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Looking for big tansformer cores for high frequency use... Answered

Although I have made more and more progress with my home made ferrite I am not in the need for a big transformer core for testing purposes.
Desired frequency range: 30-120kHz
Required power: 2kW

I looked through endless pages of theoretical science stuff, a lot of useless online listings and thought:
Why not do what everyone does instead of using Google and ask my friends here? ;)

So far I think an iron powder core might be better in this case than the more traditional ferrite cores due to the power and saturation levels.
But what size would I really need so the  whole thing won't saturate or overheat?
Ring core or better a pot core?

Discussions

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iceng

Best Answer 2 years ago

I took these pictures of grain oriented tape cores for you.

The first four pictures could do 2KW at 20 to 40kHz... I like the Supermalloy 20W/lb at 10kHz that's still a lot of weight though.

http://www.mkmagnetics.com/dataSheets/pdf/brochure...

Picture 5 shows a rare tape core sealed in Oil and a bunch of ferrite cores.

CutCore-Bobbin3.jpgCutCore-Bobbin4.jpgCutCore_2031.JPGTape-Torroid6.jpgTorroidCores.jpg
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Downunder35miceng

Answer 2 years ago

Very nice collection indeed!
Seems I have to find a more efficient way to my problem as otherwise I will go broke for the core or the core is heavier than all the other things I need combined ROFL
Who know maybe I can make it work and get a patent on a light weight HF transformer system ROFL

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icengDownunder35m

Answer 2 years ago

I think the ferrite pot cores are your best down size, weight at high FQ for power transfer as size goes down proportionally to frequency.

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Downunder35miceng

Answer 2 years ago

That is true but I have to stick to a certain inductivity as well as a certain DC resistance.
So size does matter in this case but I will see what I come with in terms of pot cores or a "direct-transformer" with external core.

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Jack A Lopez

2 years ago

If you are looking for a new piece of ferrite, to sacrifice unto the gods of high voltage, or big flux, magic smoke, whatever it is you're working on...

I have always wondered: Can the big lump of ferrite found attached to the neck of a CRT tube be used itself as a transformer core?

I mean, this lump is made out of some kind of ferrite, its shape is approximately toroidal, and it is big. The bigness seems attractive to me. Other things being equal, the power-handling ability of any transformer seems to scale with size.

I dunno. Maybe I just think it would be neat if that part of an old CRT monitor, or television set, could be useful for something, essentially just a perverse desire to use every part of the buffalo.

You probably know the CRT part I am talking about. I think its original function was for focusing and deflecting the electron beam. Just to be clear I'll attach some pictures. The first pic is borrowed from Wikipedia article on "Cathode ray tube". The second and third are pics I took myself of a piece from my own junk collection.

By the way, regarding your goal to come up with a usable recipe for homemade transformer cores, I think this is a noble goal, and you should keep at it. I mean, it would be immensely useful for those of us who like to build homemade power converters.

Which reminds me: other amateurs are working on similar things. I noticed while looking at your Youtube video for your magnetite-plaster-of-paris mixture, there seem to be some videos from other 'tubers, also about homemade transformer cores, in Youtube's "related" panel on the right there. Who knows? Maybe it has been awhile since you checked out the "competition" there, or maybe you could find some inspiration.

Crt14-from-wikipedia.jpgcrt-ferrite-01.jpgcrt-ferrite-02.jpg
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Downunder35mJack A Lopez

Answer 2 years ago

I thought about those too but after taking a few old TV's apart I was disappointed to see that they only have a coil but no core.
My old monitor had a massive core but when it went to the bin years agao I did not consider keeping the core :(
I already inspired myself to take a whole new approach to the matter.
Due to the price and availability of certain ferrite powders I decided to stick to the basics everyone can obtain.
Once I am able to compare the results with a real core of similar size I can make adjustments in size and diameter to get closer to the real material.
So far I can only say that it is not easy to get it all right in terms of physical strength, flux desitiy and such simple things as core saturation.
The last is not really much of an issue if the material is weak anyway so there is room for improvement that might justify another Ible just for this.

I like to experiment and currently I like HF experiments LOL

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Downunder35msteveastrouk

Answer 2 years ago

That link confirmed some of the problems I am facing right now.
My approach with iron powder was not bad but I would like to be able to make a comparison with a proper core so I actually know if my new mix is any good.