard surrounds the pickups on a guitar, which are basically small magnets. This in itself would create an interesting pattern in the iron filings, but there is more. The pickups in an electric guitar work by inducing an alternating current with a frequency that matches (and was actually created by) the vibration of the strings.

This means that you essentially have two magnetic fields on a guitar: 1) the constant field of the magnets, and 2) the non-constant field of the variable-current carrying wires. These fields interfere with each other to different degrees depending on the current in the wire, which correlates directly to the music you play.

Thus, as you happily strum your new VMF Guitar, the magnetic field pulses and flickers along with you, tossing the iron filings this way and that and creating a visual rendition of your performance!

The only way I could see that this wouldn’t work is if the interference of the current field cancels itself out. Since it is an alternating current, the interference would change between constructive and destructive very rapidly and you may not be able to see any difference. I’m not entirely sure if it would work this way though and my gut tells me that there should be some visual effect produced…
-- luecke, Oct 22 2003

(?) Magnetic fluid
-make your own from copier toner [csea, Jan 13 2005]

Apparently we're picking up a reputation that way. Given the past few days worth of ideas, it's easy to see why...
-- RayfordSteele, Oct 22 2003

I'll buy one! [+]
-- kmlabs, Jan 12 2005

>which was filled with iron filings and a suitable liquid to suspend the filings against the force of gravity,

You might search for a product called Magna-see, I recall using this back in the 1960's to view track alignment on magnetic tape.

Some enterprising highschool students discovered how to make thier own ferrofluid - apparently copier toner is magnetic - see [link.]
-- csea, Jan 13 2005

It seems to me that the magnetic fields would be oscillating at the same frequencies as the strings, a frequency range which is too high for human eyes to see. Also, the magnetic viewing liquid might have a low-pass characteristic, in that it simply cannot respond to magnetic fields that oscillate that rapidly. (I don't know—just a guess.)

However, if you were able to engineer magnetic viewing liquids that reacted in a DC manner to AC fields, and had different sensitivity bands over the range of frequencies produced by guitar strings, you could put those different liquids into different areas of the pick guard and get a kind of spectrum visualizer.
-- notexactly, Nov 11 2018

That idea is rather difficult to swallow ...

An OLED display underlying the frets would allow a sophisticated animation of the strings, or the music in general if not a solo guitar. Since that portion of the instrument faces away from the performer, it wouldn't be distracting.

In fact, pretty much the whole of the front of the guitar could be an animated display.

If the display were also a touchscreen, all sorts of other functions could be implemented; perhaps even (although this is very unlikely) actual music.
-- 8th of 7, Nov 11 2018

random, halfbakery