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From: Bastien ROUCARIES <roucaries.bastien@gm...>  20071230 16:29:15

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@...= com =2D= =2D DO NOT WRITE TO roucaries.bastien+blackhole@... OR BE BLACKLISTED 
From: Stefan Jahn <stefan@gr...>  20071230 15:45:59

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 Qtbased 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, 3dcartesian, locus and polarsmith 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 QtLibs >= 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. 
From: Stefan Jahn <stefan@gr...>  20071229 12:59:52

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 pivotstrategy give slightly different results due to numerical errors Thus the question is: Is there a preconditionmethod 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 pivotstrategy is used. Hope this is a question in fact, Stefan. 
From: Stefan Jahn <stefan@gr...>  20071229 12:31:37

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. 
From: Stefan Jahn <stefan@gr...>  20071229 12:24:35

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 >> > moreorless 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 reorder >> 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 righthand 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 preconditionknowledge I would be glad if you can share it... Cheers, Stefan. 
From: Bastien ROUCARIES <roucaries.bastien@gm...>  20071229 12:19:01

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 > > moreorless 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 reorder > 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. > > >  > 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/ > _______________________________________________ > Qucshelp mailing list > Qucshelp@... > https://lists.sourceforge.net/lists/listinfo/qucshelp =2D=20 "ROUCARIES Bastien" roucaries.bastien@...= com =2D= =2D DO NOT WRITE TO roucaries.bastien+blackhole@... OR BE BLACKLISTED 
From: Stefan Jahn <stefan@gr...>  20071229 12:13:59

Am Fr, 14.12.2007, 12:22, schrieb Doom3d: > Hi, Hello Szalai, > I wanted to use an IRFZ34N enhancement nchannel 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 subcircuitry 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 BUK923755A. 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... 
From: Stefan Jahn <stefan@gr...>  20071229 12:07:58

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 moreorless 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 reorder 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. 
From: Stefan Jahn <stefan@gr...>  20071229 12:00:24

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 zeroresistance 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="1e16" MaxIter="150" reltol="0.001" abstol="1 pA" vntol="1 uV" > Temp="26.85" LTEreltol="1e3" LTEabstol="1e6" 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. 
From: Stefan Jahn <stefan@gr...>  20071229 11:49:48

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. 
From: Clifford Wolf <clifford@cl...>  20071227 00:45:04

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  For extra security, this message has been encrypted with doubleROT13. 
From: Stefan Jahn <stefan@gr...>  20071226 21:23:09

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. 
From: Bastien ROUCARIES <roucaries.bastien+<qucs@gm...>  20071226 21:14:55

Le mercredi 26 d=E9cembre 2007, Stefan Jahn a =E9crit=A0: > Am Di, 25.12.2007, 18:20, schrieb Clifford Wolf: > > Hey, > > Hello! > > > I've spend the whole day tring to do a transient simulation of a simple > > multi vibrator. > > Oscillators are sometimes difficult to simulate. > > > The simulation just hangs or returns bogus results with > > the > > normal transistor model. I've now tried with the the BC549 Model and set > > the initial voltage of one of the transistor bases to 0.8V, which > > looks already close to what I'd expected. > > > > But the simulation aborts after some time with the following error > > message: > > ... > > > > I have to admit that I don't know anything about the math behind this > > simulations, so I can't tell whats going on here. > > > > Depending on resistor and capacitor values this message pops up earlier > > or later. > > > > is there anything I can do about it? I also havent found anything in the > > qucs documentation about stuff like this (e.g. which Integration Method > > has > > what pros and cons, I'm just mentioning this topic because I got much > > worse > > results using the standard Integration Method and it is better since I > > switchd to 'Euler'). > > > > Is there any documentation on this topics? > > Unfortunately not. > > 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= =20 small resistor in serie with capacitor./ What do you think about this kind = of=20 workarround? (Because it will smooth the tranfert function) BTW what is relaxTSR?. Regards Bastien > Cheers, 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/ > _______________________________________________ > Qucshelp mailing list > Qucshelp@... > https://lists.sourceforge.net/lists/listinfo/qucshelp =2D=20 "ROUCARIES Bastien" roucaries.bastien+qucs@...= com =2D= =2D DO NOT WRITE TO roucaries.bastien+blackhole@... OR BE BLACKLISTED 
From: Stefan Jahn <stefan@gr...>  20071226 19:58:47

Am Di, 25.12.2007, 18:20, schrieb Clifford Wolf: > Hey, Hello! > I've spend the whole day tring to do a transient simulation of a simple > multi vibrator. Oscillators are sometimes difficult to simulate. > The simulation just hangs or returns bogus results with > the > normal transistor model. I've now tried with the the BC549 Model and set > the initial voltage of one of the transistor bases to 0.8V, which > looks already close to what I'd expected. > > But the simulation aborts after some time with the following error > message: > ... > > I have to admit that I don't know anything about the math behind this > simulations, so I can't tell whats going on here. > > Depending on resistor and capacitor values this message pops up earlier or > later. > > is there anything I can do about it? I also havent found anything in the > qucs documentation about stuff like this (e.g. which Integration Method > has > what pros and cons, I'm just mentioning this topic because I got much > worse > results using the standard Integration Method and it is better since I > switchd to 'Euler'). > > Is there any documentation on this topics? Unfortunately not. 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... Cheers, Stefan. 
From: Stefan Jahn <stefan@gr...>  20071226 19:32:36

Am Mi, 26.12.2007, 19:05, schrieb Clifford Wolf: > Hi, Hello! > I was playing around with the noise current and voltage sources today. > Am I right that they are noops in transient simulation? Yes. > 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... > Another thing I would need are filebased voltage and current sources, so > I > could provide current or voltage data in a file and they would then be > used > in the simulation. I can record csv files with my oszi and it would be > great to be able to use them as teststimuli.. These are already in CVS. Cheers, Stefan. 
From: Stefan Jahn <stefan@gr...>  20071226 19:27:06

Am Di, 25.12.2007, 22:01, schrieb Clifford Wolf: > Hi, Hello! > While an eq. defined device with "I1=5" provides 5A as expected, an eq. > defined device with "I1=sqrt(25)" provides only 6.74e316 A in a transient > simulation (havent tried any others). Is this a bug? Yep, its a known bug in 0.0.12. It is fixed in CVS already. Anyway, thanks for reporting!! > (see attached *.sch and *.dat files) > > BTW: Why is qucs adding virtual resistors serial to my explicit > greaterthan0Ohm resistors? There is no ground somewhere in the schematic. That's why :))) Cheers, Stefan. 
From: Clifford Wolf <clifford@cl...>  20071226 18:09:57

Hi, I was playing around with the noise current and voltage sources today. Am I right that they are noops in transient simulation? 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.. ;) Another thing I would need are filebased voltage and current sources, so I could provide current or voltage data in a file and they would then be used in the simulation. I can record csv files with my oszi and it would be great to be able to use them as teststimuli.. yours,  clifford  "Gee, I wish we had one of those doomsday machines."  dr. strangelove, the movie 
From: Clifford Wolf <clifford@cl...>  20071226 10:44:18

Hi, 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 zeroresistance 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="1e16" MaxIter="150" reltol="0.001" abstol="1 pA" vntol="1 uV" Temp="26.85" LTEreltol="1e3" LTEabstol="1e6" 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 yours,  clifford  "Backups are for wimps. Real men upload their data to an FTP site and have everyone else mirror it."  Linus Torvalds 
From: Clifford Wolf <clifford@cl...>  20071226 08:20:20

Hi, 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 moreorless 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? thanks for your help. yours,  clifford PS: In digital simulation there usually (= verilog does it this way ;) are two state arrays  one for the old and one for the new state, which are swaped after each time slice. This way the evaluation order of the elements is irrelevant..  "The generation of random numbers is too important to be left to chance."  Robert R. Coveyou, Oak Ridge National Laboratory. 
From: Clifford Wolf <clifford@cl...>  20071225 21:13:53

On Tue, Dec 25, 2007 at 10:01:28PM +0100, Clifford Wolf wrote: > (see attached *.sch and *.dat files) oops. here are the file.. ;)  A: No. Q: Should I include quotations after my reply? 
From: Clifford Wolf <clifford@cl...>  20071225 21:05:46

Hi, While an eq. defined device with "I1=5" provides 5A as expected, an eq. defined device with "I1=sqrt(25)" provides only 6.74e316 A in a transient simulation (havent tried any others). Is this a bug? (see attached *.sch and *.dat files) BTW: Why is qucs adding virtual resistors serial to my explicit greaterthan0Ohm resistors? snip WARNING: TR1: inserted virtual resistance at node `_net1' connected to [R1,Pr1] WARNING: TR1: inserted virtual resistance at node `_net4' connected to [R2,Pr2] snap (this is with qucs 0.0.12 on 32bit x86) yours,  clifford  2B OR (NOT 2B) That is the question. The answer is FF. 
From: Clifford Wolf <clifford@cl...>  20071225 18:02:54

Hi, On Tue, Dec 25, 2007 at 06:47:14PM +0100, Bastien ROUCARIES wrote: > > ERROR: TR1: Jacobian singular at t = 6.531e02, > > aborting transient analysis > > > > I have to admit that I don't know anything about the math behind this > > simulations, so I can't tell whats going on here. > > > > Depending on resistor and capacitor values this message pops up earlier or > > later. > > Add a small resistor vin serie with capacitor. It is a classical mistake in > this kind of circuit to not put dissipative element. If you do not put > dissipative element slope is too high for good simulation and you will get > divide by zero. I've added 50 Ohm resistors in series with my capacitors and now I do get: ERROR: TR1: Jacobian singular at t = nan, aborting transient analysis t = nan ??? looking at the data generated by the simulation it should be something like t = 0.007. I also don't think that this should make much of a difference.. or am I wrong when I assume that the BC549 model always has at least some BE resistence? So even if there is no CE resistance (which I woukd consider a bug in the device model), the capacitors would never be discharged or charged without a loadresistor.. yours,  clifford  [..] If it still doesn't work, rewrite it in assembler. This won't fix the bug, but it will make sure no one else finds it and makes you look bad. 
From: Bastien ROUCARIES <roucaries.bastien@gm...>  20071225 17:45:50

Le mardi 25 d=E9cembre 2007, Clifford Wolf a =E9crit=A0: > Hey, > > I've spend the whole day tring to do a transient simulation of a simple > multi vibrator. The simulation just hangs or returns bogus results with t= he > normal transistor model. I've now tried with the the BC549 Model and set > the initial voltage of one of the transistor bases to 0.8V, which > looks already close to what I'd expected. > > But the simulation aborts after some time with the following error messag= e: > > snip > WARNING: Unphysical model parameter Nf =3D 0.996496 in BJT `BC549_1' > WARNING: Unphysical model parameter Nr =3D 0.993 in BJT `BC549_1' > WARNING: Unphysical model parameter Nc =3D 0.996 in BJT `BC549_1' > WARNING: Unphysical model parameter Nf =3D 0.996496 in BJT `BC549_2' > WARNING: Unphysical model parameter Nr =3D 0.993 in BJT `BC549_2' > WARNING: Unphysical model parameter Nc =3D 0.996 in BJT `BC549_2' > WARNING: Unphysical model parameter Nf =3D 0.996496 in BJT `BC549_1' > WARNING: Unphysical model parameter Nr =3D 0.993 in BJT `BC549_1' > WARNING: Unphysical model parameter Nc =3D 0.996 in BJT `BC549_1' > WARNING: Unphysical model parameter Nf =3D 0.996496 in BJT `BC549_2' > WARNING: Unphysical model parameter Nr =3D 0.993 in BJT `BC549_2' > WARNING: Unphysical model parameter Nc =3D 0.996 in BJT `BC549_2' > WARNING: TR1: inserted virtual resistance at node `_net2' connected to > [_Rc#BC549_2,C2,BC549_2,R4] WARNING: TR1: inserted virtual resistance at > node `_emitter#BC549_1' connected to [_Re#BC549_1,BC549_1] WARNING: TR1: > inserted virtual resistance at node `_emitter#BC549_2' connected to > [_Re#BC549_2,BC549_2] WARNING: TR1: inserted virtual resistance at node > `_net1' connected to [_Rc#BC549_1,C1,BC549_1,R1] WARNING: TR1: inserted > virtual resistance at node `_collector#BC549_2' connected to > [_Cbcx#BC549_2,_Rc#BC549_2,BC549_2] WARNING: TR1: inserted virtual > resistance at node `_base#BC549_1' connected to [_Rbb#BC549_1,BC549_1] > WARNING: TR1: inserted virtual resistance at node `_collector#BC549_1' > connected to [_Cbcx#BC549_1,_Rc#BC549_1,BC549_1] WARNING: TR1: inserted > virtual resistance at node `_base#BC549_2' connected to > [_Rbb#BC549_2,BC549_2] ERROR: TR1: Jacobian singular at t =3D 6.531e02, > aborting transient analysis snap > > I have to admit that I don't know anything about the math behind this > simulations, so I can't tell whats going on here. > > Depending on resistor and capacitor values this message pops up earlier or > later. Add a small resistor vin serie with capacitor. It is a classical mistake in= =20 this kind of circuit to not put dissipative element. If you do not put=20 dissipative element slope is too high for good simulation and you will get= =20 divide by zero. Regards Bastien Joined: corrected circuit > is there anything I can do about it? I also havent found anything in the > qucs documentation about stuff like this (e.g. which Integration Method h= as > what pros and cons, I'm just mentioning this topic because I got much wor= se > results using the standard Integration Method and it is better since I > switchd to 'Euler'). > > Is there any documentation on this topics? > > yours, >  clifford > > PS: I have attached my multivib.sch and multivib.dpl files for reference. > > PPS: I haven't tried this circuit in real. But I am _pretty_ sure that it > should work fine and that the resistor/capacitor values make sense.. =2D=20 "ROUCARIES Bastien" roucaries.bastien@...= com =2D= =2D DO NOT WRITE TO roucaries.bastien+blackhole@... OR BE BLACKLISTED 
From: Clifford Wolf <clifford@cl...>  20071225 17:24:40

Hey, I've spend the whole day tring to do a transient simulation of a simple multi vibrator. The simulation just hangs or returns bogus results with the normal transistor model. I've now tried with the the BC549 Model and set the initial voltage of one of the transistor bases to 0.8V, which looks already close to what I'd expected. But the simulation aborts after some time with the following error message: snip WARNING: Unphysical model parameter Nf = 0.996496 in BJT `BC549_1' WARNING: Unphysical model parameter Nr = 0.993 in BJT `BC549_1' WARNING: Unphysical model parameter Nc = 0.996 in BJT `BC549_1' WARNING: Unphysical model parameter Nf = 0.996496 in BJT `BC549_2' WARNING: Unphysical model parameter Nr = 0.993 in BJT `BC549_2' WARNING: Unphysical model parameter Nc = 0.996 in BJT `BC549_2' WARNING: Unphysical model parameter Nf = 0.996496 in BJT `BC549_1' WARNING: Unphysical model parameter Nr = 0.993 in BJT `BC549_1' WARNING: Unphysical model parameter Nc = 0.996 in BJT `BC549_1' WARNING: Unphysical model parameter Nf = 0.996496 in BJT `BC549_2' WARNING: Unphysical model parameter Nr = 0.993 in BJT `BC549_2' WARNING: Unphysical model parameter Nc = 0.996 in BJT `BC549_2' WARNING: TR1: inserted virtual resistance at node `_net2' connected to [_Rc#BC549_2,C2,BC549_2,R4] WARNING: TR1: inserted virtual resistance at node `_emitter#BC549_1' connected to [_Re#BC549_1,BC549_1] WARNING: TR1: inserted virtual resistance at node `_emitter#BC549_2' connected to [_Re#BC549_2,BC549_2] WARNING: TR1: inserted virtual resistance at node `_net1' connected to [_Rc#BC549_1,C1,BC549_1,R1] WARNING: TR1: inserted virtual resistance at node `_collector#BC549_2' connected to [_Cbcx#BC549_2,_Rc#BC549_2,BC549_2] WARNING: TR1: inserted virtual resistance at node `_base#BC549_1' connected to [_Rbb#BC549_1,BC549_1] WARNING: TR1: inserted virtual resistance at node `_collector#BC549_1' connected to [_Cbcx#BC549_1,_Rc#BC549_1,BC549_1] WARNING: TR1: inserted virtual resistance at node `_base#BC549_2' connected to [_Rbb#BC549_2,BC549_2] ERROR: TR1: Jacobian singular at t = 6.531e02, aborting transient analysis snap I have to admit that I don't know anything about the math behind this simulations, so I can't tell whats going on here. Depending on resistor and capacitor values this message pops up earlier or later. is there anything I can do about it? I also havent found anything in the qucs documentation about stuff like this (e.g. which Integration Method has what pros and cons, I'm just mentioning this topic because I got much worse results using the standard Integration Method and it is better since I switchd to 'Euler'). Is there any documentation on this topics? yours,  clifford PS: I have attached my multivib.sch and multivib.dpl files for reference. PPS: I haven't tried this circuit in real. But I am _pretty_ sure that it should work fine and that the resistor/capacitor values make sense..  bash c "gcc o mysdldemo Wall O2 lSDL lm pthread x c <( echo e ' #include <SDL/SDL.h>\n#include <complex.h>\nint main(){SDL_Surface*s;SDL_Event e;int x,y,n;SDL_Init(SDL_INIT_VIDEO);s=SDL_SetVideoMode(640,480,32,0);for(x=0; x<640;x++)for(y=0;y<480;y++){float _Complex z=0, c=((x400)/200.0) + ((y240)/ 200.0)*1.0fi;for(n=1;n<64;n++){z=z*z+c;if(cabsf(z)>2){((Uint32*)s>pixels)[x+y *640]=n<<3;n=99;}}}SDL_UpdateRect(s,0,0,s>w,s>h);do SDL_WaitEvent(&e); while (e.type!=SDL_QUIT&&e.type!=SDL_KEYDOWN);SDL_Quit();return 0;}' ); ./mysdldemo" 
From: Bastien ROUCARIES <roucaries.bastien+<qucs@gm...>  20071225 15:19:24

Le jeudi 20 d=E9cembre 2007, Manoj Rajagopalan a =E9crit=A0: > Hi, > > It would be useful to have a function that removes opencircuit wires > such as those resulting from removing a bunch of components. Such a > function could also trim wire protrusion artifacts that sometime result > from the way users wire or move components. Sorry for the delay. I have noted this task to be done. Please prod us in = mid=20 january. In fact you want a function likein labview or xilinx: "remove broken wire". Regards Bastien > Thanks > Manoj > >  > SF.Net email is sponsored by: > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services > for just about anything Open Source. > http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketpl= ac >e _______________________________________________ > Qucshelp mailing list > Qucshelp@... > https://lists.sourceforge.net/lists/listinfo/qucshelp =2D=20 "ROUCARIES Bastien" roucaries.bastien+qucs@...= com =2D= =2D DO NOT WRITE TO roucaries.bastien+blackhole@... OR BE BLACKLISTED 