XPost: sci.electronics.repair   
   From: bobnospam@gmail.com   
      
   Don Pearce wrote:   
   > On Mon, 6 May 2013 07:08:15 -0700, "Bob F"    
   > wrote:   
   >   
   >> Don Pearce wrote:   
   >>> On Sun, 05 May 2013 23:04:35 -0700, isw  wrote:   
   >>>   
   >>>>>>> Looks OK to me. It's configured as a series common mode stopper.   
   >>>>>>> What's the problem?   
   >>>>>>>   
   >>>>>> Will this design eliminate ground loop problems? My concept of   
   >>>>>> baluns was that   
   >>>>>> they isolated the two ends by placing them on opposite windings   
   >>>>>> of a transformer. I am no expert, which is why I asked.   
   >>>>>>   
   >>>>>   
   >>>>> That is a different thing. You need a transformer to kill a ground   
   >>>>> loop entirely, but yes, provided there is enough inductance in the   
   >>>>> coils this will still make a good job of getting rid of hum from a   
   >>>>> ground loop.   
   >>>>   
   >>>> If there's enough inductance to attenuate 60 (or 50) Hz from the   
   >>>> power line, why won't it do the same for similar frequencies in the   
   >>>> desired signal?   
   >>>>   
   >>>   
   >>> No, because of the way the windings are arranged their inductances   
   >>> cancel each other out for the audio signal, but not for the induced   
   >>> hum.   
   >>   
   >> The windings being on a transformer arranged so that common mode   
   >> noise cancels, and the signal doesn't?   
   >>   
   >>   
   > That's it. The windings are wound in the same direction on the two   
   > sides. That means that the forward and reverse signal currents on the   
   > two windings are always in opposite directions magnetically. So the   
   > signal doesn't see any net inductance.   
   >   
      
   Is this design going to avoid ground loop problems? Those signals would just be   
   on the one side, so would they be canceled?   
      
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