Unwinding a steel laminate core inductor? Formula?

[AudioLapDance]

I have a 15 gauge steel laminate core 10mH inductor that I want to unwind to 6.4mH.

I can't remember where I found this:

"Inductance scales as the number of turns squared.
Count the number of turns across the coil and then from the inner diameter to outer. Multiply these together and you have the number of turns. Call this N1.
L1/L2 = (N1/N2)^2
N1/N2 = sqrt(L1/L2)

N2=N1/sqrt(L1/L2)"

But I think the author wasn't sure if it only applied to air cores.

Will this work for steel cores too?

Thanks,
Jeff

 

[Bill Fuss]

Hi Jeff,
I don't think it works like that with steel cores. If you have a scope and signal gen you can measure it by making a tuned circuit with a cap of known value. Very accurate also.

Bill