From: pallison49@gmail.com   
      
   Ralph Mowery wrote:   
      
   =====================   
      
   > > >   
   > > ** That does  *NOT* happen  !!!!   
   > >   
   > > With square wave input, a simple RC filer converts the wave to a TRIANGLE   
   shape if the frequency is high.   
   > >   
   > > Your ancient Sprague ( Black Beauty ?) is almost certainly leaky due to   
   moisture ingress.   
   > >   
   > > A DMM on ohms should show you that.   
   > >   
   > >   
   > > >   
   > When I said resembled sine waves, I knew they were not really sine,but   
   > did not crank the sweep far enough to see what they actually were.  It   
   > has been a while back that I did any thing with what circuit converts   
   > what, but did remember that LC low pass filters converted to the sine   
   > wave.   
      
   ** Yes, cos they filter with a -12dB/octave slope wiping out all the harmionic   
   of a square wave.   
      
   >   
   > The Sprague is not the Black Beauty lable.  I think it is the next   
   > generation, but not sure.  I don't recall the value, but at 500 volts dc   
   > it had less  than .1 ma leakage.  It did surprise me that it did not   
   > have a lot of leakage.   
      
   ** Equates to 5M ohms so would fully self discharge in about 1 second.   
      
    ( 5exp6 times 0.06exp-6 = 0.3 seconds )   
      
    Easily enough to upset many capacitance meters.   
      
    A good film cap of such value has a R value in the Gohm range and leakage   
   under 1uA.   
      
      
   ....   Phil   
      
      
      
      
   .....  Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)