Steve,
        I take a different approach to transistor devices. 'Most' follow a
normal standard for pins 1,2,3,(4?) so I use this method and over-ride any
manufacturers which do not follow the same standard. I stick to the
1,2,3,(4?) based upon the most common occurrence of SOT23, TO92, TO220
numbering. To hell with the rogue manufacturers.
        I do make custom symbols for each transistor device configuration
that I come across, naming them by the manufacturers part number and
assigning a matching footprint. There are just too many combinations of
transistors to try and standardize a symbol and footprint for all transistor
devices. I have also seen too many board errors over the years from trying
to standardize transistor symbol/part management down to standard symbols
and footprints to cover all cases. For example my symbol library would
contain transistors named Q_2N2201, Q_2N4401, Q_MMBT3904, Q_IRFR5305, etc.
Each would be pin numbered to match a standard footprint pin numbering. This
way any tech or engineer does not have to find each and every manufacturer's
datasheet to know where pin 3 is on a particular device, or to know here the
emitter is on a particular device, as long as he has the schematic in front
of him and knows the standard pin numbering for the particular package
rather then the custom (non-standard) pin numbering from 'ABC' manufacturer.
Yeah I know, somebody is going to say that someone using the manufacturers
datasheet is going to get confused but likewise in the opposite case someone
is going to get confused and that confusion can too easily cause scrap PCBs.
The engineer should always have the schematic as well as the manufacturers
datasheet and the schematic will set him straight.

TIP: The "Q_..." name convention for symbols allows for all devices to be
easily found in one area of the library without exhaustive searches.
Similarly I use "U_..." for all IC devices, "D_..." for all diodes, "X_..."
for crystals, etc.

Sincerely,

Brad Velander
Lead PCB Design
Norsat International Inc.
#100 - 4401 Still Creek Dr.,
Burnaby, B.C., Canada.
V5C6G9.
voice: (604) 292-9089 (direct line)
fax:    (604) 292-9010
email: [EMAIL PROTECTED]
www: www.norsat.com


-----Original Message-----
From: Steve Wiseman [mailto:[EMAIL PROTECTED]]
Sent: Monday, February 26, 2001 9:50 AM
To: Multiple recipients of list proteledausers
Subject: RE: [PROTEL EDA USERS]: Library Management




On Mon, 26 Feb 2001, Brad Velander wrote:

>       As for your POT symbol/footprint problem, I have seen manufacturer's
> parts specs that would have fit your symbol pin numbering (pin #3 is
wiper).
> So is the symbol you used wrong? No it was simply not the symbol which you
> wanted to use. Assume nothing when it comes to vendor supplied libraries!
> When you make a library part document it in a way that think is suitable
to
> ensure others don't make similar mistakes using your library.

Also, there's no need to use dull pin numbers like 1, 2 and 3. For a pot,
I'd go for CW, CCW and WIP , just to hammer it home. Same goes for my big
collection of SOT23 footprints, given that I can't trust any manufacturer
for pin names, I'll do it myself, and it's dead handy while debugging
boards T3.E means more to me than T3.3 (assuming I got it right at
schematic time). 

Steve

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