HELP!

[AaronR84]

I am trying to get my node voltage  and mesh current analysis  for parts 1 and 2 of my prelab to match up to my simulations in multisim and have hit a brick wall.  If anyone could at least tell me that my simulation is correct or what I need to do to make my simulation correct, I would be forever grateful. I stopped my calculations once I solved the system of equation because they did not match my simulations, but you can see the node volatges and mesh currents. It has been a while since I have done these calculations plus I am very new to multisim, so things may be way off in both cases. Any help is appreciated.

Thanks, Aaron

[controlswhiz]

Hi,

I havent managed to look at all of the circuit, but heres some of what I've found.

In Lab3cctABopen, you had the ammeter connected to the AB terminals. Remember that the ammeter has no resistance (at least theoretically) and in effect make, at least, a short from A to B. Also, you may want to double check your multimeters polarity.

In Lab3cctshortAB, your 10V and 5V supplies were connected in reverse.

Tell me how it goes. Cheers.

[AaronR84]

You were right, I switched the Ammetter back to a Voltmeter but something is still wrong.  The DC voltage sources are connected correctly, at least I think. If you take a look at the third file, calculations, from my first post it shows the cct I am supposed to be building.  I am wondering, do I need to place another ground somewhere?

[controlswhiz]

Sorry. What I meant is that the polarity of the DC supplies were connected in reverse (Lab3cctshortAB).

Theres no need to add another ground. After removing the ammeter and reversing the polarities of the DC supplies I think your simulations are ok.

[AaronR84]

[URL=http://s1333.photobucket.com/user/aaronwrice/media/1_zps431fa807.png.html][IMG]http://i1333.photobuc...

[AaronR84]

Ok, so by reversing the polarity do you mean flipping them upside down or making voltage a negative value? 

[AaronR84]

I see what you mean now. I did not realize on  the shortAB file I had not corrected this. Sorry for the confusion.  From I understand it should not matter if you flip a source or make it a negative value which is why I asked.

[AaronR84]

Ok, thank you so very much, I almost have it now.  Once I reversed the polarity of the two dc sources on the shortAB cct, my mesh current equations matched the simulation perfectly.

So now that I know my simulation is correct and I have placed a voltmeter on the the ABopen cct, I just need to fix my node voltage equations to give me the correct answers.

[controlswhiz · Accepted solution]

Cool. You may want to check your answers here. 

http://www.math.odu.edu/~bogacki/cgi-bin/lat.cgi?c=sys

[AaronR84]

So... you were right again.  My node voltage equations were correct but I used a linear systems of equations solver instead of a general systems of equations solver.  I calculated the node voltages again and got the right answers.  Thanks again, Aaron