Finding Equivilent Thevinen Resistance in this circuit

[Asphyxiated]

Homework Statement

This is what I have it reduced to so far, http://images3a.snapfish.com/232323232fp733:2>nu=52::>379>256>WSNRCG=335:;25;94347nu0mrj", but I am not sure if R2 and R3 can be considered in series or not. Please let me know how to handle the next step here as I am lost. I am trying to find Vth of AB but I need Rth first.

Homework Equations

The Attempt at a Solution

 

[Asphyxiated]

Or perhaps I can do a wye to delta transform with R1 R2 and R4 and then i will have R1 R2 and R4 in series and not take into account the 5ohm resistor (R3) because the Vdrop of the 5 ohm resistor is after the AB circuit.

 

[lorenb]

I usually start away from the nodes and work towards... I'd start off with R3 AND R1 in series. Then it looks like the combination of those two are sharing nodes with R2. Then the result of the parallel resistors will be in series with r4.

try doing this and redrawing the circuit after each combination. the more you do it, the faster it'll be and u can skip the new drawings...

 

[Asphyxiated]

thanks, I eventually got it but then i realized that Vth and Isc (short circuit) was easy to find and I could use Vth/Isc=Rth but none-the-less thanks for the help!