[sdiy] RE: RE: [sdiy] DIY Heaven

[Tom Arnold]

On Fri, Sep 02, 2005 at 12:56:06AM +0300, Samppa Tolvanen wrote:
> On 9/2/05, Tom Arnold <xyzzy at sysabend.org> wrote:
> > 
> > Most of the sharing now is in Eagle format files.  Problem with the free
> > software that several of the PCBfabs are passing out is they dont do
> > schematic capture and have limited support for netlist import and things
> > like ratsnests that I depend on.
> > 
> 
> Please clarify. I didn't understand a bit.

Board layout, at least for me, is easy.  I used to use PADS and I could
churn out a mixed digital/analog board for the CAMAC crates we used in about
2 days ( without sleep ).  These were multilayer boards.  Very ugly stuff.

I think schematic entry is where the mistakes are made.

IMHO to properly lay out a board, you should take a working schematic, enter
it into schematic capture, generate your netlist, then go to PCB layout.  In
PCB Layout you basically have your list of componants, connectors, LEDs,
whatever, and the netlist that shows how they are all connected.  You place
the components and then turn on the rats nest.  It shows, in straight lines,
where everything connects.  As you connect pins on the board itself, each
ratsnest connection goes away.  When you have no ratsnest left, you can be
fairly confident that everything is connected on the board.  Then start
looking at ways to optimize the board for layout, noise, etc.  If you move
something and break the connections, the ratsnest reappears for you to fix.

Probably a bad description of it but I tried.

The only company I know that at least discounts a full featured PCB Layout
and schematic capture is Douglas, which heavily discounts DouglasCAD when
you use them to make the board.  Also discounts on Designworks which is the
schematic capture side of things.  All the other packages I've played with
have been just PCB layout, I cant think of any off the top of my head that
had even netlist import.

Hrm.  Actually, I just looked again at http://www.pcb123.com and they do in
fact have schematic capture now so maybe things are changing.

-- 
 ------------------------------------------------------------------------
 - Tom Arnold -       When I was small, I was in love,                  - 
 - Sysabend   -       In love with everything.                          -
 - CareTaker  -       And now there's only you...                       - 
 --------------         -- Thomas Dolby, "Cloudburst At Shingle Street" -