EE233 Lab Introduction to Basic Instruments (1)

EE233CircuitTheory BasicLaboratoryInstruments

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IntroductiontoBasicLaboratoryInstruments

Contents:1.Objectives...................................................................................................................22.LaboratorySafety.......................................................................................................23.BasicLaboratoryInstruments....................................................................................24.UsingaDCPowerSupply...........................................................................................25.UsingaFunctionGenerator.......................................................................................3

5.1TurnontheInstrument.....................................................................................35.2SettingSignalType............................................................................................45.3SettingSignalFrequency...................................................................................45.4SettingSignalAmplitude...................................................................................45.5SettingaDCOffset............................................................................................45.6SettingaDutyCycle..........................................................................................5

6.UsingaMultimeter....................................................................................................56.1TurnontheInstrument.....................................................................................56.2MeasuringaDCVoltage....................................................................................56.3MeasuringanACVoltage(ACcoupledRMSValue)..........................................56.4MeasuringResistance.......................................................................................66.5MeasuringDCCurrent......................................................................................66.6MeasuringACCurrent(RMSValue)..................................................................6

7.UsinganOscilloscope.................................................................................................67.1TurnontheInstrument.....................................................................................77.2DisplayingaWaveformonCH1........................................................................77.3SettingtheHorizontalTimeDivisionforBothChannels...................................77.4SettingintheTRIGGERMENU..........................................................................77.5MeasuringSignalParametersusingtheScope.................................................8

7.5.1Measuringtimeintervalbetweentwopoints........................................87.5.2Measuringvoltagedifferencebetweentwopoints................................87.5.3Automaticmeasurements.......................................................................87.5.4Savingwaveforms...................................................................................9

8.FurtherResearch........................................................................................................9


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1.Objectives1.Tolearnsafetyproceduresinthelaboratory.2. To learn how to use basic laboratory instruments: power supply, functiongenerator,multimeter,andoscilloscope.

2.LaboratorySafetyTheTAwillgooversafetyprocedures in the laboratory.Electricalvoltagesused intheexperimentsareusuallylow(e.g.5Vupto15V)butACvoltagesusedtooperatetheinstrumentsthemselvesaredangerous.Donotcutorinterferewithpowercordsfor these equipment, and do not plug your circuits into the 115V outlets. Otherutilityequipmentsuchaspliers,wirecutters,etc.issharpandcancutdeeply.Whenawire isbeingstrippedof insulators,takeextremeprecautionthatstrippedplasticsectionsorwiresegmentsarenotdirectedateyes,peoplesfaces,etc.Whenever you arenot sure aboutusingequipment (electricalormechanical),asktheTAorthetechnicianinthelab.

3.BasicLaboratoryInstrumentsThe basic instruments used in EE 233 are: DC power supply, function generator,multimeterandoscilloscope.Thisdocumentdescribestheprocedurestousetheseinstruments available in the UW laboratory and serves as reference in futurelaboratoryexperiments. Ifthiscourse istaughtatanother institutionwithdifferentinstruments than those described below, the instructor needs to provide adocumenttodescribetheprocedurestousetheavailableinstruments.TheinstrumentsavailableatUWare:a.DCpowersupply:HPE3630AtripleoutputDCpowersupply.b. Function generator: Tektronix AFG 3021 25MHz/ 250Ms/s Function / ArbitraryWaveformGenerator.c.Multimeter:HP34401A.d.Oscilloscope:TektronixTDS2004B.

4.UsingaDCPowerSupplyTheDCpowersupplyonmostlabbenchesistheHPE3630AtripleoutputDCpowersupply. This instrument canprovide variousDC power supply voltages up to +6V,+20V,and20V.ProceduretosetaspecificDCpowersupplyvalue:1.Turnontheinstrument(ON/OFFswitchatlowerleftoffrontpanel).


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2. Connecting GROUND: the Ground connection of the instrument is usuallyconnectedtotheCOMconnectionandisusedasthegroundforalltheinstrumentsandcircuitsundertest.ConnectthisGroundtoyourcircuitGround.3.ConnectingDCpowersupplyandsettingvalue: a) Ifthepowersupplyis+6Vorless,pushthe+6VbuttonintheMETERsection

ofthepanelandconnectthecircuittothe+6Voutput.Usethe+6Vknob intheVOLTAGEADJUSTsectiontosetthepowersupplyvalue,startingfrom0Vandadjustingupward.

b) If thepowersupply isbetween+6Vand+20V,push the+20Vbutton in theMETERsectionofthepanelandconnectthecircuittothe+20Voutput.Usethe +/20V knob in the VOLTAGE ADJUST section to set the power supplyvalue,startingfrom0Vandadjustingupward.

c) Ifdualbalancedpower supplies (e.g.+15Vand15V)areneeded,push the+20VbuttonintheMETERsectionofthepanelandconnectthecircuittothe+20Vand20Voutputs.Usethe+/20VknobintheVOLTAGEADJUSTsectiontoset thepower supplyvalue.Tomake sure that thepositiveandnegativesuppliesarebalanced, turn theTracking ratioknob in theVOLTAGEADJUSTsectiontothefixedsetting.

IfaDCinputsignalisneededandtheDCpowersupplystillhasunusedoutputs,thesimplestway istouseoneoutputoftheDCpowersupplytoprovideaDCsignaltothecircuitundertest.

5.UsingaFunctionGeneratorThe FunctionGenerator onmost lab benches is the Tektronix AFG 3021 25MHz/250Ms/sFunction/ArbitraryWaveformGenerator.Thisinstrumentcanprovideonesignaloutputtothecircuitundertest(OUTPUTconnectoratthe lowerrightcornerof the front panel) and a synchronizing output to the oscilloscope (SYNC outputimmediatelyabovetheOUTPUTconnector).Onmostlabbenches,theSYNCoutputisalreadyconnectedtotheoscilloscopeEXTTRIG(EXTernalTRIGgerinput).Thebasicsignaloutputmaybeasinewave,asquarewave,andarampsignal.ThegeneratorisalsocapableofprovidingvariousmodulatedsignalsbutwewillnotusethemintheEE233experiments.Thespecificexamplebelowshowsyouhowtosetthefunctiongeneratortooutputasinewavewithfrequency8.9KHz,amplitude1.5V(orpeaktopeakvalueof3.0V),andoffset+100mV.

5.1TurnontheInstrumentPush POWER button (lower left of panel) to ON. At poweron, the instrumentautomaticallysetsthesignaltypetosinewave,frequencyto1KHz,amplitudeto100mVpeaktopeak(usuallyabbreviatedaspp),andoffsetto0V.


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5.2SettingSignalTypeTo set the waveform type (sine, square, symmetric ramp, sawtooth), push theappropriatebuttononthefrontpanel(FUNCTION/MODULATIONsubpanel).Forthisspecificexercise,pushthesinewavebutton.

5.3SettingSignalFrequency1.PushtheFrequency/PeriodbuttonintheFUNCTION/RUNMODEsubpanel.2.Therearetwowaystosetthesignalfrequency,whichisasfollows:(a)Thereisageneralknobontherightsideofthepanel.Usetheknobtochangethefrequency. (b) To set the frequency to the specified one, use the decimal knob on the rightcornerofthepanel.3.When setting the frequency, select the unit youwant to use in the screen byenteringtheappropriateknob.4.Tocorrectanexistingdigitinthefrequencysetting,pushtheBKSPbuttonuntilthedesireddigitflashes.

5.4SettingSignalAmplitudeThe instrumenthas internal50output impedance.Thepoweronvalue is100mVpp(into50Wterminationor load). Ifthegenerator isconnectedtoacircuitwithdifferent input impedance, the amplitude value is different due to the inputimpedanceofthecircuitundertest.Thebestwaytofindouttheamplitudevalueistousetheoscilloscopetomeasureit.1.PushtheAmplitudebutton.2.Therearealsotwowaystosettheamplitude,seemoredetailsinthestep2of5.33.When setting the amplitude, select the unit youwant to use in the screen byenteringtheappropriateknob.5.Notethattheinstrumentislimitedto100mVppminimumand20Vppmaximum.For50ohmload,thelimitsareexactlyhalf.

5.5SettingaDCOffsetMostACsignalsarereferredtoground(themidlevelvalueis0V).SometimesanACsignalneedstobeoffsetbyaDCvalue,whichcanbepositiveornegative.Tosettheoffsetof+100mV,followthisprocedure:1.PushtheOffsetbutton.2.Pushthebuttontosetthepolarity.


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3.Use themethod above (seedetails in the step2of5.3) to set the appropriatevalueofDCoffset.4.NotethatthedisplaypanelshowsOffsetinthelowerrightcorner.ThisdisplayisONwhenevertheoutputwaveformhasanonzerooffset.

5.6SettingaDutyCycleA squarewaveusuallyhas50%duty cycle: the time interval forHIGHvalue is thesameasthetime interval forLOWvalue.For thisspecificexercise,refertosection5.2andsetthewaveformtopulsewavefirst.Toadjustthedutycycleofthissquarewave,usethisprocedure:1.Push theDuty/Widthbutton then the%Dutybutton (markedabove theOffsetbutton).2.UsetheDecimalNumberknoborGeneralknobtoadjustdutycycleimmediately.Otherwise,after10secondsofthepreviousstep,the instrumentreturnstonormalmode.

6.UsingaMultimeterThemultimeteronmost labbenches is theHP34401A.This instrument isused tomeasurevoltages,currents,andresistances.6.1TurnontheInstrumentPushPowerbutton(leftsideofpanel)toturninstrumentON.

6.2MeasuringaDCVoltage1. Push the DC V button. The ranges are 100 mV to 1000 V, with maximumresolutionof100nV inthe100mVrange.Theinstrumentautomaticallyselectstherange.2.Connectthetwo InputV (HIandLO)terminalsontheupperrightcornerofthepaneltothetwopointswhosevoltagedifferenceistobemeasured.ApositivevaluemeansthenodeconnectedtotheHIinputispositivewithrespecttotheothernode.

6.3MeasuringanACVoltage(ACcoupledRMSValue)1.PushtheACVbutton.2.Connectthetwo InputV (HIandLO)terminalsontheupperrightcornerofthepaneltothetwopointswhosevoltagedifferenceistobemeasured.


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6.4MeasuringResistance1.Pushthe2Wbutton(2wiredmeasurement).Therangesare100Wto100MW.Theinstrumentautomaticallyselectstherange.2.Connectthetwo InputV (HIandLO)terminalson theupperrightcornerofthepaneltothetwopointswhoseresistanceistobemeasured.Note:4wired(4Wbutton)resistancemeasurementisusedonlyinhighprecisionmeasurementsandwillnotbecoveredinthisintroductorylaboratory.

6.5MeasuringDCCurrent1.Push theShiftbutton then theDCVbutton forDCcurrentmeasurementmode(blueDCImarkingabovetheDCVbutton).Therangesare10mAto3A.2.ConnecttheLOand I inputterminals (onthe lowerrightcornerofthepanel)tothe twopointsofacircuitbranchwhosecurrent is tobemeasured.Note that theinstrumentmustbeconnectedinserieswiththebranch.ApositivevaluemeansthebranchcurrentflowsfromtheIinputtotheLOinputthroughthebranch.

6.6MeasuringACCurrent(RMSValue)1.Push theShiftbutton then theACVbutton forDCcurrentmeasurementmode(blueACImarkingabovetheACVbutton).Therangesare1Ato3A.2.ConnecttheLOand I inputterminals (onthe lowerrightcornerofthepanel)tothe twopointsofacircuitbranchwhosecurrent is tobemeasured.Note that theinstrumentmustbeconnectedinserieswiththebranch.

7.UsinganOscilloscopeThe oscilloscope (or scope) available for EE 233 is the Tektronix TDS 2004B. Thescopeisthemostversatilemeasuringinstrumentinthelaboratory.Eachscopecandisplay foursignalssimultaneouslyonChannel1 (CH1),Channel2(CH2),Channel3 (CH3)andChannel4 (CH4). Inthedescriptionbelow,wewillusethisterminology:1.SIDEMENUbuttonsrefertothecolumnofbuttonsontherighthandsideofthedisplay.2.MAINMENUbuttonsrefertotherowofbuttonsbelowthedisplay.3.TheknobwithoutanymarkingatthehighestverticalpositiononthefrontpanelistheGeneralPurposeknob.


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7.1TurnontheInstrumentPushON/STBYbutton (at the lower left cornerof the frontpanel) to turnon thescope.Ittakesashorttimeforthedisplaytocomeon.

7.2DisplayingaWaveformonCH11.ConnecttheChannel1scopeprobetothesignaltobedisplayedandthegroundoftheprobe(attachedtothesideoftheprobe)tothegroundofthecircuit.2.PushthebuttonCH1ontheleftsideofthesubpanel.3.Push theCH1MENUbutton.Use theSIDEMENUbuttons toselectDCcoupling(direct connection of the signal to the scope) or AC coupling (connection of thesignaltothescope,ignoringanyDCoffsetinthesignal).4.Use thePOSITION knob (above theVERTICALmenubutton) toplace the signaltraceattheverticalpositionyouwantonthedisplay. 5.UsetheVOLT/DIVknobtosetthescale(voltperdivision)forchannel1.Thevaluesetisshownonthedisplay.The sameprocedure isbeused todisplayawaveformonChannel2 (connect thesignaltoChannel2probeinstep1andpushtheCH2buttoninstep2).

7.3SettingtheHorizontalTimeDivisionforBothChannels1.UsetheSEC/DIVknob in theHORIZONTALsubpanel.Thevalueset isshownonthedisplay (last line,M1ms indicating1msperhorizontaldivision).Note that thetimeaxisiscommontobothchannels.2.Tomoveasignalalongahorizontaldirection:a)PushCH1button(orCH2buttonasappropriate)intheVERTICALsubpanel.b)Use thePOSITIONknob in theHORIZONTAL subpanel tomove this signal.Thismoveaffectsonlyonechannel,notboth.

7.4SettingintheTRIGGERMENUThe scope ispreset to trigger from theEXTTRIG signalprovidedby theFunctionGenerator. If theFunctionGenerator isnotused,push theTRIGGERMENUbuttonand use the SIDEMENU buttons to set triggering on Ch1 or Ch2 to get a stabledisplayofthewaveforms.Thekey istogetastabledisplayofthesignals.TheSIDEMENU button Ext corresponds to using external trigger: in this case, an externalsignalmustbeconnectedtotheEXTTRIGinput(thelowerrightcornerofthefrontpanel)ofthescope.Triggering is a difficult concept to explain. See the document in the section onFurtherResearchbelow.Thisconceptwillberevisitedinlaterlaboratories.


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7.5MeasuringSignalParametersusingtheScopeMostofthebuttonsandknobmentionedbelowareneartheupperrightcornerofthe front panel of the scope (except of course the SIDEMENU andMAINMENUbuttons,whicharealongtherightsideandbelowthescopedisplayitself).7.5.1Measuringtimeintervalbetweentwopoints1.PushtheMEASUREbutton.2.PushtheCURSORbutton.3.UsetheGeneralPurposeknobtopositionthesolidverticalmarkeratpoint1.4.UsetheGeneralPurposeknobtopositionthesecondverticalmarker(solid line)atpoint2.Thetimeintervalbetweenthese2pointsisthe valueappearingonthetoprightcornerofthescopetracedisplay. 7.5.2Measuringvoltagedifferencebetweentwopoints1.PushtheMEASUREbutton.2.PushtheCURSORbutton.3.UsetheGeneralPurposeknobtopositionthesolidhorizontalmarkeratpoint1.4.UsetheGeneralPurposeknobtopositionthesecondhorizontalmarker(solidline)atpoint2.Thevoltagedifferencebetweenthese2pointsisthe valueappearingonthetoprightcornerofthescopetracedisplay. 7.5.3Automaticmeasurements1. Push the CH 1 or CH 2 button in the VERTICAL subpanel to performmeasurementsonaspecificsignal.2.PushtheMEASUREbutton.3.UsetheSIDEMENUbuttonsasfollows:

a) PushPeriodtomeasureperiod.ThedisplayshowstheperiodimmediatelytotheleftoftheSIDEMENU.

b) PushFrequencytomeasurefrequency. c) Push Rise Time to measure rise time (10% to 90% points of the signal

waveform). d) Push Fall Time to measure fall time (90% to 10% points of the signal

waveform).


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e) PushMeanforthemeanvalueofthesignalwaveformTherearesomeotherbuttonscalledpkpk,cycRMS,Min,Max,which issimilartothebuttonaboveandwillnotbetalkedaboutanymore.7.5.4Savingwaveforms TheproceduretosavewaveformsviaUSBforfurtherdataanalysisispostedateachlabbench.

8.FurtherResearch1.ThereisanexcellentguidetousinganaloganddigitaloscilloscopesonthewebatURL:htttp://www.tek.com/Measurement/App_Notes/XYZs/.Theguidecoversmuchmorethanthespecificscopewehave inthe laboratory. Ifyouwanttounderstandmoreaboutscopes,spendsometimestudyingthisguide.2.Playaroundwiththecapabilitiesofthe instruments,especiallythescope.Tryasmanyoptionsaspossibleandlearnmoreaboutusingtheseinstruments.3.Equipmentmanufacturers suchHewlettPackard,Tektronix, Flukemaintain verygoodwebsitesforUsersGuideoftheirinstruments.Checkouttheirsitesespeciallyifyouuseinstrumentsdifferentthanthoseavailableinthelaboratory.

EE233 Lab Introduction to Basic Instruments (1)

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