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Ash Small

Tue Jan 22 2013, 09:09AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

2Spoons wrote ...

If you read through that wiki page you will see that fine milling (<2um particles!) and sintering seems to be crucial for good magnetic properties. If melt casting of ferrite were feasible it would be done industrially as it would result in a denser product and potentially higher mu.

That's the point I was trying to make. You need a fine powder. Melting it and casting a larger core won't work, even of you don't change the chemical properties in the process.

I realised I didn't get all the details correct, and that they contain other metals as well. Sintering requires very high pressures.

BTW, Thanks for the link.

StormInABottle

Tue Jan 22 2013, 11:57AM

Registered Member #9252 Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253

I found someone that sells ferrite cores locally i will visit him soon.

He has sticks.

I wonder if i can stick 4 of them togeather using epoxy and make a square which i shall wind on

Or he said he has U shapes. If i find at him large i will buy it. Wish me luck guys :D

Ash Small

Tue Jan 22 2013, 02:50PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Arcingnoob wrote ...

I found someone that sells ferrite cores locally i will visit him soon.

He has sticks.

I wonder if i can stick 4 of them togeather using epoxy and make a square which i shall wind on

Or he said he has U shapes. If i find at him large i will buy it. Wish me luck guys :D

Yes, you can 'stick them together'. but they have to be tightly pressed together, unless you are using 'flyback topology', as any gaps are effectively 'air gaps'. For example, when you use a flyback and drive it from a Mazilli ZVS driver, you remove the airgap. You generally don't want gaps when using 'push-pull' topology.

Generally, it's 'the bigger, the better' because you can get more volts per turn, but there comes a point where cooling the core becomes an issue.

The transformer I'm building has two sets of U cores side by side, with the windings wound around both, to double the volts per turn.

StormInABottle

Tue Jan 22 2013, 03:53PM

Registered Member #9252 Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253

then can we take it as far as winding the secondary on a stick of ferrite 10 cm long and 1 cm thick. Just a normal circular stick? and the primary over it?

Also so 2 U Side by side doubles the voltage i get when using an O and forming that O by sticking 2 U togeather.?

So lets say i use the normal O core. and get 4000 kv
i use the U side by side to get 8000 kv?

StormInABottle

Wed Jan 23 2013, 05:58AM

Registered Member #9252 Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253

Why ain't no one replying

paris

Wed Jan 23 2013, 09:16AM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

I thought you can buy powdered iron from china , seen that on some site a year or so ago.
maybe ferrite mix I dont know

Ash Small

Wed Jan 23 2013, 09:16AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

A stick of ferrite 1cm in diameter will give ~1V per turn. My 2 sets of U cores side by side (4 U cores in total) will have a cross sectional area of @18cm^2, and I'm hoping for 20-30V per turn. Hope this helps.

(I didn't answer earlier, as I'm in the UK, and it's early morning here now.)

StormInABottle

Wed Jan 23 2013, 11:08AM

Registered Member #9252 Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253

1 v per turn isn't good at all..
i 'd have to do something like 12,000 turns lol.

But that 2 cores idea seems interesting

So lets say that we have a normal flyback core. A side is square and and the other is for some reason circular

So now i take 2

Square sides facing the same direction and circle side opposite direction.

And then wind on the square side the secondary

Then 4 on one side of the circular and 4 on the other. And center tap them. That sounds like a pretty weird idea lol

Ash Small

Wed Jan 23 2013, 03:48PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Arcingnoob wrote ...

1 v per turn isn't good at all..
i 'd have to do something like 12,000 turns lol.

But that 2 cores idea seems interesting

So lets say that we have a normal flyback core. A side is square and and the other is for some reason circular

So now i take 2

Square sides facing the same direction and circle side opposite direction.

And then wind on the square side the secondary

Then 4 on one side of the circular and 4 on the other. And center tap them. That sounds like a pretty weird idea lol

If you're describing what I think you're describing, it's been done several times before. You are on the right track, though.

A flyback will usually take a few volts per turn in push-pull mode, if it's a fairly large one.

StormInABottle

Wed Jan 23 2013, 06:25PM

Registered Member #9252 Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253

So your saying that using it with push pull or flyback modes reduce V/turn?

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