G Minch wrote:
> I recently started using Eagle to lay out PCBs. Most of the issues I've
> run into are typical of learning any new program and generally are
> resolved via RTFM. There is one problem that doesn't look like it will
> go away: generic devices in the library are sp

You are apparently sending paragraphs as single long lines which get
truncated somewhere.  You should adjust your mailer settings if you want
everyone to be able to read your messages.

> So, I want to put a 1/2 watt carbon resistor on my board. Great. What
> package is that? I haven't a clue. What if I want a 1/4 W metal film
> resistor? Same problem. This reduces me to a trial-and-error approach
> to picking the correct package size.

I like Eagle, but I'm not impressed with their libraries.  After various
regrets using parts from their libraries, I long ago learned to make my own
devices.  The Eagle ones are sometimes too wierd (too European ?), the
symbols are sloppy or annoying to look at, not well laid out, pads are
sometimes strange shapes, not the sizes I want to fit with my line/space
widths, etc.  Attention to detail is important, and the Eagle libraries look
like they were made by someone who didn't care and just wanted to get thru
the task.

> What I'd like to do is whip out my Instrument of Measurement (commonly
> known as a "ruler") and eyeball the component, then consult a chart and
> pick the closest package size.

Bad idea.  There is no way you can eyeball the measurements to the required
tollerance with a ruler.  Even if you could, that only tells you the
dimensions of that particular part, not the tolerance range.  There is no
substitute for getting the dimensions from the data sheet.  Only then can
you carefully create the right package for your device.

> My question is this: Where can I find a general reference for package
> designations and sizes (US units) for passive components? Preferably,
> something free and on the 'net.

The manufacturer's data sheet for whatever component you want to use.  These
are nowadays usually available for free on the net.


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