fall 2001engr-201 example 4.81 example 4.10 irwin, page 127 find the thevenin equivalent circuit at...
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Fall 2001 ENGR-201 Example 4.8 1
Example 4.10 Irwin, Page 127Find the Thevenin equivalent circuit at points A-B for the circuit shown.
We need to find two quantities: VTH = Voc and RTH = Voc/ISC
If we use nodal analysis and/or mesh analysis or any other appropriate techniques, we find VTH = 0V and ISC = 0A (because there are no independent sources of power in the circuit)
RTH = Voc / ISC = 0V/0A = ?????
VTH = 0V is equivalent to a short circuit
ISC = 0A is equivalent to an open circuit The Thevenin (Norton) equivalent consists of a single resistor.
Fall 2001 ENGR-201 Example 4.8 2
Example 4.10 – Find RTH
To make our work easier, we will find RTH to the at points C-D first.
THS
1VR =
I
To find RTH apply a known voltage source (1V) and determine the amount of current demanded. .
Fall 2001 ENGR-201 Example 4.8 3
Example 4.10 – Find RTH at C-D
X
X X
S X
TH
1VI = 1mA
1kV =2000I =2V
1V-2VI =I + 1mA-0.5mA =0.5mA
2k1V
R 2k0.5mAC D
We can now replace the circuit to the left of points C-D with its Thevenin equivalent.
Fall 2001 ENGR-201 Example 4.8 4
Example 4.10 – Find RTH
The Thevenin (and Norton) equivalent circuit, then, is
TH A-B
TH A-B
R =2k || 3k 2k
R 1.43k
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