Looks like Inkscape is the most popular but with a moderate to possibly steep learning curve but I also found Circuit Diagram 3 which seems easier to learn and use. Both applications were listed in the very well written WikiProjects Electronics page s See the featureparison at the bottom of the page. I also found ProfiCAD that can be used for general schematic creation gets a lot of Google hits and good reviews but many of the download sites seem questionable; however this can be downloaded directly Download ProfiCAD s June 18 216 After finally getting some time to check these tools out I found Circuit Diagram 3 to be too italic basic it appears that you can only draw horizontal or vertically oriented wire lines andponents so useless for drawing delta and wye connections even though it is possible to add these s ofponents by writing and thenpiling XML descriptions with aponentpiling tool that can be downloaded separately. Circuit Diagram is great for standard rectilinear circuit layouts but I found it to be a little laggy and glitchy. Inkscape on the other hand is too italic plex finding out how to draw the lines needed to create schematics like the wonderfully rendered example on the Wiki page was mind-numbingly difficult because Inkscape is oriented towards graphic artistry even though it does have a (very) limited library of electronic symbols. Inkscape (online manual ) Frustrated out of my head I researched again and found good words for the Dia Diagram Editor which has a fairly extensive set of electronic symbols available and the LibreOffice Draw application 9 Flowchart Tools for Creating Charts and Diagrams Draw electronic schematics using LibreOffice LibreOffice Still s (most stable release of LibreOffice) No time to try these but they do seem to fit the bill for free high-quality diagramming tools that seem to be well documented.