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Filter Choke Design



I',m curious about another issue in filter choke design. Namely, are people 
considering the saturation flux density (Bmax) of their chokes? If not, then
the inductance of a choke which is exceeding Bmax is not the same value one 
measures beforee the choke is actually used in  tesla coil circuit. 

Suppose that a 100 turn choke sees:
10,000volts at 100kHz

reproducing the desing formula for flux density B:


          8 
   V x 10^
B= ------------------
    4.44 x f x N x A


where 
B=peak flux density in gauss
V=rms voltage
f=frquency in Hz
N=number of turns
A=core area in sq cm

then assuming the torriod has a square cross section A=1cmxcm

B=22,000 gauss

which is about 9x bigger than the Bmax for type 43 ferrite (Marlin P Jones 
ferrite torroids).


Has anyone checked their chokes to see if they're becoming magnetized or if 
the inductance has changed? Or am I missing something?

-Ed Harris



aside: Does anyone have info on the Bmax of powdered iron?