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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.
Contents
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 |
Now owned by Autodesk and based on a subscription model, and integrated into their
Fusion 360 suite. Native versions for PC, Mac and Linux.
Free version (although you still need to sign up) limited to
two schematic sheets,
two signal layers,
and 80 cm2 PCB board area (half Euro card 100 mm x 80 mm).
|
Win Linux OSX |
DesignSpark |
A custom-made CAD package from the
WestDev
stable for RS Components.
Does not have limits as Eagle does. There are rumours that this might
run on Linux under Wine. Requires a DesignSpark account to run.
|
Win |
PCB Artist |
From the same software house as DesignSpark PCB, EasyPC and Pulsonix,
this time tied to Advanced Circuits with a sting in the tail: you only get the gerbers
after they have made the first board run for you.
|
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.
Note that development of the original FreePCB has ceased, but it lives on in the form of
FreePCB-2.
|
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 |
EasyEDA |
A cloud-based EDA suite with an offline client version. The free version is sufficient for
hobby projects, and it looks like one day they'll monetise it. The simulator is apparently based on LTSpice.
One nice feature is the collaboration with
JLCPCB for turning your design into a thing.
|
Cloud Win Linux OSX |
Gerber Viewers
Name |
Comment |
OS |
gerbv |
Now that GC-Prevue is no more I find this useful tool from the geda project
is good enough for checking Gerber files before submitting them to the fab. |
Win Linux |
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) |
PCB Fabs
After schematic capture, after board layout, and after gerber checking... it's time to etch! Here are some
fabs I've used over the years both personally and professionally.
Before listing the companies I've used, there is a very useful tool I use all the time:
PCBShopper. It is a price comparison website
for PCBs - enter your board specs and then see what is available, for what price, and how quickly.
Note: I have used, or likely will use, these services. But I cannot offer any guarantee
that your experiences will be as good or better than mine. Caveat emptor, etc.
Name |
Comment |
JLCPCB |
A very vertically-integrated PCB vendor, with their own CAD
front end (EasyEDA) and parts store (LCSC).
|
PCBWay |
Used by several synthesizer companies, with overall very good results.
So far very pleased with their assembly service.
|
WellPCB |
Another new service, but looks quite capable, and looks like
competitive pricing.
|
SeeedStudio |
Seeed gets a good write-up in the maker community, and they're good.
They now offer PCB assembly as well.
|
PCBCart |
I first started with PCBCart, and the service was pretty good. No problems
and price was reasonable.
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PCB Train |
Part of Newbury Electronics here in the UK. Used them for work.
Pricey compared to Chinese fabs.
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Cambridge Circuit Co |
Local firm, great for specialised boards, and rapid turn-around, but cannot compete price-wise with Chinese fabs.
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Auto Part Generation
Generating schematic symbols and PCB footprints can be a right pain. Thankfully the
ECAD industry is developing solutions to this tedious task, with several competing - and incompatible -
solutions. The following table attempts to link up the formats with distributors and CAD package support
(bold names means the package is integrated into the named CAD tool).
Format |
Distributors |
CAD Tools |
Ultra Librarian |
Digikey, Arrow |
Altium,
Eagle,
KiCad,
OrCAD,
PADS, Pulsonix,
Quadcept |
SnapEDA |
Digikey |
Altium,
CircuitStudio,
DipTrace, DesignSpark,
Eagle,
KiCad,
OrCAD,
PADS & DxDesigner, PCB123, P-CAD, Proteus,
Target 3001! |
Library Loader (SamacSys) |
Mouser, RS, Future Electronics |
Altium,
CADStar, CircuitStudio, CR-5000, CR-8000,
DipTrace, DesignSpark,
Eagle, EasyEDA, EasyPC,
KiCad,
OrCAD,
PADS, PCB123, P-CAD, Proteus, Pulsonix,
Quadcept,
Solidworks PCB,
Target 3001!,
Xpedition,
Zuken
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One thing to note about these services is that for some parts the schematic
symbols are not very good at all. Almost all integrated circuits are drawn as
rectangular blocks with the pins arranged in numerical or package order. For
example, opamps are not the standard triangle shape, even worse for dual or quad
versions (one large block with 8 or 14 pins, rather than two or four triangles).
So either accept them as-is, or prepare to spend some time redrawing them.
The PCB footprints are more useful as they are defined by the mechanical dimensions
of the package, and there are standards to which the footprints can/must conform to
(e.g., IPC-7351).
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 |
Simetrix |
Widely respected Spice simulator. The free Elements version
supports designs up to 170 nodes, enough for a reasonable sized circuits. |
Win |
PSPice for TI |
Industry-standard Spice simulator, TI version. Comes with lots of TI models
and of course works well with OrCAD./TD>
| Win |
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† OSX |
TINA-TI |
TI also jumped on the free analogue simulation bandwagon by licensing a
cut-down version of the full TINA simulation engine, dedicated to TI products.
Some folks rave about it, others swear at it. A pretty good tool once you get used to the
UI. |
Win |
Micro-Cap |
Originally sold by Spectrum Software for many years as one of the top SPICE
analogue simulators. Now that Spectrum has closed the author has released Micro-Cap as a free
unsupported program. It is an extremely powerful circuit simulation tool, which can cope with
anything from IC designs at the individual transistor level, through to complete multi-chip
systems.
|
Win |
SuperSpice |
Another well-regarded SPICE simulator running on the Windows platform,
and where the author has retired and moved the software to a free licence (abandonware?).
|
Win |
Qucs |
An interesting addition to the Spice simulation field. Seems geared
towards RF circuits, with support for S parameters, Smith charts, etc.
|
Win Linux OSX |
Ngspice |
A very comprehensive and powerful SPICE engine that is incorporated in
many open-source and commercial ECAD tools for circuit simulation (KiCad, Eagle, Qucs-S, etc).
I've been looking at this as a possible future replacement for LTSpice using
XSchem
as the schematic front end. Ngspice itself is a sort-of command line tool, but the interative command
interpreter does support data plotting.
For more comprehensive plotting there is gaw
which XSchem can communicate with to support cross-probing.
|
Win Linux OSX |
Icarus Verilog |
A very capable Verilog simulator. |
Win Linux OSX |
GTKWave |
Waveform viewer that goes well with Icarus Verilog. |
Win Linux OSX |
MacSpice 3 |
Not to be outdone by the likes of LTSpice, here is an excellent SPICE toolkit for
Mac users. |
OSX |
OpenEMS |
openEMS is a free and open electromagnetic field solver using the FDTD method.
It uses Matlab or Octave and Python as flexible scripting interfaces. |
Win Linux |
Xyce |
Xyce is an open source, SPICE-compatible, high-performance analog circuit simulator,
capable of solving extremely large circuit problems by supporting large-scale parallel computing
platforms. It also supports serial execution on all common desktop platforms, and small-scale
parallel runs on Unix-like systems. |
Win Linux OSX |
From front panels to mounting brackets its not all about solder. 2D mechanical design
covers traditional technical drawing, together with specific applications such as front panels.
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.
Has lots of pro features including engineering
calculators, constraints, parametric engineering, goal seeking, and so on. |
Win |
The world is 3D. With cheap 3D printers and increasingly powerful home computing brings
a plethora of free 3D CAD packages.
Name |
Comment |
OS |
FreeCAD |
Early days (currently at version 0.17) but a pretty powerful 3D parametric CAD system.
|
Win Linux OSX |
Autodesk 123D |
No longer supported, but an old favourite and if you hunt around on the interwebs you can
still find the installer. A basic, solid, useable tool from a (if not THE) mechanical CAD vendor.
|
Win |
Sclic3r |
A useful multi-platform 3D slicer program. While intended to drive 3D printers I use it
as a quick sanity check on the print files before sending to the printer, in the same way that I use
Gerber viewers to check the files before sending to the fab.
|
Win Linux OSX |
OpenSCAD |
A quick and easy 3D modelling tool that is script-driven rather than mouse-click driven.
|
Win Linux OSX |
IDA-STEP |
3D is used in all sorts of CAD tools these days, not just mechanical but very much in electronic
CAD as well -- it seems all half-decent PCB layout tools have a 3D renderer. This is a useful tool for
viewing 3D CAD files.
|
Win |
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.
|
Win Linux OSX |
Octave |
Matlab clone now with comprehensive GUI. I use this at work for signal processing experiments. |
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 |
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 |
Exljbris |
This guy makes some really nice fonts, and a few of them are free. Why be stuck with the
same old boring fonts that come with your OS when you can stand out from the crowd with a subtle hint
of difference?
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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 |
Visual Studio Code |
A very powerful and extensible editor, across all platforms. Becoming my editor-of-choice.
|
Win Linux OSX |
NEdit |
The classic GUI editor for Unix, also ported to OSX (requires X11). |
Linux OSX |
Notepad++ |
Widely used Windows. Can be run on Linux thanks to Wine. |
Win Linux |
Geany |
Nice GUI editor which I mainly use on Linux. |
Win Linux OSX |
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 |
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. |
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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 |
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