1. Lecture 341 Source Transformation

2. Lecture 342 Equivalent Sources An ideal current source has the voltage necessary to provide its rated current. An ideal voltage source supplies the current necessary to provide its rated voltage. A real voltage source cannot supply arbitrarily large amounts of current. A real current source cannot have an arbitrarily large terminal voltage.

3. Lecture 343 A More Realistic Source Model vs(t)vs(t) RsRs + - The Circuit The Source i(t)i(t) + - v(t)v(t)

4. Lecture 344 I-V Relationship The I-V relationship for this source model is v(t) = v s (t) - R s i(t) v(t)v(t) i(t)i(t)

5. Lecture 345 What are the points where the I-V characteristics intersect the axes?

6. Lecture 346 What do these intersection points represent physically?

7. Lecture 347 Open Circuit Voltage If the current flowing from a source is zero, then it is connected to an open circuit. The voltage at the source terminals with i(t) equal to zero is called the open circuit voltage: v oc (t)

8. Lecture 348 Short Circuit Current If the voltage across the source terminals is zero, then the source is connected to a short circuit. The current that flows when v(t) is zero is called the short circuit current: i sc (t)

9. Lecture 349 v oc (t) and i sc (t) v(t)v(t) i(t)i(t) v oc (t) i sc (t)

10. Lecture 3410 v oc (t) and i sc (t) Since the open circuit voltage and the short circuit current determine where the I-V line crosses both axes, they completely define the line. Any circuit that has the same I-V characteristics is an equivalent circuit.

11. Lecture 3411 Equivalent Current Source is(t)is(t)RsRs The Circuit i(t)i(t) + - v(t)v(t)

12. Lecture 3412 Voltage and Current Sources VsVs + - RsRs IsIs RsRs

13. Lecture 3413 Source Transformation Equivalent sources can be used to simplify the analysis of some circuits. A voltage source in series with a resistor is transformed into a current source in parallel with a resistor. A current source in parallel with a resistor is transformed into a voltage source in series with a resistor.

14. Lecture 3414 Averaging Circuit How can source transformation make analysis of this circuit easier? + - V out 1k  V1V1 + - V2V2 + -

15. Lecture 3415 Source Transformations + - V out 1k  V1V1 + - V2V2 + -

16. Lecture 3416 Source Transformations + - V out 1k  V 1 /1k  1k  V 2 /1k 

17. Lecture 3417 A Single Node-Pair Circuit!