Re: How to put Air-Gap in EI cores?

siliconmike wrote: 
Its a solid ferrite EI core, not laminated core. How to create air gap
in the center leg (while not creating air gap in the side legs) ?

Or is this not possible ?

The equations gave me air gap to be put in the center leg. How can I
"distribute" this air gap, so that all 3 legs have the same air gap ?

default wrote: 
On 15 Dec 2005 04:14:46 -0800, "siliconmike" <siliconmike@xxxxxxxxx>
wrote:

One application note helped me calculate the Air Gap in the center
branch of EI core, for my SMPS design.

I'm about to purchase an EI core and bobbin. But how do I create the
Air Gap (0.4 mm) ?

Thanks
Mike

You don't interleave the laminations and keep the I's and E's on their
own sides -  slide a piece of paper or plastic of the required
thickness between the sides and tighten the frame or housing.

One can't just do the center this way, for that you need to lap the
center down with abrasives, or buy iron that is already stamped.

Hand lapping is somewhat variable in results.  Place I worked at we
used a 1/2 inch thick piece of plate glass, epoxied and screwed the
E's together and a strip of emery cloth. - that was only done for very
specialized transformers where we wanted part of the core to saturate
so we weren't cutting away the whole center leg.  That was very rare
(once in two years).  The paper in the gap is pretty common . . .

BTW cutting and grinding operations on stacked or wrapped laminations
frequently results in laminations connecting to their neighbors - that
raises eddy currents.  The cut end may be etched with acid to remove
the connecting burrs.
--

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----


for ferrite cores you have to specify the gap when you order them.
rw
.

Relevant Pages

  • Re: How to put Air-Gap in EI cores?
    ... Its a solid ferrite EI core, ... How to create air gap ... The equations gave me air gap to be put in the center leg. ... > You don't interleave the laminations and keep the I's and E's on their ...
    (sci.electronics.misc)
  • Re: Loosely coupled transformer windings
    ... My drawing probably wasn't too clear, but there was an air gap in the middle ... leg. ... I figure that I can wind the 3 windings, ... then increase the air gap to reduce the coupling to the secondary until, ...
    (sci.electronics.design)
  • Re: How to put Air-Gap in EI cores?
    ... ferrite can be ground back with the right abrasives, do you intend ... > The equations gave me air gap to be put in the center leg. ...
    (sci.electronics.misc)
  • Re: Crotch Rockets
    ... core muscles; or switch to a less aggressive riding position. ... All leg stretches ... Sport bikes are made for hard and deep ...
    (rec.motorcycles)
  • Using ferrites on thermocouples
    ... I have incoming 8 type T thermocouples (they share a common constantan leg) ... figure 8 dual-hole core, presumably for better "matching". ... will not be too pretty (the common leg will have 8 ferrites on it). ...
    (sci.electronics.basics)
Quantcast