Honestly I and reading my circuit analysis book and it just says "create KCL equation for all super nodes not containing a reference node." and trying to search the web for the answer and they just say use a different node as reference. So I tried that at each other node and it is not matching spice. My mesh analysis matches spice. I just want to know if it is possible to use a super node that includes the reference node and if not, why not? If you can help me with this problem that is just a bonus.

Thank you.

 

If one of the nodes in the supernode is the reference node, then there is no point in creating the supernode. Remember, to use a supernode you need to establish constraint equations that describe the voltages on the supernode ports in terms of one of them. Well, if one of them is the reference node, then you have the voltages of all the ports.

For instance, in your diagram if the bottom node is the reference node, then the voltage on V2 is simple 6·Vx. No need to write supernode equation.

 

Remember that one of the things you need to do with a supernode is write constraint equations that relate the voltage at all but one of the supernode ports to the remaining port. If one of your ports is the reference node, then the supernode serves no purpose. Just write the constraint equations.

For instance, in your problem if the bottom node is the reference node, then V2 = 6Vx. No need to apply KCL to the supernode.

 

That's what I figured would happen, but am still critiquing my engineering intuition so thank you. Also in my diagram I don't know if you saw i scribbled out the reference that was drawn in and made the new on on the left node. (Chassis ground symbol)

Thank you.

(Original post: *Honestly, I am)

 

It appears you posted this same thing in three different threads. That causes all kinds of problems. In this case, I saw another one of your threads and didn't see my reply, which I thought I had replied to, but thought perhaps I hadn't submitted it. So I went back in my history to see if my reply was saved in my browser and, since it wasn't, replied again. Multiple threads on the same problem just causes confusion. One of the other mods deleted the other two. In the future, please, one thread per problem.

And, yes, I saw where you had moved the reference node, but then you have a classic supernode without an embedded reference node, so it is not of interest for this issue. Though it does underscore that while choice of reference is arbitrary, a well-chosen reference can save considerable work in the analysis. You can always move the reference to another place once the circuit has been analyzed by just subtracting the voltage at every node by the voltage at the new reference, reducing it to 0 V.

 

Here is a comparison of the nodal analysis where a) the reference node has been shifted to the left, and b) the original configuration as given with a super-node reference node. In each case the reference node has been tinted blue and node equations are written for the red & green nodes. Also, the control voltage & super-node offset voltage need to be expressed in terms of the two node voltages. Note that I can't detect any particular advantage from shifting the reference node. However, it seems to improve engineering intuition to color code the nodes and to annotate the control variables & super-node offsets directly onto the diagram. With that I can type the node equations directly into a symbolic algebra engine just by looking at the circuit.

 

I did post it under the "Homework" section and "General Questions" section, because this question was very urgent, and I didn't know how effective this website would be, which has proven to be EXTREMELY HELPFUL!!!!

Thank you so much guys!