# Maximum power transfer

Discussion in 'Homework Help' started by Evilsanta31, Jan 19, 2015.

1. ### Evilsanta31 Thread Starter New Member

Dec 29, 2014
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0
I have a circuit with two sources and three resistors in it and I have to determine the value the load resistor should be to deliver maximum power to the load.

E1 11V
E2 22V
R1 160 ohms
R2 200 ohms
RL 220 ohms.

RL is in the centre of the circuit and R1 is below E1 which is flowing in a clockwise position and R2 is below E2 which is flowing anti-clockwise. The only examples Ive seen is with one power source so Im lost a bit

Thanks Alan

2. ### crutschow Expert

Mar 14, 2008
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4,464
I'm lost also.
Please post a schematic.

3. ### Evilsanta31 Thread Starter New Member

Dec 29, 2014
23
0
Sorry prob makes it easier with a schematic

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4. ### WBahn Moderator

Mar 31, 2012
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5,758
Are you familiar with Thevenin's Theorem and Thevenin equivalent circuits?

5. ### evilsanta New Member

Nov 10, 2013
1
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Yes had to do a thevenin equivalent for this circuit, so I should simplify it to one source and one load and go from there?

6. ### WBahn Moderator

Mar 31, 2012
20,247
5,758
Almost -- but I think you may not quite have it.

You want to remove the load from the circuit and then find the Thevenin equivalent for everything that's left as seen between the terminals where the load was connected. That will give you a source in series with a resistance that models the behavior of everything else in the circuit in terms of voltage and current at the terminals where the load was. You then put the load back between the terminals using the Thevenin equivalent and go from there.

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7. ### crutschow Expert

Mar 14, 2008
16,551
4,464
You are prob right.

8. ### Evilsanta31 Thread Starter New Member

Dec 29, 2014
23
0
apologies havent been back on to thank people for their posts. After a nudge in the right direction of the Thevenin circuit I found the task easy enough as I had already completed the Thevenin equivalent for the circuit in the next question so just used the Vth and Rth and had a variable RL to determine maximum power equal to Rth, proved using a graph.