From: pallison49@gmail.com   
      
    Jeroen Belleman wrote:   
   ===================   
   >   
   > Iron is good in low-frequency transformers because it has a high   
   > saturation field and high permeability, so you can get away with   
   > relatively few turns for the windings. Its disadvantage is that it   
   > is conductive, so there will be eddy current losses, which get   
   > rapidly worse with higher frequency. Those losses can be reduced   
   > by making the core out of thin insulated laminations, but this   
   > gets impractical quite fast.   
   >   
      
   **  Typical iron core transformers intended for 50/60 Hz can be used to 20kHz   
   and beyond with no such issue.   
        As the operating frequency rises, core magnetisation falls cancelling any   
   rise in losses.   
      
      
      
   .......  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)