Bengt Nilsson

As I mentioned, my circuit has some startup behaviour that I want to improve. It is stable after 2 seconds, and I would like the .op to run to this point for my convenience. optran 0 0 0 0.1m 2000m 0did not produce the result that I wanted. But I now realise that my "realistic" and naive sceme to include a AC source and a diode rectifier will NEVER reach a stable point and this is maybe why it will not work. I should instead try to arrange a DC source with a similar rise time.

Ok, thanks. I will have to find where qucs-s handles .spiceinit. Is it possible to say how optran (which parameters) should be used to do what I want, once it is entered properly in .spiceinit? Would the optran example 1 described in the manual do the job?

I am sorry, since I am a qucs-s (are you familiar with it?) user I have not worked with explicit ngspice directives, most of the action is behind the scenes for me. The only "access" I have is a text file for "extra simulator parameters". qucs-s is quite robust, it gives more often useful results compared to e.g. KiCad PCB disgn circuit simulation. It is unclear why, both are using ngspice as the simulation engine. Maybe qucs-s is more adaptive. But as I said, this is behind the scenes for me. I...

I am sorry, since I am a qucs-s (are you familiar with it?) user I have not worked with explicit ngspice directives, most of the action is behind the scenes for me. The only "access" I have is a text file for "extra simulator parameters". qucs-s is quite robust, it gives more often useful results compared to e.g. KiCad PCB disgn circuit simulation. It is unclear why, both are using ngspice as the simulation engine. Maybe qucs-s is more adaptive. But as I said, this is behind the scenes for me. As...

Thank you for the information that .op does not take parameters. I did not understand this. I did read the .OP section in the manual. How should the .op section look like when using optran? .op optran 0 0 0 1u 1000m 0 giver me no syntax error, but not the result that I want. To me, it looks like .op indeed takes the optran line as a parameter in this case? I have to admit I have not studied the complete manual.

Hi, I am using qucs-s with ngspice. I am trying to analyse a circuit's transient startup behaviour, like peak supply current surges before the feedback control is working properly, etc. This analysis is working satisfactory, if the transient simulation is included and the initial DC operating point analysis is turned off. I get stable behaviour after 1-2 seconds. I have two problems. qucs-s has a function called "Calculate DC bias", which is doing the nigspice operating point analysis. This function...