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Re: gEDA-user: Reinventing the wheel

On Thu, May 19, 2011 at 02:12:06PM -0400, Vanessa Ezekowitz wrote:
> On Thu, 19 May 2011 08:36:50 -0600
> John Doty <jpd@xxxxxxxxx> wrote:
> > On May 19, 2011, at 8:21 AM, Kai-Martin Knaak wrote:
> > 
> > > Vanessa Ezekowitz wrote:
> > > 
> > >> KMK didn't say what he means by "unusable", 
> > > 
> > > Most immediately: The symbols in the default lib do not contain footprint 
> > > attributes. Not even an empty ones. This prevents them to "just-work" for 
> > > the most common work-flow of geda: gschem -> gnetlist -> pcb -> gerbv 
> > 
> > What's the footprint for a transistor? A resistor? A 7400? All of these
> > come in many packages and many also expect a 1:1 mapping from package to
> > footprint, but that isn't how it works.
> But that *is* how it works - to a new user or a seasoned user, ultimately footprint = package.  We've had this discussion before, and the answer is clear:
> Choose some reasonable defaults that will work for the majority of use cases.  Through hole or large gauge SMT unless there is no other option, and using the most commonly available parts.
> If a person instantiates a transistor, give it a TO92-3 footprint (though I prefer TO-18 for its retro look).
> Resistors?  I use a footprint I created that fits 1/8 and 1/4W and folds the resistor in half to save board space.

This already invalidates your point. Many hobbyist users don't
care about TO resistor footprints, since you can fit the leads
into pretty well any hole spacing.

Me, I use 0805's since I have a lot of those. I have a friend
who always uses 0603's for the same reason. Sometimes the I
use massive SMT footprints or weird TO spacing to fit a lot of
traces under the part.

The moral is that defaults cannot make sense for even the
simplest of parts. Capacitors are much worse, transistors
worse still. 

All this without even considering paste width, etc.

Andrew Poelstra
Email: asp11 at sfu.ca OR apoelstra at wpsoftware.net
Web:   http://www.wpsoftware.net/andrew/

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