[sdiy] I could use a few pointers on doing a board layout

[clark at andrews.edu]

> While we're talking about eagle, I've still got a few pressing questions.
> I've got some nice schematics drawn up (like the ARP 4035 ladder filter
> module) and believe I'm ready to being making a board. And here the
> process
> comes to a screeching halt. I've now made several attempts, but really
> can't
> get anything remotly exceptable. Should I try to lay down traces for the
> supplies and ground first? why don't the icons for supply show up as
> something on the board screen? I'm using the freeware version so I don't
> have the autorouter, is this worth the money?

   Hi Jeff,

   There's been some good replies to the topic, so I don't necessarily
have anything extra to add.  :)  I will state that autorouting is a
joke.  Even on my very expensive OrCAD program.  Maybe for simple
boards, but for complex boards such as Jim's vocal board, it'd make a
horrible mess.  As someone else pointed out, the algorithms for
autorouting just cannot take into account common sense.  Also, once a
track is laid down, the autorouter will not move it (or won't move it
sufficiently) if another trace would benefit more from using the same
space.
   Sure, there are tons of rules that can be used to help the autorouter,
but I say that time is better spent just doing it yourself.
   There is, however, one PERFECT use for the autorouter.  And that is
catching any UNROUTED traces.  Say you've routed your entire PCB and
are ready to get it made, but what if you forgot one tiny segment
somewhere on the PCB?  The autorouter will catch it.  And since the
board is 99.9% done, the autorouter will usually finish any short
segment traces without screwing it up.  Of course, at least with OrCAD,
if I see the autorouter trying to finalize a trace, I usually stop it
and then go in and fix the issue.
   So that'd be the only good use for an autorouter that I know of!

   Cheers,

   Tony

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