I watched Hel­vetica over the week­end, and it must have stim­u­lated that part of my mind that thinks graph­i­cally. I had been com­plain­ing at work that our new schematic sym­bol for resis­tors has seem­ingly unnat­ural pro­por­tions, but I couldn’t quite put my fin­ger on why. What is “nat­ural” about a resis­tor symbol?

To try to answer this ques­tion, I culled a selec­tion of resis­tors from a bunch of old schemat­ics I have worked on. These include default sym­bols from OrCAD, Eagle, Gschem, and Altium. Often you can look at a schematic and imme­di­ately iden­tify the tool that was used to cre­ate it. That graphic sig­na­ture is not unlike a font, I think.

The two sym­bols on the left are the offi­cial shapes set forth in IEEE 315-1975 (“Graphic Sym­bols for Elec­tri­cal and Elec­tron­ics Dia­grams”), which is the reign­ing stan­dard in North Amer­ica (ANSI, CSA, Dept of Defense). Notice how none of the real-world exam­ples seems to repro­duce them too faithfully.