Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!pasteur!ucbvax!hplabs!hp-pcd!hplsla!tomb
From: tomb@hplsla.HP.COM (Tom Bruhns)
Newsgroups: sci.electronics
Subject: Re: "Tape-wound" toroid for R-E xformer???
Message-ID: <5170056@hplsla.HP.COM>
Date: 5 Sep 89 15:50:01 GMT
References: <53180@psuecl.bitnet>
Organization: HP Lake Stevens, WA
Lines: 24

peg@psuecl.bitnet writes:

>Anyway, any feedback on tape-wound toroidal ferrite cores or the
>project in general would be appreciated!  (Almost wish I'd taken
>a course in power, now...)

>Paul E. Ganter

>p.s.  their specs:     1 mil tape-wound
>                       1.460 x 0.915 x 0.345 "
>                       Magnetics, Inc.  #50029-ID
>----------

Tape-wound cores are NOT ferrite!  The tape is a thin magnetic metal
alloy -- 1 mil thick in the example you mention -- that is wound like
a roll of Scotch (tm) tape.  Thus it's torroidal.  They are generally
wound with a (silicone?) liquid insulating the turns from eachother (at
least the few I've taken apart :)  , and encased in an aluminum form
sealed with an insulator on one side.  Alternatively, they can be 
encased in plastic.  I thought "Reference Data for Radio Engineers"
had something about them, but only find reference to molybdenum-
permalloy powder and carbonyl powdered iron cores at the moment.  
Magnetics, Inc., publishes catalogs listing characteristics of their 
cores as a function of things like frequency.