From: fake@ddress.no   
      
   I have been thinking about the way a variac works. One thing that   
   puzzles me, is the wiper design:   
      
   If the wiper is too narrow, the output voltage will cut out when the   
   wiper is between two turns of the coil.   
      
   If the wiper is too wide, it will bridge two contact points, causing   
   one turn of the transformer to be directly shorted. Although it is not   
   a lot of voltage, it is also not a long piece of copper, so the short   
   circuit current, I expect, would be considerable.   
      
   Obviously, getting the wiper the perfect with, and also the wire   
   spacing equally perfect is not a practical approach.   
      
   How to they do it in practice? Is there some kind of snap action that   
   makes the wiper click from one turn to the next?   
   --   
   RoRo   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)