# Thevenins Theorem

Can someone please help, I'm struggling with this circuit. I don't quite understand what I need to do, mainly with whats series and parallel. My tutor is not helpfull in the slightest! He' only given me some very very basic examples to look at and when I ask him any questions he mutters a few things and walks off! I've searched online to find a circuit thats similar but can't find anything.

The way i understand it is you remove the load, remove the voltage source, then calculate the resistance looking from the left

Any help to steer me in the right direction would be very much appreciated • If a resistor shares the same node with another resistor, then those two resistors are in parallel. For solving the Thevenin resistance, start from the right side of this circuit. – KingDuken Mar 17 at 16:28
• Thanks KingDuken,So would that calculate as R7+R6 // R5+R4 // R3+R2 // R1+R8 – samflatt Mar 17 at 16:34
• @samflatt: Use brackets please: you equation is open for interpretation. As KingDuken says start at the right hand side so start with R9. (R9...) – Oldfart Mar 17 at 16:38
• Is R9 supposed to be the load, or part of the circuit you want the equivalent of? – The Photon Mar 17 at 17:01
• There might be some significance to the fact that R9 has its nodes labelled A and B. – Neil_UK Mar 17 at 17:03

I'll try to point you in the right direction.

You say that R9 is the load, so you remove it. The voltage source (an independent source) becomes a short (0V). With those changes, your circuit reduces to: simulate this circuit – Schematic created using CircuitLab

With that, it should not be that difficult to find the equivalent Thevenin resistor looking into the circuit from A and B. Notice that in the previous circuit R1 and R2 are in parallel. You can solve that first and apply a similar procedure as needed. In the end, you will end up with an equivalent resistance for the combined R1, R2, R3, R4, R5, and R6 and that equivalent will need to be added with R7 and R8.

Hope it points you in the right direction.

Thanks @Big6. I think/hope I understand!  