Magnetite Cores

[69iron69]

I wonder if you ran current through the coils while the resin was liquid would help the magnetic alignment after the fact.

[johnb003]

You mentioned black sand in an earlier comment. I've heard this makes a good core for very fast switching, but I have not tested it. Have you tried it? What do you know about it?

So how would this compound compare to say, an iron core? I'm guessing since it's non-conductive there wouldn't be any eddy currents, but if it responds to the magnetic field, shouldn't it have strong attraction to magnets?

[codygillespie]

Chemically, black sand is the same stuff that im using. Iron will give you a lot more inductance but is subject to more magnetic eddies and dosnt completly release all its residual magnetism like Fe304. It has a weaker attraction to magnets than iron. More suited for using strong neo mags or high frequency applications.

[TATTOOTRAINING]

cool i was thinking i had to forge the iron to the shape i need. and the bridge or yoke you made ..you said it make it draw less and put out more? where can i read more info on this

[codygillespie]

well i would not go forging iron for a core, it would be better to buy some laminated silicon steel and have some one cut it for you like standard transformer cores are made if your wanting to use iron. I believe robert adams talks about connecting the backs of his coils for improved efficiency. Other than that i dont know where to look, just play around with it, its easy. When you connect the backs you will see the amp draw go down and the rpm's go up.

[TATTOOTRAINING]

cool, will do .thanks

[rudiblackrahmadi]

hi,

i just bought a bag of fe3o4 from my local chemist store.

i found that the powder is not attracted to a magnet bar.

i wonder if yours is also not attracted to a magnet or i bought a wrong 1.

btw, i got a red colour 1... does it matter?

thx

[codygillespie]

hi,

It should weakly be attracted to a magnet, your magnet might not be strong enough to notice it. I got a tip that it is better to mix it into a thick putty like paste and ram it into your mold, rather than the runny mixture i show. The red stuff is Fe2O3, i have a buddy that was testing mixing the red with the black to try and match natural black sand proportions, but i have no results on that to report. Good luck and thanks, keep me posted if you have any success.

cody

[rudiblackrahmadi]

hi cody.

thx for the info. i was using ndfeb to test my red powder... and as i said it does not react to it.

does your black powder react better?

im googling about ferrofluid...it seems it takes more than 2 to tango..

the hardest part of making it.. is i dont have any chemist knowledge and i dont what is the common human name for that stuff :(

[codygillespie]

Yea, the black stuff is what you want, thats Fe3O4 (magnetite). And it does react to the magnet. The red stuff Fe203 (hematite) is not what you want. They must have sold you the wrong stuff. Go to ebay and search for Fe3O4 They also call it black iron oxide.

[fdoca]

Hello:

U can hammer down to any magnets to powder then mix with resin, this will create the magnatic ferrite core.

[codygillespie]

I suppose you could. But that would not be the same thing that i have here. Pure magnetite is not magnetic at all. Lodestone, is magnetic and made from magnetite, again not what im doing here. If you want to play with magnetic cores you probably dont have to crush magnets, just wrap your coils around them.

[twilight1138]

The red stuff is most likely Fe2O3, which is not magnetic and won't work as a coil core.

[marthale7]

Ok, I have to know how well did this work for you? :)

[codygillespie]

Well to be honest i have not really got to put them to good use yet. You defiantly need to use neo mags on the rotor with these cores, and i dont have the ones i need and im also are redoing my motor again. So it may be a while, you know how it goes. Ill post updates when i get there : )

[rudiblackrahmadi]

hi cody.

further testing of my 'red powder'... as i said it does not react by using my ndfeb magnet, however, when i use a compass, the neadle react weakly. to me, it seems the red powder has a very weak Fe in it. is it good for my core? hmmm... i guess it is if i'm going to make a vhf/uhf (mhz) coil core.

futher reading about core material, the Fe is said good up to 100khz.. which i guess already fast enough for my project.. i think i need to add more fe material in it to meet my need.

[GBluer]

Very Nice Cody

Thank you for showing this.

Have you tried making any toroid cores for like a joule thief?

[codygillespie]

Thanks GBluer! I have not tried to make any toroids with it yet, but i dont think it would be very hard to do if you wanted to try it. You could probably just put a small tube within a large tube glued on a flat surface and fill the space between them. Interesting idea.

[GBluer]

Thanks agine Cody

I'll have to give it a try.

It would be lot cheaper that buying torids and then you can make any size you want.

[codygillespie]

Ah you have brought up a good topic: $Price$

fiberglass resin 15$ (lowes)

5lb bag Fe304 15$ (ebay)

Total  30$

That should make quite a few cores, i still have plenty left for more projects so far.

[lApEkv2l]

Very cool man. They all came out nice.

[codygillespie]

Thank you IApekv21. Hopefully it will work as good as it looks : )