Stephen R. Gregory wrote:
>
> Hey ya'll...

        Hey back, Mr. Steve!

> You know that old saying; "Long lead goes in the square hole."?...not on this
> board it don't...it bit me AGAIN! Dammit!! Why is it that there are a only a
> very few board designers that go against the rest of the world when it comes
> to going along with the same kind of polarity markings or conventions that
> everybody else uses? It seems to be more with LED's too...this is not the
> first time this has happened to me, and I'm sure it won't be the last. But
> that's what it wuz...

        I suspect it starts with the schematic libraries.  Have
        noticed that some schematic systems appear to call
        the Anode as pin 1, where most of us refer to the Cathode
        as pin 1.

        Of course, many (but not all) LED suppliers also call the
        anode pin 1, making the likely outcome so near 50% that we
        should ship a dentist's mirror with all prototypes that
        include an LED....

        Oh, and if it has two colors, bank on the wrong one being
        lit.  Go through this cycle enough times and you start to
        structure your product so you can change this in firmware.

        Thoughts to live by/with:

        - Always delete any and all vendor supplied library symbols,
          in CAE or CAD.  Get 'em off the backups too, or "they're
          baaaaack"
        - When you're sure you have the LED correct, reverse it

        Signing off before more "design-isms" bubble out.

        G'year,
--

      Jeff Seeger                         Applied CAD Knowledge Inc
      Chief Technical Officer                  Tyngsboro, MA  01879
      jseeger "at" appliedcad "dot" com                978 649 9800

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