XPost: alt.engineering.electrical, sci.electronics.design, sci.e   
   ectronics.repair   
      
   On Wed, 9 Nov 2011 12:10:19 -0800, Bob E.  wrote:   
      
   >> What does U4 do?   
   >   
   >Provides a Vcc/2 local "ground" so I can use these op amps with a single   
   >supply voltage.   
      
   Hint:  Don't use the chassis ground symbol as a "Vref" symbol.  It's confusing   
   and someone along the line might get hurt.  Grounds should be.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)