- …tube.
  - I've never been averse to using props during
presentations.  At this point I whipped out an actual 6SN7 I'd bought
a couple of days before at Electronics Plus.  Unfortunately, neither
nanotechnology nor multimedia have as yet advanced to the point where
I can make a vacuum tube pop out of the page as you read this.  But,
you can turn to page 
 and see a schematic of the
circuit I'm talking about.  All is one.  Or something.