[sdiy] What's the best freeware schematic capture and PCB layout software

[Donald Tillman]

Indeed, the main goal of a schematic editor is to generate a netlist.  And the user interaction of the CAD system is all about doing that clearly, completely, and accurately.  

(Although this particular discussion was about capturing historical documents.  So I dunno...)

But netlists are not complicated.

Back in the 80s I used SUDS (Stanford University Drawing System) for industrial digital design.  SUDS was used by Stanford, MIT, DEC, Sun, Cisco, and many others, for large projects.  And the SCALD system (Valid Logic Systems) was based on it.  But I guess SUDS needs a PDP-10 and a graphics terminal to run it.   :-)  

SUDS wasn't exactly pretty, but it was the system of choice for many large industrial projects.

I've designed and built about 30 boards in gEDA and I've been very happy with it.  I have never heard of that backward diode issue; 'sounds like a weird library part.

I don't see a "tension" between a pretty diagram and a correct netlist.  Features in one are not at the expense of the other.

And gEDA is not advertised as a pretty diagram generator.  I was just delighted when I saw what a great job it did exporting drawings.  A gEDA schematic with a nicely built library can easily be "publication quality".

  -- Don
--
Donald Tillman, Palo Alto, California
https://www.till.com

> On May 13, 2024, at 9:49 AM, mskala at northcoastsynthesis.com wrote:
> 
> On Mon, 13 May 2024, Donald Tillman wrote:
> 
>> To be clear... I said "publication quality".  And by that I mean, worthy
>> of a graphic you would see in a textbook.  We have a long history of
>> electronics textbooks with elegant schematic diagrams.  As someone who
> 
> As you're surely aware, the "schematic capture" part of a CAD suite has
> another function beyond making a visually appealing diagram:  it is
> creating the input for the PCB design software, electrical rules checker,
> BOM generator, and so on.  What's being created is really more of a
> database than a schematic diagram at all, and the schematic shown on the
> screen is just a view of the database.  There's tension between creating
> the prettiest picture and creating a correct database in minimum work
> time, and it's understandable that the designers of the software may not
> make the tradeoff in favour of visual appearance every time.
> 
> There's also a strong element of user choice:  most people doing schematic
> capture are primarily interested in going on to the next stages of PCB
> design, manufacturing, and so on.  So they may make trade-off decisions
> like using a ready-made symbol from a library that isn't ideal but gets
> the message across, because drawing a nicer one would be a lot of work and
> wouldn't provide any important benefit to them.
> 
> Kicad output from someone who knew what they were doing and who was
> specifically focused on making a good-looking diagram, might be
> better-looking than Kicad output intended purely for the functional
> purpose of feeding the PCB design program.  But someone who had the goal
> of a pretty picture probably would be using drawing software instead of
> any schematic capture software.  It's called schematic "capture" for a
> reason:  the underlying assumption is that you have your schematic
> already, which you drew with something else (like a pen!), and now you're
> just entering it into the machine so the CAD software can work with it.
> 
> Saying "publication quality" may not be the best standard given that when
> one really looks hard at them, most publication schematics are *actually
> bad*.  The standard should be the best publications, or what we wish
> publications could be; not necessarily what most publications really are
> in practice.
> 
> The schematics of my own with whose appearance I've been happiest, have
> been the ones I made in LaTeX with the Circuit_macros package.  That isn't
> schematic capture software and it doesn't generate input that would be of
> any use to CAD software.  It is *only* for drawing the pictures.  And it's
> too cumbersome for any but the smallest circuits.  I wouldn't care to use
> that for the circuit of an entire synth module unless someone was paying
> me to do so, with more money than I can plausibly get just by selling
> modules.
> 
> I use Circuit_macros for many of the small schematics in documentation of
> my commercial modules; but whole-module schematics, and large clips from
> them, are done with Kicad to save time and readers just have to suck that
> up.  They're as good as the schematics other companies have published for
> their products for the last several decades, and these days, customers
> rightly consider themselves lucky to get a schematic at all.
> 
>> gEDA gschem allows me to export to PostScript or PDF, and it handles the
> 
> I wrote off gEDA after I found that it would reverse the anode and cathode
> of diodes between schematic and board by default, and I was rudely treated
> on the relevant mailing list when I suggested that that wasn't an ideal
> way for it to operate.  But if you're only using it to draw the schematic,
> then electrical correctness of the data going to the PCB software doesn't
> matter.
> 
> -- 
> Matthew Skala
> North Coast Synthesis Ltd.
> 

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