Electronics > Beginners
Help! Mesh analysis, I'm totally lost (engineering student level)
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victoriak:
Hello, it's my first post here :) I'm getting totally lost with my circuit analysis class's assignments, I still struggle to grasp the basics but I'm here in the lab trying to figure it out.

During yesterday's class, our professor left us this mesh analysis circuit, he told us it had a trick on how to implement it. I have been trying to draw the circuit in Multisim (have Proteus as well) just to begin, but couldn't even figure out even the way to redraw it with pencil/paper.

The task involves "implementing, modifying (redrawing) and calculating the currents in the circuit ( we just covered the supermesh analysis, how to eliminate the source and to generate an auxiliary equation of the supermesh, and then solving the equation system), with the only caveat/warning/tip to use different grounds for each power source. With 4 mesh and its own current.


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Here its my attempt on multisim:


https://i.imgur.com/feakKLf.png


I will try to resolve the resistors in parallel first to get a more simple circuit.

I have the impression this may be easier than I think, but I'm clueless. I couldn't start calculations cause I cant be sure how to redraw it. Them I have to set it up on the breadboard. Guy,s I'm getting desperate here, if you guys can pinpoint me on the right direction or what I'm doing wrong let me know. I appreciate your time and help in advance.
rstofer:
You can replace the 1k the 2.7k and the 500 Ohm in the lower part with a single equivalent resistor
You can replace the 1k and 100k in the upper left with a single equivalent resistor

Now that horizontal rail in the middle of the diagram looks a lot like 'ground'.

Now that there is so little circuit left, the supermesh approach will be fairly easy.



Just set the 6V source to 0V and follow along with the discussion.
dmills:
Firstly, step away from the breadboard and put that simulator down :palm: This is a pencil and paper (and maybe a calculator if feeling lazy) problem, not something that needs spice.

I would observe that the bottom and right hand sides are a common node and that the 100k and 1k around the upper current source are in parallel and can be collapsed to a single resistor of ~1k without touching any loop you care about.

Not sure if this counts as mesh current analysis, but I would do it in two stages, set the 5mA source to open circuit and calculate the 4 currents, then open the 10mA source and turn the 5mA one back on, recalculate the currents, then just add em up.

Regards, Dan.
rstofer:
Collapse all the parallel resistors I mentioned above (and any I forgot), solve for the mesh currents and then calculate the node voltages.  Use these voltages with the original circuit to find the various component voltages and currents.
victoriak:
Thank you so much for your help! I can't be more thankful really, I'm doing really bad so far and this kind of circuits are confusing to me, I will collapse all the resistors and first then, I think I now have way more of a grasp how to solve it with your help.  :)
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