Rivkin, you explanation sounds most interesting, as well as you links, which I will read - and hope I will understand

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I must say, that I am overwhelmed by the inputs and the quality of the inputs, thank you very much.
capt.smash, no you are not out of your depth, on the contrary. You are dead on mark. Yes the fils must be used only in one direction, or it wont work. All the litte pieces of iron would be all confused otherwise

. Thank you for answering.
Jens