How to simplify this complex circuit? I am new to circuit solving and I tried to simplify this circuit, but I am unable to do so. I can't figure out which resistances are in series and which resistances are in parallel.
Do I have to use star-delta conversion here or the circuit can be solved without conversion?
I just need a simplified circuit diagram and the rest I can solve. Thanks for any help!

 A: My recommendation is that if you cannot easily simplify a circuit then don’t bother. Just solve it unsimplified. The extra effort to simplify a confusing circuit is rarely worth it.
In this case, since it is drawn as a non-planar circuit, you should use the node voltage approach instead of the mesh currents approach. You could re-draw it as a planar circuit in this case, but with the node voltage approach you don't need to do that.
Simply give each node voltage a variable and write down Kirchoff’s current law at each node. You will get a linear system of four equations in four unknowns, which can be more easily solved (in my experience) than simplifying the original circuit.
A: First combine resistors $R_B$ and $R_C$ as parallel resistors forming resistor $R_{B//C}$.
Next perform a $\Delta-Y$ transform on resistors $R_A$, $R_E$ and $R_{B//C}$. All three of these resistors share a common node; consider the node of resistor $R_A$ that is not the common node to be node $1$, the node of resistor $R_E$ that is not the common node to be node $2$ and the node of resistor $R_{B//C}$ that is not the common node to be node $3$. The $\Delta-Y$ transform takes $R_A$, $R_E$ and $R_{B//C}$ and gives us $R_{1-2}$, $R_{2-3}$ and $R_{3-1}$ corresponding to the node names just provided.
Notice now $R_{2-3}$ and $R_D$ are in parallel so we combine them to form $R_{\alpha}$
Now we see that $R_{1-2}$ and $R_G$ are in parallel we combine them to form $R_{\beta}$, and also $R_{3-1}$ and $R_F$ are in parallel we combine them to form $R_{\gamma}$.
From here equivalent resistance seen by the voltage source is clearly $(R_{\alpha}+R_{\gamma})//R_{\beta}+R_H+R_I$
A: When you have such seemingly complex circuits, the best way to approach the problem is to name each node and see which elements are in series and parallel. Keep on finding the equivalent resistances of groups of elements like the two resistors in parallel on the extreme right of the circuit. When you hit a hurdle, use star-delta transformations to simplify the configurations.
A: I would define 5 current loops (making sure that each resistor is in at least one loop). Then write 5 voltage loop equations (summing voltage drops). Solve for the currents.
