Re: gEDA-user: Transistor pinout in gschem and pcb

[Wojciech Kazubski <wk@xxxxxxxxxxxxx>]

Dnia piątek, 3 lutego 2006 08:19, Klaus Rudolph napisał:
> Hi together,
>
> > > Some people deffends that gschem must have "generic" pnp and npn
> >
> > transistors.
> >
> > > In my opinion, these generic transistors only generate more confusion.
> >
> > If I
> >
> > > cant buy a generic transistor, there must be no generic transistors in
> > > gschem.
> > > ...
> >
> > First there are other uses for a schematic besides building boards
> > of purchased parts.  For simulating a theoretical circuit or for
> > documenting an asic, ... I want a generic transistor symbol.
> >
> > Second my preference for all schematic symbols is to have one symbol
> > per device type.  This then has attributes which give the specific
> > type (if known), and footprint.  Since the graphics is common, there
> > should only be one copy.  That is easier to do if the tool has support
> > for it, like the ability to create a menu where entries specify the
> > attributs, or the ability to include a symbol within a symbol...
>
> I think that transistors are allways have BCE pins and so there should
> be a simple sulution for the problem. But I can't see it! Most TO92
> and TO220 have same pinout so this hsould be no problem. What are
> the other geda tools expect? Which pinname on which pin should
> be used! I think the tools are pretty good, but the librarys are
> unusable and confusing. Which pinout we have to use for spice and others?

This is not true for TO92, for this case the most common pinout in Europe 
(BC...) is EBC but US types (as PN2222) usually have CBE and Japanese ones 
(and some high power types) use BCE. To make more confusion some RF types use 
BEC pinout to make output far away from input. Even for integrated circuits 
in TO92 there are two styles of numbering pins.
For TO220 all makers use BCE pinout except some RF transistors from Motorola 
which had BEC pinout and  emiter on tab to make RF amplifier easier to build 
and more stable.
For spice, the pinseq is is important, so collector pin should have pinseq=1, 
base should have pinseq=2 and emiter should have pinseq=3 for any pin 
numbering.
>
> Anybody out there having an idea to solve the problem?
>
I use the following solution:
1) have several symbols for transistor with different pinouts (or even special 
symbols for popular ones with footprint already added).
2) have single footprint for PCB with pin numbered 1 2 3.

I have a few generic symbols for different pinout. They are named npn-ebc.sym, 
npn-bec.sym etc. to indicate what electrode goes to each pin.

Wojciech Kazubski

> Again:
> I need an info, which! side I have to change to make it a tool chain!!!
> Changing symbols in gschem or changing elements in pcb?
> Sorry, I have no experience with simulations here, so I can´t get
> the correct answer myself.
>
>
> Regards
>    Klaus