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>Hi All,
>May be I missed this thread, but needed to lay out a pcb with
>amongst others two low power 5 volt regulators. In addition needed
>a TO-247 footprint and opened the the Transistors.lib as well as
>PCB Footprints.lib libraries.  If you browse the two libraries and
>examine the TO92(A or B or C) in the Transistors.lib and the TO-
>92(A or B) in the PCB Footprints.lib that positions of pad 1 are
>The same applies in the schematic libraries.  I selected a
>LP2950CZ5.0 from the NSC Power Supply Circuit Library and a
>Voltreg from the Miscellaneous library and the Input and Output
>pins on the two decals are also reversed.  A good way to destroy
>some regulators!
>I am using Protel99SE /SP6


Doesn't surprise me; one of the reasons I do not like numeric numbering of 
pins and pads for these sort of components (TO92, SOT23, etc etc).

Yet another argument for three things, as I see it:
1) Use descriptive pin and pad numbers (they can be alphanumeric) where it 
is sensible

2) Set up your own library and use the Protel ones as a source of starter 
symbols and footprints that you check as you copy into your working 
library(ies). Do not trust the Protel libraries - or any packaged library - 
until you have checked carefully.

3) Consider making copies of the symbols and footprints for commonly used 
parts and copying and renaming them to be specific. If you use LP2950CZxxx 
a lot then make a symbol for this and call it that and a footprint as well 
and call it the same.  Add the footprint to the sch symbol. Make sure the 
pins match and have sensible names (eg Vin, Vout, Com).  Some people take 
this to a further extreme and say that all parts used will have unique Sch 
symbols (yes even R's and C's) and footprints of all but very standardized 
packages are unique as well (SO packs, 0805 etc are std, SOT-23 are not).

Point 3) is contentious but makes for easy part list generation as the 
read-only fields can have full manufacturers and ordering info embedded at 
the library level. It is quite suitable for smaller teams and does away 
with the need for database accesses etc.  It does look daunting as well 
(the number of components will be huge, won't it?).  But most of us do not 
use that many unique components a few hundred to a few thousand and they 
are easy to copy and update as a new one is needed.  I quite like this 
method, but am not totally keen on it *until* Protel allows *all* parts 
fields (except for the designator) to be locked at the library level.

Here hoping for the next version,
Ian Wilson

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