electronic circuits and electronic devices

7/29/2019 Electronic Circuits and Electronic Devices

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Electronic Circuitsand Electronic

Devices

David A. Bell Electronic Circuits and Electronic Devices

Copyright Oxford University Press, 2010


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PREFACE

Thelaboratoryinvestigationsinthismanualaredesignedtodemonstratetheelectronicstechnology theory explained inmybook Electronic Circuits and Electronic Devices.Atotal of43laboratoryinvestigationsareofferedinvolvingtheconstructionandtestingofcircuitsdiscussedinthetextbook.Eachlaboratoryinvestigationconsistsof:

atitle anintroductionthatbrieflydescribestheinvestigation alistofrequiredequipmentandcomponents circuitdiagramsandconnectiondiagrams

step

by

step

procedures

to

be

followed

alaboratoryrecordsheetforrecordingdata ananalysissectionforprocessingthedata

Eachinvestigationcannormallybecompletedwithinatwohourperiod.Theprocedurescontain some references to the textbook;however,allnecessarycircuitand connectiondiagramsareprovidedinthemanual,sothattheinvestigationscanbeperformedwithoutthetextbook.

DavidBell




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CONTENTS

1 Semiconductor Diode Characteristics 42 Diode Rectifier Circuits 93 Zener Diode .. 74 BJT Characteristics .. 195 BJT Bias Circuits 246 BJT Switching Circuits . 287 BJT Common Emitter Circuit . 338 BJT CC and CB Circuits . 379 JFET Characteristics ... 4210 JFET Bias Circuits ... 47

11 Basic JFET Circuits . 5212 CapacitorCoupled BJT Amplifier 57

13 DirectCoupled BJT Amplifier 6214 SCR Characteristics and 90 Phase Control 6715 SCR and TRIAC Control Circuits . 7216 UJT and PUT Circuits .. 7617 Photoconductive Cell, LED, and Solar Cell . 8218 Series Resistive Circuits 8719 Parallel Resistive Circuits 95

20 Seriesparallel Circuits. 100

21 Resistive Networks 104

22 Network Theorems 110

23 DC RCCircuit 11524 Oscilloscope 120

25 Rectifier Voltmeter 12526 AC RLCircuit. 12927 AC RCCircuit. 13328 Series & Parallel Impedance Circuits 137

29 Series Resonance 143

30 Parallel Resonance 147




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LABORATORY

INVESTIGATION 1SemiconductorDiode

Characteristics

Introduction

Theforward

characteristics

of

alow

current

switching

diode

and

amedium

current

recti

fierdiodeareinvestigated.Eachdeviceisforwardbiasedtogiveseveralcurrentlevels,andtheforwardvoltageismeasuredateachcurrent.ThisproducesatableofVF andIFquantitiesforplottingthecharacteristics.Diodereversecurrentisalsoinvestigated.

Equipment

DCpowersupply(050V,100mA)DCvoltmeter(50V)DCammeter(100mA)DCammeter(20 A)Lowcurrentswitchingdiode,e.g.,1N914

Rectifierdiode,

e.g.,

1N4005

Resistors(470 ,5W),(68k ,0.25W),(1k ,0.5W)Circuitboard

Procedure1 Low-CurrentDiode Characteristics

11 ConstructthecircuitshowninFig.11accordingtotheconnectiondiagraminFig.12.Notethatthelowcurrentdiode(D1)isconnectedtoterminalsAandBwithforwardbiasedpolarity.

100mA

Powersupply

1k AA

R

1

V D1

B

Figure 1-1 Circuit for determining low-current diode forward characteristics.




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Ammeter

Powersupply

AV

A COM

Voltmeter

VV

AR1 A COM

D1

BCircuitboard

Figure 1-2 Connection diagram for determining diode forward characteristics.

12 Adjustthepowersupplyvoltagecontrolforzerooutput.

13 SwitchonthepowersupplyandcarefullyadjustthevoltagetogivethecurrentlevelslistedforProcedure13onthelaboratoryrecordsheet.(Donotexceedadiodecurrentof20mA.)Ateachcurrentlevel,recordthediodeforwardvoltageontherecordsheet.

14 Adjustthepowersupplytoreturnthediodevoltagetozero.Switchoff;thenusingthe20 Arangeammeter,reconstructthecircuitasshowninFig.13.Notethatthediode

polarity

is

reversed,

the

ammeter

is

connected

directly

in

series

with

the

diode,andR1 isa68k resistor.20 A

Powersupply

68kA A

R1

V D1

B

Figure 1-3 Circuit diagram for determining diode reverse characteristics.

15 Switchonthepowersupplyandadjustthedevice(reverse)voltageto30V.Recordthediodereversecurrentonthelaboratoryrecordsheet.




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Procedure2 RectifierDiode Characteristics

21 Resetthepowersupplyoutputtozeroandremovethelowcurrentdiodefromthecircuit.

22 ReconstructthecircuitasillustratedinFig.14,andconnecttherectifierdiode(D2)withforwardbiasedpolaritytoterminalsAandB.NotethatR1 isnow470 andthatthevoltmeterisconnecteddirectlyinparallelwithD2.

100mA

Powersupply

470 AA

R1

V D2

B

Figure 1-4 Circuit for determining rectifier diode forward characteristics.

23 Switch on the power supply and adjust the diode voltage in steps as listed forProcedure23onthelaboratoryrecordsheet.(Donotexceedadiodecurrentof60mA.)At each voltage step, record thediode forward current on the laboratory recordsheet.

24 SwitchoffthepowersupplyandrearrangethecircuitasinFig.13,usingtherectifierdiodeanda20 Aammeter.

25 Switchonthepowersupplyandadjustthedevice(reverse)voltageto30V.Record

the

reverse

current

on

the

laboratory

record

sheet.

Analysis

1 Plot the forwardcharacteristicof the lowcurrentdiode (D1) from the resultsofProcedure1.

2 Plot the forward characteristic of the rectifier diode (D2) from the results ofProcedure2.

3 Fromtheforwardcharacteristics,determinetheapproximateforwardvoltagedropanddc forwardresistance forD1 andforD2.Estimate theac resistance foreachdiode.

4Comment

on

the

results

of

Procedures

1

5

and

2

5

(reverse

biased

diode

current

measurements).




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RecordSheetL1-1

RecordSheetLab.#1 Semiconductor Diode Characteristics

Date

Procedure 1-3

Low-Current Diode Forward Characteristics

IF(mA)

VF (V)

0.1 1 2 3 5 10 15 20

Procedure 1-5

Reverse BiasVR IR

30 V

Procedure2-3

Rectifier Diode Forward Characteristics

IF(mA)

VF (V)

0.5 1 5 10 20 30 40 50 60

Procedure2-5

Reverse BiasVR IR

30 V




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RecordSheetL1-2

Low-Current Diode Forward Characteristics

(mA)

20

15

IF10

5

00 0.1 0.2 0.3 0.4

VF

0.5 0.6 0.7 0.8(V)

Rectifier Diode Forward Characteristics

(mA)

60

50

40

IF30

20

10

00 0.1 0.2 0.3 0.4

VF

0.5 0.6 0.7 0.8(V)




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LABORATORY

INVESTIGATION 2Diode Rectifier Circuits

Introduction

Ahalfwaverectifiercircuitisconstructed,anditsinputandoutputwaveformsareinvestigated.Thenafullwavebridgerectifiercircuitisconstructedandtested.Finally,atwodiodefullwaverectifiercircuitusingacentretappedtransformerisconstructed,anditsoutputwaveformsareinvestigated.

Equipment

115V,60Hzvariablevoltagetransformer(variac)115V,60Hz,1:1isolatingtransformer115V,60Hz,transformerwithcentretappedsecondaryOscilloscopeLowcurrentdiodes(4 1N914)Resistor(100 ,0.5W)Circuitboard

Procedure1 Half-WaveRectification

11 ConstructthehalfwaverectifiercircuitshowninFig.21accordingtotheconnectiondiagraminFig.22.(ThisistherectifiercircuitinFig.31ainthetextbook.)

115V

60Hz

VariacIsolatingtransformer

D1

RL

100

Vi

Vo

Tooscilloscope

Figure 2-1 Half-wave rectifier test circuit.




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Oscilloscope


Circuitboard

D1

RL

Figure 2-2 Connection diagram for the half-wave rectifier test circuit.

12 Adjustthevariacforthelowestoutputvoltage;thenconnectthe115V,acsupply.

13 Switchontheacsupplyandslowlyincreasethevariacoutputuntilthediodecircuitinputwaveform(attheisolatingtransformeroutput)measures10Vpeaktopeakasdisplayedontheoscilloscope.

14 Measurethepeaklevelofthediodecircuitoutputvoltage.Neatlysketchthecircuit

inputand

output

waveforms

on

the

laboratory

record

sheet

and

record

the

measured

peaklevels(ViandVo).

15 Increasethediodecircuitinputto20VpeaktopeakandrepeatProcedure14.

16 Switchofftheacsupplyandreversethediodeterminals.

17 SwitchontheacsupplyandrepeatProcedure14withVi 10Vpeaktopeak.

Procedure2 Full-Wave Bridge Rectifier

21 Construct the fullwave rectifiercircuit shown inFigs. 23 and24. (This rectifiercircuitisthesameasinFig.36inthetextbook.)

22Repeat

Procedures

1

2

through

1

5.

23 Switch off the ac supply, and then disconnect (opencircuit) one terminal of onediode.

24 Switchontheacsupply,andnotetheopencircuiteffectontheoutput.




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Vi

115V60Hz

Isolating

Variac

transformer

D1 D3Vo

RL100

Tooscilloscope

D2 D4

Figure 2-3 Bridge rectifier circuit.

Tooscilloscope

Isolatingtransformer

Circuitboard

Tooscilloscope

Fromvariac

D1 D3

RLD2 D4

Figure 2-4 Connection diagram for the bridge rectifier circuit.

Procedure3 Two-Diode Full-Wave Rectifier

31 ConstructthefullwaverectifiercircuitshowninFig.25accordingtotheconnectiondiagraminFig.26.(ThisrectifiercircuitisthesameasinFig.33inthetextbook.)

32 RepeatProcedures12through15.

115V60Hz

Variac

Transformerwithcentre

tappedsecondary

D1 RL

100

D2

Vi

Vo To

oscilloscope

Figure 2-5 Two-diode full-wave rectifier circuit.




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Fromvariac

Transformerwith

centretapped

secondary

Tooscilloscope

Circuitboard

D1

Tooscilloscope

RL

D2

Figure 2-6 Connection diagram for the two-diode full-wave rectifier circuit.

Analysis

1 DiscusstheresultsofProcedure1.Explainthedifferencebetweentheinputandoutputwaveforms.

2 DiscusstheresultsofProcedure2.Explaintheeffectofopencircuitingonediode.3 DiscusstheresultsofProcedure3.Comparethetwodiodefullwaverectifiertothebridgerectifier.Whataretheadvantagesanddisadvantagesofeachcircuit?




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RecordSheetL2-1

RecordSheetLab.# 2 DiodeRectifier Circuits

Date

Half-WaveRectifier Circuit

Procedure 1-4

Input voltage. Vi = 10Vp-to-p

Output voltage. Vo =

Procedure 1-5

Input voltage. Vi = 20 Vp-to-p


Procedure 1-7






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RecordSheetL2-2

RecordSheet 2Lab.#2

Full-Wave Bridge Rectifier Circuit

Procedure2-2





Date

Procedure2-4

Procedure3-2








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LABORATORY

INVESTIGATION 3

ZenerDiode

Introduction

ThereversecharacteristicsofaZenerdiodeare firstinvestigated.Thedevice is reversebiasedinstepvoltagelevels,andthereversecurrentismeasuredateachstepuntilreversebreakdown occurs.After thebreakdown voltage is reached, the reverse current is increasedinstepsandthediodevoltageismeasuredateachstep.InthiswayatableofVRandIRquantitiesisobtainedforplottingthereversecharacteristics.(Zenerdiodeforwardcharacteristicscanbeinvestigatedinthesamewayasforanordinarylowcurrentdiode.)AsimpleZenerdioderegulatorcircuitisconstructedandtestedusingahalfwaverectifier

powersupply

as

an

input.

Equipment

DCpowersupply(050V,100mA)OscilloscopeDCAmmeter(050mA)Multirangedcvoltmeter(020V)4digit(orbetter)digitalvoltmeter115V,60Hzvariablevoltagetransformer(variac)115V,60Hz,1:1isolatingtransformer

Zenerdiode1N753

Lowcurrentdiode1N9141Wresistors120 ,150Capacitor(330 F,25V)Circuitboard

Procedure1 1N753 Characteristics

11 Connect the circuit and test equipment as shown in Fig. 41a according to theconnection diagram in Fig. 41b. Note that the Zener diode is connected withreversebiaspolarity.

12 Adjustthepowersupplyforzerooutput;thenconnectitsacsupplyandswitchon.




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Power

supply

150kA

R1

V

D1

1N753

Ammeter

Voltmeter(a)Circuit

PowersupplyA

VA COM

VV

A

CircuitR1 A COM

board D1

B

(b)Connection

diagram

Figure 4-1 Determination of Zener diode characteristics.

13 CarefullyincreasethediodereversevoltageinstepsaslistedforProcedure13onthe laboratory record sheetuntil thediodegoes into reversebreakdown.Ateachvoltagestep,recordthediodereversecurrentontherecordsheet.

14 When thediodebreakdownvoltage isreached,carefullyadjustthepowersupplyvoltagetosetthediodecurrenttothestepslistedforProcedure14onthelaboratoryrecordsheet.Ateachcurrentstep,recordthemeasuredreversevoltage.

Procedure2 Zener DiodeRegulator

21 Construct the halfwave rectifier power supply and Zener regulator shown inFig.42, togetherwith the test equipment. (This is the regulator circuitdesignedinExample317inthetextbookandanalyzedinExample318.)

22 Adjustthevariacforzerooutput;thenconnectthe115Vacsupply.

23 Switchontheacsupplyandslowlyincreasethevariacoutputtogivea16Vdcinput(Vi(dc))totheregulator.MeasureandrecordtheregulatoroutputvoltageattheZenerdiodeterminals.

24 Usingtheoscilloscope,measuretheregulatorpeaktopeakinputripplevoltage(Vri)andthepeaktopeakoutputripplevoltage(Vro).

2

5

Adjust

the

ac

input

voltage

to

increase

Vi(dc)by

10%.

Measure

and

record

the

dc

out

putvoltagechange(theregulatorsourceeffect), Vo(source).

26 ResetthevariactosettheregulatorinputbacktoVi(dc) 16V.

27 DisconnectoneendofRL andobservetheoutputvoltagechangefromfullloadtonoload(theregulatorloadeffect), Vo(load ).Record Vo(load ).




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C

0195429885_016- 019_ch04. qxd 2/ 13/ 08 4: 17 PM Page 18

115V

60Hz


D11N914

C1330 F V Vi(dc)

R1

150

D21N753

RL

120

Vri

Vro

V

Tooscilloscope

(a)Circuit

Voltmeter

VV

A COM

Tooscilloscope

R1D1

1 D2

4digitvoltmeter

VV

A COM

RL

Variac Isolatingtransformer Circuitboard

(b)Connectiondiagram

Figure 4-2 Zener diode regulator test circuit.

Analysis1 FromtheresultsofProcedures13and14,plotagraphshowingtheZenerdiodereversecharacteristics.

2 From theZenerdiode reverse characteristics,determine the reversevoltage atIZ 20mA.Calculatethedynamicimpedanceforthedevice.

3 Calculate the line regulation, load regulation,and ripple reduction factorproducedby theZenerdioderegulator.Compare theresults to thosecalculated inExample318inthetextbook.




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RecordSheetL4-1

RecordSheetLab.#4 ZenerDiode

Date

Zener DiodeReverseCharacteristics

Procedure 1-3VR(V) 2

IR(mA)

4 6 6.05 6.1 6.2

Procedure 1-4VR(V)

IR(mA) 5 10 20 30 40

Zener DiodeRegulator

Procedure2-3 Output Voltage Vo = VZ =

Procedure2-4 Peak-to-peakripple Voltage:

Vri = Vro =

Procedure2-5 Source effect Vo(source)=

Procedure2-7 Load effect Vo(load) =




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LABORATORY

INVESTIGATION 4

BJT Characteristics

Introduction

Thecommonemitter(CE)andcommonbase(CB)outputcharacteristicsaredeterminedforaBJTbythepointbypointprocess.ThetransistorisfirstconnectedinCEconfigurationanditsbasecurrent(IB)issetataparticularlevel.Thecollectoremittervoltage(VCE)invariedinsteps,andthecollectorcurrent(IC)isnotedateachVCE step.ThisgivesatableofICversusVCE levelsfromwhichtheCEoutputcharacteristiccanbeplotted.TheprocessisrepeatedforseveralIB levelstogiveafamilyofCEcharacteristics. TheBJTcommonbase(CB)outputcharacteristicsaredeterminedinasimilarway,andtheCEandCBcurrent

gaincharacteristics

are

derived

from

the

output

characteristics.

Equipment

2dcpowersupplies(0to20V)DCvoltmeter(0to25V)DCammeter(0to100 A)2dcammeters(0to10mA)Resistors(2.2k ,0.5W),(100k ,0.25W)LowcurrentgeneralpurposenpnBJT(e.g.,2N3904)Circuitboard

Procedure1 Common Emitter Output Characteristics

11 ConnectthecircuitandtestequipmentasshowninFig.71aaccordingtotheconnectiondiagraminFig.71b.(Notethatthebasecurrentammeteristomeasureinmicroamps.)

12 Setbothpowersuppliesforzerooutput,andthenswitchon.

13 SetVCE to15V,andthenincreasethebasebiasvoltagetogiveIB 10 A.

14 ReadtheIC levelandrecorditonthelaboratoryrecordsheet.

15 MaintainingIB constant,adjustVCE toeachofthevoltageslistedforProcedure1on

thelaboratory

record

sheet.

Record

the

measured

IC at

each

VCE level.

(At

each

IC

measurement,carefullycheckandadjustIB ifnecessary.)




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IC

AIB

R1

APower

Powersupply

100k VA supply

(a)CEtestcircuit

Ammeter(IB) Ammeter(IC) Voltmeter(VCE)

VA

VA COM

AVA COM

VA COM

Powersupply

R1 CBEQ1

Powersupply

Circuitboard


Figure 7-1 Circuit and connection diagram for determining BJ T CE characteristics.

16 ReadjustVCE to15VandsetIB to20 A.ReadtheIC levelandrecorditonthelaboratoryrecordsheet.

17 RepeatProcedure15.

18 ReadjustVCE to15VandsetIB to30 A.ReadtheIC levelandrecorditonthelabo

ratory

record

sheet.


110 ReadjustVCE to15Vandset IB to40 A.Read the IC levelandrecord iton thelaboratoryrecordsheet.





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Procedure2 Common Base Output Characteristics

21 Set thepowersupplyvoltages tozero,switchoff,and thenmodify thecircuitasshowninFig.72.

IE ICR1

Powersupply

A2.2k A

PowerV supply

(a)CBtestcircuit

Ammeter(IE) Ammeter(IC) Voltmeter(VCE)

VA

VA COM

AV

A COM

VA COM

R1CBEQ1

Power

supply

Power

supply

Circuitboard


Figure 7-2 Circuit and connection diagram for determining BJ T CB characteristics.

22 Withbothpowersuppliessettozero,switchon.

23 AdjustVCB to15V;thenincreasethebasebiasvoltagetoproducea1mAemittercurrent(IE).

24Read

the

IC level

and

record

it

on

the

laboratory

record

sheet.

25 MaintainingIE constant,adjustVCB toeachofvoltageslistedforProcedure2onthelaboratoryrecordsheet.RecordthemeasuredIC ateachVCB level.(AteachICmeasurement,carefullycheckandadjustIE ifnecessary.)

26 ReadjustVCB to15VandsetIE to3mA.ReadtheIC levelandrecorditonthelaboratoryrecordsheet.




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28 ReadjustVCB to15VandsetIE to5mA.ReadtheIC levelandrecorditonthelabo ratoryrecordsheet.

29Repeat

Procedure

25.

Analysis

1 PlottheBJTCEcharacteristicsfromtheresultsofProcedure1.2 DrawaverticallineontheCEcharacteristicsatVCE 5V.Fromtheintersectionsofthislinewiththedevicecharacteristics,prepareatableofcorrespondingIC andIB levels.Seethelaboratoryrecordsheet.

3 CalculatethehFEvaluesforeachIC levelintheVCE 5VcolumnintheIC/IBtable,andrecordtheseinthetable.

4Plot

the

BJT

CE

current

gain

characteristics

from

the

IC/IBtable.

5 PlottheBJTCBcharacteristicsfromtheresultsofProcedure2.6 DrawaverticallineontheCBcharacteristicsatVCB 5V.Fromtheintersectionsofthislinewiththedevicecharacteristics, prepareatableofcorrespondingICandIElevels.Seethelaboratoryrecordsheet.

7 CalculatethehFBvaluesforeachIC levelintheIC/IEtable.8 PlottheBJTCBcurrentgaincharacteristicsfromtheIC/IEtable.




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RecordSheetL7-1

RecordSheetLab.# 7 BJTCharacteristics

Date

Procedure 1 Common-Emitter Characteristics

(IB= 10 A)

(IB= 20 A)

(IB= 30 A)

(IB= 40 A)

VCE(V)

IC(mA)

IC(mA)

IC(mA)

IC(mA)

0.5 1 2 5 10 15

Fromthe CE Characteristics

(VCE = 5 V) IB(A) 10

IC(mA)

hFE

20 30 40

Procedure2 Common-Base Characteristics

(IE = 1 mA)

(IE= 3 mA)

(IE= 5 mA)

VCB(V)

IC(mA)

IC(mA)

IC(mA)

0.5 1 2 5 10 15

Fromthe CB Characteristics

(VCB = 5 V) IE(mA) 1 3 5

IC(mA)

hFB




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LABORATORY

INVESTIGATION 5

BJT Bias Circuits

Introduction

ThreebasicBJTbiascircuitsareinvestigated:basebias,collectortobasebias,andvoltagedividerbias.TwotransistorswithdifferenthFEvalues(hFE(A)andhFE(B))areusedtodemonstratethedccurrentgaineffectoneachbiascircuit.Eachcircuitisconstructed,andthedcvoltagesthroughoutthecircuitaremeasuredfortheBJTwithhFE(A) andthenfortheBJTwithhFE(B).Theresultsarecomparedwithcircuitsinthetextbook.

Equipment

DCpower

supply(0

to

20

V)

DCvoltmeter(0to20V)0.25Wresistors470k,270k,33k,12k,2.2k,1.2k,1k2differenttypeoflowcurrentnpnBJTs(e.g.,2N3904and2N718)Circuitboard

Procedure1 Base Bias and hFE Values

11 IdentifythetwotransistorsasAandB.

12 UsingtransistorA,connect thebasebiascircuitand testequipmentasshown inFig.91.

13Switch

on

the

power

supply

and

adjust

its

output

to

give

VCC 18

V.

14 MeasureVCE. IftransistorQ1 issaturated,increasethebaseresistorasnecessarytomoveQ1outofthesaturatedstate.Onthelaboratoryrecordsheet,recordVCEandtheresistanceofRB forthebasebiascircuitwithtransistorA.

15 Switchoffthepowersupply,andsubstitutetransistorBfortransistorA.

16 SwitchthepowersupplyonandagainandcheckthatVCC 18V.

17 MeasureVCE andagain increaseRB ifnecessary tomove the transistoroutof thesaturatedstate.RecordVCE andtheresistanceofRB forthebasebiascircuitwithtransistorBonthelaboratoryrecordsheet.




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Powersupply

VCC

18V

VoltmeterCircuitboard

RCRB470k RC2.2k V RB

VA COM

Q1

CB Q1E

(a)Basebiastestcircuit (b)Connectiondiagram

Figure 9-1 Base bias test circuit and connection diagram.

Procedure2 Collector-to-BaseBias

21 UsingtransistorA,connectthecollectortobasebiascircuitandtestequipmentasshowninFig.92.

Powersupply

VCC

18V

RC

VoltmeterCircuitboard

RC

RB270k

2.2kQ1

V

VA COM

RB

CB Q1E

(a)Collectortobasebiastestcircuit (b)Connectiondiagram

Figure 9-2 Collector-to-basebias test circuit and connection diagram.

22 SwitchonthepowersupplyandadjustitsoutputtogiveVCC 18V.

23Measure

VCE,

and

on

the

laboratory

record

sheet,

note

the

measured

voltage

for

collectortobasebiaswithtransistorA.


25 SwitchthepowersupplyonandagaincheckthatVCC 18V.

26 MeasureVCE againandrecordthemeasuredvoltageforcollectortobasebiaswithtransistorB.




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Procedure3 Voltage DividerBias

31 UsingtransistorA,connect thevoltagedividerbiascircuitand testequipmentasshowninFig.93.

R1 RC

VCC

18V VoltmeterCircuitboard

Powersupply

33k

R212k

1.2kQ1

RE1k

V

VA COM

R1 RC

CB Q1E

R2 RE

(a)Voltagedividerbiastestcircuit (b)Connectiondiagram

Figure 9-3 Voltage divider bias test circuit and connection diagram.

32 SwitchonthepowersupplyandadjustitsoutputtogiveVCC 18V.

33 MeasureVC andVE andnotethemeasuredvoltagesforvoltagedividerbiaswithtransistorAonthelaboratoryrecordsheet.


35 SwitchthepowersupplyonandonceagaincheckthatVCC 18V.

36 MeasureVC andVE againandnotethemeasuredvoltagesforvoltagedividerbiaswithtransistorBonthelaboratoryrecordsheet.

Analysis

1 FromtheresultsofProcedure1calculatehFE(A)andhFE(B).2 OnthelaboratoryrecordsheettabulatethemaximumandminimumVCE levelsforeachbiascircuitfortransistorsAandB.UsethemeasuredvoltagestocalculateIC

for

each

circuit.

Record

the

IC levels

in

the

table

on

the

laboratory

record

sheet.

3 Drawadcloadlineandmarkthebiaspointextremesforeachbiascircuit.4 ComparethecircuitstabilityforeachbiascircuittothesimilarcircuitsinSection55inthetextbook.

5 UsingthemeasuredhFEvalues,analyzeeachcircuittocalculateICandVCE.Comparethecalculatedandmeasuredquantities.




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RecordSheetL9-1

RecordSheetLab.#9 BJTBias Circuits

Date

Procedure 1

Transistor A

Transistor B

VCE RB IB IC hFE

Procedure2

Transistor ATransistor B

VCE RB IB IC

Procedure 3

Transistor A

Transistor B

VC VE VCE IC

Analysis

VCE(min)

VCE(max)

IC(min)

IC(max)

Basebias Collector-to-base

bias

Voltage divider

bias




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0195429885_045- 049_ch10. qxd 2/ 13/ 08 4: 23 PM Page 45

LABORATORY

INVESTIGATION 6BJT Switching Circuits

Introduction

AdirectcoupledBJTswitchingcircuit isconstructedand testedwithdc inputvoltagesandwithasquarewaveinput.Twocapacitorcoupledswitchingcircuitsarealsotested:onewiththeBJTbiasedinanormallyonstate,andtheotherwiththeBJTnormallyoff.

Equipment

OscilloscopeSquarewavegenerator2dcpowersupplies(0to20V)DCvoltmeter(0to20V)Resistors(4.7k ,0.25W),(8.2k ,0.25W),(27k ,0.25W),(39k ,0.25W)Capacitors(0.22 F,25V)LowcurrentgeneralpurposenpnBJT(e.g.,2N3904)Circuitboard

Procedure1 Direct-Coupled Switching Circuit

11 ConstructthedirectcoupledBJTswitchingcircuit inFig.101. (This isthecircuitdesignedinExample522inthetextbook.)

VCC

12V Powersupply

CircuitboardPowersupply

RB

27k

RC8.2k

Q1

RC

RB CB Q1E

(a)Directcoupledswitchingcircuit (b)Connectiondiagram

Figure 10-1 Direct-coupled BJ T switching circuit.




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RB

0195429885_045- 049_ch10. qxd 2/ 13/ 08 4: 23 PM Page 46

12 SwitchonthecollectorpowersupplyandadjustVCC to12V.

13 SwitchonthebasepowersupplyandadjustVB to0V.

14 MeasureandrecordVCE.

15 AdjustVB to5VandagainmeasureandrecordVCE.

16 SubstitutethesignalgeneratorforthebasesupplyvoltageasinFig.102,andconnecttheoscilloscope(using10:1probes)tomonitorthewaveforms.

VCC

12V

Tooscilloscope

Powersupply

Tooscilloscope

RB

RC8.2k

Q1

SignalgeneratorRC

CQ

B 1

27kE

(a)Directcoupledcircuit

Circuitboard


Figure 10-2 Waveform investigation for a direct-coupled BJ T switching circuit.

17 Setthesignalgeneratoroutputfora;3V,10kHzsquarewave.

18 Sketchthecircuitinputandoutputwaveformsonthelaboratoryrecordsheet,andnotetheupperandlowerpeakvoltages.

19Increase

the

signal

frequency

to

investigate

the

circuit

switching

times.

110 Measureandrecordtheturnontime(ton)andtheturnofftime(toff),andsketchthewaveformsontherecordsheet.

Procedure2 Normally-On Capacitor-CoupledSwitching Circuit

21 ConstructthenormallyoncapacitorcoupledBJTswitchingcircuitinFig.103.(Thiscircuit is designed inExample 523 in the textbook.)Leave the signal generatorunconnectedatthistime.

22 SwitchonthecollectorpowersupplyandadjustVCC to9V.

23Measure

VCE and

note

the

voltage

on

the

record

sheet.

24 ShortcircuitthetransistorbaseandemitterterminalsandagainmeasureandrecordVCE.Removetheshortcircuit.

25 Connectthesignalgeneratorandadjustthesignaltoa;3V,10kHzsquarewave.





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E

0195429885_045- 049_ch10. qxd 2/ 13/ 08 4: 23 PM Page 47

RB39k

VCC

9V

RC

Tooscilloscope

Powersupply

Tooscilloscope

4.7kSignalgenerator

RBRC

C1

Q1

0.22 F

CB Q1E

C1

(a)Normallyoncircuit

Circuitboard


Figure 10-3 Normally-on capacitor-coupled BJ T switching circuit.

Procedure3 Normally-OffCapacitor-CoupledSwitching Circuit

31 Switchoffthepowersupply,andreconstructthecircuitintothenormallyoffcapacitorcoupledswitchingcircuitinFig.104.

To RC

VCC

9V

Tooscilloscope

Powersupply

oscilloscope 4.7kC1

Q10.22 F

SignalgeneratorRC

CQ

RB39k B 1C1 RB

(a)Normallyoffcircuit

Circuitboard


Figure 10-4 Normally-off capacitor-coupled BJ T switching circuit.

32 SwitchonthepowersupplyandsetVCC to9V.

33 MeasureVCE andnotethevoltageontherecordsheet.

34 Connectthesignalgeneratorandadjustthesignaltoa;3V,10kHzsquarewave.





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Analysis

1 Discuss themeasuredvoltagesandwaveforms for thedirectcoupled switching

circuit.2 Analyze thedirectcoupledcircuit todetermine IC,IB,andhFE(min).Calculate the

minimumbaseinputvoltagetodrivethetransistorintosaturation.3 Discussthecircuitswitchingtimes.4 Discussthemeasuredvoltagesandwaveformsforthenormallyoncapacitorcoupledswitchingcircuit.

5 AnalyzethenormallyoncapacitorcoupledcircuittodetermineIC,IB,andhFE(min).Calculatetheminimumbaseinputvoltagetodrivethetransistorintocutoff.

6 Discussthemeasuredvoltagesandwaveformsforthenormallyoffcapacitorcoupledswitchingcircuit.




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RecordSheetL10-1

RecordSheetLab.# 10 BJTSwitching Circuits

Date

Procedure 1-4

Procedure 1-5

Procedure 1-8

+Vo(pk) =Vo(pk) =

(Vi = O)

(Vi= 5 V)

VCE =

VCE =

Input

waveform

Output

waveform

Procedure 1-10

ton=toff=

Input

waveform

Output

waveform

Procedure2-3

Procedure2-4

Procedure2-6

+Vo(pk) =Vo(pk) =

(Vi = O)

VCE =

VCE =

Input

waveform

Output

waveform

Procedure3-3

Procedure3-5

+Vo(pk) =Vo(pk) =

VCE =

Input

waveform

Output

waveform




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0195429885_050- 053_ch11. qxd 2/ 13/ 08 4: 24 PM Page 50

LABORATORY

INVESTIGATION 7BJT Common EmitterCircuit

Introduction

ABJT commonemitter circuit is constructed and tested for dc and ac performance.Circuitmaximumacoutputvoltageisinvestigatedtogetherwithacvoltagegain,inputimpedance,andoutputimpedance.Thecircuitisthenmodifiedtohaveanunbypassedemitterresistor,andtheacperformanceisagaininvestigated.

Equipment

DCpowersupply(0to20V)DCvoltmeter(0to20V)OscilloscopeSignalgenerator0.25Wresistors3.9k,4.7k,56k,68k,82k15Vcapacitors0.12 F,10 F,180 FLowcurrentgeneralpurposenpnBJT(e.g.,2N3904)

Circuitboard

Procedure1 DC and AC Conditions

11 ConstructthecircuitinFig.111.(ThisisthecircuitinFig.624inthetextbook.)Leavethesignalgeneratorandoscilloscopeunconnectedatthistime.

12 SwitchonthepowersupplyandadjustitsoutputforVCC 12V.

13 MeasureandrecordthelevelsofVB,VE,andVC.

14 ConnectthesignalgeneratorandoscilloscopetothecircuitasillustratedinFig.111b.

15 Setthesignalgeneratortoproducea3kHzsinewaveandadjustthesignalamplitudetogivemaximumundistortedoutputfromthecircuit.(Notethatitmaybenecessary

touse

avoltage

dividertypically

a100

k and

a100

resistorto

reduce

the

signalamplitude.)

16 Sketch the input and outputwaveforms, and record the peak input and outputvoltages.

17 Adjustthesignalamplitudetoproducea;1Voutput.RecordthepeaklevelsofViandVo andcalculatethecircuitvoltagegain.




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0195429885_050- 053_ch11. qxd 2/ 13/ 08 4: 24 PM Page 51

R168k RC3.9k

VCC

12V

C3

C1

10 F

vs R256k

Q1

RE4.7k

0.12 F

C2180 F

RL82k Tooscilloscope

R1

Tooscilloscope

RCC3

(a)Commonemittertestcircuit

Signalgenerator

C1

R2 RE

PowersupplyCB QE

C2 RL

Circuitboard


Figure 11-1 Common-emitter circuit and test equipment.

Procedure2 Input and Output Impedances

21 SetthesignalgeneratorasinProcedure17.

22 Temporarilydisconnect thesignalgeneratorandconnecta1.8k resistor (Ra) inserieswiththesignalgeneratorandthecircuitinput,asillustratedinFig.112.

Ra

1kvs

R168kC1

R256k

Tooscilloscope

R1

C1

Tooscilloscope

RCC3

Powersupply

(a)Circuitmodification

Signalgenerator

Ra

R2 RE

CB Q1E

C2 RL

Circuitboard

(b)Connectiondiagrammodification

Figure 11-2 Common-emitter circuit input resistance measurement.




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0195429885_050- 053_ch11. qxd 2/ 13/ 08 4: 24 PM Page 52

23 CheckthatthesignalvoltageamplitudeappliedtoRa isthesameasthatmeasuredinProcedure17.

24 Observe theamplitudeof thecircuitacoutputvoltage.Change the resistanceof

Ra asnecessary

to

give

an

output

amplitude

which

is

half

of

that

measured

in

Procedure15.RecordtheresistanceofRa asthecircuitinputimpedance(Zi).

25 Disconnect Ra, reconnect the signal generator, and adjust the signal level to thatmeasuredinProcedure17onceagain.

26 Temporarilydisconnectthe82k loadresistor(RL)andsubstitutea3.9k resistor(Rb)forRL.

27 Observe theamplitudeof thecircuitacoutputvoltage.Change the resistanceofRb as necessary togive anoutput amplitudewhich ishalfof thatmeasured inProcedure16.RecordtheresistanceofRb asthecircuitoutputimpedance(Zo).

Procedure3 UnbypassedEmitter Resistor31 DisconnectRbandreconnectRL.

32 Disconnecttheemitterbypasscapacitor;thenrepeatProcedure17.

33 RepeatProcedures21through27startingwithanewresistanceofRa 27k andusingRb 3.9k ,asbefore.

Analysis

1 FromtheresultsofProcedure1,plotthedcandacloadlinesfortheCEcircuitandshowthemaximumoutputvoltageswing.

2Analyze

the

circuit

to

determine

the

dc

voltages

and

compare

to

the

measured

voltages.3 Analyze the circuit todetermineAv,and compare to theAv from the resultsofProcedure17.Commentonthephaserelationshipbetweentheinputandoutputwaveforms.

4 AnalyzethecommonemittercircuittoestimateZiandZo.ComparethecalculatedvaluestothosemeasuredinProcedure2.

5 FromtheresultsofProcedure33,calculatethevoltagegain(Av)forthecommonemittercircuitwithanunbypassedemitterresistor.AnalyzethecircuittodetermineAvandcomparetothemeasuredAv.

6 AnalyzethecommonemittercircuitwithanunbypassedemitterresistortoestimateZiandZ

o

.ComparethecalculatedvaluestothosemeasuredinProcedure33.




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RecordSheetL11-1

RecordSheetLab.#11 BJTCommon-Emitter Circuit

Date

Procedure 1-3 VCC VB VE VC

Procedure 1-6Input

wavefor

m

Output

wavefor

m

Procedure 1-7 Vi(pk) = Vo(pk) = Av =

Procedure2-4 Zi =

Procedure2-7 Zo =

Procedure3-2 Vi(pk) = Vo(pk) = Av =

Procedure3-3 Zi = Zo =




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0195429885_054- 058_ch12. qxd 2/ 13/ 08 4: 25 PM Page 54

LABORATORY

INVESTIGATION 8

BJT CC and CB Circuits

Introduction

BJTcommoncollectorandcommonbasecircuitsareconstructedandtestedfordcandacperformance.Voltagegain,inputimpedance,andoutputimpedanceareinvestigatedforbothcircuits.

Equipment

DCpowersupply(0to20V)DCvoltmeter(0to20V)OscilloscopeSignalgenerator0.25Wresistors(56 ,1k ,1.2k ,3.9k ,4.7k ,27k ,56k ,68k ,82k )15Vcapacitors(0.12 F,10 F,180 F)LowcurrentgeneralpurposenpnBJT(e.g.,2N3904)Circuitboard

Procedure1 Common-CollectorCircuit (EmitterFollower)

11 ConstructthecircuitinFig.121.Leavethesignalgeneratorandoscilloscopeunconnectedatthistime.


13 MeasureVB,VE,andVC,andrecordthevoltagesonthelaboratoryrecordsheet.

14 ConnectthesignalgeneratorandoscilloscopetothecircuitasillustratedinFig.121.

15 Setthesignalgeneratorfrequencyto3kHzandadjustthesignalamplitudetogivea;0.5Voutput.

16 Sketchtheinputandoutputwaveformsonthelaboratoryrecordsheet,andrecordthepeakinputandoutputvoltagelevels.

17Temporarily

disconnect

the

signal

generator

and

connect

a27

k resistor

(Ra)

in

serieswiththesignalgeneratorandthecircuitinput.

18 CheckthattheacsignalvoltagetoRa isthesameasthecircuitinputvoltagemeasuredinProcedure16.




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1

0195429885_054- 058_ch12. qxd 2/ 13/ 08 4: 25 PM Page 55

R168k

VCC

12V

C1

Q110 F C2

Powersupply

vR2

s 56kRE

4.7k 180 F RL1kTooscilloscope

R1

(a)Commoncollectortestcircuit

Signalgenerator

C1

R2 RE

CB Q ToE

oscilloscope

C2 RL

Circuitboard


Figure 12-1 BJ T Common-collector circuit and test equipment.

19 Observetheamplitudeofthecircuitacoutputvoltage.ChangetheresistanceofRaasnecessarytogiveanoutputamplitudewhichishalfofthatmeasuredinProcedure16.RecordtheresistanceofRaasthecircuitinputimpedance(Zi).

110 DisconnectRa,reconnect thesignalgenerator,andagainadjust thesignal level tothat

measured

in

Procedure

16.

111 Temporarilyconnecta56 resistor(Rb)inparallelwithRL;thenreadjusttheinputamplitudetogivethemaximumundistortedoutput.

112 DisconnectandreconnectRb toseeifitspresencereducestheoutputamplitudebyafactorof2.ChangeRb asnecessary togivethiseffect.RecordtheresistanceofRbasthecircuitoutputimpedance(Zo).

Procedure2 Common-Base Circuit

21 ConvertthecommoncollectorcircuitintoacommonbasecircuitbythemodificationsshowninFig.122.Leavethesignalgeneratorandoscilloscopeunconnectedatthis

time.(The

circuit

in

Fig.

12

2a

is

the

same

as

in

Fig.

638

in

the

textbook.)


23 MeasureVB,VE,andVC,andrecordthevoltagesonthelaboratoryrecordsheet.

24 Connect the signal generator and oscilloscope to the circuit as illustrated inFig.122.




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s R

0195429885_054- 058_ch12. qxd 2/ 13/ 08 4: 25 PM Page 56

R168k RC3.9k

VCC

12V

C3Circuitboard

C3

Powersupply

R2C110 F

0.12 FQ1

C2

180 F

R1

RL82k

C1R

RC

CB Q1E

Tooscilloscope

56k RE v4.7k E2 C2 RL

(a)Commonbasetestcircuit

Tooscilloscope

Signalgenerator


Figure 12-2 BJ T Common-base circuit and test equipment.

25 Setthesignalgeneratorfor3kHzsinewaveandadjustthesignalamplitudetogivea;1Voutputfromthecircuit.

26 Sketchtheinputandoutputwaveformsonthelaboratoryrecordsheetandrecordthepeakinputandoutputvoltagelevels.

27 Temporarilydisconnectthesignalgeneratorandconnecta56 resistor(Ra)inseries

withthe

signal

generator

and

the

circuit

input.

28 CheckthattheacsignalvoltagetoRa isthesameasthecircuitinputvoltagemeasuredinProcedure26.

29 Observetheamplitudeoftheacoutputvoltage.ChangetheresistanceofRa asnecessarytogiveanoutputamplitudewhichishalfofthatmeasuredinProcedure26.RecordtheresistanceofRaasthecircuitinputimpedance(Zi).

210 DisconnectRa,reconnectthesignalgenerator,andadjustthesignalleveltothatmeasuredinProcedure26onceagain.

211 Temporarilydisconnecttheloadresistor(RL)andsubstitutea3.9k resistor(Rb)forRL.

212 Observe theamplitudeof theacoutputvoltage.Change the resistanceofRb as

necessaryto

give

an

amplitude

which

is

half

of

that

measured

in

Procedure

26.

RecordtheresistanceofRb asthecircuitoutputimpedance(Zo).




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Analysis

1 From the resultsofProcedure1,plot thedcandac load lines for the common

collectorcircuit

and

show

the

maximum

output

voltage

swing.

2 Calculate the commoncollector circuit voltage gain (Av) from the results ofProcedure 16.Analyze the circuit to determineAv, and compare it to theAvcalculatedfromthemeasurements.

3 Analyze thecommoncollectorcircuit toestimateZi andZo.Compare thecalculatedvaluestothosemeasuredinProcedure1.

4 From the resultsofProcedure2,plot thedcandac load lines for thecommoncollectorcircuitandshowthemaximumoutputvoltageswing.

5 Calculate the commoncollector circuit voltage gain (Av) from the results ofProcedure26.AnalyzethecircuittodetermineAv,andcomparetotheAv calculatedfromthemeasurements.

6 AnalyzethecommoncollectorcircuittoestimateZiandZo.Comparethecalculated

valuesto

those

measured

in

Procedure

2.




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RecordSheetL12-1

RecordSheetLab.# 12 BJT CCandCB Circuit

Date

Procedure 1-3 VCC VB VE VC

Procedure 1-6Vi(pk) =

Vo(pk) =

Av =

Input

wavefor

m

Output

wavefor

m

Procedure 1-9 Zi =

Procedure 1-12 Zo =

Procedure2-3 VCC VB VE VC

Procedure2-6Vi(pk) =

Vo(pk) =

Av =

Input

wavefor

m

Output

wavefor

m

Procedure2-9 Zi =

Procedure2-12 Zo =




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0195429885_059- 063_ch13. qxd 2/ 13/ 08 4: 26 PM Page 59

LABORATORY

INVESTIGATION 9JFET Characteristics

Introduction

DrainandtransfercharacteristicsareconstructedforannchannelJFETbythepointbypointprocess.TheJFETisfirstconnectedinCSconfiguration,anditsgatevoltage(VGS)issetatzero.Thedrainsourcevoltage(V

DS) invariedinsteps,andthedraincurrent(I

D)

is noted at eachVDS step.This gives a tableof ID versusVDS levels fromwhich thedraincharacteristiccanbeplotted.TheprocessisrepeatedforseveralVGS levelstogiveafam ilyofdraincharacteristics.TheJFETtransfercharacteristicispreparedinasimilarwaybyholding VDS constantwhilevarying VGS andnoting the corresponding levelsofID andVGS.DraincharacteristicsarealsoobtainedbytheuseofanXYrecorder.

Equipment

2dcpowersupplies(0to20V)DCvoltmeter(0to25V)DCammeter(0to20mA)

Resistors(1k ,

0.25

W),

(1

M ,

0.25

W)

LowcurrentgeneralpurposenchannelJFET(e.g.,2N5486)CircuitboardXYrecorder

Procedure1 Drain Characteristics

11 ConnectthecircuitandtestequipmentasshowninFig.131aaccordingtotheconnectiondiagraminFig.131b.

12 Setbothpowersuppliesforzerooutput;thenswitchon.

13 Maintaining VGS constant, carefully adjust VDS to eachof thevoltages listed for

Procedure1on

the

laboratory

record

sheet.

Record

the

measured

IDat

each

VDS level

forVGS 0.

14 CarefullyadjustVGS to 1V;thenrepeatProcedure13toproduceatableofcorrespondingVGS andID levelsforVGS 1V.

15 RepeatProcedure13forVGS 2Vand 3V.




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ID

A

R

1

Powersupply

VGS V

1M Q1 V VDS Powersupply

Voltmeter

(a)JFETtestcircuit

Voltmeter Ammeter

V VV

A COM

VA COM

AVA COM

Powersupply

DR1 S

G

Q1

Circuitboard


Powersupply

Figure 13-1 Circuit and connection diagram for determining J FET characteristics.

Procedure2 TransferCharacteristics

21 Usingthesamecircuitas inFig.131,setVGS to0andVDS to10V.MeasuretheID level,andrecorditonthetableforProcedure2onthelaboratoryrecordsheet.

22 Maintaining VDS constant at 10V, adjust VGS to each of the voltages listed forProcedure 2 on the laboratory record sheet. Record the measured ID at eachVGSlevel.

Procedure3 Drain Characteristic Plotting on XY Recorder31 Connect the circuit and test equipment as shown in Fig. 132a according to the

connectiondiagraminFig.132b.

32 SetbothpowersuppliesforzerooutputandtheXYrecordersensitivityfor1V/cmverticaldeflectionandhorizontaldeflection.




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1

0195429885_059- 063_ch13. qxd 2/ 13/ 08 4: 26 PM Page 61

XYrecorder R21k

R1Q1

1MV

Drainpower

supply

V

Gatepowersupply

(a)JFETtestcircuit DrainpowersupplyV=

(1V/cm)

ID

VDS

XYrecorder

Vertical

Horizontal

R2

DS QG

R1

V/A COM

V=

(1V/cm)

Circuitboard


Gatepowersupply

V/A COM

Voltmeter

Figure 13-2 Use of an XY recorder to draw J FET drain characteristics.

33 InstallsuitableplottingpaperintheXYrecorder,switchontheXYrecorder,adjustitspentoasuitablezerovoltagestartingpoint,andlowerthepenontothepaper.

34 SlowlyincreasethedrainvoltagetoproduceasuitabletracerepresentingtheJFETdraincharacteristicforVGS 0.

35 RaisetheXYrecorderpenatthemaximumpointonthecharacteristic;thenreducethedrainsupplyvoltagetozero.

36 CarefullyincreasethegatepowersupplyvoltagetoproduceVGS 1V.

37 Lower thepen again; then slowly increase thedrainvoltage toproduce a tracerepresentingtheJFETdraincharacteristicforVGS 1V.

38Raise

the

XY

recorder

pen

at

the

maximum

point

on

the

characteristic;

then

reduce

thedrainsupplyvoltagetozero.

39 RepeatProcedures36through38forVGS levelsof 2Vand 3V.

310 RaisetheXYrecorderpenatthemaximumpointonthelastcharacteristicandremovethepaper.




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Analysis

1 PlottheJFETdraincharacteristicsfromtheresultsofProcedure1.

2Plot

the

JFET

transfer

characteristics

from

the

results

of

Procedure

2.

3 FromthedraincharacteristicforVGS 0,determinethevaluesoftherD andYosparameters.

4 From the transfer characteristic,determine thevalues of the Yfs parameters atVGS 1VandVGS 4V.

5 DrawhorizontalandverticalscalesonthedraincharacteristicsplottedbytheXYrecorder.IdentifyeachcharacteristicaccordingtotheVGS level.PrinttheJFETtypenumberonthecharacteristics.




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RecordSheetL13-1

RecordSheetLab.# 13 JFETCharacteristics

Date

Procedure 1 Drain Characteristics

(VGS = 0)

(VGS = 1 V)

(VGS = 2 V)

(VGS = 3 V)

VDS (V)

ID (mA)

ID (mA)

ID (mA)

ID (mA)

0.5 1 2 3 4 5 10

Procedure2 Transfer Characteristic

(VDS = 10 V)

VGS (V) 0

ID (mA)

1 2 3 4 5 6 7 8




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LABORATORY

INVESTIGATION 10JFET Bias Circuits

Introduction

ThreebasicJFETbiascircuitsareinvestigated:gatebias,selfbias,andvoltagedividerbias.Twotransistors(Q1andQ2)areusedtodemonstratetheeffectofdifferentVGS(off) andIDSSvalues.Eachcircuit isconstructed,and thedcvoltages throughout thecircuitaremeasured,firstwithQ1 inthecircuitandthenwithQ2.Theresultsarecomparedwithcircuits

inthe

textbook.

Equipment

DCpowersupply(0to20V)DCvoltmeter(0to20V)0.25Wresistors470k,270k,33k,12k,2.2k,1.2k,1k2 lowcurrent general purpose nchannel JFETs of different types (e.g., 2N5457 andMPF102)

Circuitboard

Procedure1 DeviceParameters and Gate Bias

11 IdentifythetwoJFETsasQ1andQ2;thenusingQ1,connectthegatebiascircuitandtestequipmentasshowninFig.141.

12 SwitchonthepowersuppliesandadjustVGS tozeroandVDD to18V.

13 MeasureIDandrecorditonthelaboratoryrecordsheetasthedrainsourcesaturationcurrentIDSS forQ1withVGS 0.

14 IncreaseVGS to 1VandmeasureID.RecordIDonthelaboratoryrecordsheetrecordforQ1withVGS 1V.

15 Increase VGS untilID fallstoapproximately0.1mA.

16 MeasureVGS andrecorditasthegatesourcecutoffvoltageVGS(off) forQ1withID 0.

17Switch

off

the

power

supplies

and

substitute

transistor

Q2 fortransistorQ1.

18 RepeatProcedures12through16usingJFETQ2.




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S

0195429885_064- 068_ch14. qxd 2/ 13/ 08 4: 27 PM Page 65

ID

A

R1

Powersupply

VGS V

1M Q1 V VDS Powersupply(a)Gatebiascircuit

Voltmeter Voltmeter Ammeter

V VV

A COM

VA COM

AV

A COM

Powersupply

R1DG

Q1

Circuitboard


Powersupply

Figure 14-1 J FET gate bias circuit and connection diagram.

Procedure2 JFET Self Bias

21 UsingtransistorQ1,connecttheselfbiascircuitandtestequipmentasshown inFig.142.

22 SwitchonthepowersupplyandadjustVDD to18V.

23 MeasureVD andVSandnoteonthelaboratoryrecordsheetfortransistorQ1.

24 SwitchoffthepowersupplyandsubstituteQ2 forQ1.

25 SwitchthepowersupplyonandagaincheckthatVDD 18V.

26 MeasureVD andVS againandrecordthevoltagesfortransistorQ2.




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Powersupply

RD4.7k

VDD

18V

Voltmeter

Circuitboard

RD

RS680

DV S

G

RS

VA COM

(a)Selfbias circuit (b)Connectiondiagram

Figure 14-2 J FET self bias test circuit.

Procedure3 JFET Voltage DividerBias

31 UsingtransistorQ1,connectthevoltagedividerbiascircuitandtestequipmentasshowninFig.143.

R1 RD

VDD

18VCircuitboard

Powersupply

2.2M

R2560k

2.7k

RS2.7k

Voltmeter

V

VA COM

R1 RD

DSG

R2 RS

(a)JFETvoltagedividerbiascircuit (b)Connectiondiagram

Figure 14-3 J FET voltage divider bias test circuit.

32 SwitchonthepowersupplyandadjustVDD to18V.

33Measure

VD,

VS,

and

VG and

note

the

levels

on

the

laboratory

record

sheet

for

the

voltagedividerbiascircuitwithQ1.

34 SwitchoffthepowersupplyandsubstituteQ2 forQ1.

35 SwitchthepowersupplyonandagaincheckthatVDD 18V.

36 MeasureVD,VS,andVGonceagainandnotethelevelsonthelaboratoryrecordsheetforthevoltagedividerbiascircuitwithQ2.




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Analysis

1 OnthelaboratoryrecordsheettabulatetheVDS levelsforeachbiascircuitfortran

sistorsQ1 and

Q2.

Use

VDS to

calculate

ID for

each

circuit

and

record

it

in

the

tableonthelaboratoryrecordsheet.2 Drawadcloadlineandmarkthebiaspointextremesforeachcircuit.3 ComparethecircuitstabilityforeachbiascircuittothesimilarcircuitsinSection105inthetextbook.

4 Using themeasuredVP and IDSS valuesand the ID levelsforVGS = 1V,drawapproximatemaximumandminimumtransfercharacteristicsforQ1andQ2.

5 Drawbias lines for each circuit on the transfer characteristics, and determineVDS(max) andVDS(min).Comparethecalculatedandmeasuredquantities.




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RecordSheetL14-1

RecordSheetLab.# 14 JFETBias Circuits

Date

Procedure 1 Gate BiasIDSS(VGS = 0) IDS(VGS = 1 V) VGS(off)

Transistor Q1

Transistor Q2

Procedure2 SelfBias

VDD VD VS ID = VS/RS

Transistor Q1

Transistor Q2

18 V

18 V

Procedure3 Voltage-DividerBias

Transistor Q1

Transistor Q2

VDD

18 V

18 V

VD VS VG

Analysis

VDS(min)

VDS(max)

Gate bias Selfbias Voltage divider

bias




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LABORATORY

INVESTIGATION 11Basic JFET Circuits

Introduction

AJFETcommonsourcecircuitisconstructedandtestedfordcconditions.Theacvoltagegain,inputimpedance,andoutputimpedancearemeasured.Thecircuitisthenconvertedinto commondrain and commongate configurations,and the acperformanceof eachconfigurationisinvestigated.

Equipment

DCpowersupply(0to25V)DCvoltmeter(0to25V)OscilloscopeSinusoidalsignalgenerator;1V,3kHz0.25Wresistors(2 2.7k),120k,1M,5.6M25Vcapacitors(0.02 F,0.15 F,10 F)LowcurrentgeneralpurposenchannelJFET(e.g.,2N5486)

Circuitboard

Procedure1 Common-Source Voltage Gain

11 Construct thecircuit inFig.151. (This is thecircuit inFig.119 in the textbook.)Leavethesignalgeneratorandoscilloscopeunconnectedatthistime.

12 SwitchonthepowersupplyandadjustitsoutputforVDD 25V.

13 MeasureVG,VS,andVD.Recordthevoltagesonthelaboratoryrecordsheet.


15 Setthesignalgeneratorfrequencyto3kHzandadjustthesignalamplitudetogivea;1Voutputfromthecircuit.

16 Sketchtheinputandoutputwaveformsonthelaboratoryrecordsheet,andrecordthepeakinputandoutputvoltages.




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1

C

0195429885_069- 073_ch15. qxd 2/ 13/ 08 4: 28 PM Page 70

R15.6M RD2.7k

VDD

25V

C3

C1

0.02 F

vsR21M

Q1

RS2.7k

0.15 F

C210 F

RL120k

Tooscilloscope

R1

Tooscilloscope

RDC3

(a)Commonsourcetestcircuit

Signalgenerator

DC1 SQG

R2 RS

RLC2

Powersupply

Circuitboard


Figure 15-1 J FET common-sourcecircuit and test equipment.

Procedure2 Common-Source Input and Output Impedance


22 Temporarilydisconnect thesignalgeneratorandconnecta1M resistor (Ra) inserieswiththesignalgeneratorandthecircuitinput,asillustratedinFig.152.

R1

Ra C1

1MR1

1

Ra

Signalgenerator

vs R2 R2

(a)Circuitmodification (b)Connectiondiagram

Figure 15-2 Common-source circuit input resistance measurement.


24 Observe the amplitudeof the circuit ac outputvoltage.Change the resistance ofRaasnecessarytogiveanoutputamplitudewhichishalfofthatmeasuredinProcedure15.RecordtheresistanceofRaasthecircuitinputimpedance(Zi).




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1

0195429885_069- 073_ch15. qxd 2/ 13/ 08 4: 28 PM Page 71


26 Temporarilydisconnectthe loadresistor(RL)andsubstitutea2.7k resistor(Rb)

forRL.

27 Observetheamplitudeofthecircuitacoutputvoltage.ChangetheresistanceofRbasnecessarytogiveanoutputamplitudewhichishalfofthatmeasuredinProcedure16.RecordtheresistanceofRbasthecircuitoutputimpedance(Zo).

Procedure3 Common-Drain Circuit (Source Follower)

31 Modify the circuit to convert it into commondrain configuration as shown inFig.153. (RD isreplacedwithashortcircuit,and theoutput is takenat theJFETsourceterminal.)

R15.6M

C1

0.02 F

vs R21M RS

2.7k

VDD

25V

Q1

C3

0.15 F RL120k

Signalgenerator

Tooscilloscope

R1

C1

Tooscilloscope

C3

DS QG

R

VDD

(a)Common

drain

test

circuit

R2S

RL

Circuitboard


Figure 15-3 J FET common-draincircuit and test equipment.

32 SwitchonthepowersupplyandcheckthatitsoutputgivesVDD 25V.

33 RepeatProcedures15and16.

Procedure4 Common-Gate Circuit

41 ConvertthecommondraincircuitintoacommongatecircuitbymakingthemodificationsshowninFig.154.

42 SwitchonthepowersupplyandcheckthatitsoutputgivesVDD 25V.

43 RepeatProcedures15and16.




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R15.6M RD2.7k

Q1

VDD

25V

C2

C3

0.15 F

RL

Tooscilloscope

Tooscilloscope

C10.02 F

R21M RS2.7k 10 F vs 120k R1 RD

C2

C3

DS Q1

VDD

(a)CommongatetestcircuitSignalgenerator

G

R2 RSC1 RL

Circuitboard


Figure 15-4 J FET common-gate circuit and test equipment.

Analysis

1 FromtheresultsofProcedure13,plotthedcandacloadlinesfortheCScircuitandshowthemaximumoutputvoltageswing.

2 CalculatetheCScircuitvoltagegainfromtheresultsofProcedure16.3 Analyze theCScircuit todetermineAv,Zi,andZo.Compare thecalculatedandmeasured

values.

Comment

on

the

phase

relationship

between

the

input

and

output

waveforms.4 FromtheresultsofProcedure33,calculatetheCDvoltagegain.AnalyzethecircuittodetermineAvandcomparetothemeasuredAv.

5 FromtheresultsofProcedure43,calculatetheCGvoltagegain(Av).AnalyzethecircuittodetermineAv andcomparetothemeasuredAv.Commentonthephaserelationshipbetweentheinputandoutputwaveforms.




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RecordSheetL15-1

RecordSheet 1Lab.# 15 BasicJFETCircuits

Date

Procedure 1-3 VDD VG VS VD

Procedure 1-6Vi(pk) =

Vo(pk) =

Av =

Input

wavefor

m

Output

wavefor

m

Procedure2-4 Zi =

Procedure2-7 Zo =


Vo(pk) =

Av =

Input

wavefor

m

Output

wavefor

m


Vo(pk) =

Av

=

Input

wavefor

m

Output

wavefor

m




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LABORATORY

INVESTIGATION 12

Capacitor-Coupled BJT Amplifier

Introduction

ABJT capacitorcoupled commonemitter amplifier circuit consisting of two identicalstagesisconstructedandtestedfordcandacperformance.Eachstageisfirsttestedfordcconditionsandacvoltagegain(Av).Thecircuitoverallvoltagegain,frequencyresponse,andinputandoutputimpedancesarealsoinvestigated.

Equipment

DCpowersupply(0to25V)DCvoltmeter(0to25V)OscilloscopeSignalgenerator;1V,(50Hzto5kHz)0.25Wresistors120k ,2 (3.9k ,12k ,39k ,120k )25Vcapacitors0.12 F,2 (10 F,150 F)2lowcurrentgeneralpurposenpnBJTs(e.g.,2N3904)Circuitboard

Procedure1 DC Conditions

11 Constructthecircuit inFig.161.(This is thecircuit inFig.1218 inthe textbook.)Leavethesignalgeneratorandoscilloscopeunconnected.


13 MeasureVB, VE, andVC foreachstageand record thevoltageson the laboratoryrecordsheet.

Procedure2 AC Measurements

21Connect

the

signal

generator

and

oscilloscope

to

the

circuit

as

illustrated

in

Fig.

16

1.

22 Setthesignalgeneratorfrequencyto3kHzandadjustthesignalamplitudetogivea;1VoutputatthecollectorterminalofQ2.(Notethatitmaybenecessarytousearesistiveattenuator(typically560 and560k )toreducethesignalamplitude.)




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0195429885_074- 078_ch16. qxd 2/ 13/ 08 4: 44 PM Page 75

R1120k R312k R5C3 120k R712k

VCC

24V

C5

C1

10 Fvs

R2

2NQ1 3904

10 F

R6

2NQ2 3904

0.12 F

RL

rs 39k R43.9k 39k2 R83.9k 120kC4600 150 F 150 F

(a)Capacitorcoupledtwostageamplifier

Tooscilloscope

Tooscilloscope Powersupply

R7

R1 R3RL

R5C5

C3 C

SignalgeneratorC1

C2R2

CB Q1E

R6

B Q2E

C4

R4 R8


Figure 16-1 Two-stage capacitor-coupled BJ T amplifier.

23 Sketchtheinputandoutputwaveformsforeachstageonthelaboratoryrecordsheetandrecordthepeakvoltages.

24 Adjustthesignalfrequencyinstepsaslistedonthelaboratoryrecordsheet,takingcaretokeepthesignalamplitudeconstant.Recordtheoutputvoltageamplitudeateachsignalfrequency.


31Set

the

signal

generator

as

in

Procedure

22.

32 Temporarilydisconnectthesignalgeneratorandconnecta1.5k resistor(Ra)inserieswiththesignalgeneratorandthecircuitinput.





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34 Observetheamplitudeofthecircuitacoutputvoltage.ChangetheresistanceofRaasnecessarytogiveanoutputamplitudewhichishalfofthatmeasuredinProcedure22.RecordtheresistanceofRaasthecircuitinputimpedance(Zi).

35Disconnect

Ra,

reconnect

the

signal

generator,

and

adjust

the

signal

level

to

that

measuredinProcedure22onceagain.

36 Temporarilydisconnecttheloadresistor(RL)andsubstitutea12k resistor(Rb)forRL.


Analysis

1Compare

the

dc

voltages

for

each

stage

of

the

amplifier

to

the

design

levels

in

Example122inthetextbook.Explainanydifferences.2 FromtheresultsofProcedure23calculatethevoltagegainofeachstageandtheoverallvoltagegain.

3 Analyzethecircuittodeterminetheacvoltagegainforeachstageandtheoverallacvoltagegain.Comparethecalculatedandmeasuredquantities.

4 FromtheresultsofProcedure24,plotthe(lowerend)frequencyresponsefortheamplifier,andestimatethecircuitlowercutofffrequency(f1).Comparethemeasuredf1 tothedesignvalueusedinExample126.

5 DiscussthecircuitinputandoutputimpedancesasmeasuredforProcedure3.




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RecordSheetL16-1

RecordSheetLab.# 16 Capacitor-Coupled BJTAmplifier

Date

Procedure 1-3 VCC VB1 VE1 VC1 VB2 VE2 VC2


Vo1(pk) =

Vo2(pk) =

Av 1 =

Av2 =

Av =

Q1inputwavefor

m

Q1outputwavefor

m

Q2output

waveform

Procedure2-4

f(Hz) 30 50

Vo(V)

Av

70 100 150 200 300

f(Hz)

Vo(V)

Av

400 600 800 1 k 2 k 5 k 10 k

Procedures 3-4 and3-7

Zi =

Zo =




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LABORATORY

INVESTIGATION 13Direct-Coupled BJT Amplifier

Introduction

ABJTdirectcoupledtwostagecommonemitteramplifiercircuitisconstructedandtestedfordcandacperformance.Thedcconditionsthroughthecircuitarefirstchecked;thentheacvoltagegain (A

v) is investigated foreach stage.Thecircuitoverallvoltagegainand

frequencyresponsearealsoinvestigated.

Equipment

DCpowersupply(0to25V)DCvoltmeter(0to25V)OscilloscopeSignalgenerator0.25Wresistors68k ,47k ,39k ,5.6k ,4.7k ,(2 3.9k )25Vcapacitors(2 150 F),15 F,0.47 FLowcurrentgeneralpurposenpnandpnpBJTs(2N3904and2N3906)

Circuitboard

Procedure1 DC Conditions

11 ConstructthecircuitinFig.171.(This isthecircuitinFig.1222inthetextbook.)Leavethesignalgeneratorandoscilloscopeunconnectedatthistime.


13 MeasureVB,VE,andVC foreachstageandrecordthevoltagelevelsonthelaboratoryrecordsheet.

Procedure2 AC Measurements


22 Setthesignalgeneratorfrequencyto3kHzandadjustthesignalamplitudetogivea;1VoutputatthecollectorterminalofQ2.




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1

v

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0195429885_079- 083_ch17. qxd 2/ 13/ 08 4: 45 PM Page 80

R3R5

VCC

14VC3

R168k

5.6k 3.9kQ2

150 F

2N

C1

Q 2N3904

3906C4

15 Fs

R2

0.47 F

RL

rs600

47k R44.7k C2150 F R63.9k 39k

(a)Directcoupledtwostageamplifier

To

oscilloscope

(vi) (vo1)

Powersupply

R1 R3 R53

SignalgeneratorC1

CB Q1E

EB Q2C

C4Tooscilloscope

C2

R6R2

R4

RL(vo2)


Figure 17-1 Two-stage direct-coupled BJ T amplifier.

23 Sketch the input and outputwaveforms for each stage on the laboratory recordsheet,andrecordthepeakvoltagelevels.

24 Adjustthesignalfrequencyinstepsaslistedonthelaboratoryrecordsheet,takingcaretokeepthesignalamplitudeconstant.Recordtheoutputvoltageamplitudeateachsignalfrequency.



32 Temporarilydisconnectthesignalgeneratorandconnecta1k resistor(Ra)inserieswiththesignalgeneratorandthecircuitinput.




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34 Observe the amplitude of the circuit ac outputvoltage.Change the resistance of

Raasnecessary

to

give

an

output

amplitude

which

is

half

of

that

measured

in

Proce

dure22.RecordtheresistanceofRaasthecircuitinputimpedance(Zi).


36 Temporarilydisconnectthe loadresistor(RL)andsubstitutea3.9k resistor(Rb)forRL.


Analysis

1 FromtheresultsofProcedure13,calculatethecurrentlevelsthroughoutthecircuit.2 Analyzethecircuittodeterminethedcconditions,andcomparetothemeasureddcvoltageandcurrentlevels.

3 FromtheresultsofProcedure23calculatethevoltagegainofeachstageandtheoverallvoltagegain.

4 Analyzethecircuittodeterminetheacvoltagegainforeachstageandtheoverallacvoltagegain.Comparethecalculatedandmeasuredquantities.

5 FromtheresultsofProcedure24,plotthe(lowerend)frequencyresponsefortheamplifierandestimatethecircuitlowercutofffrequency.

6Analyze

the

circuit

to

determine

the

lower

cutoff

frequency

for

stage

1and

the

circuit

lowercutofffrequency.Comparethecalculatedandmeasuredcutofffrequencies.7 DiscussthecircuitinputandoutputimpedancesasmeasuredforProcedure3.




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RecordSheetL17-1

RecordSheetLab.#17 Direct-Coupled BJTAmplifier

Date

Procedure 1-3 VCC VB1 VE1 VC1 VB2 VE2 VC2


Vo1(pk) =

Vo2(pk) =

Av 1 =Av2 =

Av =

Q1input

wavefor

m

Q1output

waveform

Q2 output

waveform

Procedure2-4

f(Hz) 30 50

Vo(V)

Av

70 100 150 200 300

f(Hz)

Vo(V)

Av

400 600 800 1 k 2 k 5 k 10 k

Procedures 3-4 and3-7

Zi =

Zo =




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LABORATORY

INVESTIGATION 14

SCRCharacteristics

and 90 Phase Control

Introduction

ThecharacteristicsofanSCRarefirstdeterminedbyapplyingaconstantanodevoltage(VA)and increasing thegatecathodevoltage (VGK)until theSCRswitcheson.Thegatecurrentandvoltagearenotedattheswitchoninstant,andVAK ismeasuredafterswitchon.TheprocessisrepeatedwithdifferentlevelsofVA.AnSCR90phasecontrolcircuitisnext

constructed

and

tested

by

monitoring

the

ac

supply

and

load

waveforms

for

various

control

elementsettings.

Equipment

Twodcpowersupplies;(0to20V)Twodcvoltmeters(0to20V)DCammeter(0to100mA)DCammeter(0to20 A)Oscilloscope115V,60Hzvariablevoltagetransformer(variac)115V,60Hz,1:1isolatingtransformer

0.25W

resistors120

,270

,(2

1k),1.5k,2.2k0.5Wpotentiometer1.5k

3Wresistor100LowcurrentSCR2N5064Lowcurrentdiode1N914Circuitboard

Procedure1 SCRForwardCharacteristics

11 Construct the SCR circuit in Fig. 391a according to the connection diagram inFig.391b.

12Set

both

power

supply

voltages

to

zero;

then

switch

on

and

adjust

VA to

5V.

At

this

timeVGK,IG,andIA shouldallbezero.




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R

G

0195429885_188- 192_ch39. qxd 2/ 13/ 08 5: 24 PM Page 189

A

R4 IA1k

R1 R3

1.5k 1kV R2

SCR1

A

IG

VA

V VAK

G270 V

VGK

(a)Circuit

Voltmeter(VGK)

V

Ammeter(IG) KGA

Bottomview2N5064

Voltmeter(VAK) Ammeter(IA)

VA COM

AV

A COM V

Powersupply(VG)R4 V

A COM

AV

A COM

A

R3 K1 SCR1

R2


Powersupply(VA)

Figure 39-1 Circuit for investigating SCR characteristics.

13 SlowlyincreaseVGuntiltheSCRfires(IAsuddenlyincreases).RecordthelevelsofIGandVGK at(orjustbefore)theinstantIA increases.(Itmaybenecessarytorepeattheprocessseveraltimestogetaccuratemeasurements.Todoso,VG shouldbereducedtozero,andVAshouldbeswitchedoffandthenonagain.)

14 RecordVAK

andI

AwhentheSCRison.

15 ReduceVG tozero; thenswitchVA offandon,andagainnote the levelsofVAKandIA.

16 AdjustVA to10V.

17 Slowly increaseVG untiltheSCR firesagain.Record IG andVGK asexplained inProcedure13.RecordVAK andIAwiththeSCRon.




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18 ReduceVG tozero,andthenswitchVA offandonagain.

19 AdjustVA togiveVAK equalto15V.

110 SlowlyincreaseVG untiltheSCRfiresagain.RecordtheIG andVGK onceagainasexplained

in

Procedure

13.

Record

VAK andIAwiththeSCRononceagain.

111 ReduceVG tozeroandreconnecttheVGK voltmetertomeasureVA.ThenprogressivelyadjustVA to4V,3V,and2V,recordingVAK andIAateachstep.

112 DisconnectthevoltmetermeasuringVAK;then,observingIA,slowlyreduceVA from3Vtozero.NotethelowestlevelofIA thattheSCRconductsat(theholdingcurrent)beforeitswitchesoff.

Procedure2 SCR 90 Phase ControlCircuit

21 ConstructthephasecontrolcircuitshowninFig.392,keepingtheacsupplyoffand

the

variac

set

for

zero

output.

(This

is

the

circuit

designed

in

Example

20

2

in

the

textbook.)

115V60Hz


R12.2k

R21.5k

SCR1

D1

R3120

RL100

(a)Circuit

Variac

Isolatingtransformer

R1

R2 D1

R3

SCR1AGK

RL

Vi

Tooscilloscope

VL


Figure 39-2 SCR 90 control circuit.




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22 AdjustpotentiometerR2 forminimumgatecathodevoltage(VGK).

23 SwitchontheacsupplyandadjustthevariactogiveVi 30Vpeakasmonitoredontheoscilloscope.

24Investigate

the

waveform

(VL)developedacrossRL forvarioussettingsofR2.Note

therelationshipbetweenVi andVL,andsketcheachwaveformontherecordsheet.

Analysis

1 PlottheSCRcharacteristicsfromtheresultsofProcedures13through110.2 DiscusstherelationshipbetweentheSCRanodecathodevoltageandthegatecurrentrequiredtofiretheSCR.

3 ExplaintheresultsofProcedures111and112.4 Notethemeasuredforwardonvoltage(VTM),thegatetriggeringcurrent(IG),andtheholdingcurrent(IH),andcomparethemtothespecifiedquantitiesfortheSCRused.

5 Discusstheloadwaveformproducedbythe90controlcircuitandtheeffectofadjustingR2.ComparetherangeofwaveformadjustmentwiththatspecifiedforExample202inthetextbook.




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RecordSheetL39-1

RecordSheet DateLab.# 39 SCR Characteristicsand 90 Phase Control

Procedure 1-3 and 1-4(VA = 5 V) IG VGK VAK IA

Procedure 1-5VAK IA

Procedure 1-7

(VA = 10 V) IG VGK VAK IA

Procedure 1-10

(VA = 15 V) IG VGK VAK IA

Procedure 1-11

Procedure 1-12

VA VAK

(V) IA

(mA)

IH =

4 V 3 V 2 V

Procedure2-4

R2(min) R2(max)

Vi

VL




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LABORATORY

INVESTIGATION 15SCRand TRIAC Control Circuits

Introduction

AnSCR180phasecontrolcircuitisconstructed,anditsoutput(load)waveformiscomparedtotheacsourcewaveform.Thecontrolelementisadjustedtodeterminethemaximumandminimumanglesoftheoutputwave.Thewaveformdevelopedacrossthecapacitorinthecontrolcircuitisalsoinvestigated.ATRIAC180phasecontrolcircuitisconstructedandtestedinasimilarwaytotheSCRcircuit.

Equipment

Oscilloscope115V,60Hzvariablevolta

electronic circuits and electronic devices

Documents