Bruce, The Cd:Sn eutectic point is at 30:70, but the magic low thermal emf foo powers seem to happen in the 60:40 to 70:30 range... at least that is what all the references that I have found say. _________________________________________________________________ Hotmail: Powerful Free email with security by Microsoft. http://clk.atdmt.com/GBL/go/171222986/direct/01/

Mark Sims wrote: > Bruce, > > The Cd:Sn eutectic point is at 30:70, but the magic low thermal emf foo powers seem to happen in the 60:40 to 70:30 range... at least that is what all the references that I have found say. > According to an article in J Sci Instruments thermal emf against copper is about 300nV/C for the eutectic. If you read Russian the following article from 1956 covers a wide range of Cd Sn solder compositions and temperatures: http://www.springerlink.com/content/wj11xr8737770103/fulltext.pdf?page=1 http://books.google.co.nz/books?id=dunqt1rt4sAC&pg=PA266&lpg=PA266&dq=cadmium+tin+thermal+emf&source=bl&ots=oUwLjlaFW5&sig=khJZ0LAoiemkoNL6nuLpV8vKFws&hl=en&ei=9e8qS9m3LZGGswOtzLXWAw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CCAQ6AEwBQ#v=onepage&q=cadmium%20tin%20thermal%20emf&f=false <http://books.google.co.nz/books?id=dunqt1rt4sAC&pg=PA266&lpg=PA266&dq=cadmium+tin+thermal+emf&source=bl&ots=oUwLjlaFW5&sig=khJZ0LAoiemkoNL6nuLpV8vKFws&hl=en&ei=9e8qS9m3LZGGswOtzLXWAw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CCAQ6AEwBQ#v=onepage&q=cadmium%20tin%20thermal%20emf&f=false> suggests a low Sn lead tin solder (Sn:Pb 10:90) http://www.iop.org/EJ/abstract/0022-3735/9/12/029 Suggest a minimum in the thermoemf at about 18% tin. See the Czech article for the theoretical basis. Bruce