qucs-help — For those in need of help using Qucs. Please subscribe before posting.

Re: [Qucs-help] Support for Indices in Texts

[Clifford W. <cli...@cl...>]

Hi stefan, hi list,

On Thu, Jan 03, 2008 at 10:09:40PM +0100, Stefan Jahn wrote:
> > If a more sofisticated support for indices is needed it would propably
> > be a good idea to extent the ViewPainter class to provide a helper
> > function which wraps the details of drawing texts with indices..
> 
> Can you extend this patch for
>  1) name_{subindex}
>  2) name_{superindex}
> 
> This could be very useful, as well.

yup. done now.. (see attached patch)

For this I had to change the rules for allowed component names and wire
labels. It doesn't look like this is breaking the Schematioc editor
load/save code but I have not checked if it is still possible to simulate a
circuit if one is having resistor names such as:

	R_1foo_{bar}Sm^all^{Te}st

yours,
 - clifford

-- 
When your hammer is C++, everything begins to look like a thumb.

Re: [Qucs-help] Question about transient simulation

[Stefan J. <st...@gr...>]

Am Do, 3.01.2008, 11:11, schrieb st...@st...:

> HI,

Hello!

> I have been using the QUCS for a few days now and I think it is an
> excellent program.

Thanks.

> I have one query about the transient simulation.  Is there a maximum time
> limit for a transient simulation?  It works perfect for anything up to 1
> second but over that (even 1.01s) it hangs and wont finish the simulation.

Actually there is no such built-in limit.  Can you please send the
schematic to check?

Cheers, Stefan.

Re: [Qucs-help] Qucs Membership

[Stefan J. <st...@gr...>]

Am Di, 1.01.2008, 15:32, schrieb Daddy:

> Hello Qucs (Michael/Stefan/Jens,etc)

Hi Mike!

Sorry for the long delay...

> I would like to join the qucs project as a member (I already joined
> SourceForge). I have
> been compiling qucs for the Puppy Linux distribution and hosting it at
> my website
> www.qsl.net/wn2a/qucs.html  (main page is www.qsl.net/wn2a) .
> I am an electrical engineer of 30+ years experience currently at
> Aeroflex in New Jersey.
> My main area is RF/Microwave design , and mixed signal systems. I am
> self-learning C and
> C++, primarily out of strong Linux/Amateur Radio interest, but
> professionally I use much more
> Labview and assembly code.
>  I think I can contribute to the qucs project by:
>  1) compiling qucs packages for Puppy Linux
>  2) adding microwave models and math functions to qucs, especially as my
> C programming improves.
>  3) providing help-forum assistance

Help is always welcome, also in testing the software...

Have you anything special in mind you want to contribute?

Cheers, Stefan.

Re: [Qucs-help] Support for Indices in Texts

[Bastien R. <rou...@gm...>]

Le jeudi 3 janvier 2008, Stefan Jahn a =E9crit=A0:
> Am Do, 3.01.2008, 13:06, schrieb Clifford Wolf:
> > Hi,
>
> Hello!
>
> > On Thu, Jan 03, 2008 at 12:05:20PM +0100, Clifford Wolf wrote:
> >> first of all a little patch to the patch. It should read
> >>     if (txt.isNull()) {
> >> of course..  ;-)
> >
> > attached you will find an updated version of the patch. This one is usi=
ng
> > the underscore character to seperate the index and supports indices for:
> >
> > 	* Graphic Text
> > 	* Component Names
> > 	* Component Values
> > 	* Wire Labels
> >
> > This pretty much fits my needs so I think I won't spend more time on it.
> >
> > If a more sofisticated support for indices is needed it would propably =
be
> > a
> > good idea to extent the ViewPainter class to provide a helper function
> > which wraps the details of drawing texts with indices..
>
> Can you extend this patch for
>  1) name_{subindex}
>  2) name_{superindex}
name^{super} I supose
>
> This could be very useful, as well.

We could hook something like=20
http://www.nought.de/tex2im.html
Will be nice and quite easy. The only problem is portability and external=20
dependance

> Thanks so far,
>   Stefan.
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Qucs-help mailing list
> Quc...@li...
> https://lists.sourceforge.net/lists/listinfo/qucs-help



=2D-=20

"ROUCARIES Bastien"
                                              roucaries.bastien+qucs@gmail.=
com
=2D------------------------------------------------------------------------=
=2D-----
DO NOT WRITE TO rou...@gm... OR BE BLACKLISTED

Re: [Qucs-help] Support for Indices in Texts

[Stefan J. <st...@gr...>]

Am Do, 3.01.2008, 13:06, schrieb Clifford Wolf:

> Hi,

Hello!

> On Thu, Jan 03, 2008 at 12:05:20PM +0100, Clifford Wolf wrote:
>> first of all a little patch to the patch. It should read
>>     if (txt.isNull()) {
>> of course..  ;-)
>
> attached you will find an updated version of the patch. This one is using
> the underscore character to seperate the index and supports indices for:
>
> 	* Graphic Text
> 	* Component Names
> 	* Component Values
> 	* Wire Labels
>
> This pretty much fits my needs so I think I won't spend more time on it.
>
> If a more sofisticated support for indices is needed it would propably be
> a
> good idea to extent the ViewPainter class to provide a helper function
> which wraps the details of drawing texts with indices..

Can you extend this patch for
 1) name_{subindex}
 2) name_{superindex}

This could be very useful, as well.

Thanks so far,
  Stefan.

Re: [Qucs-help] Support for Indices in Texts

[Clifford W. <cli...@cl...>]

Hi,

On Thu, Jan 03, 2008 at 12:05:20PM +0100, Clifford Wolf wrote:
> first of all a little patch to the patch. It should read
>     if (txt.isNull()) {
> of course..  ;-)

attached you will find an updated version of the patch. This one is using
the underscore character to seperate the index and supports indices for:

	* Graphic Text
	* Component Names
	* Component Values
	* Wire Labels

This pretty much fits my needs so I think I won't spend more time on it.

If a more sofisticated support for indices is needed it would propably be a
good idea to extent the ViewPainter class to provide a helper function
which wraps the details of drawing texts with indices..

yours,
 - clifford

-- 
A: No.
Q: Should I include quotations after my reply?

Re: [Qucs-help] Support for Indices in Texts

[Clifford W. <cli...@cl...>]

Hi,

first of all a little patch to the patch. It should read

    if (txt.isNull()) {

of course..  ;-)

On Thu, Jan 03, 2008 at 11:55:58AM +0100, Bastien ROUCARIES wrote:
> Le jeudi 3 janvier 2008, Clifford Wolf a ?crit?:
> > Hi there,
> >
> > I've added support for indices in text fields (see attached patch). I
> > wanted to ask if the syntax (Name||Index) is ok for you guys before I start
> > adding the Feature to other code paths.
> 
> I will prefer a tex like syntax. Sorry but || is ugly :-(

The problem is: the way my patch is working you cant add a text lable like

	U_1 = R_1 * I_1

because the Label has just one index part at the end. So my plan was to
use the || syntax in graphictext.cpp and _ for the cases where a single
identifier is used.

> BTW I have some code that will allow to use directly latex notation (not latex 
> but eps generated form latex) in qt using gs. If you want I can send you this 
> program.

yes please. In fact I don't care what the schematics in qucs look like - I
just need nice looking pngs. if you have something to create .tex i can use
tex and dvipng to generate the pngs I need...

> > Actually I'm not sure whether seperating name and Index using the last
> > underscore in the text wouldn't be a better idea..
> >
> > Also I'm not sure in which places a support for indices would make sense.
> > I in fact only need it in the text labels and component attributes
> > displayed in the schematic to make the schematic look better. Especially
> > when using this for sweeped parameters, etc. would would be better to stay
> > within the nameing conventions for variables and thus use the underscore.
> > But I'm not sure whether this would break anything or would confuse users
> > because then a variable would be displayed using the index in one place and
> > using the underscore in another..
> 
> > what do you think?
> 
> I think that we must use latex in qucs. For now we can use your patch but 
> please be compatible with latex syntax, do not try to invent a new one

But Latex syntax would only be one charater. So I would also need to add a
parser for { .. } to allow grouping of multiple characters which in turn
would need more escape sequences and so forth..

..that's to much effort for me for the problem I'd like to solve atm.  ;-)

In fact a (command-line) converter for creating .tex code from .sch files
would be the perfect solution imo.

I'd really love to see the code you mentioned above..

yours,
 - clifford

-- 
for(var d,i=<>just</>,j=function(){d~=i~(defined(i=next[*],i)?" ":"
");},just,another,SPL,hacker;defined i||({debug d;return 0;});j());

Re: [Qucs-help] Question about transient simulation

[Bastien R. <rou...@gm...>]

Le jeudi 3 janvier 2008, st...@st... a =E9crit=A0:
> HI,
>
> I have been using the QUCS for a few days now and I think it is an
> excellent program.
>
> I have one query about the transient simulation.  Is there a maximum time
> limit for a transient simulation?  It works perfect for anything up to 1
> second but over that (even 1.01s) it hangs and wont finish the simulation.

Could you send scheamtic exemple please.

Regards
> Best Regards
>
> Stewart
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Qucs-help mailing list
> Quc...@li...
> https://lists.sourceforge.net/lists/listinfo/qucs-help



=2D-=20

"ROUCARIES Bastien"
                                              roucaries.bastien+qucs@gmail.=
com
=2D------------------------------------------------------------------------=
=2D-----
DO NOT WRITE TO rou...@gm... OR BE BLACKLISTED

Re: [Qucs-help] Support for Indices in Texts

[Bastien R. <rou...@gm...>]

Le jeudi 3 janvier 2008, Clifford Wolf a =E9crit=A0:
> Hi there,
>
> I've added support for indices in text fields (see attached patch). I
> wanted to ask if the syntax (Name||Index) is ok for you guys before I sta=
rt
> adding the Feature to other code paths.

I will prefer a tex like syntax. Sorry but || is ugly :-(
BTW I have some code that will allow to use directly latex notation (not la=
tex=20
but eps generated form latex) in qt using gs. If you want I can send you th=
is=20
program.

> Actually I'm not sure whether seperating name and Index using the last
> underscore in the text wouldn't be a better idea..
>
> Also I'm not sure in which places a support for indices would make sense.
> I in fact only need it in the text labels and component attributes
> displayed in the schematic to make the schematic look better. Especially
> when using this for sweeped parameters, etc. would would be better to stay
> within the nameing conventions for variables and thus use the underscore.
> But I'm not sure whether this would break anything or would confuse users
> because then a variable would be displayed using the index in one place a=
nd
> using the underscore in another..

> what do you think?

I think that we must use latex in qucs. For now we can use your patch but=20
please be compatible with latex syntax, do not try to invent a new one

Regards Bastien
>
> yours,
>  - clifford



=2D-=20

"ROUCARIES Bastien"
                                                   roucaries.bastien@gmail.=
com
=2D------------------------------------------------------------------------=
=2D-----
DO NOT WRITE TO rou...@gm... OR BE BLACKLISTED

[Qucs-help] Support for Indices in Texts

[Clifford W. <cli...@cl...>]

Hi there,

I've added support for indices in text fields (see attached patch). I
wanted to ask if the syntax (Name||Index) is ok for you guys before I start
adding the Feature to other code paths.

Actually I'm not sure whether seperating name and Index using the last
underscore in the text wouldn't be a better idea..

Also I'm not sure in which places a support for indices would make sense.
I in fact only need it in the text labels and component attributes
displayed in the schematic to make the schematic look better. Especially
when using this for sweeped parameters, etc. would would be better to stay
within the nameing conventions for variables and thus use the underscore.
But I'm not sure whether this would break anything or would confuse users
because then a variable would be displayed using the index in one place and
using the underscore in another..

what do you think?

yours,
 - clifford

-- 
"Premature optimization is the root of all evil." - Donald Knuth

[Qucs-help] Question about transient simulation

[<st...@st...>]

HI,

I have been using the QUCS for a few days now and I think it is an
excellent program.

I have one query about the transient simulation.  Is there a maximum time
limit for a transient simulation?  It works perfect for anything up to 1
second but over that (even 1.01s) it hangs and wont finish the simulation.

Best Regards

Stewart

Re: [Qucs-help] Qucs Membership

[Bastien R. <rou...@gm...>]

Le mardi 1 janvier 2008, Daddy a =E9crit=A0:
> Hello Qucs (Michael/Stefan/Jens,etc)
>
>
> I would like to join the qucs project as a member (I already joined
> SourceForge). I have
> been compiling qucs for the Puppy Linux distribution and hosting it at
> my website
> www.qsl.net/wn2a/qucs.html  (main page is www.qsl.net/wn2a) .
> I am an electrical engineer of 30+ years experience currently at
> Aeroflex in New Jersey.
Nice to hear that
> My main area is RF/Microwave design , and mixed signal systems. I am
> self-learning C and
> C++, primarily out of strong Linux/Amateur Radio interest, but
> professionally I use much more
> Labview and assembly code.
>  I think I can contribute to the qucs project by:
>  1) compiling qucs packages for Puppy Linux
>  2) adding microwave models and math functions to qucs, especially as my =
=20
> C programming improves.
About models we are happy that you will join us. But do not forget to docum=
ent=20
the model used and the code using doxygen. Documentation is pretty importan=
t=20
for us.=20
About math function, I have some code in order to add airy function (and in=
=20
near future bessel function). I need review, if you want to contribue :-)
>  3) providing help-forum assistance
4) document existing code :-) I am trynig to do that during my sparse time,=
=20
and it is really important in order to help people contribuing.

Nice to hear that.
> Thank You for a professional open-source project of superb quality!
> Mike Masterson
> Budd Lake, NJ USA
> emails: wn...@qs...  or:    ga...@op...
>
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Qucs-help mailing list
> Quc...@li...
> https://lists.sourceforge.net/lists/listinfo/qucs-help



=2D-=20

"ROUCARIES Bastien"
                                              roucaries.bastien+qucs@gmail.=
com
=2D------------------------------------------------------------------------=
=2D-----
DO NOT WRITE TO rou...@gm... OR BE BLACKLISTED

[Qucs-help] Qucs Membership

[Daddy <ga...@op...>]

Hello Qucs (Michael/Stefan/Jens,etc)


I would like to join the qucs project as a member (I already joined 
SourceForge). I have
been compiling qucs for the Puppy Linux distribution and hosting it at 
my website
www.qsl.net/wn2a/qucs.html  (main page is www.qsl.net/wn2a) .
I am an electrical engineer of 30+ years experience currently at 
Aeroflex in New Jersey.
My main area is RF/Microwave design , and mixed signal systems. I am 
self-learning C and
C++, primarily out of strong Linux/Amateur Radio interest, but 
professionally I use much more
Labview and assembly code.
 I think I can contribute to the qucs project by:
 1) compiling qucs packages for Puppy Linux
 2) adding microwave models and math functions to qucs, especially as my 
C programming improves.
 3) providing help-forum assistance

Thank You for a professional open-source project of superb quality!
Mike Masterson
Budd Lake, NJ USA
emails: wn...@qs...  or:    ga...@op...

Re: [Qucs-help] [ANNOUNCEMENT] Qucs 0.0.13

[Bastien R. <rou...@gm...>]

Le dimanche 30 d=E9cembre 2007, vous avez =E9crit=A0:
> Qucs 0.0.13 has been released.

I should add you need to upgrade adms to lastest version.

Regards




=2D-=20

"ROUCARIES Bastien"
                                                   roucaries.bastien@gmail.=
com
=2D------------------------------------------------------------------------=
=2D-----
DO NOT WRITE TO rou...@gm... OR BE BLACKLISTED

[Qucs-help] [ANNOUNCEMENT] Qucs 0.0.13

[Stefan J. <st...@gr...>]

Qucs 0.0.13 has been released.

The Qucs project (Qucs = Quite Universal Circuit Simulator) today
announced the immediate availability of Qucs 0.0.13, a Qt-based
advanced and powerful microwave circuit simulator for GNU/Linux and
other UNIXes.

Qucs, including all its libraries and its applications, is available
as free (as in speech) software under Open Source licenses.  Qucs can
be obtained in source code from <http://sourceforge.net/projects/qucs>.

Features

Qucs provides a GUI based on Qt for setting up electrical and
electronic circuitry, a simulator, which is able to simulate the small-
and large signal as well as the noise behaviour of these circuits.
The results can be shown on a special presentation page in different
formats (rect, polar, smith, tabular, 3d-cartesian, locus and
polar-smith combinations).  Pure digital simulations are also
supported.

Compiling Qucs 0.0.13

The complete source code for Qucs 0.0.13 may be freely
downloaded.  Instructions on compiling and installing Qucs 0.0.13 are
included in the software archive.  Only Qt-Libs >= 3.1 (but < 4.x) and
the glibc are required.

About Qucs

Qucs is an independent project of only a few developers, translators,
etc, collaborating over the Internet to create and freely distribute a
sophisticated, customizable and stable microwave circuit simulator.
For enhancing the development speed we are looking for more
developers, who want to support the Qucs Project.

Changes in this release

The new release comes with some new components, i.e. file based
current and voltage sources, a modular operational amplifier and the
HICUM L2 v2.22 device model. In equations immediate vectors and
matrices are allowed as well as engineering notation of numbers; also
some more functions have been added (random, srandom, StabFactor and
StabMeasure).  Touchstone files can be exported and CSV files can be
imported using the command line data converter QucsConv.

Thanks

A lot of thanks go to the translators and to the supportive user
responses so far encouraging us to improve the software.  We couldn't
have done it without you!

So long,
  the Qucs team.

Re: [Qucs-help] Same schematic, different results

[Stefan J. <st...@gr...>]

Am Sa, 29.12.2007, 13:27, schrieb Bastien ROUCARIES:

Hello!

> In fact I know a world class specialist of precondionning and inversion
> problem. He is sitting in the building near me at uni. I will try to talk
> to
> him about the problem.
>
> Could you give me some pointer to documentation? He is a pure math guy, so
> in
> order to have a quick and efficient tip, we need to ask him a mathematical
> question. THerefore could you explain fully the problem?

It is something like this:

 * equation systems can be solved with different solvers (e.g. LU, QR,
   SVD, inversion, etc.)
 * the given matrix and right hand side can be modified (exchanging
   columns or rows) without chaning the euqation system
 * during some of the solution algorithms pivoting is used; this leaves
   also a degree of freedom (pivot element can be choosen)
 * the method, matrix order as well as the pivot-strategy give
   slightly different results due to numerical errors

Thus the question is:

Is there a precondition-method which allows a solver to solve the
equation system more accurate (even for almost singular matrices).
I think a precondition always must consider which solver/decomposer
is used and also which pivot-strategy is used.

Hope this is a question in fact,
  Stefan.

Re: [Qucs-help] BJT noise model

[Stefan J. <st...@gr...>]

Am Mo, 8.10.2007, 18:31, schrieb Markus Mettenleiter:

> Dear QUCS team,

Hi!

And sorry for the very looooong delay.

> Since I'm currently dealing with BJT noise (in a very low noise TIA
> application), I had a closer look at the BJT noise model (fig. 10.15)
> and related equations. The noise sources ib^2 and ic^2 from equations
> 10.145 and 10.146 are very clear to me, but how do the contributions of
> the ohmic resistances Rbb, Rc, Re (equ. 10.144) fit into the figure
> 10.15 noise model ? None of the terms shows up there, but at least Rbb
> can not be neglected for a decent noise calculation.
>
> To my knowledge the noise contribution of Rbb can be regarded as voltage
> source with ubb^2 = 4KTRbb and placed in series with Rbb of figure
> 10.10. But what about the noise contributions of Rc and Re - convert
> them into voltage sources and place them in series with Rc and Re of the
> figure 10.10 model as well ?  However, it's not quite clear from this
> document, what the simulator actually calculates....

The noise current in parallel to the resistances Rbb, Re and Rc are
computed as 10.144 states.  The figure 10.15 leaves them, because
it only shows the "intrinsic BJT".

> So could you please enhance the fig. 10.15 noise model with the Rbb, Rc,
> Re noise sources - or let me know what I overlooked !

Well, I think it's so very easy, that we decided to leave that.  I am
not yet unsure if I should really add these...

Cheers, Stefan.

Re: [Qucs-help] Same schematic, different results

[Stefan J. <st...@gr...>]

Am Sa, 29.12.2007, 13:20, schrieb Bastien ROUCARIES:

Hello!

>> > I'm still playing around with multivibrators in transient simulation.
>> > This one is nice: attached you will find two identical schematics
>> which
>> > produce almost the same netlist. The only difference between the
>> netlists
>> > is the order of the statements. But the results of the transient
>> > simulation are very different. (the first one fails after producing
>> > more-or-less accurate results and the other one runs thru but nothing
>> > vibrates..)
>> >
>> > I think the problem is that in the 2nd case the evaluation order of
>> the
>> > nodes is different so the transistor is evaluated after the value of
>> its
>> > base contact has been calculated, overwriting the initial DC value I
>> have
>> > set using the label. Which is quite strange because I thought that my
>> > label
>> > would cause the initial dc analyses to charge the capacitor on this
>> wire
>> > so
>> > the wire should stay longer on a high voltage that just for step 0.
>> >
>> > Whats the error in my understanding of what's going on when doing a
>> > transient simulation of this circuit?
>>
>> This one is also known... And an ugly one, I know.
>>
>> Right now the position in the netlist in fact determines somehow, how
>> nodes are put into the circuit matrix to be solved which in turn may
>> affect the result due to numerical issues.
>>
>> One of the solution of this problem may be to find a way to re-order
>> the matrix to be solved in a way to
>>
>>  1) get a deterministic ordering
>>  2) and find an order which makes the matrix "easier" to solve
>>
>> If someone on the list has a better clue than me right now how to
>> achieve (2) then please tell me.  In the qucsator core there is
>> already an sorting algorithm, but this just cares about pairs of
>> +1 and -1 (e.g. voltage sources) and not about the actual node
>> order...
>
> Could you please give me the equation to solve?
> I suppose it is an inversion.

Some of the implemented equation system solvers (e.g. LU, QR, SVD)
decompose the matrix, then solve the system using additionally the
right-hand side...

> IF so the magic key is preconditionning.

I know :)))

> I can try to help when I will come back form vaccation (ie 2008/01/08).

If you have some precondition-knowledge I would be glad if you can
share it...

Cheers, Stefan.

Re: [Qucs-help] Same schematic, different results

[Bastien R. <rou...@gm...>]

Le samedi 29 d=E9cembre 2007, Stefan Jahn a =E9crit=A0:
> Am Mi, 26.12.2007, 09:15, schrieb Clifford Wolf:
> > Hi,
>
> Hello!
>
> > I'm still playing around with multivibrators in transient simulation.
> > This one is nice: attached you will find two identical schematics which
> > produce almost the same netlist. The only difference between the netlis=
ts
> > is the order of the statements. But the results of the transient
> > simulation are very different. (the first one fails after producing
> > more-or-less accurate results and the other one runs thru but nothing
> > vibrates..)
> >
> > I think the problem is that in the 2nd case the evaluation order of the
> > nodes is different so the transistor is evaluated after the value of its
> > base contact has been calculated, overwriting the initial DC value I ha=
ve
> > set using the label. Which is quite strange because I thought that my
> > label
> > would cause the initial dc analyses to charge the capacitor on this wire
> > so
> > the wire should stay longer on a high voltage that just for step 0.
> >
> > Whats the error in my understanding of what's going on when doing a
> > transient simulation of this circuit?
>
> This one is also known... And an ugly one, I know.
>
> Right now the position in the netlist in fact determines somehow, how
> nodes are put into the circuit matrix to be solved which in turn may
> affect the result due to numerical issues.
>
> One of the solution of this problem may be to find a way to re-order
> the matrix to be solved in a way to
>
>  1) get a deterministic ordering
>  2) and find an order which makes the matrix "easier" to solve
>
> If someone on the list has a better clue than me right now how to
> achieve (2) then please tell me.  In the qucsator core there is
> already an sorting algorithm, but this just cares about pairs of
> +1 and -1 (e.g. voltage sources) and not about the actual node
> order...

Could you please give me the equation to solve?
I suppose it is an inversion. IF so the magic key is preconditionning.
I can try to help when I will come back form vaccation (ie 2008/01/08).

Regards=20

Bastien

> Cheers, Stefan.
>
>
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"ROUCARIES Bastien"
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Re: [Qucs-help] QUCS: power Mosfets- unphysical N<1 parameter

[Stefan J. <st...@gr...>]

Am Fr, 14.12.2007, 12:22, schrieb Doom3d:

> Hi,

Hello Szalai,

> I wanted to use an IRFZ34N enhancement n-channel power MOSFET from the
> Mosfet component library. As a first step, I tried to get Id vs Ugs
> characteristics. I got immediately some warning messages, telling that
> D1,D3,D4 diodes in sub-circuitry have unphysical N<1 parameters.
>
> After modifying N values to 1.04, it works w/o errors, but I am not
> sure, that the characteristic curves are still valid.

The warnings are ok.  Don't care.  Changing the values will give you
different characteristics in fact.

> Actually I wanted to create a Luxeon Rebel LED+ dynamo based bycycle
> lighting circuitry, including a hybrid rectifier bridge (mosfets on low
> side, schottky's on high side) using BUK9237-55A. I wanted to base my
> BUK9237 def file on IRFZ34N..

:)))

> BTW, I created a Luxeon Rebel white LED 1.5A def by curve fitting, but
> am not sure, that my parameters are physically correct, and also don't
> know real Id values for Uf<3V. It is based on the 20mA red LED def.
>   Please, could You have a look on it?

I'll give a look later...

Cheers, Stefan.

PS: Sorry for the looooooooooooong delay...

Re: [Qucs-help] Same schematic, different results

[Stefan J. <st...@gr...>]

Am Mi, 26.12.2007, 09:15, schrieb Clifford Wolf:

> Hi,

Hello!

> I'm still playing around with multivibrators in transient simulation. This
> one is nice: attached you will find two identical schematics which produce
> almost the same netlist. The only difference between the netlists is the
> order of the statements. But the results of the transient simulation are
> very different. (the first one fails after producing more-or-less accurate
> results and the other one runs thru but nothing vibrates..)
>
> I think the problem is that in the 2nd case the evaluation order of the
> nodes is different so the transistor is evaluated after the value of its
> base contact has been calculated, overwriting the initial DC value I have
> set using the label. Which is quite strange because I thought that my
> label
> would cause the initial dc analyses to charge the capacitor on this wire
> so
> the wire should stay longer on a high voltage that just for step 0.
>
> Whats the error in my understanding of what's going on when doing a
> transient simulation of this circuit?

This one is also known... And an ugly one, I know.

Right now the position in the netlist in fact determines somehow, how
nodes are put into the circuit matrix to be solved which in turn may
affect the result due to numerical issues.

One of the solution of this problem may be to find a way to re-order
the matrix to be solved in a way to

 1) get a deterministic ordering
 2) and find an order which makes the matrix "easier" to solve

If someone on the list has a better clue than me right now how to
achieve (2) then please tell me.  In the qucsator core there is
already an sorting algorithm, but this just cares about pairs of
+1 and -1 (e.g. voltage sources) and not about the actual node
order...

Cheers, Stefan.

Re: [Qucs-help] BUG Subcircuit with directly connected ports

[Stefan J. <st...@gr...>]

Am Mi, 26.12.2007, 11:39, schrieb Clifford Wolf:

> Hi,

Hello!

> when I create a subcircuit in which I simply connect ports without any
> devices in between, the simulation gives me bogus results. It works fine
> with zero-resistance resistors thought.
>
> So the following netlist does not work:
>
> --snip--
> .Def:xwire _net0 _net0 _net1 _net1
> .Def:End
> --snap--
>
> While this one is working fine:
>
> --snip--
> .Def:xwire _net0 _net1 _net2 _net3
> R:R1.0 _net1 _net0 R="0"
> R:R2.0 _net3 _net2 R="0"
> .Def:End
> --snap--
>
> Here is the full working netlist:
>
> --snip--
> # Qucs 0.0.12  /home/clifford/.qucs/DEMO_prj/xwire_test.sch
>
> .Def:xwire _net0 _net1 _net2 _net3
> R:R1.0 _net1 _net0 R="0"
> R:R2.0 _net3 _net2 R="0"
> .Def:End
>
> Vdc:V1 _net0 _net1 U="1 V"
> .TR:TR1 Type="lin" Start="0" Stop="1 ms" Points="11"
> IntegrationMethod="Trapezoidal" Order="2" InitialStep="1 ns"
> MinStep="1e-16" MaxIter="150" reltol="0.001" abstol="1 pA" vntol="1 uV"
> Temp="26.85" LTEreltol="1e-3" LTEabstol="1e-6" LTEfactor="1"
> Solver="CroutLU" relaxTSR="no" initialDC="yes" MaxStep="0"
> VProbe:Pr2 _net2 _net3
> R:R1 _net3 _net2 R="4 Ohm" Temp="26.85" Tc1="0.0" Tc2="0.0" Tnom="26.85"
> IProbe:Pr1 _net7 _net2
> R:R2 _net6 _net7 R="1 Ohm" Temp="26.85" Tc1="0.0" Tc2="0.0" Tnom="26.85"
> Sub:XWire1 _net0 _net4 _net1 _net5 Type="xwire"
> Sub:XWire2 _net5 _net3 _net4 _net6 Type="xwire"
> --snap--

This one, about the "two or more subcircuit ports, but same node", is
known already.  I've not yet come to an implemented solution, but it
is on my todo list.

Thanks for reporting,
  Stefan.

Re: [Qucs-help] Noise Source and File-Source in Transient Simulation

[Stefan J. <st...@gr...>]

Am Do, 27.12.2007, 01:40, schrieb Clifford Wolf:

> Hi again,

Hello Clifford!

>> > Are there any plans to add noise sources to transient simulation? With
>> > a random seed as optional parameter so there is 'reproduceable
>> > randomness' to would be nice..  ;-)
>>
>> Not yet.  Let me think about this...
>
> I've just seen on the webpage that there is a random() function in CVS. Do
> I guess right that this could be used in an eq defined device to create a
> noice current source - and thus create a noice voltage source by adding
> a current controlled voltage source, or by adding a parallel resistor if
> the voltage source doesn't need to be an ideal voltage source (Norton's
> theorem)?

Hm.  You may give it try in fact...

Cheers, Stefan.

Re: [Qucs-help] Noise Source and File-Source in Transient Simulation

[Clifford W. <cli...@cl...>]

Hi again,

On Wed, Dec 26, 2007 at 08:32:23PM +0100, Stefan Jahn wrote:
> > Are there any plans to add noise sources to transient simulation? With
> > a random seed as optional parameter so there is 'reproduceable
> > randomness' to would be nice..  ;-)
> 
> Not yet.  Let me think about this...

I've just seen on the webpage that there is a random() function in CVS. Do
I guess right that this could be used in an eq defined device to create a
noice current source - and thus create a noice voltage source by adding
a current controlled voltage source, or by adding a parallel resistor if
the voltage source doesn't need to be an ideal voltage source (Norton's
theorem)?

yours,
 - clifford

-- 
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Re: [Qucs-help] Multivibrator Transient Simulation

[Stefan J. <st...@gr...>]

Am Mi, 26.12.2007, 22:16, schrieb Bastien ROUCARIES:

Hi!

>> All of the transient simulation options may have effects on the
>> simulation behaviour.  I just tried to change "relaxTSR" with your
>> example and then the simulation went through...
>
> In my school we teach in this case to put capacitor between CE or to put a
> small resistor in serie with capacitor./ What do you think about this kind
> of
> workarround? (Because it will smooth the tranfert function)

Indeed it works in some cases.

> BTW what is relaxTSR?.

It relaxes the "Time Step Raster".  With set to yes, time point
calculation is not forced to hit the exact time points requested
in the simulation (start stop steps), but allows simulation to
choose a time point near that point.  With the option set to "no"
kind of break points are introduced to hit exact point points.

Cheers, Stefan.