I want to build myself some electromagnets. For the coil I would use annealed copper, something like this: http://www.radioshack.com/product/index.jsp?productId=2036277
However I am trying to find some additional options for the core. I sort of like these ferrit cores: http://www.dextermag.com/products-page/b65611d0000r048-p-36x22-n48-7600-30-20.html (btw. can someone guess what unit the measurement is given in? I assume they mean inches right?)
However, I am wondering what other things, which you could find around the house, or at the doller store or wallmarts etc. might be used.
I have some of these here: (weights for the fancy mouse I need, couse I am at the computer too much... :-/..)
Or sewing machine bobbins:
I dimly remember, that cores which consist of multiple layers are stronger than simple iron cores (google wasnt helpful here, but maybe I didnt ask the right question.). Does anyone have any other ideas for materials to use for building electromagnets? Does anyone know, or have a link to, what the proporties of the ideal core should be?
Does anyone have any tips in general on building electromagnets?
What I need are two (times 4) small electromagnets which I can switch to either attract or repuls eachother. They dont need to be able to excert a whole lot of fource, but they should be able to attract each other trough 2 sheets of regular printing paper. Ideally I would like them to be around 1cm x 1cm x 0.6cm