[Amps] amp schematic drafting?

[Paul Kelley N1BUG]

I hope this isn't too far off topic...

Can anyone recommend free or low cost software for drawing tube 
amplifier schematics? I have been searching for some time but 
haven't found anything with a component library well suited to this 
purpose (often missing are such things as variable caps, 
potentiometers, tubes, relays, switches, and other parts common to 
amps). Or do I need to make my own component library to do this?

Many years ago I had built my own component library for some old DOS 
  'paint' type program, which worked well enough. Sadly a series of 
stupid actions on my part resulted in loss of those files long ago.

73,
Paul N1BUG