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Inductor Polarity??
Inductor Polarity??
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Old 21st October 2019, 03:38 PM   #11
DF96 is offline DF96  England
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Quote:
Originally Posted by DBruce
Yet some people cannot hear the difference but some people can.
I understand that the truth is that most people cannot hear absolute phase with most music. A minority of people can hear absolute phase on some music.

The talk about electrons and coils is too unclear to comment on in detail, but I strongly suspect it to be bunkum.
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Old 21st October 2019, 04:31 PM   #12
Mark Tillotson is online now Mark Tillotson
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It all depends on impedance. Say the outside of the component has 0.1pF stray capacitance to some mains wiring that's been routed close to the pcb. That means the capacitive pickup will be 7.5nA (for 240V 50Hz).

In a 1k impedance circuit that's 7.5µV, in a 100k impedance circuit its 0.75mV. The latter is likely to appear as obvious hum in a preamp circuit. The former is only going to be an issue for something like a sensitive microphone or phono preamp.

This is one of the reasons for using low impedances in solid state circuitry, the other being less Johnson noise and less magnification of current noise.

But its rare to see an inductor in an audio signal path these days, so its rather a moot point. For capacitors in filter circuits it is a valid concern at times, but most people ignore it.
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Old 21st October 2019, 05:39 PM   #13
DBruce is offline DBruce
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Originally Posted by Zero Cool View Post
Ok I know that sounds like a silly question, but is it?

Some high quality film caps are marked with an "In" and "Out" lead marked on which lead is connected to the inner or outer part of the cap.

and while I was looking as some foil inductors It dawned on me that maybe they have a "preferred" direction related to signal flow as well?? Would we want the "In" to enter from the inside of the inductor and exit out the outer part? or the reverse?

ZC <---over thinking things once again!
For capacitors, I would take the same theory as in my previous post, i.e. for a spiral type capacitor, it is harder to gather electrons at the inner film than at the outer film, if electrons can actually travel in capacitors, they would flee from the inner film to the outer more easily.

So if one needs a capacitor with lower leakage, he can connect the outer film to the more negative side and make it harder for electrons to travel or leak between films.

Likewise, if a flyback transformer has multi-layer windings, to connect the outer layer to the positive source would be a logical selection.

My previous discussion is mainly focused on the crossover inductors which is bulky and the current is high. Some people have been complaining that when they switch the two leads of their inductors in the crossover circuit, they can hear the speaker sound is different. I was just trying to bring out a possible theory for it, i.e. inductor polarity might be causing asymmetrical distortions.

Or maybe there are some other better explanations for this.
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Old 21st October 2019, 06:02 PM   #14
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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Inductors (mainly with higher frequencies) behave better when the inner turns are liver than exterior ones, this way the electric field near the inductor is much less, while magnetic field is unaffected, because lower RF potential turns act as a shield for E. I generally manufacture my own coils in such a way.
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Old 21st October 2019, 09:27 PM   #15
DF96 is offline DF96  England
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Originally Posted by DBruce
So if one needs a capacitor with lower leakage, he can connect the outer film to the more negative side and make it harder for electrons to travel or leak between films.
You will have to run that one past me again. The leakage current in a film capacitor (i.e. symmetric non-polar dielectric) will depend on the DC polarity of the outer foil?
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Old 21st October 2019, 10:30 PM   #16
Elvee is offline Elvee  Belgium
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In addition to all of the above, inductors can have an absolute (DC) polarity if they are of the cored variety: if the core is magnetized, the amplitude inductance will be different for the two polarities (which doesn't mean it could be used for rectification though).

This property was abundantly used in the CRT display era for various corrections: a small, generally adjustable magnet was attached to the ferrite core.

Note that even soft ferrites can retain a small remanent field
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Old 21st October 2019, 11:22 PM   #17
Mark Tillotson is online now Mark Tillotson
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Originally Posted by DBruce View Post
For capacitors, I would take the same theory as in my previous post, i.e. for a spiral type capacitor, it is harder to gather electrons at the inner film than at the outer film, if electrons can actually travel in capacitors, they would flee from the inner film to the outer more easily.



So if one needs a capacitor with lower leakage, he can connect the outer film to the more negative side and make it harder for electrons to travel or leak between films.
That makes no sense to me, the issue is that the outer film has more stray capacitance to the surroundings than the inner film. Nothing whatsoever to do with leakage which is a property of the dielectric film.
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Old 22nd October 2019, 01:11 PM   #18
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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Quote:
Originally Posted by Mark Tillotson View Post
That makes no sense to me, the issue is that the outer film has more stray capacitance to the surroundings than the inner film. Nothing whatsoever to do with leakage which is a property of the dielectric film.
As normally occurs that the capacitance of the coupling cap is several order of magnitude larger than the stray capacitance, the cap shorts both ends at the frequencies in which strays are relevant.
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Old 22nd October 2019, 01:25 PM   #19
DBruce is offline DBruce
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The figure below shows what I meant, though you might think it's trivial.
Electrons stay at the inner film have higher potential to each other. They have a tendency to travel to the outer film.

Click the image to open in full size.

Note: if you cannot see the figure, try right-click and open in new window. Sorry for this. It took me some time to share the figure.

Last edited by DBruce; 22nd October 2019 at 01:34 PM.
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Old 22nd October 2019, 01:41 PM   #20
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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If "electrons stay", then they are quiet. So, no AC currents are involved (Only DC), so no audio signal, so no stray capacitance effect at AC voltages or currents. It is a self contradiction.
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