EE201 Lecture 11 P 1 Source Transformations Source Transformations A technique for analyzing circuits that does not require solving simultaneous equations Terminology A two terminal network is an interconnection of circuit elements which has only two accessible terminals for connection to other networks i v EE201 Lecture 11 P 2 Equivalent two terminal networks are twoterminal networks with the same terminal currentvoltage relationship but different internal details i 2 v 6V RL v 6 2i i 3A 2 i 3 v 2 v 6 2i This is a source transformation v RL EE201 Lecture 11 P 3 Source transformations are possible for two terminal networks with dependent sources as shown below i R v VS IS VS R i IS R RL v RL EE201 Lecture 11 P 4 Look at equivalence from I V plots compare with P 5 iL R vs iL vS R RL vL vs R iL vL RL 0 short iL vS R vL R RL open vS vL EE201 Lecture 11 P 5 Consider equivalence from I V plots compare with P 4 iL iS R vL RL is iL vL R iL iS RL 0 short iL iS vL R Equivalent if is vs R RL open iS R vL EE201 Lecture 11 P 6 Example 2 18 V 3 2 1A 15 V Use source transformations to find power absorbed by the 5 resistor 5 EE201 Lecture 11 P 7 Solution Step 1 Replace current source parallel resistor combination with voltage source series resistor combination Vs Is R 2 2 18 V 3 2V 15 V 5 EE201 Lecture 11 P 8 Step 2 Sum series resistors and voltage source outputs to simplify circuit 4 3 16 V 15 V 5 EE201 Lecture 11 P 9 Step 3 Replace each voltage source resistor pair with parallel current source resistor pair 4A 4 3 5A 5 Step 4 Find equivalent resistance of parallel resistors 4A 12 7 5A 5 EE201 Lecture 11 P 10 Step 5 Combine effects of current sources in accordance with principle of superposition 1A 12 7 5 Step 6 Using current division find current through 5 resistor I5 2 4 12 2 4 12 7 12 1 12 47 A Step 7 Calculate power through 5 resistor P5 I2 R 12 47 2 5 0 326 W
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