Use Multi-Section Windings to Reduce Self-Capacitance

[Bagpipe]

0000000000000000000

[rjb]

Shush... is he asleep? 46 posts on his first day here, insulted everyone in sight. That's got to be a record.

[Bagpipe]

Shush... is he asleep? 46 posts on his first day here. That's got to be a record.

You may do dirty things to the hole at my back - but please do not make fun out of other users. I point this out a second time to users, which contributed -well- almost nothing to the thread.

Look into the mirror, if you want to laugh about humans.

P.S.: Nietzsche was just an overwhelming huge asshole. That is my opinion. Flush his so.called philosophy down the toilet and start reading Kant and Weishaupt. I am german. I know who i am talking about.

[Antigua]

Because the geometry of the turns of the coil or coils (in the two views) is essentially unchanged. Those turns have no ide what a single-section bobbin is, or how it differs from a two-section bobbin. Imagine the turns floating in space, ignoring all the stuff that holds those turns up off the floor.

If what you were saying was true, the inductance would have a linear relationship with the turn count, which is to say a simple multiplication, but that's not the case, it's the square of the turn count, due to flux linkage.

[Antigua]

The application specific implications of Miller capacitance are still not entirely clear, but that aside, I still think a low C guitar pickup is valuable for the same reason a low C guitar cable is valuable. It comes from the basic assumption that voltage is the objective, that L and C are unwanted side effects, and that to the extent they're not, you're afforded more flexibility if you add them back in, in a deliberate way.

I've seen threads talking about lower capacitance due to thicker build magnet wire or "scatter winding", and the lowest C I've ever measured in a typical Strat pickup comes out to around 80pF at best. If a capacitance as low as 30pF can be achieved with a sectioned coil, it pretty much renders all other that other discussion moot.

[Mike Sulzer]

Because the geometry of the turns of the coil or coils (in the two views) is essentially unchanged. Those turns have no ide what a single-section bobbin is, or how it differs from a two-section bobbin. Imagine the turns floating in space, ignoring all the stuff that holds those turns up off the floor.

No, the geometry is different. You can look at this as two coils, each with inductance L, where the inductance of the series combination is greater than 2L but less than 4L, because they couple, and we do not know the coupling coefficient. In the single coil case you have to consider the coupling of each turn with each other turn. Of course, you can look at the split bobbin case as one coil, and then you have to consider the coupling of each turn with every other turn also. I see no reason say the two cases are the same, or different, or by how much.

[Mike Sulzer]

What is this big deal about the Miller effect? It just means that the input impedance of the amplifier is higher than you might expect if you did not know about it.

[Helmholtz]

If I had to speculate about the results of a PU coil with 2 winding sections wired in series (aka chambered coil), I would guess, that
- total self-capacitance will be noticeably reduced
- total inductance is reduced
- output would be more or less the same, given the partition wall is very thin. The upper coil will contribute about twice the signal voltage of the lower one*.
- frequency response will show one or two strong secondary resonances (anomalies).

*@ Antigua, didn't you mention that you once wound such kind of stacked coil?

[Mike Sulzer]

If I had to speculate about the results of a PU coil with 2 winding sections wired in series (aka chambered coil), I would guess, that
- total self-capacitance will be noticeably reduced
- total inductance is reduced
- output would be more or less the same, given the partition wall is very thin. The upper coil will contribute about twice the signal voltage of the lower one*.
- frequency response will show one or two strong secondary resonances (anomalies).

*@ Antigua, didn't you mention that you once wound such kind of stacked coil?

Yes, that is what I would hope for (the decreased inductance). Thus a skilled winder could get a bit more output without losing highs. And a skilled salesman could make a big deal out it. But at least it would be based on reality, unlike a lot of other sales claims.

[Helmholtz]

Yes, that is what I would hope for (the decreased inductance). Thus a skilled winder could get a bit more output without losing highs. And a skilled salesman could make a big deal out it. But at least it would be based on reality, unlike a lot of other sales claims.

I thought so and see the chance as well.

[ken]

Quote Originally Posted by Helmholtz View Post
If I had to speculate about the results of a PU coil with 2 winding sections wired in series (aka chambered coil), I would guess, that
- total self-capacitance will be noticeably reduced
- total inductance is reduced
- output would be more or less the same, given the partition wall is very thin. The upper coil will contribute about twice the signal voltage of the lower one*.
- frequency response will show one or two strong secondary resonances (anomalies).

*@ Antigua, didn't you mention that you once wound such kind of stacked coil?

I thought Duncan was famous for making this same type of stacked humbucking pickup

Maybe somebody really needed to switch to decaf before joining forums...


Ken

[Helmholtz]

Maybe somebody really needed to switch to decaf before joining forums...

I once read about a desease called the tourette syndrome, that can't be cured by decaf.
BTW, who cured our problem?

[John_H]

I once read about a desease called the tourette syndrome, that can't be cured by decaf.
BTW, who cured our problem?

Maybe he found his meds. He was off the rails! After reading through the thread, I realized that a couple of the things being discussed with Joe's original post impacted some multi coil pickups that I'm making.

I found a couple of good articles on the subject, and came out of it better informed. I got a good laugh when one of the articles mentioned that if you wanted to stir the pot on a message board, "start a discussion about reducing parasitic capacitance by using multiple coils".

[rjb]

BTW, who cured our problem?

It appears that the problem self-corrected.
But I think Warren Zevon helped.

WZ deployed 10:58 pm; reply to WZ 11:03-11:16 pm; posts edited to "000000..." 11:31-11:41 pm.

-rb

PS (Edited): While we're speculating (AKA gossiping) here, fasting can screw up different people's metabolism/brain chemistry in different ways. IIRC, wasn't there some mention of Ramadan?
Maybe fasting exacerbated a manic episode?

[Antigua]

*@ Antigua, didn't you mention that you once wound such kind of stacked coil?

I just compared the output levels of both halves of a stacked humbucker, which is geometrically similar Fender Vintage Noiseless, Analysis and Review | GuitarNutz 2 , the bottom coil produced about 9dBV less than the top coil. If the partition was thinner, the loss would not be as great, but I'm sure it would still be significant.

Note that with a stacked humbucker, the lower coil is out of phase with the upper coil, so the series output of both coils is lower than the top coil by itself. The loss in that case is about 3dBV.