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  • 7/25/2019 Lecture 2d

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    Lecture #2 By Yohandri 1

    Rangkaian Pembag i

    Tegangan dan A rus

    Voltage and Current Divider Circuit

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    Lecture #2 By Yohandri 2

    Kompetensi Dasar

    Mahasiswa dapat menganalisis rangkaian

    pembagi tegangan dan pembebanan,rangkaian pembagi arus serta rangkaian

    setara Thevenin dan Norton

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    Lecture #2 By Yohandri 3

    1. Series And Paral lel Circu its

    Circuits consisting of just one battery and one load

    resistance are very simple to analyze, but they are notoften found in practical applications. Usually, we find

    circuits where more than two components are connected

    together. There are two basic ways in which to connect

    more than two circuit components: series and parallel.

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    Lecture #2 By Yohandri 4

    1.1. Resis to rs in series

    The first principle to understand about series circuits is

    that the amount of current is the same through any

    component in the circuit. This is because there is only

    one path for electrons to flow in a series circuit, and

    because free electrons flow through conductors.

    Two resistors, R1 and R2, connected in series have

    voltage drop V = I(R1 + R2). That is, they have a

    combined resistance Rs given by their sum:

    This generalizes for n series resistors to

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    Lecture #2 By Yohandri 5

    OR

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    Lecture #2 By Yohandri 6

    1.2. Resis to rs in paral lel

    Two resistors, R1 and R2, connected in parallel have

    voltage drop V = I.Rp, where

    21

    111

    RRRP

    This generalizes for n parallel resistors to

    21

    21

    RR

    RRR

    P

    R1

    R2

    There are many paths for electrons

    to flow, but only one voltage across all components

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    Lecture #2 By Yohandri 7

    OR

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    Lecture #2 By Yohandri 8

    2.1. Voltage Divider

    2. Voltage Devider and Load ing (Pembagi tegangan dan pembebanan)

    A voltage divider consists of two

    resistances R1 and R2 connected in

    series across a supply voltage Vs. The

    supply voltage is divided up between

    the two resistances to give an output

    voltage Vo which is the voltage across

    R2. This depends on the size of R2

    relative to R1

    VsRR

    RVo

    21

    2

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    Lecture #2 By Yohandri 9

    2.2. Pembebanan

    Apabila keluaran suatu rangkaian dibebani maka

    pada keluaran rangkaian tersebut dapat terjadi

    penurunan tegangan atau jatuh tegangan, peristiwa

    ini disebut pembebanan

    E

    R2

    R1

    RL

    VsRR

    RVo

    21

    2

    Tegangan keluaran tanpa RL

    Tegangan keluaran dengan RL

    )//( 21 LRRR

    E

    I

    )//.( 2 LOL RRIV

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    Lecture #2 By Yohandri 10

    Contoh

    E

    R2

    R1 1K

    1K Vo

    12VE

    R2

    R1

    RL

    1k

    1k

    12V

    ERR

    RVo

    21

    2

    )//( 21 LRRR

    EI

    )//.( 2 LOL RRIV

    Tegangan keluaran tanpa RL

    VVo 61211

    1

    Tegangan keluaran dengan RL

    Misal RL = 1K

    mAI 8)1//1(1

    12

    VVOL

    4)1//1.(8

    Vo = 6 4 = 2V

    Jatuh tagangan

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    Lecture #2 By Yohandri 11

    3. Current Devider

    A parallel circuit is often called a current divider for its

    ability to proportion or divide the total current intofractional parts

    E R2R1

    I

    I1 I2 E = I RT RT = R1//R2

    I1 = VR1/ R1

    For parallel circuit VR1 = VR2 = E

    Current through R1

    IR

    RI

    T

    1

    1 21

    21

    RR

    RRR

    T

    IRR

    RR

    RI

    2

    1

    1

    21

    1

    1

    I

    RR

    RI

    21

    2

    1

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    Lecture #2 By Yohandri 12

    4. Rangkaian Setara Thevenin dan Norton

    Rangkaian setara sangat penting dalam elektronika, dengan

    rangkaian setara dapat dilakukan pengukuran pada

    masukan dan keluaran suatu alat atau rangkaian tanpaperlu tahu bentuk rangkaian di dalamnya.

    Ada dua bentuk dasar rangkaian setara yaitu

    Rangkaian setara Thevenin

    Rangkaian setara Norton

    Rangkaian setara Thevenin : Menggunakan sumber

    tegangan tetap, yakni suatu sumber tegangan ideal

    dengan tegangan keluaran yang tidak berubah,

    berapapun besarnya arus yang diambil darinya.

    Rangkaian setara Norton : Menggunakan sumber arus

    tetap, yang dapat menghasilkan arus tetap, berapapun

    besarnya hambatan yang dipasang pada keluarannya

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    Lecture #2 By Yohandri 13

    4.1. Rangakaian Setara Thevenin

    Setiap rangkaian dengan dua ujung atau gerbang tunggal,

    dapat digantikan dengan suatu sumber tegangan tetap

    atau suatu gaya gerak listrik (ggl) dan suatu hambatan

    seri dengan ggl tersebut

    Ri Ro

    Ei EoVo

    ViRo

    ETHVo

    Thevenin's Theorem

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    Lecture #2 By Yohandri 14

    Analisis Rangkaian Thevenin

    E

    R2

    R1

    Vo

    21

    21

    RR

    RRR

    TH

    ERR

    RE

    TH

    21

    2

    RTH dapat dihitung dengan menggantiE dengan hubungan singkat, sehingga

    Dan ETH dapat dihitung dengan sistem

    pembagi tegangan

    Contoh :

    Tentukan rangkaian setara

    UntukR1 = 1 K

    R2 = 1 K

    Bagaimana jika

    R1 = 100 R2 = 100

    Amati jika pada keluaranya

    dari model 1 dan 2 diambil

    arus 10 mA

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    Lecture #2 By Yohandri 15

    R1

    E

    R2 R3 Vo

    Latihan

    Ro

    ETHVo

    Diketahui : R1 = 1 K

    R2 = 2 K

    R3 = 1 K

    E = 12V

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    Lecture #2 By Yohandri 16

    4.2. Rangakaian Setara Norton

    Rangkaian setara ini terdiri dari sumber arus tetap INparalel dengan suatu hambatan R

    O

    RoIN

    Ro

    ETH

    Bila ujung kelauarn Thevenin dan Norton sama-sama

    dihubung singkatkan maka arus yang mengalir pada

    keluaran akan bernilai sama

    N

    THI

    Ro

    RIos

    Iosadalah arus keluaran jika

    dihubungkan singkat

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    Lecture #2 By Yohandri 17

    R1

    E

    R2 R4

    R3

    Example

    R1 = 1K

    R2 = 2K

    R3

    = 1K

    R4 = 1K

    E = 12V