Re: [Qucs-devel] misc stuff

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

Am Fr, 9.02.2007, 10:07, schrieb Oswald Buddenhagen:

Hello Oswald,

>> > i think i assumed too much ideality from the standard components (i
>> > tried the default transistors before the BC5*) - probably because it
>> is
>> > highly inconsistent (compare the opamp model).
>>
>> the default transistors/diodes are quite ideal in fact.  no series
>> resistance, no junction capacitances and alike.
>>
> hmm, but there must be some timing dependance. i guess one'd have to do
> further analysis.

There is no timing dependency whithout Caps and Transit times.

>> > some actual bugs in the gui now:
>> > - the schematic view has some selective repainting problems.
>>
>> that's probably a Qt "proplem"?
>>
>> > - the widgets in the component properties dialog have weird
>> > repainting problems
>>
>> that is as well a Qt problem which is known to us.
>>
> given that both happen only sporadically, i tend to suspect that we are
> seeing the effects of some serious memory corruption ...
>
>> >   this sounds a lot like this thing should go through valgrind.
>>
> ... so i can't stress this enough.

Yep.  Please do.

> just for fun ;) i attached another schematic. this is supposed to be a
> synchronous rectifier.
> in the current configuration it aborts with a jacobian singular (wtf?)
> before the end of the first period.
> with ideal opamps it doesn't even get started (in finite time, that is).
> i managed to get it move a bit by adding capacitors between the opamp's
> pins, but that didn't help *that* much, either.
> if you have some tips or even an estimate whether this has a chance of
> working in reality, i'd be glad to hear it.

The singular Jacobian appears with ill-conditioned matrices.  The Jacobian
is the derivative matrix of the actual circuit matrix.

That's just for your information.

I played a bit with simulation options.  Also with the input voltage which
is now 10V.

Attached the "working" circuit.  It lasts 1/2 hour or so...  So this is
actually not acceptable because you might be faster to build it in this
time for real...  But it's a start.

Cheers, Stefan.