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

Bas Basic ic El Elec. ec. En Engr gr. . Lab Lab EC ECS S 204 04/2 /210 Dr. Prapun Suksompong prapun@siit.tu.ac.th Office Hours: BKD 3601-7 Tuesday 15:00-16:00 Friday 14:00-16:00 1

Lab 2  Thevenin’s and Norton’s Theorem  New toy: Potentiometer  Building a “fake” current source 2

Thevenin’s and Norton’s Theorem 3

Lab 2: Circuit under consideration R 1 330 ohms A B R 2 470 ohms R L 1200 ohms V ps C D 12V (A.4) R3 330 ohms I L E 4

Outline of the lab Part A R TH C R 1 A B V TH R L I L R 2 D V ps C C R L R 3 I L R N = R TH R L I N I L D D Part B 5

Part A: Thevenin Equivalent (1) Part A R TH C R 1 A B V TH R L I L R 2 D V ps C R  (A.12) 3 V V C   R L TH ps R 3 R R R 1 2 3 I L   (A.13)   R N = R TH R L I N R R / / R R TH 3 1 2 I L D V  (A.14) TH I D  L R R TH L 6

Part A: Thevenin Equivalent (2) Part A R TH C R 1 A B V TH R L I L R 2 D V ps C C R L Directly measure V TH (A.5) and R TH (A.8) R 3 I L Build simplified circuit to measure I L R N = R TH R L I N (A.11) I L D D 7

Part B: Norton Equivalent  R R N N R TH V  (B.6) C ps I  N R R R 1 1 2 A B V TH R L R  N I I (B.7)  I L L N R 2 R R L N D V ps C C R L R 3 I L R N = R TH R L I N I L D D Part B 8

Part B: Norton Equivalent R TH C Directly measure I N (B.2) R 1 Build simplified circuit to measure I L (B.5) A B V TH R L I L R 2 D V ps C C R L R 3 I L R N = R TH R L I N I L D D Part B 9

Lab 2: Summary Part A R TH (A.14) C (A.11) R 1 A B V TH R L I L R 2 D V ps C C R L R 3 I L R N = R TH R L I N (A.4) I L D D (B.7) Part B (B.5) 10

Need resistor whose value can be Lab 2: Summary adjusted arbitrarily Part A R TH (A.14) C (A.11) R 1 A B V TH R L I L R 2 D V ps C C R L R 3 I L R N = R TH R L I N (A.4) I L D D (B.7) Need current source Part B (B.5) 11

Potentiometer (Pot) 12

Pot as a variable resistor  Manually adjustable resistor  Three terminals  The resistance between the middle terminal and either of the two sides depends on the position of the wiper. 13

Current source  We do not have current source.  We will modify voltage source (power supply) to give the specified amount of current. 14