Re: [Qucs-help] Multivibrator Transient Simulation

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

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.
>
>
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