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Soviet ferrite.

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Marko

Mon Mar 07 2011, 05:14AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi all,

I was wondering about the NOS russian ferrite (bars, toroids) that tends to appear on ebay at giveaway prices. What are the specs of the material and is it any good for today's use?

What it lacked in quality, it could probably make in numbers though! I was wondering if a bunch of these bars could be stacked interleaved (pole-pig style) to produce a core for a monster HV transformer. And they have some giant toroids too.

Marko

Sulaiman

Mon Mar 07 2011, 01:34PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

With minor deviations, ferrite is ferrite.
For a given relative permeability ferrites from all manufacturers that I've investigated have approximately the same properties (u' & u'' vs freq.).
The only difference is the cosmetic qualities.

If you go with ferrite instead of iron/steel the working flux at 50/60 Hz will be less
(up to 1.8 T for silicon steel, 0.3 T for ferrite)
At 10's of kHz frequencies the ferrite wins easily.

Marko

Tue Mar 08 2011, 04:40AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Sulaiman wrote ...

With minor deviations, ferrite is ferrite.
For a given relative permeability ferrites from all manufacturers that I've investigated have approximately the same properties (u' & u'' vs freq.).
The only difference is the cosmetic qualities.

If you go with ferrite instead of iron/steel the working flux at 50/60 Hz will be less
(up to 1.8 T for silicon steel, 0.3 T for ferrite)
At 10's of kHz frequencies the ferrite wins easily.

Never said I would use it at 50Hz

I was just wondering whether this might be some sort of high-frequency/low permeability or in other ways useless material. Those toroids would make great transformers for induction heaters and alike and there are at least 160 of them available... and bars can be stacked into monster cores for transformers and inductors.

Marko

Weston

Tue Mar 08 2011, 04:55AM

Registered Member #1316 Joined: Thu Feb 14 2008, 03:35AM
Location: Cambridge, MA
Posts: 365

I found one seller that lists the permeability of the core:

I guess we can assume that all the other Russian ferrites have the same properties?

One thing to watch out for would be if any of the cores are actually powered iron....

Torchwood

Sat Mar 19 2011, 11:11AM

Registered Member #2668 Joined: Sun Jan 31 2010, 12:11PM
Location: South Australia
Posts: 18

The radio manufacturer that one seller claims they came from wasn't located in Pripyat was it?

haxor5354

Sat Mar 19 2011, 03:44PM

Registered Member #2063 Joined: Sat Apr 04 2009, 03:16PM
Location: Toronto
Posts: 352

Torchwood wrote ...

The radio manufacturer that one seller claims they came from wasn't located in Pripyat was it?

what? did they salvage it from the Chernobyl nuke plant?

Kizmo

Wed Nov 16 2011, 10:48AM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

Bumping this old thread

I just purchased bunch of 50mm id 100mm od soviet toroid ferrites.

There is no data available about material M15BA. What kind of tests i should perform? I have pretty good bk precision lcr meter, dso, signal generetor and high power h bridge inverter with adjustable frequency/dutycycle which I have been using with other homemade ferrite transformers.

I could figure out the nH/turn squared value and max flux density pretty easily but is there anything else worth of measuring with my equipment?

Steve Conner

Wed Nov 16 2011, 12:22PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

The only other relevant parameter really is the thermal limited flux density vs. frequency. It's usually a good deal less than the saturation flux density.

Ie, how many gauss peak-peak you can run at various frequencies, for a temperature rise that you consider safe, such as 30 or 50 degrees above ambient.

You could compare with another toroid of similar size and shape made from Western power ferrite, and see if the Soviet one gets hotter.

You could also find the Curie temperature and see if losses increase with temperature, with the possibility of thermal runaway.

Marko

Wed Nov 16 2011, 01:21PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hey guys

Well, I asked Zillipoper about those toroids, and he said they are a low permeability type any no good for anything like a power transformer, and I didn't dare to buy them after that... (some smaller toroids and E cores from the same seller are good by the way).

Apparently, in "M15BA" the 15 is the permeability marking :(

The ultimate way to test - use one as 1:1 transformer with a offline inverter (SG3525/TL494 flyback driver or anything like that you have around) with about 30:30 turns and see if the inverter current goes skyrocket with increase of voltage, and how well it powers a bunch of lightbulbs on secondary side...

I got a toroid from another seller anyway for which I was sure is the right material (used in a CWDRSSTC test). Would be cool if those toroids turned out to work after all as I thought they're useless (apart maybe for buck chokes?)

Marko

Kizmo

Wed Nov 16 2011, 02:39PM

Registered Member #599 Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624

How about for common mode chokes? I may need current balancing chokes in drsstc tank circuit (2 inverters and one tank circuit)

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