About eSim AC source parameter setting

I have downloaded eSim 2.0 for windows.I am using Windows 10 (64 - bit). It is working perfectly for transient analysis. But for AC analysis, for the selected eSim_AC source, the parameters (like amplitude and phase) can't be set because when I convert the kiCad circuit to NgSpice, for AC analysis, only the frequency settings window is shown. The source window shows blank. But, the message of successful convertion is appearing.The simulation also shows successful message but the plots are showing 0 V for the entire range of frequencies. Also, the netlist of NgSpice shows 0 V for the source. Can you help me why the window for AC Source is showing blank? Please help me to overcome this technical problem.

Thank you,

Dr. Ravisankar.M

eSim 23-08-20, 9:26 a.m. RavisakarM
Dear Sir, Replace the eSim_AC with 'Sine' from eSim_Sources. Place the cursor on the sine and press the 'E' key, (The E is to edit the value of the component). Remove the eSIm_AC and type AC (case insensitive) Repeat the steps of annotation and the netlist generation. Also, make sure if AC analysis is used, plot_log has to be connected to output nodes for frequency plotting. In the AC analysis tab, DEC (Decimal)should be selected. Please refer to the High pass/low pass filter from the Examples folder in the eSim installer.
23-08-20, 2:15 p.m. Gloria

Dear Ma'am,

Thank you very much for your response to my query. I already got the answer, which you have given above, from an earlier query in the same forum. But,I hope, you may be able to help me for the following problems:

1. the output plot is showing inverted from the normally expected plot. 

2. how to plot the output/input voltage (gain of an amplifier) as a function of frequency, 

I need to see the bandwidth of an inverting amplifier with opamp. Earlier, I have used extensively OrCad and Multisim. In both, these are pretty easy and straight forward. This software seems to be powerful but I am facing many problems like the ones mentioned above..

Thank you,

Dr. Ravisankar.M

23-08-20, 3:50 p.m. RavisakarM

Dear Sir,

You can type the ngspice commands for the output node. 

Example: Assume I have named my output node as 'OUT', then plot_log is used for frequency plot. In 'KiCad to Ngspice analysis', you can mention the source value.

Also, in the Ngspice prompt, you can say:

plot vdb(OUT); for db out

plot ph(OUT) ; for phase

plot v(in) v(OUT); for both input and output plot.


Can you please share the cir.out file if possible, to identify the reason for inverted output.

You can find this file in the project created at the eSim-workspace folder.


23-08-20, 6:56 p.m. Gloria

Dear Ma'am,

Thank you very much for the reply. Let me check once again,as you suggested. If the problem still persists, I will share the circuit or the the netlist. Because I am new to eSim, I am overlooking some thing. Also, I am trying to do simulations more or less the same way I was doing it with commercial softwares. I never faced with any such issues there. Now, I am trying to use only the open source softwares like Octave/SciLab, eSim etc.

Thank you once again,

Dr. Ravisankar.M

24-08-20, 6:47 a.m. RavisakarM

Dear Sir,

Thank you.

You can post your queries in this forum or mail us:contact-esim[at]fossee[dot]in

24-08-20, 2:29 p.m. Gloria

Dear Madam,

Thank you very much for your help for my query through email. When I changed the esim_plots, as per your suggestions, the NgPlots came as expected. But , the Python plot is seen inverted, as in the earlier case. Can you suggest why this is not giving the correct plots. 

Thank you for your patience,



25-08-20, 7:01 a.m. RavisakarM

Dear Sir,

Python plots are plotted wrt voltages and time. Since the input is given to inverting terminal of opamp ua741, the output is inverted.

Also, please send your query to :


I think yesterday you have mailed it to wrong email id.

25-08-20, 9:26 a.m. Gloria

Dear Ma'am,

Thank you very much.


Dr. Ravisankar.M

25-08-20, 9:35 a.m. RavisakarM

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