"Tom Bruhns" wrote in message
m...
So my first obvious question is, why would you care? If you want to
duplicate the inductor, you already know the inductance, and you can
measure saturation effects and even loss, with some ingenuity.
I could have two inductors that look the same on their outside, but have
radically different inductance values. I could have two inductors that
are of the same inductance but have radically different core material
and size.
I'm just trying to get some idea of what makes up the inductor. Turns
of wire is just one of them. Another is what kind of core material is
used. I think that if I know the turns, it will give some idea of the
core material.
[snip]
Cheers,
Tom
"Watson A.Name - \"Watt Sun, the Dark Remover\""
wrote in message
...
Suppose that I have an inductor that's covered with epoxy or similar
that prevents me from seeing or finding out how many turns of wire
are
on the core. The core is open, so that it's uncovered and most of
the
magnetic field is outside outside of the inductor. Obviously it's a
bobbin type core.
I have measured the inductor with an inductance meter, so I know
what
the inductance and other parameters are.
Suppose I take some wire, say roughly small if the inductor is
small,
and wind it around the inductor, over the existing windings so that
it's
within the magnetic field. I wind enough wire onto the inductor so
that
I get about 1/9, or 1/16 or 1/25 the inductance in the new coil.
Since the inductance is the square of the turns, I can say that if I
have wound 10 turns and the inductance is 1/16th that of the
original
coil, then the turns ratio is 4 to 1, so the original coil is about
40
turns.
Obviously the Real WOrld kicks in, and things may not always be
exactly
as they should be. But I haven't tried this, and I'm wondering if
any
other person has, and if it's a not unreasonably accurate[1] way to
guesstimate the turns, or if it is prone to a large amount of error.
I
guess it would also apply to a toroid if there is enough room to
loop
some wire thru the center hole, but this hole may be filled or
covered
up.
So has anyone played around with this contrivance?
[1] A not uncommon journalistic contrivance nowadays; seems like
these
authors just uncan stop not undoing this, and have unremembered to
not
undo it the old fashioned way, and just say "common".
--
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