Challenging and exciting new design needs a guru !

[J M Fahey]

Well, I found it an interesting problem too, although I'm clearly out of the pickup design/construction field.
So you say the OP is real close to the solution, and needs only very minor tweaking?

[Chuck H]

That's what the unpaid consultations were for (regardless of any contrary expressed intent). To anyone here who PM'd and offered advice, were any future royalties agreed upon? Anyone get that sweet carrot of a job as the build engineer? Honestly, what kind of nuclear rocket engineer that would work on this project is so exclusive that they need someone else to make the prototypes? Pffft.

Edit: I'm just being a cranky wise a$$. This has been an interesting read with the exception of my rants.

[LtKojak]

ThI'm just being a cranky wise a$$. This has been an interesting read with the exception of my rants.

Now, c'mon, Chuck. Don't underestimate the entertainment value of your excerpts. I, for one, being a cranky old fart, did appreciate lots.

[Mike Sulzer]

.....
Placing the magnetic field in parallel with the strings results in a higher output...

These directional things are confusing, but here is how I think it works:

When the conductor moves, we have a choice of two equivalent views, the law of magnetic induction, or an analysis of the force on an electron moving in a magnetic field. The latter is often simpler. If you take the cross product of the velocity with the magnetic field, you get the magnitude and direction of the force on the electron. The direction is perpendicular to both the velocity and the field. The current and voltage develop in this direction since that is the direction along which charge separation occurs.

For a ribbon microphone, it works like this: "In ribbon microphones, a current is induced at right angles to both the ribbon velocity and magnetic field direction." (Ribbon microphone - Wikipedia, the free encyclopedia)

You want to develop a voltage and current along the string. When you place a magnet under a guitar string so that the field is parallel with the string, this cannot happen. However, there is a significant perpendicular component near each end of the magnet as the field curls down to enter the pole. Then motion of the string parallel to the top of the guitar (usually referred to as horizontal, visualizing the guitar resting on the work bench) is perpendicular to this vertical component, and it drives a current perpendicular to both, that is, along the string.

Does this make sense?

[salvarsan]

... Anyone get that sweet carrot of a job as the build engineer?

That was no carrot, merely my observation.

If Gittler LLC wants more than one working prototype by NAMM '11 in January, they'll need
some skilled tech assistance to run through experimental designs more quickly.

If they reduce their goal to a Gittler Guitar made of modern alloy with pickups that don't
squeal or hum, and which have adequate output for production guitar amps, then
they are already there.

[bbsailor]

These directional things are confusing, but here is how I think it works:

When the conductor moves, we have a choice of two equivalent views, the law of magnetic induction, or an analysis of the force on an electron moving in a magnetic field. The latter is often simpler. If you take the cross product of the velocity with the magnetic field, you get the magnitude and direction of the force on the electron. The direction is perpendicular to both the velocity and the field. The current and voltage develop in this direction since that is the direction along which charge separation occurs.

For a ribbon microphone, it works like this: "In ribbon microphones, a current is induced at right angles to both the ribbon velocity and magnetic field direction." (Ribbon microphone - Wikipedia, the free encyclopedia)

You want to develop a voltage and current along the string. When you place a magnet under a guitar string so that the field is parallel with the string, this cannot happen. However, there is a significant perpendicular component near each end of the magnet as the field curls down to enter the pole. Then motion of the string parallel to the top of the guitar (usually referred to as horizontal, visualizing the guitar resting on the work bench) is perpendicular to this vertical component, and it drives a current perpendicular to both, that is, along the string.

Does this make sense?

Mike,

It is more like Lorentz Law where the current induced is related to the length of the magnetic field. Lorentz force - Wikipedia, the free encyclopedia

The magnet I used (from K&J Magnetics) is .25" wide X .125" thick X 2" long with the north and south poles oriented through the thickness. I clamped a Tektronics current probe on the string and used a heavy jumper to short the string ends together to form a current loop. The longer the magnetic field, the higher the current and the higher the voltage that comes from the output of a step up transformer attached to the ends of each string.
When I rotate the magnet 90 degrees to be perpenduclar under the strings, the magnet length, from the strings perspective, changes from 2" to 0.25" and the output clearly drops. When I place a ferrous metal plate under the magnet, the field is more focused and the string output increases somewhat.

I am sure there is an opportunity to model the impedance of each string and optimize the magnetic field model of a moving conductor (string) in a magnetic field. The mass, velocity and displacement of each string while vibrating produces a variable output (depending on individual string impedance and physical size) that would seem to have an optimum transformer turns ratio combination to produce a more balanced output beween strings.

The output of the voltage across a ribbon (in a ribbon microphone) is measured in microvolts while the guitar string output is up into the millivolt range due to the higher velocity of movement.

This is how I see Lorentz Law being related to this discussion.

Joseph Rogowski

[J M Fahey]

NAMM '11 in January

Don't worry, they won't be there.
Why do I think so?
Because judging from what I see, their letter to the NAMM administration may have read:
<ironic mode>"Dear Sirs, we want a booth, we won't pay for it, if we find it useful we might consider renting one the next year, for which we might consider payment."</ironic mode>
<serious mode> If I had an important event on short notice, and had a problem, no matter what, I would gladly PAY for consulting, and not try to see what could I get, (if anything at all) for free.</serious mode>
*Many* times "free" is not the cheapest option.
Guru Juanmanuelaj-ji Faheynanda Yogi
he he

[Mike Sulzer]

The magnet I used (from K&J Magnetics) is .25" wide X .125" thick X 2" long with the north and south poles oriented through the thickness.

That makes sense. The field is then perpendicular to the top of the guitar, and when the string moves parallel to the top of the guitar (horizontal with guitar on the bench), current flows along the string.

I would prefer to use only 1/4" along the string rather than 2" in order to keep more high frequencies, and so I would use a thicker magnet to keep the field strength up.

[Steve Conner]

I see this has been jacked into another Rogowski Ribbon Guitar thread.

The string-as-pickup idea is great, but is it relevant to the topic of this thread, the Gittler guitar? Is Joe Rogowski proposing it as a pickup for the Gittler? The metal neck would certainly be a convenient way to complete the circuit, but where would you hide the matching transformers in that minimalist body?