Date: Tue, 21 Sep 2004 20:45:21 +0200
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From: "Hans-Albrecht Haffa" <dk8nd@web.de>
To: rsgb_lf_group@blacksheep.org
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Subject: LF: Re: LF components ...more Magamps still are in use. DK 8 ND
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Dear wWolf and others, 

yes, mag- amps are used in SMPS, toroid cores of vitruos metals  (Metallische Gläser) manufactured by Vacuumschmelze Hanau  ore similar material by Micrometals(US) are used. These are metal wound toroids in protective encapsulation . These controllers are very fast and cause less interference than step down converters.  A good controller IC is UC3838 by Unitrode (Texas Instruments). It is just that nobody of the development engineers likes mag amp circuits, due to little knowledge on magnetics.
55,
Hans-Albrecht
DK 8 ND

Literature:
Transduktorregler in Schaltnetzteilen. Dipl.-Phys. D. Grätzer  und Dipl.-Ing. W. Loges
Vacuuumschmelze GmbH, Hanau. Technische Informationsschrift TB-410-1, Mai 1988.


"Designing Magnetic Amplifiers using toroidal strip-wound cores made of VITROVAC 6025Z"
PV-010
 
Toroidal strip-wound cores of VITROVAC 6025Z. PV-007, Edition 10/89


rsgb_lf_group@blacksheep.org schrieb am 18.09.04 10:48:06:
> 
> Hi Alan,
> 
> from the days of repairing TV's I remember the permanent magnets on certain "coils" too. Guess they used this to distort the current waveform in a controlled fashion for the deflection unit.
> About the DC-bias winding: Sounds a bit like a "transductor" - ancient magnetic component, sometimes called magnetic amplifier. The basic idea was to control a strong AC current with a weak DC current. But I cannot imagine these are used in SMPSU's.
> 
> About the slots in ferrite rods: Yes, they are used to reduce eddy currents. Especially in those high-permeability types which are more semiconductors than insulators (you can tell with an ohmmeter). I have a large bundle of them in my radio-direction finding antenna for VLF ;-)
> 
> Regards, and have a good LF season,
> 
> Wolf DL4YHF
> 
> 


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