Amorphous metal tape

On Saturday, May 29, 2021 at 7:31:27 PM UTC+10, palli...@gmail.com wrote:
> Mike Coon wrote: 
> ===============
> > 
> > > But for an inductor you want a gap, and R-core (or any tape-wound core) 
> > > won't give much of that SFAIK. 
> > > 
> > Why? I thought the point of core designs was largely to minimise any 
> > gap, but I haven't been following the whole argument...
> ** FYI : 
> 
> any "gapless" magnetic core saturates very easily, losing its magnetic properties when used as an *inductor". 

It saturates at lower ampere turns than a gaped core, and the permeability of an ungapped core tenbds to be a bit less predictable.

> Transformers are a different story, since primary off load currents are small. 

That does depend on the application.

> For a compact inductor that passes significant AC or DC current, a carefully sized air gap is essential. 

It can useful, but "essential" depends on the details of the appllcation.

> This apples to laminated steel or solid ferrite cores - but not so much to powdered iron cores as the air gap is intrinsic. 
> 
> Not a simple topic, bore your self to tears looking it all up. 

There 's a shortage of good texts, and a liberal supply of bad ones.

https://www.amazon.com/Soft-Ferrites-Second-Properties-Applications/dp/0408027606

E.C.Snelling's "Soft Ferrite" is about a bad as they get. It's got all the information you could ever need presented in way that is particularly confusing and unhelpful. 

The Siemen's Soft Ferrite data book and application notes was much less ambitious, and enormously more helpful. Siemens ferrites as now EPCOS parts, and it''s part of TDK. The late great Tony Williams e-mailed a couple of megabyte worth of most of them to his friends some time ago.

-- 
Bill Sloman, Sydney

In article <e95c9102-be08-4eb6-898d-e8c39e133c6an@googlegroups.com>, 
pallison49@gmail.com says...
> 
>  Mike Coon wrote:
>   ===============
> > 
> > > But for an inductor you want a gap, and R-core (or any tape-wound core) 
> > > won't give much of that SFAIK. 
> > >
> > Why? I thought the point of core designs was largely to minimise any 
> > gap, but I haven't been following the whole argument...
> 
> ** FYI  :
> 
>  any "gapless"  magnetic core saturates very easily, losing its magnetic properties when used as an *inductor". 
> Transformers are a different story, since primary off load currents are small.     
> 
> For a compact inductor that  passes significant AC or DC current, a carefully sized air gap is essential.  
> This apples to laminated steel or solid ferrite cores -  but not so much to powdered iron cores as the air gap is intrinsic. 
> 
> Not a simple topic, bore your self to tears looking it all up. 
> 
> 
> 
> .....   Phil 
> 
> 
>             

No need, that was sufficient unto the day, thanks!