A couple of questions that have come up as I've been making some symbols and footprints for various parts for a project that I need to send off real soon now:
Looking at Bill Wilson's guide to defining transistors (1), despite an initial feeling of unease, I find I'm pretty much convinced this is a good plan. So how come I don't see evidence that it's ever been implemented (or where did I not look to find it)? A couple of parts I needed to draw both symbols and footprints for are PC-mounting connectors for external connections - so they need to be mounted at an edge of the board, with attention to aligning their individual mounting planes with the intended location of the panel they will mount to. After pondering this for a while, I have come to the not really savory conclusion that a small kluge is as good a solution as possible: I placed the footprint's "mark" on the center line of the connector's axis, in the plane of that external panel. So in normal use these would all be placed somewhat off the edge of the PC board, which doesn't seem quite right, but does seem less awful than having no indication of the mounting plane present at all (really didn't care for having a silk line out there, although the vendor I expect to be using says they simply delete such extraneous silkscreen marks). There was one more... oh, right. Not immediately relevant, but pondering the location of the mark for the horizontal connectors led me to think about the footprints for vertical mounting versions. In this case it seems to me that the mark should be placed at the center (for a round bodied connector) or other mechanical reference point. As with the horizontal sort described earlier, the mounting requirements are what really determines the placement, and PCB has to accomodate the resulting pad positions, be they on the grid or off. At least that's how my thinking is working today. :-) (1) http://geda.seul.org/wiki/geda:transistor_guide -- During much of that epoch [the thirties and early forties], I gained my livelihood writing for the silver screen, an occupation which, like herding swine, makes the vocabulary pungent but contributes little to one's prose style. -- S J Perelman _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
