Cedric Chang wrote: >>On Jun 28, 2007, at 2:07 AM, Vasile Surducan wrote: >> >>On 6/28/07, Cedric Chang 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 > > Have you considered this: The slug is moving back and forth in the coil form. The slug with the brass ends sliding in a brass tube would make a good wear surface. I have a book about making your own soleniods. It is a reprint from 1914. But it has some interesting info on how to make your own. and the basic of operation. http://www.lindsaybks.com/bks4/solen/index.html They have a lot of "Make your own " books that are not to expensive. The books are all reprints. http://www.lindsaybks.com/prod/index.html RECON -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist