serial inductors

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
so not really pi-wound, but wind each coil\tap in a quadrant of the donut; seems like you brought this up 4 years ago--the pi wind\distribute the C  thing...

long winter need more vit. C--and E
 
> for some reason, leakage C is a bigger problem with the toroid cores

On E-I core, the window is nearly square, maybe 2:1 rectangle.

Toroid, the wire-build is long and flat. Much more surface area for same volume of wire.

You could wind "narrow and fat", not using the whole circumference of the toroid. But then it gets tight in the hole, more surface area against the core.

For very lowest C you might go E-I-like except a round build in a square window. Inded some very high voltage windings approach round builds, partly for capacitance but also for smooth surface and less corona.
 
abbey road d enfer said:
Reverse winding or insulating tape won't help about leakage capacitance
I remember reading somewhere reverse winding could influence leakage C.  Here : "Balances the primary-secondary capacitance" http://www.groupdiy.com/index.php?topic=4242.40 .... is it to reduce the leakage inductance or capacitance ? and then what's the point of doing reverse winding for the secondary in a dual coils, humbucking configured Tx like the neve input if not for that ?

Splitting the inductor in two halves results in two smaller inductances and two smaller capacitances, each one having a higher resonant frequency.
So we are talking about dual sections bobbin or more on the same core to reduce capacitance, right ?  :)

Could we use that to reduce C for a Tx ?  I mean I think its already what we are doing with the dual coils Tx with UI lams (having 2 sections/bobbins then less turns but higher L leakage) but what about a multiple sections bobbin with EI lams for exemple ? I though it was for PowerTx , to separate the secondary from the primary high voltage....but could it be use to reduce C leakage or it increases too much L leakage compared with  the benefit of capacitance ?
 
today the toroid cores are a lot better,

so you can use less turns to get the same inductance,

this means you can skip the fancy winding techniques, like pie winding, back and forth winding,

leakage C in a toroid has to due with the pitch at which the wire is wound,

so you speed up the rotation of the core when machine winding.

EI lams will work, keep the turns down so you get less hum,

toroid self shielding properties are nice but if you shield an EI inductor, you should be ok.
 
Mzaar said:
abbey road d enfer said:
Reverse winding or insulating tape won't help about leakage capacitance
I remember reading somewhere reverse winding could influence leakage C.  Here : "Balances the primary-secondary capacitance" http://www.groupdiy.com/index.php?topic=4242.40 .... is it to reduce the leakage inductance or capacitance ?
Leakage capacitance is the sum of many unitary capacitances, which have different impact according to the placement. Capacitance between adjacent turns is not very significant because they end up in series, but capacitance between layers may be worse if the voltage between them is high. Reverse winding may be good or bad. Using RW and ending with the end close to the start is bad. On a toroid, it may be good to reverse wind in order to make the winding short and separated from the other winding (that's how safety transformers are made). You have to look at the geometry of the finished xfmr to evaluate all the possibilities.
So well, RW influences leakage capacitance, but does not necessarily reduces it. Better a large-ish but balanced cap than a small unbalanced one.
As to balancing "the primary-secondary capacitance", consider the voltages at the primaries. If one primary has the "hot" point on top and the other has "hot" on bottom, the secondaries will receive the same capacitive coupling on both sides (see attached).
then what's the point of doing reverse winding for the secondary in a dual coils, humbucking configured Tx like the neve input if not for that ?
RW is a necessity in humbuck configuration, so external fields cancel and internal fields add up.
Splitting the inductor in two halves results in two smaller inductances and two smaller capacitances, each one having a higher resonant frequency.
So we are talking about dual sections bobbin or more on the same core to reduce capacitance, right ?  :) 
It's equally valid for both cases, segmented or separate.
Could we use that to reduce C for a Tx ?  I mean I think its already what we are doing with the dual coils Tx with UI lams (having 2 sections/bobbins then less turns but higher L leakage) but what about a multiple sections bobbin with EI lams for exemple ? I though it was for PowerTx , to separate the secondary from the primary high voltage....but could it be use to reduce C leakage or it increases too much L leakage compared with  the benefit of capacitance ?
You answered your own question. I've never seen a case of a solid-state audio circuit that needed segmented construction for this reason.
 

Attachments

  • RW leakage.jpg
    RW leakage.jpg
    44.3 KB · Views: 19
Mzaar said:
try this one instead :
https://www.distrelec.it/set-nucleo-rm8-n41-uc-2u/tdk-epc/b65811-j1600-k41/332126

1 tap  start
2 tap  680 mH  (652 turns)
3 tap  1.3 H (900 turns)
4 tap  2 H (1120 turns)
very thanks
it's all right  ;)
 

Attachments

  • DSC_0520.jpg
    DSC_0520.jpg
    225.9 KB · Views: 35
Cool...that looks well filled.....brian, do you have a link for that diagram AWG/number of turns for those epcos coils ? I managed to get a diagram for another brand but not for the epcos cores.

pic #1 in 600*800 :
 

Attachments

  • 15s25ja.jpg
    15s25ja.jpg
    124.6 KB · Views: 12
abbey road d enfer said:
then what's the point of doing reverse winding for the secondary in a dual coils, humbucking configured Tx like the neve input if not for that ?
RW is a necessity in humbuck configuration, so external fields cancel and internal fields add up. 
Thx for the schem, abbey.

About the RW in humbucking configuration, I think there is a misunderstanding about what I meant. I was talking about RW inside each coil (for example with a structure P-S like in neve input) and not the fact that the first spool has to be wounded clockwise for example and the other anticlockwise (or we can flip the second spool/coil, right ?) to be in an humbuck config. just like with guitar pickup.

Here is a post about St Ives/Marinair neve input Tx and the difference was that StIves Tx didn't have the reverse winding.
http://www.groupdiy.com/index.php?topic=8633.0
I don't think the OT meant that StIves trannies aren't in humbuck config (it would be weird since they aren't mu-shielded and a simple flip of the 2d coil would make them in humbuck config ) but he probably wanted to say that each coil didn't have 1 or more layers reverse wounded vis-a-vis  the other layers of the same coil. Anyway that's what I understood but I could be wrong....

pic #2 in 600*800 :
 

Attachments

  • 5559fk.jpg
    5559fk.jpg
    184.4 KB · Views: 12
Mzaar said:
abbey road d enfer said:
then what's the point of doing reverse winding for the secondary in a dual coils, humbucking configured Tx like the neve input if not for that ?
RW is a necessity in humbuck configuration, so external fields cancel and internal fields add up. 
Thx for the schem, abbey.

About the RW in humbucking configuration, I think there is a misunderstanding about what I meant. I was talking about RW inside each coil (for example with a structure P-S like in neve input) and not the fact that the first spool has to be wounded clockwise for example and the other anticlockwise (or we can flip the second spool/coil, right ?) to be in an humbuck config. just like with guitar pickup.

Here is a post about St Ives/Marinair neve input Tx and the difference was that StIves Tx didn't have the reverse winding.
http://www.groupdiy.com/index.php?topic=8633.0
I don't think the OT meant that StIves trannies aren't in humbuck config (it would be weird since they aren't mu-shielded and a simple flip of the 2d coil would make them in humbuck config ) but he probably wanted to say that each coil didn't have 1 or more layers reverse wounded vis-a-vis  the other layers of the same coil. Anyway that's what I understood but I could be wrong....
I'm not savvy to the StIves/Marinair subtleties.
A transformer does not lend itself to much choice compared to guitar pick-ups.
Windings must have a large coupling factor, so the field generated by the primary is the governing element. Humbucking transformers can be done two ways:
One is to have two identical xfmrs mounted head-to-head, with the primaries in parallels, which results in RW coils, but small coupling factor between both cores.
The other is to have the windings done on two opposite legs of the core, then there is no such thing as RW. The direction of winding is continuous. Reversing the travel direction (in order to minimise leakage cap) is not Reverse-Winding.
 
reverse winding

either reverse your motor on your winder to reverse wind,

or keep the same motor direction but flip the mandrel around,

the mandrel is the thing that holds the coil while you are winding it,

reverse winding can be used for balancing leakage C or canceling noise.

if a EI core with one coil like the Neve output has reverse winding, it is to balance leakage C.

if a UI or L lam is used, then the transformer will have two coils instead of one as with the EI core.

if reverse winding is done on a two coil transformer like the Neve input, then it is more for humbucking than leakage C.

toroid output transformer might ply tricks with reverse winding to balance DC current,

now there is another way to wind coils besides fwd and rev,

you can wind a layer, but instead of winding back across to where you started,

you bring the wire all the way across the layer and start a new layer.

this lowers leakage C by dropping the potential between the starts of the 2 layers,

if you wind R to L and then L to R, you have twice as much voltage between the the starts of the layers, and thus, more leakage C.

called Ipower web hosting but all vacuumbrain stuff was purged 2 weeks after they screwed me out of my domain name,
so back up everything folks, Doh!  ;D

here is a jpg, hard to read but cool on reverse winding,








 

Attachments

  • revwind.jpg
    revwind.jpg
    251.1 KB · Views: 38
CJ said:
reverse winding
either reverse your motor on your winder to reverse wind,
or keep the same motor direction but flip the mandrel around,
the mandrel is the thing that holds the coil while you are winding it,
This may be thought as mechanically reverse-wound, but electrically, the winding direction is unchanged.
Real RW in a transformer can only result in loss of voltage.
 
Back
Top