Bas Basic ic El Elec. ec. En Engr gr. . Lab Lab EC ECS S - - PowerPoint PPT Presentation

• Dr. Prapun Suksompong

prapun@siit.tu.ac.th

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Bas Basic ic El Elec.

• ec. En

Engr gr. . Lab Lab

EC ECS S 204 04/2 /210

Office Hours: BKD 3601-7 Tuesday 15:00-16:00 Friday 14:00-16:00

Lab 2

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 Thevenin’s and Norton’s Theorem  New toy: Potentiometer  Building a “fake” current source

Thevenin’s and Norton’s Theorem

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Lab 2: Circuit under consideration

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R1 330 ohms R2 470 ohms A B C D E RL 1200 ohms R3 330 ohms Vps 12V IL

(A.4)

Outline of the lab

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part B Part A

Part A: Thevenin Equivalent (1)

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part A (A.12) (A.13)

 

3 1 2 3 3 1 2

/ /

TH ps TH TH L TH L

R V V R R R R R R R V I R R        (A.14)

Part A: Thevenin Equivalent (2)

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part A Directly measure VTH (A.5) and RTH (A.8) Build simplified circuit to measure IL (A.11)

Part B: Norton Equivalent

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part B (B.6)

1 2 N N ps N N L N L N

R R V I R R R I I R R      (B.7)

Part B: Norton Equivalent

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part B Directly measure IN (B.2) Build simplified circuit to measure IL (B.5)

Lab 2: Summary

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part B Part A (A.4) (A.14) (A.11) (B.7) (B.5)

Lab 2: Summary

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IN RN = RTH C D RL RTH VTH C D R1 R2 A B C D RL R3 Vps IL RL IL IL

Part B Part A (A.4) (A.14) (A.11) (B.7) (B.5) Need resistor whose value can be adjusted arbitrarily Need current source

Potentiometer (Pot)

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Pot as a variable resistor

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 Manually adjustable resistor  Three terminals  The resistance between the middle terminal and either of the

two sides depends on the position of the wiper.

Current source

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 We do not have current source.  We will modify voltage source (power supply) to give the

specified amount of current.