Inductance value of the drum core inductor

[kudjung]

Hi,

Anybody has a formula for calculating the inductance value of the Ni-Zn drum core inductor. I've some of this inductor with this drum core that I want to re-wind. For ferrite core, there's easier method that we can use Al value for this. (Al =L/N^2). I can't seem to find any manufacturer provided the Al data for this drum core.

TIA,

 

[FvM]

Measure the inductance and determine an AL value on your own. Generally, open magnetic path inductors will have the AL value more depend on winding geometry than a closed path type, but it should at least allow an estimation. For bobbin cores, you find AL values from several manufacturers, e.g. Fair-Rite or Feroxcube.

 

[atripathi]

L=μ*Ac*N*N/l

n, number of turns
Ac, cross section area of the core
μ, permittivity of the free space or if no air gap the permittivity of the ferrous material
l, length of the air gap or if no air gap the length of the ferrous materials loop