Ngspice/C2/Operating-point-analysis-in-NGspice/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Dear Friends, Welcome to this spoken tutorial on “Operating point analysis" in NGspice. |
| 00:08 | In this tutorial, we will learn: |
| 00:10 | To perform operating point analysis |
| 00:13 | To verify Kirchoff's voltage law, using ngspice in-interactive mode command-line interface and commandscript included in netlist file. |
| 00:24 | Ubuntu 12.04 is the operating system used with ngspice version 23 installed. |
| 00:33 | Basic knowledge of electronic circuits is a prerequisite for this tutorial. |
| 00:38 | Basic knowledge of Ubuntu Linux and shell commands is also required. |
| 00:43 | We will use the example circuit shown. |
| 00:47 | The circuit consists of three prominent nodes- |
| 00:52 | a, b |
| 00:55 | and c. |
| 00:57 | In addition, a fourth node called as reference or the datum node must be marked as node “0”. |
| 01:06 | This is mandatory for any circuit. |
| 01:09 | Let us open the ngspice netlist "example1.cir" file, corresponding to the circuit schematic shown before, in a text editor. |
| 01:19 | I have already opened this in gedit text editor. |
| 01:27 | Note that the netlist file is saved with ".cir" extension. |
| 01:32 | We can see all the components like voltage source, resistors and current source. |
| 01:41 | Also, the information about nodes connecting them together. |
| 01:46 | ".op" command, included in netlist file, is used to perform operating point analysis. |
| 01:54 | Now we will simulate this circuit and verify Kirchoff's voltage law using the interactive mode-command-line interface. |
| 02:02 | Let us open ngspice through terminal. |
| 02:06 | Go to top left corner of Ubuntu desktop screen. |
| 02:10 | Click on theDash home. |
| 02:13 | In the search bar, write "terminal" and press Enter. |
| 02:22 | This will open Terminal window. |
| 02:26 | Let me resize this window. |
| 02:30 | Now, I will go to the folder where the netlist file "example1.cir" is saved. |
| 02:38 | I do this as follows: |
| 02:40 | On terminal, I will type: cd space Desktop slash op hyphen analysis and press Enter. |
| 02:55 | Now, let us simulate the ngspice file. |
| 02:59 | Let us see how this can be done. |
| 03:01 | On terminal, type: ngspice space example1.cir and press Enter. |
| 03:17 | Here, you will notice that we have entered into the ngspice command line interface. |
| 03:23 | Type: "run" and press Enter. |
| 03:28 | This will simulate the circuit and store the results. |
| 03:33 | We will verify Kirchoff's voltage law using the above simulation results. |
| 03:39 | According to Kirchoff's voltage law, voltage around outer loop should be equal to the value of the dc voltage source V1. |
| 03:51 | Calculate voltage around the outer loop. |
| 03:54 | For this, let us do the following: |
| 03:59 | In the ngspice command line interface, on the terminal, |
| 04:03 | type: print space v of a comma b plus v of b comma c plus v of c and press Enter key. |
| 04:21 | Here, v of a comma b denotes the voltage drop between the nodes 'a' and 'b' and so on. |
| 04:29 | print command displays the results of the calculation mentioned to its right side. |
| 04:36 | Notice the result of the calculation on the terminal. |
| 04:39 | It is 30 volt as shown. |
| 04:42 | Now, calculate the value of DC voltage source V1 that is v(a). |
| 04:50 | Type: print space v of a and press Enter. |
| 05:00 | Notice the result of the calculation on the terminal. |
| 05:04 | If both the results are equal then Kirchoff's voltage law is verified. |
| 05:10 | Since both voltage values are equal, the Kirchhoff's Voltage law is verified for outer loop- a, b, c and 0. |
| 05:21 | Now, we will simulate this circuit and verify Kirchoff's voltage law, using the command script included in the netlist file. |
| 05:31 | Modified netlist file example hyphen modified dot cir is as shown. |
| 05:40 | As you can see, all the commands we executed in command-line interface are included in this netlist as control statements. |
| 05:50 | That is, the statements in between the dot control and the dot endc statements. |
| 05:57 | Echo command will echo the text written to its right side, on the terminal window. |
| 06:04 | You can see that we have included the print statements in the netlist. |
| 06:10 | Now, we execute the modified netlist file. |
| 06:14 | source command is used to simulate the netlist from within the ngspice simulator environment. |
| 06:22 | On the terminal, type: source space example hyphen modified dot cir and press theEnter key. |
| 06:37 | This will run the simulation and directly show the results for KVL verification. |
| 06:43 | You can see that results are the same as seen earlier. |
| 06:48 | This brings us to the end of this tutorial. |
| 06:52 | Quit the ngspice simulator by typing quit and press the Enter key. |
| 07:00 | Now, let us summarize what we learnt in this tutorial. |
| 07:03 | In this tutorial, we learnt- |
| 07:05 | To perform operating point analysis of a given circuit. |
| 07:09 | To verify Kirchhoff's voltage law using ngspice through interactive mode-command line interface , command script included in the netlist file. |
| 07:20 | Watch the video available at the following link. |
| 07:24 | It summarizes the Spoken Tutorial project. |
| 07:28 | If you do not have good bandwidth, you can download and watch it. |
| 07:32 | The Spoken Tutorial project team: |
| 07:34 | Conducts workshops using spoken tutorials. |
| 07:38 | Gives certificates for those who pass an online test. |
| 07:41 | For more details, please write to:contact at spoken hyphen tutorial dot org |
| 07:47 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 07:52 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 07:59 | More information on this mission is available at: |
| 08:02 | spoken hyphen tutorial dot org slash NMEICT hyphen Intro. |
| 08:09 | Thank you for joining. |
| 08:11 | Hope you found this tutorial useful. |
| 08:13 | This script is contributed by Abhishek Pawar and this is Rupak Rokade from IIT Bombay, signing off. |
| 08:19 | Thank You. |
