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Chapter 12. Thevenin, Norton and Maximum Power Transfer Theorems. Thevenin’s Theorem. Why Thevenin’s Theorem is useful. What is Thevenin’s Theorem?.
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Chapter 12 Thevenin, Norton and Maximum Power Transfer Theorems
Thevenin’s Theorem • Why Thevenin’s Theorem is useful
What is Thevenin’s Theorem? • Everything in the original circuit, except the load, maybe replaced by an equivalent circuit. The equivalent circuit consists of a series combination of a voltage source and a resistance.
Steps to make a Thevenin Circuit Write these on white board
Calculating RTHEVENIN (RTH) RTH = 5kΩ
Calculating VTHEVENIN (VTH) VTH = 10V
Equivalent Thevenin Circuit Now you can place any load in the circuit you want and the calculations are EASY! .66mA =10kΩ
Using the Thevenin Theorem Determine VTH Solving for VTH 10V 5V VTH = VA – VB = 5V
Using the Thevenin Theorem Determine RTH
Solving for RTH What is the resistance from point a to b?
B A Turning Figure 12.15C into Figure 12.15D 10kΩ 9kΩ 10kΩ 3kΩ
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Norton’s Theorem • Everything in the original circuit, except the load may be replaced by an equivalent circuit. The equivalent circuit consists of a parallel combination of a current source and a resistance.
What a Norton Circuit Looks Like Norton Resistance Norton Current IN 2mA
Norton Shortcut • There are a bunch of rules for how to calculate the Norton Current and Norton Resistance. However, a shortcut is to find the Thevenin Equivalent circuit and then convert it to a Norton
Other Circuit Analysis Techniques • Besides using traditional circuit analysis using Ohm’s Law, or Superposition, Mesh Analysis, Thevenin’s Theorem, and Norton’s Theorem, there are other circuit analysis techniques. A couple include: • Nodal Analysis and Millman’s Theorem Do more hw problems from back of chap 12 (9, 10, 11, or 12) if time
Practice Problem • In the following circuit solve for VTH, RTH, IN, RN, IL and VL
Another Practice Problem Solve for VL using traditional Ohm’s Law technique, Mesh Analysis, and Thevenin Analysis
Maximum Power Transfer • See notes
What load resistor would you use for the following circuit to have max power transferred?
What load resistor would you use for the following circuit to have max power transferred? ? What circuit analysis technique can we use to solve for this? Thevenin’s Theorem. RTH = 5kΩ I’ve checked this technique using Ohm’s law and it works. See following numbers: 5mW @ 5kOhm 4.94mW @ 4kOhm 4.96mW @ 6kOhm
What load resistor would you use for the following circuit to have max power transferred?
Switches SPST SPDT DPST DPDT