In a message dated 7/19/00 1:52:33 PM Eastern Daylight Time, sean@........... writes: << I have found a useful source of magnets in the McMaster Supply catalog (www.mcmaster.com; 3000 page catalog 630-833-0399). They have two pages of Alnico-5 and Alnico-8, and another two pages of rare earth magnets and ceramic multipoles. I am using a bonded neodymium ring magnet for a new feedback transducer. I think that their offering is more complete and consistent than Edmund Scientific. THey have some rather large offerings >> Sean-Thomas, Thanks for the above information. McMaster has a huge offering of magnets available, an order of magnitude more than Edmund Scientific. I found just what I wanted to replace the rather temperature-sensitive "Wondermagnet" Neodymium magnets I was using on my McWilliams torsion-balance magnetometer. Alnico magnets are much less temperature sensitive than the rare earth magnets. I ordered an Alnico 8 magnet 3/8-inch diameter by 4-inches long. Alnico 8 has a lower temperature coefficient than the more commonly available Alnico 5. For my purpose a favorable temperature coefficient is more important than field strength. In a torsion balanced magnetometer the TC of the magnet and the TC of the torsion wire add to cause drift error. Many thanks, Cap __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>