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Free CAD Software

One aspect of electronic music instrument design you cannot escape from is the use of CAD software, be it schematic, PCB, simulation, or mechanical. A little background project of mine has been to explore the various free CAD tools on offer around the web. This web page lists the results of this on-going project.

Some of these tools are PC-only. Others can run on Linux († = with Wine), and some are truly cross-platform (including Mac OSX).

While the title of this page has the word free in it the software listed on this page is a mixture of:

  • open-source that can be used for personal and commercial use,
  • closed-source but can be used for personal and commercial use,
  • closed-source that can only be used for personal use (no commercial use).
I leave it to you to check the license terms are compatible with your intended use. My intention is that all the tools listed here are suitable for personal use. For commercial use please check with your lawyer.


Schematic / PCB Layout

Good quality tools for producing schematics and PCBs are now freely available. But, like any piece of complex software, they take time to learn to use effectively, and they all have their quirks.

Name Comment OS
Eagle Well known. Native versions for PC, Mac and Linux. Free version limited to one schematic sheet, and one 2-layer PCB up to 100mm x 80mm (half Euro card). Win
Linux
OSX
DesignSpark Apparently a free version of EasyPC custom-made for RS Components (I guess to compete with Farnell who now own CadSoft). Does not have limits as Eagle does. There are rumours that this might run on Linux under Wine. Win
Altium CircuitMaker A completely new offering from Altium, the makers of Protel. It looks like a stripped-down version of their leading Altium Designer with various hobbles: you need to be online to use it (it checks the license at startup); only two private designs are allowed, all other designs must be publicly shared with "the community"; your data files are stored in the cloud, not on your local PC. If you can live with that then it is potentially a very powerful tool. Win
PCBWeb Seems to be yet another free all-in-one tool supported by a services vendor. Looks like it has all the basics, and exports Gerbers and Excellon files. Win
Kicad Highly-recommended free Schematic + PCB package. I've not tried this for any project work, but I've heard good reports about it. Win
Linux
gEDA A well-known FOSS CAD suite. It may not have all the fancy features of KiCAD or the commercial-but-free packages, but it has a faithful following. OSX
Linux
DipTrace This program gets quite good reviews. The freeware version is limited to 300 pins, 2 layers, non-profit use. There is also an option to get a free non-profit license to go up to 500 pins. Win
Linux†
OSX
Autotrax & EasyTrax These two ancient DOS-only packages are listed for two reasons: people kept asking me why they weren't listed, and being DOS-only they can run on many different OSes using a DOS emulator such as DOSBox. More details here. DOS
TinyCAD & FreePCB Two Windows-only apps that work together to make up a basic schematic capture + PCB layout system. FreePCB can also interface to the free online FreeRoute autorouter. Win
BSch3V A basic Windows-only schematic capture tool. While very basic - that is its intention - it seems quite easy to use. You can see some examples on Sam Hoshuyama's home page at http://www5b.biglobe.ne.jp/~houshu/synth/. Win
GC-Prevue Highly-regarded Gerber viewer. Check your files before you send them off to be turned into PCBs. Win
3D Gerber Viewer This is a simple 3D viewer for Gerber files. It looks nice, and uses OpenGL to render the Gerber data into a 3D model you can play with. Win (Vista onwards)


Analogue & Digital Simulation

Simulation, if used sensibly, can be a very useful aide to developing new and interesting-sounding projects. Certainly in the case of analogue simulation treat results with care as you may not be simulating what you think you are.

Name Comment OS
LTSpice Pretty good SPICE-based simulator with a slightly quirky GUI front end. One nice feature is that it can read and write WAV files. For example, process audio files through a filter model to hear what it might sound like. Win
Linux†
Icarus Verilog A very capable Verilog simulator. Win
Linux
OSX
GTKWave Waveform viewer that goes well with Icarus Verilog. Win
Linux
OSX


Mechanical CAD

From front panels to mounting brackets its not all about solder.

Name Comment OS
Front Panel Designer Good for doing panel layouts. It will even tell you how much it will cost to make. You can either use Schaeffer directly (they're in Germany), their US counter-part Front Panel Express, or if you're in the UK then Julian at The Beast can produce panels from FPD files. Win
Linux
OSX
QCAD An impressive 2D CAD package, perfect for panel mechanical details and other traditional electronic drawing board tasks. The current free version is at 3.9.8 and is great for basic 2D drafting to a high standard. Win
Linux
OSX
LibreCAD An impressive 2D CAD package, perfect for panel mechanical details and other traditional electronic drawing board tasks. Based on a fork of QCAD 2.0 and now separately and freely developed and maintained. Win
Linux
OSX
Solid Edge 2D Drafting A free fully-featured 2D CAD package, a stripped down version of Solid Edge tool. Has lots of pro features including engineering calculators, constraints, parametric engineering, goal seeking, and so on. Win
DraftSight Another commercial entity (Dassault Systemes, who also own SolidWorks) offering a freeware 2D CAD tool, promoted as a tool to edit DWG files. Has an impressive feature set. Win
Linux
OSX


Maths

Filters, oscillators, amplifiers...its all about maths. Doing it by hand can be tedious and error-prone, but there are some really good free programs available for crunching numbers and algebra.

Name Comment OS
Maxima For doing algebra for you. Handy for designing filters and non-trivial op-amp circuit design. If you prefer a GUI front end there is wxMaxima.
You can also use maxima online.
Win
Linux
OSX
Octave Matlab clone. Win
Linux
OSX
SciLab Matlab clone with fancy GUI. Win
Linux
OSX
processing A GUI-based tool for quickly writing visual tools. Geared towards the visual arts - I use it as a rapid development tool for code ideas. Win
Linux
OSX


Graphics

Make your front panels look great!

Name Comment OS
Inkscape Great for producing panel artwork. Then use UniConverter (included in the InkScape installer) to generate HPGL PLT files which you can then load into Front Panel Designer (above). Win
Linux
OSX
Hp2xx Once you're produced a PLT file use this handy utility to convert it to a variety of formats, and on X11 or Windows to view it as well. Win
Linux


Editors

This is a very contentious subject! The editors listed here are the ones that I happen to like and/or use on a regular basis. YMMV.

Name Comment OS
NEdit The classic GUI editor for Unix, also ported to OSX (requires X11). Linux
OSX
Notepad++ My editor-of-choice on Windows. Win
Geany Nice GUI editor which I mainly use on Linux. Win
Linux
OSX
Komodo Edit Tends to be slightly better at editing web pages than Notepad++. Win
Linux
OSX


Communications

Although not technically CAD software I find the following tools very useful for communicating with other computers and embedded systems.

Name Comment OS
TeraTerm Probably the best terminal emulator for Windows. Win
MobaXterm Highly integrated communication system, including X server, SSH, serial comms, and so on. Win


Documentation

Producing documentation is a great way of communicating your ideas with others. Web pages work to some degree, but a properly-formatted document can have a greater impact.

Name Comment OS
LaTeX Its just one of those things, like Marmite. Win
Linux
OSX
Lulu Print on demand publishing service.
Scribus Professional-quality DTP package. Win
Linux
OSX
yEd Very usable graph editor, great for system diagrams, etc. Win
Linux
OSX
Pencil Supposed to be a GUI prototyping tool, but I use it a Visio clone for drawing block diagrams. Win
Linux
OSX

Copyright © 2001-2017 Neil Johnson