Norton Theorem with PSPICE

Discussion in 'Homework Help' started by zubi, Apr 23, 2008.

1. zubi Thread Starter New Member

Apr 23, 2008
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So I've got this assignment to submit on ANY question in NORTON theorem on PSPICE, but trouble is we've never been taught PSPICE

I managed to download OrCAD Capture but cant make heads or tails out of it. I tried readings some programs but still could not understand. I just need one program how to run Norton Theorem and how to input the program on PSPICE so that i can show him the stimulated answer matches my worked out answer on paper.

Any help would be greatly appreciated

Cheers,

2. guitarguy12387 Active Member

Apr 10, 2008
359
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Are you looking more for a tuitorial (placing parts, entering values, running simulations), or are you looking more of how to implement norton's theorem on pspice. I'm guessing is the former because the latter is pretty straightforward once you know how to run sims...

3. Renton Member

Apr 21, 2008
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I will try my best to help! I am not that smart, so make sure to use this only as a guide, as some of it may be wrong!

First, here is a link that shows an example I will reference in this reply, just scroll down to "Example of a Norton equivalent circuit":http://en.wikipedia.org/wiki/Norton%27s_theorem

After you open up Capture, click "File", select "New", "Project", and let it be a "Analog or Mixed A/D", name the project, and select "Create a blank project".

To create a circuit, click "Place" at the top toolbar, then click "Part". DC voltage sources are part "VDC", usually found in the "SOURCE" library. Resistors are "R", usually found in the "ANALOG" library.

On the toolbar on the right of the screen, there should be a little symbol that looks like a thin line making two right angles, and that is for wire connections. While making a wire, you can right-click and select "End wire" to end the wire anywhere you want. The symbol that shows that word "GND" is the ground, which you will have to attach to your circuit. I use the ground called "0/SOURCE".

On one of the top toolbars there are symbols for voltage and current probes that look like the letters I and V inside needles. There are also simply the symbols "I" and "V" that you click to see the currents and voltages displayed directly on your circuit.

Now, using the example in the link I posted above as a guide, first create the original circuit in PSPICE(the circuit you start off with). Make a short circuit for your load, and you can place a current probe at the appropriate node. Click "PSPICE" on the menu, "New Simulation Profile", name the profile, and then "Run". If you used the current probe, you will get a graph showing the short circuit current. You can print this graph then close the graph window, or you can see the current by clicking the "I" on the top toolbar.

Now, you can make an open circuit for the load(by extending wires out of the appropriate nodes and ending them in empty space) and then measure the open circuit voltage with the voltage probe.

Now you can calculate the Norton resistance, which is the open circuit voltage divided by the short circuit current.

I hope my explanations are clear enough, and I hope they work for your version of Capture. If you have any more specific questions on what you can't figure out, I might post again, or hopefully someone on this forum can explain this better than me.

4. JoeJester AAC Fanatic!

Apr 26, 2005
3,403
1,230
Visit texas instrument for a free version of TINA-TI. It is spiced based simulation. It's pretty easy to use.

5. zubi Thread Starter New Member

Apr 23, 2008
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@renton : thx for the reply.. but i need a circuit first.. all my notebook problems are two loop problems.. n i need a minimun 3-5 loop question for my assignment... tried googling but cudnt find anything, any help on that account?

6. Renton Member

Apr 21, 2008
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For the extra loops in the circuit, just add a few loops each with one resistor, and maybe place them all in parallel. You can do this by taking a two loop circuit, then adding another loop to it with the one resistor on the right side, then another loop with the resistor on the right side, and so on. All the Norton stuff will still apply. Just use the same loop or node equations.

If you have any specific questions on PSPICE, I will try my best to answer them, but it may take a while for me to post replies. I hope this helps a little!