ferrite or powder iron?

Question

I need to build some inductors for elliptic low pass audio filters. The values are near 0.004H and 0.007H. The output impedance is about

100ohms and the voltage level is about a volt or so. So in other words the current is in the area of 10mA. The parallel capacitance I have to put across the inductors is fairly high so that winding capacitance probably doesn't matter at all. I can use lots of turns.

My options as I know them are a higher permiability power iron or a ferrite part. Would one material be superior to another? I've got some lower permiability ferrite cores and also some small gapped EE19 ferrite coresets with about 200nh/t^2. I also have some good sized #26 powder cores.

Project is for one homebrew audio filter for ham radio and will not be mass produced.

regards, NEO

John Popelish · Accepted Answer

I think I would work with the gapped ferrite cores, especially if they are a power material (high saturation flux). These are pretty linear (by virtue of the gap) and low loss at audio frequencies. The powdered iron #26 cores are just distributed gap cores, but the iron material generally has more hysteresis loss than ferrite. I usually use #26 for DC energy storage choke uses.

Yzordderrex · Answer

Ok, thanks guys.  The gapped EE sets are 3C90 from small flybacktransformers that I designed for the boss.  They are small, free, easyto wind and mount so I'll go with those.regards,Bob

ferrite or powder iron?

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