Re: Interesting inductor observation

["Ed Phillips" <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

> 
> I can't see any reason for this. If the inductance
> is the same, the resistance is the same, and
> there are no significant nonlinear effects, as
> core saturation, an inductor is an inductor,
> nothing else.
> For high-frequency operation, there is the added
> complication of the self-capacitance and other
> parasitics, but for inductors operating at the
> power line frequency this is not important.
> 
> Antonio Carlos M. de Queiroz

	I agree completely.  Apparently the "gentleman" doesn't know what he is
talking about, or has been quoted incorrectly.  An inductor IS indeed an
inductor period.  Assuming core saturation is really not a factor, that
is.  I have always been suspicious of the use of a Variac as a ballast,
unless there is a pretty big air gap in it.

	Someone suggested using air-core ballast inductors.  If you can afford
the wire it would take to make a coil of suitable inductance and current
rating that would be a fine idea.  I would think the resistance would be
small enough not matter if the wire could carry the current.  Somewhere
(I can't find it when I want it, of course) I have a copy of a
University of Illinois Experiment Station Bulletin from the early 1930's
advocating the use of air-core inductors. Includes a lot of design
information, including discussion of optimum geometry.  I'll try to run
it down in case anyone is interested.

Ed