From: ydtechHAT@techie.com   
      
   Late at night, by candle light, flipper  penned this   
   immortal opus:   
      
   >On Tue, 20 Mar 2012 12:45:59 -0500, John Byrns    
   >wrote:   
   >   
   >>In article ,   
   >> Roger Jones  wrote:   
   >>   
   >>> On Mar 17, 9:06 am, flipper  wrote:   
   >>> > On Fri, 16 Mar 2012 23:07:58 -0700 (PDT), Fai C    
   >>> > wrote:   
   >>> > (snip)   
   >>>   
   >>> >   
   >>> > But the basic "idea" seems simple enough. Two primaries wound in   
   >>> > series opposition so the same DC current through both cancels each   
   >>> > other's magnetic field for a net DC flux of 0. The 'tertiary', as they   
   >>> > seem to call it, is then AC bypassed so it's 'out of circuit' for   
   >>> > audio, leaving the varying magnetic field of only one to couple into   
   >>> > the secondary.   
   >>>   
   >>> (snip)   
   >>>   
   >>> At face value this would appear to short out the spare secondary to   
   >>> signal since the B+ side is zero impedance and so is the presumed AC   
   >>> bypass cap, thus the whole of the OPT is shorted.  You'd need an "near   
   >>> infinite" impedance current source to do this, and match the DC mA's.   
   >>> What might I have missed?   
   >>   
   >>I don't think you have missed anything, it looks to me like C2 the 100 uF cap   
   >>pretty well shorts out the audio, excepting the effect of the transformer   
   half   
   >>primary winding resistance which prevents the capacitor from being a zero   
   >>impedance short, letting a little audio sneak through.   
   >   
   >Why do you think shorting one winding shorts the other?   
      
   Because they're magnetically coupled, just like in any old   
   transformer.   
      
   - YD.   
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