peg@psuecl.bitnet (09/03/89)
Hello there!!
In the March 1989 issue of Radio-Electronics, there is a construction
article on an audio power amp with 12VDC supply. The conversion from
12 VDC to +/- 35 VDC is accomplished using a toroidal transformer.
The article claims that the ferrite core (toroid) is a critical part
and cannot be substituted. However they give turns ratios, etc.
implying that you CAN "wind yer own". Can anyone tell me more about
this core that they call "tape-wound"? What the heck does that
mean--what's wrong with MY tape? I almost suspect the company that
designed the amp wanted R-E to sell a few xformers for them!!
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...)
Thanks!
Paul E. Ganter
p.s. their specs: 1 mil tape-wound
1.460 x 0.915 x 0.345 "
Magnetics, Inc. #50029-IDISW@cup.portal.com (Isaac S Wingfield) (09/05/89)
"Tape wound" refers to the core, not the wires wound on it. The core is wound from thin, funny alloy (square loop), metal, looking a lot like a roll of electrical tape. Give up; there's mo way you can get your hands on a quantity of the tape for any reasonable amount of money. Last time I needed tape wound cores, the raw metal sheet was $70.00 per pound, 1000 pound minimum, and that did not include slitting to the 1/2" width I needed. Good luck, Isaac isw@cup.portal.com
tomb@hplsla.HP.COM (Tom Bruhns) (09/05/89)
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.