This is the only place I can find that terminology, and it does not help me 
figure out what it means:

http://www.datadiwan.de/magazin/index_e.htm?/magazin/dz0101e_.htm

Marshall

Peter Rebaudo wrote:

> This question was initiated by an article about a device made out a old
> diathermy machine ( 10KHz). The author instructions were to connect the
> indifferent  pole of the secondary coil to 2 plates that seems to act as
> antennas.
> The instructions date to the 1940's
> That terminology does not appear in any of my physics or  electric
> books,  or dictionaries.
> Thanks you for your inputs.
>
> Peter R
> ----------------------------------------------------------------------------------------------------
> Subject:
> Re: CS>About Transformer Coils
>
> Peter,
>
> Your terminology appears a bit foreign to me. Are talking about a power
> transformer of an ignition transformer for an automobile?
>
> "Ole Bob"
>
> ----------------------------------------------------------------------------------------------------
> I am not familiar with that terminology, but my guess is that you are asking
> which pole is the one to be grounded on a spark coil. A typical spark coil
> from an old car will have one side of the secondary winding attached to
> either the case of the coil sometimes if it is a metal cased one, or to one
> of the two primary inputs.  If the coil inputs are labeled then I believe it
> is connected to the one that normally goes to the points.  But since the
> turns ratio is so high, you could use either one for the ground with very
> little difference.
>
> Marshall
>
> --------------------------------------------------------------------------------------------------
> Peter Rebaudo wrote:
>
>  Does anybody knows which one is the Indifferent pole (or Indifferential)
>  of a secondary coil.
>  And how to tell it apart from the Different pole?
>
>  Regards
>
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