>
> On Jun 28, 2007, at 2:07 AM, Vasile Surducan wrote:
>
> On 6/28/07, Cedric Chang <cc@nope9.com> wrote:
>>
>>> On Jun 27, 2007, at 10:06 PM, Vasile Surducan wrote:
>>>
>>> The key is not only the winding number/cross section (which is a
>>> problem of mechanical power versus efficiency) but the presence
>>> of the magnetic flux amplifier (brass tube as a support for
>>> windigs) and
>>> an end of the slug made from brass with a cone shape and perfect
>>> match into the
>>> negative cone of the ending brass tube.
>>>
>>> Inspire yourself from a high power DC relay design. The  
>>> efficiency of
>>> such construct is huge compared with a poor iron slug.
>>>
>>> Vasile
>>>
>> Why brass ?
>
> Because it concentrate the magnetic field.

I looked on the web and most folks said to use
ferromagnetic materials such as steel for the
magnetic flux concentrator.

http://www.ee.surrey.ac.uk/Workshop/advice/coils/mu/
http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/ 
Physical_Chemical/Permeability.htm

These indicate that brass is a bad choice.

Did I miss some important info ?

Cedric
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