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Qucs tutorial figure 20 - undefined V1

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sydney
2018-08-08
2018-08-17
  • sydney

    sydney - 2018-08-08

    In this tuorial example, after inputting the schematic and setting up the scheme, I get errors about an undefined V1 parameter in the equation. V1 is the source. This is straight out of the tutorial, but I cannot find anything wrong with what I did. The related attachments are contained in the following two replies.

     
  • sydney

    sydney - 2018-08-08

    This is the EDD from the tutorial

     
  • sydney

    sydney - 2018-08-08

    This is the test scheme.

     
  • sydney

    sydney - 2018-08-08

    This is the actual EDD, the first attachment was the error message.

     
  • sydney

    sydney - 2018-08-08

    Problem solved! There is an error in this tutorial, and an error of ommission as well! In the EDD equation block, V1 should have been V1.v for all the parameters in this equation, not as shown in the tutorial. The graphs still looked like crap so I set the transit points to 100 and all looked well. This is an error of ommission, make the chart points visable in the tutorial for the user to see. This is not the first time that I have found a problem with the tutorials, so be carefull when trying to get these things to work per tutorial.

     
  • Claudio Girardi

    Claudio Girardi - 2018-08-08

    which tutorial?
    At a first glance the EDD equation looks ok to me, V1 is the voltage across the first EDD branch.

     
  • sydney

    sydney - 2018-08-08

    In the Qucs tutorial in figure 20 there is an EDD and a test circuit. The parameters for the EDD contain V1 in the equation. This doesn't compile unless you substitute V1.v for these parametes! This document is made by Mike Brinson and is found in the help getting started selection of Qucs.

     
  • Claudio Girardi

    Claudio Girardi - 2018-08-09

    using V1 in an EDD equation must work, as described above.
    There is a ton of documents, PDF files and web pages for Qucs, please provide the PDF file name or the web page URL for the tutorial you are referring to.

     
  • sydney

    sydney - 2018-08-10

    In the Qucs help/tutorials there is a tutorial for equations and that is what I am referring to.

     
    • Claudio Girardi

      Claudio Girardi - 2018-08-11

      ok, so this is the file named equations.pdf whose complete title is "Qucs - A Tutorial - Component, compact device and circuit modelling using symbolic equations". It's easier to find it here if you give more information.

       
  • sydney

    sydney - 2018-08-10

    Sorry to say, but when I use V1 I get undefined error messages, but when I use Vi.v, the example runs according to the tutorial.

     
    • Claudio Girardi

      Claudio Girardi - 2018-08-11

      um, I created a project according to the tutorial description and if worked as expected, using "V1" in the EDD component equation.
      Enclose is a zip file with the project, please check w.r.t. your circuit.
      In general you may also include your failing project/schematic, will probably make it easier to understand what's wrong.

       
  • sydney

    sydney - 2018-08-11

    This is the zip files for two projects. The figure 20 and test schematics work. In this one I had to change VI to V1.V. The later being the input source supply. Everything works with the charts showing exactly what is shown in the tutorial! The project that you included is quite different than what I'm dealing with in the tutorial: its an inductor. In figure 23 of my project I tried a different approach. Because the I and Q properties all contained V1, which is not defined, I added into the equation the line:
    V1=PAnode-PCathode, defining V1, since these are connected to the source and ground of the EDD diode. No good. So I tried
    V1=PAnode.V-PCathode.V. Still no good! But figure 20 does! I'm betting that if I replace V1 with Vs1.V, similar to what I did in figure 20, this will work. But that would defeat the purpose of having the diode with input parameters which were never used in these examples.

     
  • sydney

    sydney - 2018-08-11

    A comment on the project that you posted (which works): The I and Q equations contain V1. V1 is the external power source. This diode should be looking at the anode and cathode terminals, so it would be independent of external sources and grounds. Since the anode and gnd are the terminals of the diode, these should be used to simulate the diode characteristics! Not the external source. Maybe assigning the anode and cathode to V1 and ground in an equation would be the way to go. As it is now, if I change V1 to V2 say, this would fall apart, showing the dependency of this diode to the external circuit. The diode should work independently from outside sources and grounds! As programmer we do this all the time.

     
  • sydney

    sydney - 2018-08-17

    I downloaded your scheme and tried it out. All went OK. I compared it to my schematic, and could see no difference between the two! The only difference that I found between the two schemes was the fact that your scheme used 0 for the values of L2, L3, and L4. I haven't gotten around to changing these values to what I was using, but will monkey around with them.
    If I could mark this post as solved as I could in other forums, I would.

     

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