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I have tried to perform Supernode Analysis on the circuit. Regardless of how many times I tried, I got incorrect results. I tried to form a system of equations, then created matrices and solved them in MATLAB to find the variables. I also tried to use graph theory, but to be honest, I couldn’t find a YouTube channel or a book that explains it well. Therefore, I couldn’t fully understand graph theory. Let me show you my attempt to solve this circuit:

Results of variables that I used:

  • VA = -10.9070 V,
  • VB = 44.7907 V,
  • VC = 35.3953 V,
  • VD = 29.3953 V,
  • VF = 31.2558 V

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    \$\begingroup\$ This seems more suitable for puzzling.stackexchange.com than for an engineering site. The answer is: whoever drew this schematic must be fired. \$\endgroup\$ Commented yesterday
  • \$\begingroup\$ I agree with Lundin; the original circuit (also where did it come from?) is totally ambiguous in its use of cross wires with or without cross connection dots. It's a really badly drawn schematic. \$\endgroup\$ Commented yesterday

3 Answers 3

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I labeled it up like this. It's about the same. I just dumped the \$+6\:\text{V}\$ 2-terminal voltage source device as unneeded:

schematic

simulate this circuit – Schematic created using CircuitLab

The equations are then:

$$\begin{align*} I_{\small{C}}&=\frac{V_{\small{C}}}{R_5} \\\\ \frac{V_{\small{B}}}{R_1}+\frac{V_{\small{B}}}{R_2}&=\frac{V_{\small{E}}}{R_2}+\frac12 I_{\small{C}} \\\\ \frac{V_{\small{E}}}{R_2}+\frac{V_{\small{E}}}{R_3}+I_1&=\frac{V_{\small{B}}}{R_2}+\frac{V_{\small{D}}}{R_3}+2\:\text{S}\cdot \left(V_{\small{A}}-V_{\small{C}}\right) \\\\ \frac{V_{\small{D}}}{R_3}+\frac12 I_{\small{C}}&=\frac{V_{\small{E}}}{R_3}+I_x \\\\ \frac{V_{\small{A}}}{R_4}+I_x+500\:\text{mS}\cdot V_{\small{B}}&=\frac{V_{\small{C}}}{R_4} \\\\ \frac{V_{\small{C}}}{R_4}+\frac{V_{\small{C}}}{R_5}&=\frac{V_{\small{A}}}{R_4}+I_1+I_2 \\\\ V_{\small{A}}&=V_{\small{D}}+V_1 \end{align*}$$

That solves out as

va: 18
vb: 4
vc: 16
vd: -6
ve: 3
ix: -2.5

An LTspice run confirms the values:

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The matrix form of the above would be:

$$ \!\!\!\!\!\!\!\!\!\!{\begin{align*}&V_A & \!V_B && V_C&&V_D&&\!\!V_E&&\!\!I_x\end{align*}} \\ \begin{matrix}\text{KCL }V_A\vphantom{\frac{-1}2}\\\text{KCL }V_B\vphantom{\frac{-1}2}\\\text{KCL }V_C\vphantom{\frac{-1}2}\\\text{KCL }V_D\vphantom{\frac{-1}2}\\\text{KCL }V_E\vphantom{\frac{-1}2}\\\text{KVL }V_A-V_D\\\end{matrix} \begin{bmatrix} \frac14&\frac12&\frac{-1}4&0&0&1 \\ 0&\frac11+\frac14&\frac{-1}{2\,\cdot\, 4}&0&\frac{-1}1&0 \\ \frac{-1}4&0&\frac14+\frac14&0&0&0 \\ 0&0&\frac1{2\,\cdot\, 4}&\frac12&\frac{-1}2&-1 \\ -2&\frac{-1}1&2&\frac{-1}2&\frac11+\frac12&0 \\ 1&0&0&-1&0&0 \end{bmatrix} \cdot \begin{bmatrix}V_A\vphantom{\frac{-1}2}\\V_B\vphantom{\frac{-1}2}\\V_C\vphantom{\frac{-1}2}\\V_D\vphantom{\frac{-1}2}\\V_E\vphantom{\frac{-1}2}\\I_x\end{bmatrix} = \begin{bmatrix}0\vphantom{\frac{-1}2}\\0\vphantom{\frac{-1}2}\\3.5\vphantom{\frac{-1}2}\\0\vphantom{\frac{-1}2}\\-0.5\vphantom{\frac{-1}2}\\24\end{bmatrix}$$

Using SymPy/Python/SageMath I get:

A = Matrix( [
    [ 1/4, 1/2, -1/4, 0, 0, 1 ],
    [ 0, 1/1+1/4, -1/(2*4), 0, -1/1, 0 ],
    [ -1/4, 0, 1/4+1/4, 0, 0, 0 ],
    [ 0, 0, 1/(2*4), 1/2, -1/2, -1 ],
    [ -2, -1/1, 2, -1/2, 1/1+1/2, 0 ],
    [ 1, 0, 0, -1, 0, 0 ] ] )
A
Matrix([
[ 1/4, 1/2, -1/4,    0,    0,  1],
[   0, 5/4, -1/8,    0,   -1,  0],
[-1/4,   0,  1/2,    0,    0,  0],
[   0,   0,  1/8,  1/2, -1/2, -1],
[  -2,  -1,    2, -1/2,  3/2,  0],
[   1,   0,    0,   -1,    0,  0]])
A.inv()*Matrix([[0],[0],[3.5],[0],[-0.5],[24]])
Matrix([
[18.0],
[ 4.0],
[16.0],
[-6.0],
[ 3.0],
[-2.5]])

Which is the same result as before.

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This kind of problem is easier solved with the superposition theorem. While it does indeed take longer to solve since you have to solve for every non-controlled source, it usually allows to simply the circuit with series/parallel equivalent resistors.

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Analysis of the given network with three methods based on network topology:

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