"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote in message ...
"Tom Bruhns" wrote in message
m...
....
But I'm still not seeing any need to know the number of turns, other
than for idle curosity. "I need to know because I want to"??

If I want to make a reasonable facsimile of the coil, I have to know a
bit about it, like what kind of ferrite material and how many turns it
has. I thought that getting the number of tuens would be alot of help
with this.

So what's wrong with just measuring the electrical properties of the
coil, if you really can't take it apart? You can measure inductance
as a function of frequency, and as a function of bias current, and you
can measure loss (or Q or ESR). It's also worthwhile knowing from the
circuit in which the inductor is used what the important
characteristics a that is, from the circuit, you should be able to
specify the inductor.

Certainly you should be able to estimate the number of turns through
transformer turns ratio, in spite of the possible errors, because you
should be able to get pretty good coupling between the coils. If K=1
there can be no difference in inductance between two coils with the
same number of turns. As Reg and others have pointed out, though, the
inductance is determined more by the air gap than by the core
permeability, so knowing the approximate number of turns may not tell
you as much about the core material as you had hoped.

Cheers,
Tom