[JN] magik ???

Grego Sanguinetti grego at sandesco.com
Tue Feb 2 22:56:16 CST 2021

Cool gadget. Is that for winding toroids?

The last "transformer" I wound was flat (planar) and used 30nm wire.
No core.
probably of no use for audio, unless you are an alien bat


On 2/2/2021 12:41 PM, Hanski via Sound wrote:
> Hi gents, my 2cents.
> magnetic energy is stored in an air gap.
> So if you need to store energy in a choke, you need an air gap.
> Sendust like other powder cores have a distributed air gap (there is 
> always some air between powder particles).
> Sendust is used in SMPS because it’s cheap and has lower magnetic flux 
> swing related losses than plain iron powder cores.
> Usually they come in toroid shapes. One could also use a gapped 
> ferrite toroid there, but it’s usually a bad idea because you would 
> need to locate all windings on top of the air gap to cancel the 
> external flux (less outside flux, less EMC).
> Other powder core materials:
> https://www.coilws.com/index.php?main_page=page&id=41 
> <https://www.coilws.com/index.php?main_page=page&id=41>
> -Hanski
> P.S. I really like homemade audio transformers.
> For small signal stuff one can use even plain SMPS ferrite. a few 
> thousand turns primary gives 200H inductance (Al = 12u) with commonly 
> available  ferrite toroid. (No DC bias)
> Just wound a couple with 50um thick wire. (My skills don’t go below 
> that, it’s already human hair thick) :)
>> ©
>> PS i’m not so sure Sendust would be that good for a transformer core. 
>> Sendust (aka Kool Mu) is often used in power supply chokes … because 
>> it stores energy well. is the capability to store energy better than 
>> other materials a good thing in an audio transformer? i don’t know 
>> (no irony). but i can imagine that the release of the stored energy 
>> «smears» the timing. isn’t the best core … an air core? because it 
>> does exactely the opposite — it doesn’t store any energy?  (btw. 
>> Sendust has seen wide spread use in audio when tape and cassette 
>> recorders were still mass produced. many of the better recorders used 
>> Sendust heads because it is very hard.)
>> _ _ _
>> aka christian rintelen
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