On Sun, 25 Feb 2001 14:14:46 +1000, you wrote:

>       Please let me know if I did something really stupid or if Prtoel did something 
>stupid and
>       I was too naive to catch it.

You are being naive and Protel could do a bit better. 

>               I made a schematic and converted it to a PCB.
>               Gripe 1: There are no matching (default) PCB footprints for the 
>schematic
>                       symbols. This stikes me as really dumb. There should be a 
>set...

There are for some symbols, where there is little confusion about
footprints. What should the footprint be for a resistor for example. 

>               Gripe 2: The schematic symbol for a pot has pin 3 as the tap/wiper.
>                       I never saw this because my pin names were off...
>                       I converted from sch to PCB and applied the generic footprint
>                       VRn - to avoid wiring problems (hah!). That what the whole 
>point of this
>                       technology is for isn't it!

The symbols in my device library have 1,2, and TAP or A,B, and W for the
pots and tapped resistors so I'm not quite sure where you got your symbols
with numbered pins from (but then I'm not quite sure where my device
library came from either). 

>                       The PCB component was correct  - pad 2 is (and as far as I 
>know is
>                       ALWAYS) the wiper. So as far as I'm concerned the schematic
>                       library component is wrong in a dangerous and dumb way.

No there are hundreds of POT designs most of which don't even attempt to
number pins let alone have some standard. 

>               Question:  Take the RETSISTOR TAPPED sch library part for eg.
>                       It does not have any hidden pins (according to library params)
>                       yet I have to use display hidden pins to see the pin nums 
>etc...
>                       Why is this so ?

In the library the pins are not hidden but show pin names and pin numbers
are turned off. In schematic turning on hidden pins also shows hidden names
and numbers on pins which are not actually hidden. 

>               Question:  What is the correct way of assiging schematic pins so they
>                       match PCB pins (how do I make the change and ensure 
>correctness)

You make sure they match :)

>               Question: Do I have to create my own compatible sch and PCB libs which
>                               seems really stupid in as "professional" a product as 
>PCB.

To some extent yes. If Protel tried to provide accurate Schematic and PCB
libraries for every component in the world they would need a 20 man team
working permanently just to keep up with additions, never mind initial
creation. They would never be able to know what all the parts in the world
were or get data for them anyway. 

My thinking...

Basically if a schematic symbol looks right you can use it although it is
wise to check anything unusual or non-trivial. Assign a very specific
footprint name in schematic. 

When it comes to layout go through your list of required footprints and
build a new PCB library using what you find in the Protel PCB libraries as
a starting point. You might just copy some parts (checking pins and hole
sizes), other parts you might copy and assign your specific name. Other
parts you will have to modify or create from scratch. IMO there is no
substitute for having the physical part in your hand and some digital
calipers for anything non-trivial. Catalogue and data sheet drawings are
often confusing and inaccurate. 

If you did the job right and were specific enough with the footprint names
there is no reason why you can't use the contents of this library next time
and keep adding to it.


Cheers, Terry.

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