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Iron core chokes (instead of ferrite & iron powder)




From: 	Adam[SMTP:absmith-at-tiac-dot-net]
Sent: 	Thursday, November 27, 1997 4:58 PM
To: 	tesla list
Subject: 	Iron core chokes (instead of ferrite & iron powder)


I know a lot of people are using ferrite and iron powder for chokes, but 
why not iron?  I understand that ferrite and iron powder are used in RF 
applications because they are less conductive than iron (by many orders 
of magnitude) so that eddy current losses are kept to a minimum.  

The question is, are these eddy current losses relevant in our particular 
application (RF chokes)?  We are not trying to make highly efficient RF 
transformers here, so shouldn't laminated iron cores be acceptable?  They 
would need to be very well insulated, of course, but this is fairly easy 
to do with just polyethylene.  Will the eddy currents be severe enough at 
100-200kHz or so that the core would be heated or otherwise compromised?  
In short, what's wrong with insulated iron laminate cores for the tesla 
choke application?

I ask because I have very little ferrite and iron powder materials at 
hand (except TV flyback U cores), but loads of E and I laminations from 
regular 60Hz transformers, some quite large.

-Adam


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Epoch, Inc. Digital Music Project

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