Schematic Library:
Suggested Orthography Rules

Tim Williams

The following file is an HTML conversion of the license notice and instructions for my schematic library. As mentioned earlier, I have a library of circuit symbols and have released it publically. This file represents two things: one, an update to the library, including many more symbols; and two, to set down a formal description of their use.

Download Symbols


This document goes with the library of symbols I created. It serves as a reference for rules on drawing and annotating schematics drawn using my font, and also as a reference for drawing legible schematics in general. Part of my motivation in writing this is to improve usage; the tube symbols are especially easy to make `ugly' drawings with. If there is any confusion in reading my own schematics, it will also bring understanding. These rules are only my suggestion, of course, and following them exactly will essentially lead to my drawing style. Schematics, as one of the engineer's arts, should be a little distinctive, so not all of these rules should be followed, but clarity and readability of the drawing is paramount, and those rules must always be followed.

Because these symbols were created by, and are used in, Microsoft Windows Paint, they are very accessible to anyone who wishes to draw schematics but doesn't have the software. It is a very tedious process, requiring attention to detail and per-pixel placement and adjustment. Personally, I complete an average sized drawing in about an hour.

These symbols are licensed under the GPL public license. You are welcome to make any modifications and distributions as you wish, so long as you include this file and give credit to the creator (myself). You don't need to credit the font in individual schematics (I know it when I see it), but I would suggest you give credit somewhere, like on your website where schematics drawn with this font are available, or where you're talking about drawings of yours which use this font.


The first of these symbols were created in December 2000, out of the need to share schematics online. Photographs of drawings never come out well, and without a scanner, I had no better choice than to draw schematics by computer. Besides, it looks better - not that I have a particularly bad hand, just that everything is neater on the computer. But not having a schematic drawing package, I went about it the same way I do everything, which is, make do with what I have. So, I used Microsoft Windows Paint, creating these pictures as monochrome bitmaps, pixel for pixel. These symbols are more or less the same as the symbols I am used to drawing, neatened up a bit. They may differ from industry standards (e.g., Internation Rectifier's IGBT symbol) or ANSI standards (e.g., shift register), but they are generally simpler and easy enough to understand.

As time goes on, more symbols have been added. The symbols are created with some style in mind; discrete semiconductors and vacuum tubes, for instance, always start with about the same diameter circle. Most active devices are circled. Tubes are usually drawn with two opposed semicircles with straight sides inbetween, forming a flat-sided oval to accommodate extra grids or sections. Integrated circuit symbols range from amplifiers and gates to anonymous rectangles. ICs are represented in several ways: as individual components (e.g., halves of an LM358, the triangle amplifier symbol), as nondescript rectangles with pins called out in order and equally spaced, or as rectangles containing a descriptive representation of their functions, pins arranged logically rather than physically. Time will tell what new symbols are added to this set.

Rules: Parts Placement and Orientation


Vacuum Tubes


V2a IC3b
1/2 12AX7 2/4 LM339

The `fraction' goes up sequentially, specifying which section is used.

Wires, Routing and Placement

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File translated from TEX by TTH, version 3.86.
On 15 Sep 2009, 11:44.

Web page maintained by Tim Williams. All rights reserved.