Use Multi-Section Windings to Reduce Self-Capacitance

[Mike Sulzer]

you (mike) write:"inductance changes with a split bobbin"

???
You mean in 1/1000 measurements, or what? Your coil gets thicker, with the same number of turns (split bobbin vs. normal bobbin) - the field should be huge enuff - i expect inductance changes in the "micro" range. Sounds a little paranoid, what you suggest here.
A split bobbin is just one: Not needed, because self-capacitance plays no role, in the face of Cable Capacitance.

Why should a different Bobbin change inductance <<<in a SIGNIFICANT>>> way?? What is the base of your assumptions - other than paranoia?

Inductance is greatly influenced by the flux created by current in one turn passing through each other turn. That is the source of the n^2 effect. Separating one coil into two or more coils in series can affect this except when you have a high permeability closed loop core. As I said, I do not know how much it affects it, or which way, but my point is that if it reduces it, that is useful because you can't the same output with a higher resonant frequency or more output with the same.

[rjb]

- What about horizontal field arrangement? North left/South right

1940s-1950s Electromuse "Eye-Beam" lap steel pickup. Next.

-rb


PS- The sun is shining here for the first time in 2 weeks. See you guys later.

[Mike Sulzer]

If you make a Jazzmaster type guitar pickup with six coils to reduce the pickup's capacitance, wouldn't this pickup be impossible to use 'normally' aka in a passive instrument's wiring environment? I think you would have to use a preamp with some strong toneshaping to sound anything like its passive counterpart.



This is interesting. Would the cable capacitance of whatever the guitar cord is made of make a bigger difference to the sound than the pickup capacitance? I remember some people using coily guitar cords for this reason.

Ken

Yes, the cable capacitance is more important the the coil capacitance.

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[Mike Sulzer]

Antigua:

Winding to Winding magnetic coupling? What are you talking about?

???, Magnetic coupling between turns is what makes high value inductors (and thus, audio transformers) possible, and so is also responsible for limiting the high frequencies in pickups..

[Mike Sulzer]

mike: Flux created by Current. I have to let that sag. Sorry... i don't seem to understand your words, nor the sense of your words. You have a static magnetic field - and you have a coil (or a split-coil) inside it. Do we still talk about the same issue here? Or are you ran away into transformers?

The static magnetic field is irrelevant in this discussion. The varying magnetic field created by ac current in the coil is what is responsible for inductance. the more this flux (field time area) is shared among turns the higher the inductance,

[Antigua]

Antigua:
What happens to the resonance peak with increased series resistance OR increased Eddy Currents (almost the same)??

Where do eddy current enter into the picture? The effects are similar but not identical.

Winding to Winding magnetic coupling? What are you talking about? There is no drop in inductance. Simple as that. A Split Bobbin Inductor has almost EXACTLY the same inductance as a single bobbin inductor. WHY should inductance fall?

The increase in inductance with added turns of wire does not increase at a linear rate, it's square the number of turns, due to magnetic coupling between the turns. If you pull the coil into two or more parts, you break up that coupling. You end up with two inductors, both having somewhat less than half the inductance of the original whole.

When you turn the volume down on your guitar, what happens to series resistance seen by the amp? And what happens to miller effect?

I don't know, you tell me.

[Mike Sulzer]

One can compensate for reduced winding space by using the next finer wire size. Unless the separators are fairly thick, inductance won't be much affected, so long as the same total number of turns is used. Cable capacitance is of course unaffected, but reducing the self-capacitance of the pickup increases our wiggle room.

I do not understand how you are so confident that the inductance does not change. Have you done this, and measured the result with an air core, or short cores as in a pickup?

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[Mike Sulzer]

Please read again, what you write. It is nonsense. Really. Not because i dislike you, but beacuse it is utter nonsense.

The varying mag. field is in truth a static magnetic field, which is disturbed by the string. This disturbance causes a disturbance in the coil - more turns - more pronounciated.

Current plays absolutely NO ROLE - except we talk of the effects of the load.

Sorry Mike - you must know, that i bear GREAT RESPECT for you. You may not be aware of it, but your publications are with me for at least 3 years now. I regard you as a star in the scene. But with this topic here, i just lose understanding for your points. Sorry. I don't want to offend you.

From inductance, Wikipedia:

Inductance is a property of an electrical conductor which opposes a change in current.^[1] It does that by storing and releasing energy from a magnetic fieldsurrounding the conductor when current flows, according to Faraday's law of induction. When current rises, energy (as magnetic flux) is stored in the field, reducing the current and causing a drop in potential (i.e., a voltage) across the conductor; when current falls, energy is released from the field supplying current and causing a rise in potential across the conductor. Mutual inductance describes the change of current in a circuit when a second circuit also experiences a change of current; energy is coupled from one circuit to the other through magnetic fields.
These effects are derived from two fundamental observations of physics: a steady current creates a steady magnetic field described by Oersted's law,^[2] and a time-varying magnetic field induces an electromotive force (EMF) in nearby conductors, which is described by Faraday's law of induction.^[3] According to Lenz's law,^[4] a changing electric current through a circuit that contains inductance induces a proportional voltage, which opposes the change in current (self-inductance). The varying field in this circuit may also induce an EMF in neighbouring circuits (mutual inductance).
The circuit component representing inductance is called an inductor. The term inductance was coined by Oliver Heaviside in 1886.<sup>[5]

Pickups cannot be understood by this "disturb the static magnetic field" thing. You need to apply Faraday's law. For example, check MacDonald (Princeton).</sup>

[Antigua]

Please read again, what you write. It is nonsense. Really. Not because i dislike you, but beacuse it is utter nonsense.

The varying mag. field is in truth a static magnetic field, which is disturbed by the string. This disturbance causes a disturbance in the coil - more turns - more pronounciated.

The residual flux of the AlNiCo or ceramic does not change as the string moves around, it is not "disturbed". Voltage is caused by magnetic change through the winds of the coil, and the primary agent of magnetic change is the moving, magnetized guitar string. The permeability of the screws, slugs or pole pieces will increase the total amount of change, but that change starts with the magnetized guitar string.

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[Antigua]

They are identical - except for the frequency dependence of eddies.

This is Transformer-Speak. Lets get back to the basics. We have an inductive sensor here. It is not just: Look the other way around at it. It is not that easy.

No - i don't. Sorry - i am no answering questions machine. And double *NOT* with people, who play - but not *are* true with their questions.

These read like non sequiturs.

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