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Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
more randomness;
I have a large ferrite rod that I made by smashing up random damaged or scrap transformers and TV CRT deflection yokes and a few toroids, and stuffing the result in pvc pipe with polyurethane varnish as a binder could have been any mix of grades, though mostly MnZn. (Ferrite; 30mm dia x 400mm, winding; 100 quad-filar turns, one of the filaments being a nylon fishing line The result is incredibly disappointing :( it is ok as a moderate Q power inductor but poor as a transformer, even allowing for the open magnetic structure I left so much space in the core that the q of coils is low ... flux leakage all along the ferrite. So, I'm fairly sure that you will need to make some kind of really high pressure press to squeeze out internal airgaps
In another thread there was mention of you possibly using NiZn mixes, given the size of your transformer, length and capacitance of wire, insulation requirements, flux leakage ... I guess <100 kHz self-resonant windings, certainly less than frequency where NiZn would be better than MnZn.
And regarding core shapes and cross-sections ... KISS until enough practice to be confident, so that you do not abandon your project, as I have many ;)
P.S. anyone requiring a trifilar flux-capacitor choke please contact me I money-back unconditionally guarantee that without one of these (or similar) you will not achieve bi-directional time travel, PLUS if your claim is explained to my satisfaction and submitted before 2016, I will pay GBP 1000 cash compensation for the rights. Only one in stock ... photo's available to serious bidders. (this is for the Mk.II version, a modification of the one described above which did not work)
Registered Member #2939
Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615
You can simply buy ferrite powder. I think I paid about 70 euro for 2 kg. I don't recall the particle size. This was for work, so I don't have it anymore, and I can't recall who the supplier was. Material choices may be limited. If you want to get really experimental, you could try making your own ferrite by co-precipitating MnZn or NiZn with magnetite - same way powders for ferrofluids are made. But I think that may be something to try later ...
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
I'm assuming it has to be oxide free MnZn right? its possible to get MnO2 and ZnO on ebay and then co-fire it with excess carbon to remove all the oxygen.
Registered Member #1749
Joined: Fri Oct 10 2008, 02:04AM
Location: Claremont New Hampshire
Posts: 497
Well I guess the first Decision I have to make is what material I should use for the mold just simple Milled Aluminum or EDM a chunk of steel? I feel it would be cheaper just to use aluminum however I am worried that 10-15 tons will start to deform such soft metal I will see if I could use Sulaiman's Idea of contacting transformer core Companies for any advise If its not some trade secret.
Also we have a heat treating furnace that removes oxygen to prevent scaling and oxidation I could try sintering with that the heat is quite even.
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