How To Draw Technical Diagrams for Notes and Documentation

Goals

Technical diagrams and drawing are a key tool in all fields of engineering, enabling you to accurately communicate complex ideas. All forms of technical drawing also have standards, some of which you can find in the Reference section. However many standards are also complemented by guidelines specific to the organisation you are working for: or working with. Thus the How To’s in the Table of Content section below cover both the universal and ‘local’ (Leeds Beckett) standards.

General Principles

  1. Avoid Ambiguity. You should not include everything, but you must provide all critical information; for example, you may not label every pin on a DIP chip, but your readers will need to know where you put Pin 1 to locate the rest. Some diagrams (for example UML activity diagrams) might need a version number, or other identifier to show which standard you are working to.
  2. Use Space Appropriately. Don’t cram every possible feature into the smallest space possible: instead use space to help guide the reader. Equally don’t use a whole page to layout a voltage divider. You aim is clarity, and the space is important to draw attention to features and show the critical aspects.
  3. Follow Conventions. Use standard symbols, and layout the circuits (and sub-units) as you have seen in modules and on datasheets. These conventions help you (and your readers) to recognise common solutions to common problems. For instance, diagrams should show logic blocks with inputs on the left, and outputs on the right. Pay attention to arrow heads, line direction, line width, shading and line types: and use them correctly. These are often a critical component of drawing standards, and will confuse your readers if conventions are not followed.
  4. Follow One Standard. Drawing ‘standards’ often have multiple standards bodies, with different interpretations or conventions. For example, the conventions in the United States are often different to European or UK conventions. You should draw circuits at Leeds Beckett using the appropriate UK or European standards if they exist. In case of any ambiguity, state the standard you are using on the drawing.
  5. Use Units Consistently. In most of the world, SI (or metric) units are common. For SI units, use the correct unit and prefix. Do not mix different units within one drawing. For instance if you are using millimetres for length, then all lengths should be in millimetres. If in doubt, state the units and the conventions on the drawing.
  6. Use Colour Sparingly. You should draw most diagrams in black and white, and use colour only where meaning is essential. Most working diagrams require copying many times, and not always in colour. This is why most drawing standard will give you explicit guidelines for line styles, shading, and other features. You must make sure your meaning is clear, even if colour is not available.

Further Reading

Table of contents