Mail Archives: geda-user/2015/07/21/23:43:50

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X-Recipient: geda-user AT delorie DOT com
Date: Wed, 22 Jul 2015 03:43:15 GMT
From: falcon AT ivan DOT Harhan DOT ORG (Spacefalcon the Outlaw)
Message-Id: <1507220343.AA03928@ivan.Harhan.ORG>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] [OT] I need help with selecting components
Reply-To: geda-user AT delorie DOT com

DJ Delorie <dj AT delorie DOT com> wrote:

> I think I use a hacked 0603 footprint for mine, which has a polarity
> indicator, says
under "Basic semiconductors":

"Conventional through hole LED is LED3 and LED5 for 3 and 5 mm
 respectively. Pin 1 is plus."

Do you use the same convention (pin 1 is the anode) for your 0603 SMT
LEDs, or the other way around?  (The same page says that for regular,
non-light-emitting diodes pin 1 is the cathode.)

Any suggestions as to just how one should mark the polarity in the
"hacked" footprint?  A silk + mark near the pad designated as the
anode?  A silk diode drawing near the footprint?

> Even then, it's hard to figure out which
> pin is which on the LED itself.

Yup, seems to be an unavoidable evil.

> However, that's the type of LED eval
> boards use.

Yes it is...  And not just eval boards, but more generally LEDs on any
random board (including commercial products) that are meant to be seen
only by engineers debugging things on a bare board.  And even many LEDs
meant to shine on a front panel etc are of the same type - they just
put a light pipe over it.

> Weidmuller makes a wide range of connectors, I use these:

OK, totally different.

For a long time I was at a loss with figuring just what connector TI
used for power input on their Leonardo board - had I known what it was
to begin with, I would have just used the same in my design without
questioning it.  But the historical schematics just call it "PWR-PCB-3"
- not very informative.  But earlier today, as I was reading all of
the suggestions I got in response to my original inquiry, I took one
more look at the full export of attributes from the OrCAD DSN
schematics someone made for me a while back, and I noticed that one of
the attributes for that component says "Farnell" and an adjacent one
says "616-084".  I typed that number into Farnell's search box, and lo
and behold, it gave me this:

Checking it out, I realized that it must be the same power connector
as can be seen in this photo of TI's D-Sample board, a close relative
of the Leonardo:

So now I know that the power input connector on the Holy Original
boards was a Weidmuller 1510460000, and it's readily available from
Farnell/Newark.  I'll use the same connector on my board, just for the
good feeling of having recreated what TI did Back Then.  In case it
isn't obvious, the board I am building is a recreation of TI's Leonardo
eval board for their Calypso GSM chipset.  Finding a physical TI-made
Leonardo board from 2003-2004 is mission impossible, and I haven't been
able to find a copy of their layout either - it appears to have been
lost in the cracks of time and obscurity - so I'm recreating it from
the historical schematics, and from experience gained from commercial
phone and modem products based on the same chipset.

Hasta la Victoria, Siempre,

- Raw text -

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