Re: [Ngspice-users] Transmission lines

[Alain P. <ala...@fr...>]

Hi Robert,

Many thanks for your help and for time you spend on my problems.
Unfortunately, I'm not able to reproduce your results :-(

Here are my results (plot 2 and plot3 are empty)

I made 2 more plots to show you the problem.

hardcopy plot4.ps v(2) ylimit -200 100 xlimit 0 1u
hardcopy plot5.ps v(2) xlimit 59u 60u

It seems my ngspice-26 installation is buggy and I don't know how to investigate.

Regards.
Alain


Le samedi 11 avril 2015 16:43:17 Robert Larice a écrit :
> Hello Alain,
> 
> > A falling front from 500V to 0V in 50ns.
>   in your ngspice variant you had :
>      Vin 1 0 Pulse(500 0 0 50n 50n 200n)
>   which does not match your description
>   and is contrary to the pspice file which has :
>      Vin 1 0 Pulse(500 0 0 50n)
>   I've changed that to the pspice variant
> 
>   and in your ngspice variant you had :
>     tran 5n 60u
>   I've changed that to the pspice variant as well
>   which is :
>     tran 5n 60u 0n 10n
>   and thus specifies the Tmax parameter
> 
>   Then I compiled exactly ngspice-26
>   and have run it with your circuit,
>     plots and source is attached.
> 
>   The plots match, as far as I can recognise,
>     to your pspice screen-shot.
> 
>   The run-time is few seconds.
>   But if I use your "tran" incantation without
>     the Tmax parameter
>   then the simulation slows down at 50us to something
>     unbearable for me.
> 
>   I hope you can reproduce this successfully now.
> 
> Regards,
>   Robert
>