I use gSCHEM which is a Free, GPL'd, easy to use Schematic Capture program.
Oh, I don't use gSCHEM currently, but yep for schematic capture, it's nice and can produce vector graphics as well. Last I checked, there wasn't really up-to-date binaries for Windows though (or MacOS for that matter), so if the OP isn't using Linux, that may be impractical. (And also, last I checked, that was a while ago, gSCHEM was hard to build on Windows/MSYS2 from source...)
(Again, for those intimidated by gSCHEM or who can't use it, KiCad does also produce vector graphics and has a much larger library AFAIK! Either way, there's really little reason to use an all-purpose drawing program for this IMO, as those schematic editors are real schematic editors, much easier to use for schematic entry, and can definitely produce vector graphics which will look every bit as good as using Illustrator or Inkscape, but a lot less clunky for this!)
For pure-Windows users that want something simpler than KiCad, there's also TinyCAD, which works fairly well, is simple to use and even though it can't produce vector graphics formats directly, it can export to EMF, which is a graphics metafile, which in turn can be imported in Inkscape (and others), and can then be exported to your favorite vector format (SVG, EPS, PDF, others...) I used to use this a few years ago and it was fine. Depending on the application you use for document editing, you may not even need to go through Inkscape (or such), because on Windows, many document editing apps can directly import EMF and will translate it to pure vector graphics.