Tkool Electronics

IIntroductionTheLM311devicesaresinglehigh-speedvoltagecomparators.Thedevicesaredesignedtooperatefromawiderangeofpowersupplyvoltages,including15-Vsuppliesforoperationalamplifiersand5-Vsuppliesforlogicsystems.TheoutputlevelsarecompatiblewithmostTTLandMOScircuits.Thesecomparatorsarecapableofdrivinglampsorrelaysandswitchingvoltagesupto50Vat50mA.Allinputsandoutputscanbeisolatedfromsystemground.Theoutputscandriveloadsreferencedtoground,VCC+orVCC.Offsetbalancingandstrobecapabilitiesareavailable,andtheoutputscanbewire-ORconnected.Ifthestrobeislow,theoutputisintheoffstate,regardlessofthedifferentialinput.CatalogIIntroductionIIPrecautionsofLM3112.1ChooseComponentsReasonably2.2IncreaseAmplitudeofInputSignal2.3AddFilteringAppliancestoOutputofComparator2.4AdoptLaggingTechnologyFAQOrdering&QuantityIIPrecautionsofLM311LM311isacommonlyusedlinearcomparator,whichiswidelyusedincomparisonandshapingcircuits,andasisshowninFigure1.Figure1.LM311CircuitDiagramHowever,LM311oftenhasunexpectedproblemsintheapplication,thatis,theoutputpulsesignalisnotasidealastheoreticalanalysis.Instead,high-frequencyoscillationoccursnearthefrontandbackedgesoftheoutputpulse,asshowninFigures2and3.Figure2.HighFrequencyOscillationbeforeOutputPulseFigure3.HighFrequencyOscillationafterOutputPulseWhentheinputsignalViamplitudeoftheLM311issmallerandthefrequencyislower,thehigh-frequencyoscillationismoreserious.Thiskindofwaveformcontaininghigh-frequencyoscillationcannotbeuseddirectly.Itwillcausemisoperationtosubsequentcircuits,suchasfrequencymeasurement.Therefore,thissituationmustbepaidattentionto,andtrytoavoidoreliminatehigh-frequencyoscillation.Thefollowingwillgiveabriefanalysisofthecausesofoscillations,andatthesametimeputforwardseveralmethodstoeffectivelyavoideliminatingoscillationsonthebasisofexperiments.Figure4.LM311Whenahigh-speedcomparatorisusedforhigh-speedinputsignalsandlowsourceimpedanceinputsignals,thenormaloutputresponseshouldbefastandstable.However,whentheinputsignalisaslowlyvaryingsignalorahigh-impedancesignalsource(1.0K-10K),thecomparatormayoscillatesuddenlyatthecomparisonthresholdpoint,whichiscausedbythehighgainandwidebandofthecomparator,andthepresenceofinterferenceisalsooneofthedirectcausesofthisoscillation.Inapplication,toavoidthiskindofoscillationandinstability,carefulconsiderationshouldbemadeinadvanceandoverallarrangementsshouldbemade.Thefollowingwillproposeseveraleffectivemethodstoavoidandovercomeoscillations:2.1ChooseComponentsReasonablyReasonablyarrangingtheoccurrenceofstructuraloscillationshasalottodowithstructuralarrangements.Theoutputsignalshouldbefarawayfromtheinputterminalpin,andshouldalsobefarawayfromthetwobalancedterminalpins,becausethefeedbacksignalsensingortouchinganypinmayalmostcauseoscillation.Ifthecomparatorusesaresistorattheinput,itspositionandresistanceareworthconsidering.Theresistanceshouldbeplacednearthetubebase,andthegeneralresistancevalueshouldbelessthan10K(orevenless),pleaserefertothecorrespondingmanualwhenusing.Positiveandnegativepowersupplyshouldadd0.1filtercapacitortofilterouttheinterferenceofthepowersupply,andputthecapacitornearthepin.Thetwobalancedendsshouldbeproperlyhandled.Whennotinuse,theycanbeshortedtogether.Forspecificuse,youcanalsorefertotherelevantmanual.2.2IncreaseAmplitudeofInputSignalThemagnitudeoftheinputsignalamplitudeisdirectlyrelatedtotheoscillation.Experimentsshowthatthesmallerthesignalamplitude,thelowerthefrequency,thegreaterthepossibilityofoscillation.Thefollowingwillmakeasimpleanalysisoftheaboveconclusions.Ifthereisazero-crossingcomparator,theinputsignalisVi=V0sin0t.Theslopeofthesignalatt=0is:Theamountofvoltagechangein△ttimeis:△Vi=K△t=V0sin0t,whichshowsthat△ViisproportionaltoV0,0,thatis,thegreatertheamplitudeoftheinputsignal,thehigherthefrequencyofthesignal.Theninthe△ttime,thelongertheamplitudechangeofVis,whendvi/dtislargeenough,theinputsignalwillquicklycrossthecomparisonthreshold,soastoachievethepurposeofeliminatingoscillation.Becausetheinputvoltagerangeofthecomparatorisgenerallyrelativelywide(forexample:thevoltageinputrangeoftheLM311is30V),thismethodisthemostsimpleandfeasible.Theexperimentprovesthataslongastheamplitudeoftheinputsignalisgreaterthan0.7V,thisdesigncanworkreliablyintherangeof10Hz~60KHz,continuetoincreasethevoltageamplitude,theworkingrangecanbeextendedtothelowfrequencyend.2.3AddFilteringAppliancestoOutputofComparatorPullingaresistorattheoutputofthecomparatorandconnectingacapacitorwithanappropriatecapacityhasasignificanteffectonfilteringandreducingoscillation.Thecapacityofthecapacitorshouldbedeterminedonthebasisoftheexperiment.Thecapacityofthecapacitorshouldnotbetoolarge,otherwisetheleadingedgeoftheoutputpulsewillbedeteriorated.Itwasfoundintheexperimentthatthisnegativeeffectisparticularlyseriousathigherfrequencies,andevenmakethepulseamplitudesmaller,sothatthecounterofthesubsequentstagecannotwork,thesituationisshowninFigure5.Figure5.PulseAmplitudeatHigherFrequenciesTherefore,thismethodhascertainlimitationsintheapplication,andthereasonablechoiceofcapacitanceisthekeytoapplyingthismethod.Ofcourse,thedeterioratedfrontcanberestoredbythe74LS14withashapingeffect.Thenegativeeffectofthismethodistoshifttheoriginalpulsefrontbackward.Inthisdesign,capacitanceC=0.01istaken.Withintherangerequiredbythesystem,thevalueofthepull-upresistorthatthecircuitcanworkreliablycannotbetoolarge.Inthisdesign,R=510.2.4AdoptLaggingTechnologyInthecomparisoncircuit,whentheinputsignalreachesthecomparisonlevel,thecomparatorshouldbereversedimmediately,butifthemeasuredsignalissuperimposedwithacertainamountofinterference,thecomparatormayoscillatenearthecomparisonlevel,asshowninthefollowingfigure(Figure6-7).Figure6.OutputofaCommonZero-crossingComparatorFigure7.OutputwithLagTechnologyTheeffectivemethodtoovercometheoscillationofthecomparatoristousethelagtechnology,thatis,addasmallamountofpositivefeedbacktoitsnon-invertingend.Thecomparisonlevelofthelagcomparatorisnolongerasinglelevel,buthastwopowerlevelsneartheoriginalcomparisonlevel.Ingeneral,forthecircuitinfigure8,theuppercomparisonlevelisrepresentedbyV+H,andthelowercomparisonlevelisrepresentedbyV+L.Figure8.CircuitwithTwoLevelsThehysteresisvoltagecanbeadjustedbyR1andR2.Aslongas△Visselectedproperly,theoscillationphenomenonofthecomparisoncircuitcanbeeliminated.Therefore,theanti-interferenceabilityisgreatlyimproved,butthepresenceofthelaglevel△Vwillmakethedetectionsensitivityworse.Therefore,△Vshouldnotbetoolarge,usuallyR1R2.FortheLM311comparator,adding3mvofhysteresiswilleliminatetheoscillationinthecircuit.Therefore,wemustconsidercarefullyandtreatseparatelywhenusingLM311.Onlyinthiswaycanwebehandywhenusingit.FAQHowtouseLM311?LM311isasingle-channelcomparator.Whenusingit,connectthereferencevoltageandthecomparedsignalvoltagetoitsnon-invertingandinvertinginputterminals(pin2andpin3),anditsoutputistheresultofthecomparison.Ifyouwantthefowardoutputresult,pin7isconnectedtothepositivepowersupplyandpin1istheoutput.Iftheresultistobeoutputinreverse,pin1isgroundedandpin7istheopencollectoroutput.lm311andlm393arebothvoltagecomparators,sowhatisthedifferencebetweenthem?LM311issinglevoltagecomparaotor,LM393isdualvoltagecopatpr.LM311hasaloadcurrentofupto50MAandavoltageof40V.Itcandriverelayswithaminimumpowersupplyvoltageof5V.TheLM393loadcurrentis16MA,andtheminimumvoltageis2Vforasinglepowersupply.WhatsthedifferencebetweenLM311andLM111?Theirfunctionsarethesame,andthe1XXseriescanbeusedinharsherenvironments.The3XXseriescanonlybeusedinacommercialenvironment,typicallytheapplicabletemperaturerangeofthedevice.Thepriceof1xxismuchmoreexpensivethan3xx.Whatdoesthe5and6-pinbalancestrobesofLM311mean?Thefunctionofbalancingthemirrorcurrentofthereversecircuitisrealizedbyconnectingapotentiometerinthemiddle.Inadditiontothebalancefunction,the6pinalsohasastrobefunction,andthe6pincanbegroundedthroughthetransistordrivecircuitforstrobeoutput.Whatisthedifferencebetweenlm311voltagecomparatordualpowersupplyandsinglepowersupply?Thecomparatorsareallopen-collectoroutputs,withoutloadresistance,theycannotoutputvoltagesignals.Dualpowersuppliescandetectsignalslowerthan0,andsinglepowersuppliescanonlydetectsignalshigherthan0.Canthelm311comparatorbepoweredbyapositiveandnegativefive-voltdualpowersupply?Ofcourse,LM311canbepoweredby5Vdualpowersupply.Itsrequirementforworkingpowersupplyisthatthevoltagedifferencebetweenthepositiveandnegativepowersupply(orsinglepowersupplyvoltage)isatleast3.5Vandthemaximumis30V,aslongasitiswithinthisrange.

DS28E01P-100+T-MAXIM

IIntroductionTheLM311devicesaresinglehigh-speedvoltagecomparators.Thedevicesaredesignedtooperatefromawiderangeofpowersupplyvoltages,including15-Vsuppliesforoperationalamplifiersand5-Vsuppliesforlogicsystems.TheoutputlevelsarecompatiblewithmostTTLandMOScircuits.Thesecomparatorsarecapableofdrivinglampsorrelaysandswitchingvoltagesupto50Vat50mA.Allinputsandoutputscanbeisolatedfromsystemground.Theoutputscandriveloadsreferencedtoground,VCC+orVCC.Offsetbalancingandstrobecapabilitiesareavailable,andtheoutputscanbewire-ORconnected.Ifthestrobeislow,theoutputisintheoffstate,regardlessofthedifferentialinput.CatalogIIntroductionIIPrecautionsofLM3112.1ChooseComponentsReasonably2.2IncreaseAmplitudeofInputSignal2.3AddFilteringAppliancestoOutputofComparator2.4AdoptLaggingTechnologyFAQOrdering&QuantityIIPrecautionsofLM311LM311isacommonlyusedlinearcomparator,whichiswidelyusedincomparisonandshapingcircuits,andasisshowninFigure1.Figure1.LM311CircuitDiagramHowever,LM311oftenhasunexpectedproblemsintheapplication,thatis,theoutputpulsesignalisnotasidealastheoreticalanalysis.Instead,high-frequencyoscillationoccursnearthefrontandbackedgesoftheoutputpulse,asshowninFigures2and3.Figure2.HighFrequencyOscillationbeforeOutputPulseFigure3.HighFrequencyOscillationafterOutputPulseWhentheinputsignalViamplitudeoftheLM311issmallerandthefrequencyislower,thehigh-frequencyoscillationismoreserious.Thiskindofwaveformcontaininghigh-frequencyoscillationcannotbeuseddirectly.Itwillcausemisoperationtosubsequentcircuits,suchasfrequencymeasurement.Therefore,thissituationmustbepaidattentionto,andtrytoavoidoreliminatehigh-frequencyoscillation.Thefollowingwillgiveabriefanalysisofthecausesofoscillations,andatthesametimeputforwardseveralmethodstoeffectivelyavoideliminatingoscillationsonthebasisofexperiments.Figure4.LM311Whenahigh-speedcomparatorisusedforhigh-speedinputsignalsandlowsourceimpedanceinputsignals,thenormaloutputresponseshouldbefastandstable.However,whentheinputsignalisaslowlyvaryingsignalorahigh-impedancesignalsource(1.0K-10K),thecomparatormayoscillatesuddenlyatthecomparisonthresholdpoint,whichiscausedbythehighgainandwidebandofthecomparator,andthepresenceofinterferenceisalsooneofthedirectcausesofthisoscillation.Inapplication,toavoidthiskindofoscillationandinstability,carefulconsiderationshouldbemadeinadvanceandoverallarrangementsshouldbemade.Thefollowingwillproposeseveraleffectivemethodstoavoidandovercomeoscillations:2.1ChooseComponentsReasonablyReasonablyarrangingtheoccurrenceofstructuraloscillationshasalottodowithstructuralarrangements.Theoutputsignalshouldbefarawayfromtheinputterminalpin,andshouldalsobefarawayfromthetwobalancedterminalpins,becausethefeedbacksignalsensingortouchinganypinmayalmostcauseoscillation.Ifthecomparatorusesaresistorattheinput,itspositionandresistanceareworthconsidering.Theresistanceshouldbeplacednearthetubebase,andthegeneralresistancevalueshouldbelessthan10K(orevenless),pleaserefertothecorrespondingmanualwhenusing.Positiveandnegativepowersupplyshouldadd0.1filtercapacitortofilterouttheinterferenceofthepowersupply,andputthecapacitornearthepin.Thetwobalancedendsshouldbeproperlyhandled.Whennotinuse,theycanbeshortedtogether.Forspecificuse,youcanalsorefertotherelevantmanual.2.2IncreaseAmplitudeofInputSignalThemagnitudeoftheinputsignalamplitudeisdirectlyrelatedtotheoscillation.Experimentsshowthatthesmallerthesignalamplitude,thelowerthefrequency,thegreaterthepossibilityofoscillation.Thefollowingwillmakeasimpleanalysisoftheaboveconclusions.Ifthereisazero-crossingcomparator,theinputsignalisVi=V0sin0t.Theslopeofthesignalatt=0is:Theamountofvoltagechangein△ttimeis:△Vi=K△t=V0sin0t,whichshowsthat△ViisproportionaltoV0,0,thatis,thegreatertheamplitudeoftheinputsignal,thehigherthefrequencyofthesignal.Theninthe△ttime,thelongertheamplitudechangeofVis,whendvi/dtislargeenough,theinputsignalwillquicklycrossthecomparisonthreshold,soastoachievethepurposeofeliminatingoscillation.Becausetheinputvoltagerangeofthecomparatorisgenerallyrelativelywide(forexample:thevoltageinputrangeoftheLM311is30V),thismethodisthemostsimpleandfeasible.Theexperimentprovesthataslongastheamplitudeoftheinputsignalisgreaterthan0.7V,thisdesigncanworkreliablyintherangeof10Hz~60KHz,continuetoincreasethevoltageamplitude,theworkingrangecanbeextendedtothelowfrequencyend.2.3AddFilteringAppliancestoOutputofComparatorPullingaresistorattheoutputofthecomparatorandconnectingacapacitorwithanappropriatecapacityhasasignificanteffectonfilteringandreducingoscillation.Thecapacityofthecapacitorshouldbedeterminedonthebasisoftheexperiment.Thecapacityofthecapacitorshouldnotbetoolarge,otherwisetheleadingedgeoftheoutputpulsewillbedeteriorated.Itwasfoundintheexperimentthatthisnegativeeffectisparticularlyseriousathigherfrequencies,andevenmakethepulseamplitudesmaller,sothatthecounterofthesubsequentstagecannotwork,thesituationisshowninFigure5.Figure5.PulseAmplitudeatHigherFrequenciesTherefore,thismethodhascertainlimitationsintheapplication,andthereasonablechoiceofcapacitanceisthekeytoapplyingthismethod.Ofcourse,thedeterioratedfrontcanberestoredbythe74LS14withashapingeffect.Thenegativeeffectofthismethodistoshifttheoriginalpulsefrontbackward.Inthisdesign,capacitanceC=0.01istaken.Withintherangerequiredbythesystem,thevalueofthepull-upresistorthatthecircuitcanworkreliablycannotbetoolarge.Inthisdesign,R=510.2.4AdoptLaggingTechnologyInthecomparisoncircuit,whentheinputsignalreachesthecomparisonlevel,thecomparatorshouldbereversedimmediately,butifthemeasuredsignalissuperimposedwithacertainamountofinterference,thecomparatormayoscillatenearthecomparisonlevel,asshowninthefollowingfigure(Figure6-7).Figure6.OutputofaCommonZero-crossingComparatorFigure7.OutputwithLagTechnologyTheeffectivemethodtoovercometheoscillationofthecomparatoristousethelagtechnology,thatis,addasmallamountofpositivefeedbacktoitsnon-invertingend.Thecomparisonlevelofthelagcomparatorisnolongerasinglelevel,buthastwopowerlevelsneartheoriginalcomparisonlevel.Ingeneral,forthecircuitinfigure8,theuppercomparisonlevelisrepresentedbyV+H,andthelowercomparisonlevelisrepresentedbyV+L.Figure8.CircuitwithTwoLevelsThehysteresisvoltagecanbeadjustedbyR1andR2.Aslongas△Visselectedproperly,theoscillationphenomenonofthecomparisoncircuitcanbeeliminated.Therefore,theanti-interferenceabilityisgreatlyimproved,butthepresenceofthelaglevel△Vwillmakethedetectionsensitivityworse.Therefore,△Vshouldnotbetoolarge,usuallyR1R2.FortheLM311comparator,adding3mvofhysteresiswilleliminatetheoscillationinthecircuit.Therefore,wemustconsidercarefullyandtreatseparatelywhenusingLM311.Onlyinthiswaycanwebehandywhenusingit.FAQHowtouseLM311?LM311isasingle-channelcomparator.Whenusingit,connectthereferencevoltageandthecomparedsignalvoltagetoitsnon-invertingandinvertinginputterminals(pin2andpin3),anditsoutputistheresultofthecomparison.Ifyouwantthefowardoutputresult,pin7isconnectedtothepositivepowersupplyandpin1istheoutput.Iftheresultistobeoutputinreverse,pin1isgroundedandpin7istheopencollectoroutput.lm311andlm393arebothvoltagecomparators,sowhatisthedifferencebetweenthem?LM311issinglevoltagecomparaotor,LM393isdualvoltagecopatpr.LM311hasaloadcurrentofupto50MAandavoltageof40V.Itcandriverelayswithaminimumpowersupplyvoltageof5V.TheLM393loadcurrentis16MA,andtheminimumvoltageis2Vforasinglepowersupply.WhatsthedifferencebetweenLM311andLM111?Theirfunctionsarethesame,andthe1XXseriescanbeusedinharsherenvironments.The3XXseriescanonlybeusedinacommercialenvironment,typicallytheapplicabletemperaturerangeofthedevice.Thepriceof1xxismuchmoreexpensivethan3xx.Whatdoesthe5and6-pinbalancestrobesofLM311mean?Thefunctionofbalancingthemirrorcurrentofthereversecircuitisrealizedbyconnectingapotentiometerinthemiddle.Inadditiontothebalancefunction,the6pinalsohasastrobefunction,andthe6pincanbegroundedthroughthetransistordrivecircuitforstrobeoutput.Whatisthedifferencebetweenlm311voltagecomparatordualpowersupplyandsinglepowersupply?Thecomparatorsareallopen-collectoroutputs,withoutloadresistance,theycannotoutputvoltagesignals.Dualpowersuppliescandetectsignalslowerthan0,andsinglepowersuppliescanonlydetectsignalshigherthan0.Canthelm311comparatorbepoweredbyapositiveandnegativefive-voltdualpowersupply?Ofcourse,LM311canbepoweredby5Vdualpowersupply.Itsrequirementforworkingpowersupplyisthatthevoltagedifferencebetweenthepositiveandnegativepowersupply(orsinglepowersupplyvoltage)isatleast3.5Vandthemaximumis30V,aslongasitiswithinthisrange.

IDescriptionInthisblog,wewillintroduceamultifunctionalelectronicthermometer.Thiskindofthermometercannotonlyaccuratelyandconvenientlymeasurebodytemperatureandfoodtemperature,butalsocanbeusedtomeasureindoorandoutdoortemperature,refrigeratortemperature,etc.Inaddition,italsohasmultiplefunctionssuchastemperaturemeasurementtiming,temperaturememory,soundprompt,backlightdisplay,andautomaticshutdown.Moreover,ithasthecharacteristicsofaccuratemeasurement,simpleoperation,portabilityandlowprice.Therefore,itcanbewidelyusedinhospitalsandhomesasageneraltemperaturemeasuringinstrument.Intermsofitsworkingprinciple,thethermometerusesthedigitaltemperaturesensorDS18B20todetecttemperatureandtransmitsthedigitaltemperaturesignaltothesingle-chipmicrocomputer.Thetemperaturevalueandmeasurementtimecalculatedandcorrectedbythesingle-chipmicrocomputeraredisplayedinrealtimebytheliquidcrystaldisplay.AtutorialonhowtousetheDallasMaxim1-WireDS18B20digitaltemperaturesensorwiththeArduino.CatalogIDescriptionIIDS18B20IntroductionIIIHardwareCircuit3.1PowerCircuit3.2DigitalTemperatureSensorandCalibration3.3MCUCircuit3.4LCDDisplay3.5AudioCircuitIVSoftwareDesignVConclusionFAQOrdering&QuantityIIDS18B20IntroductionDS18B20isasingle-wiredigitaltemperaturesensorproducedbyDALLAS.Itintegratestemperaturesensing,signalconversion,A/Dconversionandheatingfunctionsintoonechip,andbelongstoanewgenerationofintelligentdigitaltemperaturesensorswithmicroprocessors.DS18B20hasatotalof3pins,(respectivelydigitalsignalinput/output,ground,powersupply),usingTO-92small-volumepackaging.DS18B20MainSpecifications:Thetemperaturemeasurementrangeis-55℃~+125℃;Programmableto9to12bitA/Dconversionaccuracy;Thetemperaturemeasurementresolutioncanreach0.0625℃,andtheerroris0.5℃;Theworkingpowersupplycanbeintroducedattheremoteend(3-wireworkingmode)orgeneratedbyparasiticpowersupply(2-wireworkingmode);Themeasuredtemperatureisseriallyoutputwithasign-extended16-bitdigitalquantity;Eachsensorhasaunique64-bitserialnumber,whichisstoredintheROMofthesensor;Thesensoralsohastwotemperatureupperandlowerlimitstorageunits.IIIHardwareCircuitThemultifunctionalelectronicthermometerismainlycomposedofthefollowingparts:PowercircuitDigitaltemperaturesensorSinglechipcomputerLCDMonitorAudiocircuit...ItshardwarecircuitschematicdiagramisshownasinFig.1.Figure1.HardwareCircuit(rightclicktoviewbigpicture)3.1PowerCircuitU1isthemicropowerconsumptionstep-downDC/DCconverterLT3470introducedbyLinearTechnology.Here,U1convertsthe9Vdrybatteryvoltageinto5VDCvoltagetopowertheentirecircuit.So,howtostartandshutdownautomatically?WeonlyneedtopressthestartbuttonS2.Afterstarting,pin1(SHDN)ofU1getsahighlevel,pin5ofU1outputsa5VstableDCvoltage,andthethermometerstartstoworkatthistime.Then,the14-pin(P1.2)oftheone-chipcomputeroutputsahighlevelthroughD2tokeepthe1pinofU1high.When6minutesareup,the14-pinofthesingle-chipmicrocomputeroutputsalowlevel,andthe1pinofU1becomesalowlevel,andthecircuitautomaticallypowersdown.3.2DigitalTemperatureSensorandCalibrationThedigitaltemperaturesensorDS18B20isusedasatemperaturemeasuringprobetocollecttemperaturesignals.Andthedigitizedtemperaturesignalisinputthroughthe19-pin(P1.7)ofthemicrocontroller.DS18B20adopts2-wireworkingmode,andtheworkingpowerisgeneratedbyparasiticpower.Forexample,usethisthermometertomeasurethetemperatureofababy.Wecanfixthetemperatureprobeonaspecialbandageandtieittothearm.Sothatthesensorislocatedunderthearmpit.Inthisway,itcanbeavoidedthatthetemperaturemeasuringprobeisdetachedfromthetestsite.Duetoinfantactivitiesorcryingwhenmeasuringthebodytemperatureoftheinfant,andthemeasurementisconvenient.Foranotherexample,thetemperatureprobecanalsomeasureindoorandoutdoortemperature,refrigeratortemperature,etc.Thespecialprobeformeasuringfoodtemperatureadoptsnon-toxicstrawandnon-toxicsilicagelpackage,whichiseasytoclean.SinceDS18B20isintherangeof-10℃~85℃,itsmeasurementerroris0.5℃.Inordertoaccuratelymeasurebodytemperature,thisblogusesaself-madeconstanttemperaturewaterbathsystemtodeterminethetemperaturecurveofeachsensor.WecancalibratetheDS18B20accordingtothetemperaturecurvetomakethemeasurementerrorwithintherangeof25℃~50℃be0.1℃.3.2.1ConstantTemperatureWaterBathSystemTheconstanttemperaturewaterbathsystemconsistsofthefollowingthreeparts:anelectriccookerwithheatpreservation,acylindricalcopperbodywithgoodheatconduction,andanautomatictemperaturecontroller.Weneedtomake50roundholeswithadiameterof5mmandaheightof30mmonacylindricalcopperbodywithadiameterof120mmandaheightof80mm.Inthisway,thetemperaturesensorcanbefixedandthetemperatureofallthesensorsinthecopperbodycanbekeptconsistent.Putthecylindricalcopperbodyintotheelectriccooker,andadddistilledwatertosubmergethecopperbody.3.2.2DS18B20ActualTemperatureCurveMeasurementInsertmultipleencapsulatedsensorstobetested(nomorethan49)intothesmallholesofthecopperbodyoftheconstanttemperaturewaterbath;Insertthehigh-precisiondigitalthermometerintothesmallholeofthecopperbodytoaccuratelymeasurethecurrenttemperature;Thewiresofallsensorsareledoutthroughtheuppercoverholeoftheelectriccookerandconnectedtotheuppercomputer.Covertheelectriccookerwithheatpreservationmaterial;Turnonthepower,changethetemperaturesettingoftheautomaticthermostat,andcontrolthetemperatureoftheconstanttemperaturewaterbath;Monitorthetemperaturevalueofthedigitalthermometer.Wheneverthespecifiedtemperaturevalueisreached,starttheuppercomputertemperaturemeasurementprogramandsimultaneouslymeasurethecurrenttemperatureofallthesensorstobetested;From25℃~60℃,measure1setofdataevery5℃,andautomaticallygeneratetheactualtemperaturecurveofeachsensor.3.2.3CorrectionofDS18B20Byanalyzingthemeasuredtemperaturecurveofthesensor,wecanfindthatwithintherangeof25℃~50℃,theerroris-0.1℃~-0.3℃.Inthedesignofthisblog,thecurrenttemperaturevalueofDS18B20plus0.2℃isusedastheactualmeasuredtemperature,sothatthemeasurementerrorintherangeof25℃~50℃isreducedto0.1℃.3.3MCUCircuitThemicrocontroller(U2)isthecorecomponentofthethermometer.Ithasthefollowingfunctions:Temperaturesignalreading,processingcalculation,correctionTemperaturemeasurementtimingTemperaturememorySoundprompt,Automaticshutdown...ThisdesignadoptsAT89C2051single-chipmicrocomputerproducedbyAmericanATMELcompany.Itisabuilt-inflashmemorymicrocontrollerthatisfullycompatiblewiththeMCS-51series,withonly20pins.Itisthemostcompact,smallest,andcheapestFlashROMmicrocontrollerintheAT89C51series.Providesthefollowingstandardfunctions:An8-bitCPU;2kBflashmemory;128bytesRAM;Two16-bittimers;Acomplete8-bitbidirectionalI/Oport;5interruptsources.Afterstartingthethermometer,themicrocontrollerstartsaninternaltimertorecordthetemperaturemeasurementtime.ItalsoreadsthedigitaltemperaturesignalsentbyDS18B20,processesandcorrectsittoobtainthereal-timetemperaturevalue.ThetemperaturevalueandtemperaturemeasurementtimearesenttotheLCDdisplayviaserialcommunicationviapin1(P3.0)andpin2(P3.1);Whenthetemperaturemeasurementtimereaches5minutes,thecurrenttemperaturevalueisautomaticallyregistered,andpin11outputsalowleveltocontroltheaudiocircuittogiveasoundprompt;Whenthetemperaturemeasurementtimereaches6minutes,thesingle-chip14pinoutputslowlevel,andthethermometerisautomaticallypoweredoff.3.4LCDDisplayThisblogusesa3andahalfliquidcrystaldisplay(LCD)todisplaytemperatureandtemperaturemeasurementtime.Thedisplayhasthefollowingcharacteristics:Useglassencapsulation;Thereare5pinsintotal;SerialcommunicationWith3andahalfdisplayareaand℃unitdisplay;Functionwithbacklight;Thepowersupplyvoltagerangeis2V~5V.Thisdesignusesthemaindisplayareatoindicatethetemperature,andthesub-displayareatoindicatethetemperaturemeasurementtime.3.5AudioCircuitTheaudiocircuitconsistsofthefollowingparts:TransistorQ2(9015)resistanceR12;CapacitanceC12;BuzzerB1;Whenthepin11ofthesingle-chipmicrocomputeroutputslowlevel,thetransistorQ2issaturatedandturnedon,andthebuzzergeneratesanaudibleprompt.IVSoftwareDesignTheprogramiswrittenin89C51seriesClanguageanddebuggedonthesingle-chipsimulationsystem.TheprogramflowchartisshowninFigure2.Figure2.BlockDiagramofMainProgramAfterpower-onreset,initializetheDS18B20,inputandoutputports,timers,etc.ReadthetemperaturevalueofthelastmeasurementandstoragefromthelowertemperaturelimitstorageunitofDS18B20anddisplayitfor3seconds.StarttheinternaltimerT0ofthemicrocontrollertorecordthetemperaturemeasurementtime.Obtainthetemperaturevalueandcorrecttheerror.AccordingtothecommunicationprotocolofDS18B20,thetemperaturesignalisreadfromthesensor,thesignisdistinguished,andthetemperaturevalueisobtainedaftercalculationandprocessing.Then,add0.2Ctothetemperaturevalueastheactualtemperature,andcorrectthemeasurementerrorwithintherangeof25Cto50Cto0.1C.Displayoftemperature.Accordingtothecommunicationprotocoloftheliquidcrystaldisplay,thetemperaturevalueandtemperaturemeasurementtimearesenttothedisplayfordisplay.Themaindisplayareaindicatesthetemperature,andthesecondarydisplayareaindicatesthetemperaturemeasurementtime.Whenthetemperaturemeasurementtimereaches5minutes,the11-pinofthesingle-chipmicrocomputeroutputsalow-levelcontrolaudiocircuittoemitapromptsound,andthecurrenttemperatureissenttothelowertemperaturestorageunitofDS18B20forregistration,andsenttothesecondarydisplayareafordisplay.Whenthetemperaturemeasurementtimereaches6minutes,the14-pinofthesingle-chipmicrocomputeroutputslowlevel,andthethermometerautomaticallypowersdown.VConclusionComparedwithtraditionalthermometers,theDS18B20Multi-functionElectronicThermometerdesignedinthisbloghasmanyadvantages.Thelatterovercomesthedifficultyofreadingmercurythermometersandiseasytobebrokenandpollutetheenvironment.Atthesametime,comparedwithsimpleelectronicthermometers,multifunctionalelectronicthermometersalsoovercometheshortcomingsofpoormeasurementaccuracy.Becauseofitscompletefunctions,stableperformance,smallsize,lightweight,lowpowerconsumption,andlowprice,itcanbeusedasageneraltemperaturemeasuringinstrumentandwidelyusedinhospitalsandhomes.FAQWhatisDS18B20temperaturesensor?TheDS18B20isa1-wireprogrammabletemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.HowdoestheDS18B20work?Itworksontheprincipleofdirectconversionoftemperatureintoadigitalvalue.IsDS18B20athermistor?Athermistorisathermalresistor-aresistorthatchangesitsresistancewithtemperature....Thermistorshavesomebenefitsoverotherkindsoftemperaturesensorssuchasanalogoutputchips(LM35/TMP36)ordigitaltemperaturesensorchips(DS18B20)orthermocouples.HowaccurateisDS18B20?TheDS18B20readswithanaccuracyof0.5Cfrom-10Cto+85Cand2Caccuracyfrom-55Cto+125C.Whatisds1820?TheDS18B20isonetypeoftemperaturesensoranditsupplies9-bitto12-bitreadingsoftemperature....Thecommunicationofthissensorcanbedonethroughaone-wirebusprotocolwhichusesonedatalinetocommunicatewithaninnermicroprocessor.HowdoIconnectmyDS18B20tomyRaspberryPi?OnceyouveconnectedtheDS18B20,powerupyourPiandlogin,thenfollowthesestepstoenabletheOne-Wireinterface:1.Atthecommandprompt,entersudonano/boot/config.txt,thenaddthistothebottomofthefile:2.dtoverlay=w1-gpio.3.ExitNano,andrebootthePiwithsudoreboot.WhatistheworkingprincipleofDS18B20?TheDS18B20DigitalThermometerprovides9to12-bit(configurable)temperaturereadingswhichindicatethetemperatureofthedevice.Itcommunicatesovera1-Wirebusthatbydefinitionrequiresonlyonedataline(andground)forcommunicationwithacentralmicroprocessor.Inadditionitcanderivepowerdirectlyfromthedataline(parasitepower),eliminatingtheneedforanexternalpowersupply.ThecorefunctionalityoftheDS18B20isitsdirect-to-digitaltemperaturesensor.Theresolutionofthetemperaturesensorisuser-configurableto9,10,11,or12bits,correspondingtoincrementsof0.5C,0.25C,0.125C,and0.0625C,respectively.Thedefaultresolutionatpower-upis12-bit.WheretouseDS18B20Sensor?TheDS18B20isa1-wireprogrammableTemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.Itcanmeasureawiderangeoftemperaturefrom-55Cto+125withadecentaccuracyof5C.EachsensorhasauniqueaddressandrequiresonlyonepinoftheMCUtotransferdatasoitaverygoodchoiceformeasuringtemperatureatmultiplepointswithoutcompromisingmuchofyourdigitalpinsonthemicrocontroller.HowconnectDS18B20toArduino?FirstplugthesensoronthebreadboardtheconnectitspinstotheArduinousingthejumpersinthefollowingorder:pin1toGND;pin2toanydigitalpin(pin2inourcase);pin3to+5Vor+3.3V,attheendputthepull-upresistor.OnanATMega328P,whyisaDS18B20temperaturesensorreturningincorrecttemperaturevalues?Severalpossibilities:1.Ifitisjustreadingalittlehigh,itmightbecausedbyselfheating.Addaheatsinkand/ormakemeasurementslessfrequently.2.Especiallyifthevaluesarereallywhacky,itmightbecodewitherrorsormis-wiring.Useapublishedsketchtocheckoperation.3.TheDS18B20mightbedefective.Tryanother.4.Itsaccurateto0.5C.Areyouexpectingittobemoreaccurate(likedowntotheLSBofthereadvalue)?DescriptionDS18B20isatemperaturesensorofMaxim.Thesingle-chipmicrocomputercancommunicatewithDS18B20through1-Wireprotocolandfinallyreadthetemperature.Thehardwareinterfaceofthe1-Wirebusisverysimple,justconnectthedatapinofDS18B20toanIOportofthemicrocontroller.ThisVideoIntroducesDS18B20withDatasheetCatalogDescriptionDocumentandMediaDS18B20PinoutParametersAdvantageFeaturesApplicationsDS18B20CircuitSchematicDS18B20TemperatureSensorDataDS18B20BlockDiagramHowtousetheDS18B20SensorWheretouseDS18B20SensorProductManufacturerFAQOrdering&QuantityDocumentandMediaComponentDatasheetDS18B20DatasheetDS18B20PinoutPinNameFunctionSOSOPTO-921,2,6,7,82,3,5,6,7-N.C.NoConnection383VDDOptionalVDD.VDDmustbegroundedforoperationinparasitepowermode.412DQDataInput/Output.Open-drain1-Wireinterfacepin.Alsoprovidespowertothedevicewhenusedinparasitepowermode(seethePoweringtheDS18B20section.)541GNDGroundParametersAccuracy(C)0.5ChannelsOneInterface1-WireMultiDroppableYesOper.Temp.(C)-55to+125Package/PinsSOIC(N)/8,TO92/3,UMAX/8ParasitePwr.YesPartNumberDS18B20SensorTypeLocalTemp.Resolution(bits)9,10,11,12Temp.Thresh.Programmable(NV)AdvantageTheDS18B20digitalthermometerprovides9-bitto12-bitCelsiustemperaturemeasurementsandhasanalarmfunctionwithnonvolatileuser-programmableupperandlowertriggerpoints.TheDS18B20communicatesovera1-Wirebusthatbydefinitionrequiresonlyonedataline(andground)forcommunicationwithacentralmicroprocessor.Inaddition,theDS18B20canderivepowerdirectlyfromthedataline(parasitepower),eliminatingtheneedforanexternalpowersupply.EachDS18B20hasaunique64-bitserialcode,whichallowsmultipleDS18B20stofunctiononthesame1-Wirebus.Thus,itissimpletouseonemicroprocessortocontrolmanyDS18B20sdistributedoveralargearea.ApplicationsthatcanbenefitfromthisfeatureincludeHVACenvironmentalcontrols,temperaturemonitoringsystemsinsidebuildings,equipment,ormachinery,andprocessmonitoringandcontrolsystems.FeaturesUnique1-WireInterfaceRequiresOnlyOnePortPinforCommunicationReduceComponentCountwithIntegratedTemperatureSensorandEEPROMMeasuresTemperaturesfrom-55Cto+125C(-67Fto+257F)0.5CAccuracyfrom-10Cto+85CProgrammableResolutionfrom9Bitsto12BitsNoExternalComponentsRequiredParasiticPowerModeRequiresOnly2PinsforOperation(DQandGND)SimplifiesDistributedTemperature-SensingApplicationswithMultidropCapabilityEachDeviceHasaUnique64-BitSerialCodeStoredinOn-BoardROMFlexibleUser-DefinableNonvolatile(NV)AlarmSettingswithAlarmSearchCommandIdentifiesDeviceswithTemperaturesOutsideProgrammedLimitsAvailablein8-PinSO(150mils),8-PinSOP,and3-PinTO-92PackagesApplicationsConsumerProductsIndustrialSystemsThermallySensitiveSystemsThermometersThermostaticControlsDS18B20CircuitSchematicDS18B20TemperatureSensorDataDS18B20canachievethehighest12-bittemperaturestoragevaluethroughprogramming.Thetemperaturestoragevalueisstoredintheregisterinacomplementformat.Thereare2bytesintotal,LSBisthelowbyteandMSBisthehighbyte.Amongthem,MSbisthehighbitofthebyte,andLSbisthelowbitofthebyte.Forbinarynumbers,themeaningofthetemperaturerepresentedbyeachofthemisexpressed.Amongthem,Srepresentsthesignbit,andthelower11bitsareallpowersof2,whichareusedtorepresentthefinaltemperature.ThetemperaturemeasurementrangeofDS18B20isfrom-55degreesto+125degrees.Themanifestationoftemperaturedatahaspositiveandnegativetemperatures.Eachnumberintheregisterisdistributedlikethescaleofacaliper.Thelowestbitofthebinarynumberchanges1,whichrepresentsthemappingrelationshipofatemperaturechangeof0.0625degrees.Whenthetemperatureis0℃,thecorrespondinghexadecimalnumberis0x0000.Whenthetemperatureis125℃,thecorrespondinghexadecimalnumberis0x07D0.Whenthetemperatureisminus55℃,thecorrespondinghexadecimalnumberis0xFC90.Conversely,whenthenumberis0x0001,thetemperatureis0.0625℃.DS18B20BlockDiagramHowtousetheDS18B20SensorThesensorworkswiththemethodof1-Wirecommunication.Itrequiresonlythedatapinconnectedtothemicrocontrollerwithapullupresistorandtheothertwopinsareusedforpowerasshownbelow.Thepull-upresistorisusedtokeepthelineinhighstatewhenthebusisnotinuse.Thetemperaturevaluemeasuredbythesensorwillbestoredina2-byteregisterinsidethesensor.Thisdatacanbereadbytheusingthe1-wiremethodbysendinginasequenceofdata.Therearetwotypesofcommandsthataretobesenttoreadthevalues,oneisaROMcommandandtheotherisfunctioncommand.TheaddressvalueofeachROMmemoryalongwiththesequenceisgiveninthedatasheetbelow.Youhavetoreadthroughittounderstandhowtocommunicatewiththesensor.IfyouareplanningtointerfaceitwithArduino,thenyouneednotworryaboutallthese.Youcandevelopthereadilyavailablelibraryandusethein-builtfunctionstoaccessthedata.WheretouseDS18B20SensorTheDS18B20isa1-wireprogrammableTemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.Itcanmeasureawiderangeoftemperaturefrom-55Cto+125withadecentaccuracyof5C.EachsensorhasauniqueaddressandrequiresonlyonepinoftheMCUtotransferdatasoitaverygoodchoiceformeasuringtemperatureatmultiplepointswithoutcompromisingmuchofyourdigitalpinsonthemicrocontroller.ProductManufacturerMaximIntegratedprovideseaseofdesign,andspeedstimetomarket,throughanalogintegration.ThecompanysanalogICsofferextrafeaturesandfunctionalitycarefullydesignedtostreamlinecircuitandsimplifydesign.LooktoMaximforsolutionsforconsumerelectronics,personalcomputersandperipherals,mobiledevices,wirelessandfibercommunications,testequipment,instrumentation,videodisplays,andautomotiveapplications.Maximsanalogandmixed-signalsolutionsincludedataconverters,interfacecircuits,power,RFwirelesscircuits,clocksandoscillators,microcontrollers(MCUs),operationalamplifiers(opamps),andsensors.FAQWhatisDS18B20temperaturesensor?TheDS18B20isa1-wireprogrammabletemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.HowdoestheDS18B20work?Itworksontheprincipleofdirectconversionoftemperatureintoadigitalvalue.IsDS18B20athermistor?Athermistorisathermalresistor-aresistorthatchangesitsresistancewithtemperature....Thermistorshavesomebenefitsoverotherkindsoftemperaturesensorssuchasanalogoutputchips(LM35/TMP36)ordigitaltemperaturesensorchips(DS18B20)orthermocouples.HowaccurateisDS18B20?TheDS18B20readswithanaccuracyof0.5Cfrom-10Cto+85Cand2Caccuracyfrom-55Cto+125C.Whatisds1820?TheDS18B20isonetypeoftemperaturesensoranditsupplies9-bitto12-bitreadingsoftemperature....Thecommunicationofthissensorcanbedonethroughaone-wirebusprotocolwhichusesonedatalinetocommunicatewithaninnermicroprocessor.HowdoIconnectmyDS18B20tomyRaspberryPi?OnceyouveconnectedtheDS18B20,powerupyourPiandlogin,thenfollowthesestepstoenabletheOne-Wireinterface:1.Atthecommandprompt,entersudonano/boot/config.txt,thenaddthistothebottomofthefile:2.dtoverlay=w1-gpio.3.ExitNano,andrebootthePiwithsudoreboot.WhatistheworkingprincipleofDS18B20?TheDS18B20DigitalThermometerprovides9to12-bit(configurable)temperaturereadingswhichindicatethetemperatureofthedevice.Itcommunicatesovera1-Wirebusthatbydefinitionrequiresonlyonedataline(andground)forcommunicationwithacentralmicroprocessor.Inadditionitcanderivepowerdirectlyfromthedataline(parasitepower),eliminatingtheneedforanexternalpowersupply.ThecorefunctionalityoftheDS18B20isitsdirect-to-digitaltemperaturesensor.Theresolutionofthetemperaturesensorisuser-configurableto9,10,11,or12bits,correspondingtoincrementsof0.5C,0.25C,0.125C,and0.0625C,respectively.Thedefaultresolutionatpower-upis12-bit.WheretouseDS18B20Sensor?TheDS18B20isa1-wireprogrammableTemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.Itcanmeasureawiderangeoftemperaturefrom-55Cto+125withadecentaccuracyof5C.EachsensorhasauniqueaddressandrequiresonlyonepinoftheMCUtotransferdatasoitaverygoodchoiceformeasuringtemperatureatmultiplepointswithoutcompromisingmuchofyourdigitalpinsonthemicrocontroller.HowconnectDS18B20toArduino?FirstplugthesensoronthebreadboardtheconnectitspinstotheArduinousingthejumpersinthefollowingorder:pin1toGND;pin2toanydigitalpin(pin2inourcase);pin3to+5Vor+3.3V,attheendputthepull-upresistor.OnanATMega328P,whyisaDS18B20temperaturesensorreturningincorrecttemperaturevalues?Severalpossibilities:1.Ifitisjustreadingalittlehigh,itmightbecausedbyselfheating.Addaheatsinkand/ormakemeasurementslessfrequently.2.Especiallyifthevaluesarereallywhacky,itmightbecodewitherrorsormis-wiring.Useapublishedsketchtocheckoperation.3.TheDS18B20mightbedefective.Tryanother.4.Itsaccurateto0.5C.Areyouexpectingittobemoreaccurate(likedowntotheLSBofthereadvalue)?

DS28E01P-100+T-MAXIM

IDescriptionFirst,thisblogwillintroducethe1wiredigitaltemperaturesensorDS18B20.Wemainlyintroduceitsstructure,characteristicsandworkingprinciplehere.Second,wewillintroduceatemperaturemeasurementsystembasedonDS18B20andAT89S52microcontroller.Herewemainlyintroduceitshardwarestructureandassembler.Third,therewillbepartofthesourceprogramthatisdetailedanalyed.Finally,theblogalsoexplainshowitperformstemperaturemeasurementintheagriculturalfield.Thetemperaturemeasuringdevicehasaseriesofadvantages.Suchas:highdisplayaccuracy,lowprice,simplestructure,convenientexpansionandwideapplication.DS18B20TemperatureSensorTutorialCatalogIDescriptionIIIntroductionIIIDS18B20Overview3.1DS18B20Advantages3.2DS18B20Features3.3DS18B20InternalStructureIVDS18B20MCUTemperatureMeasurementDevice4.1CompositionofSystemHardware4.2DesignofInterfaceVSoftwareDesignVIApplicationinAgriculturalProduction6.1TemperatureofMildew6.2TemperatureofAgriculturalProducts6.3TemperatureDetectioninGreenhouses6.4TemperatureofSoilVIIConclusionFAQOrdering&QuantityIIIntroductionWhatistemperature?Whataretherolesoftemperature?Temperatureisaphysicalquantitythatcharacterizesthedegreeofcoolingofanobject,anditisalsoabasicenvironmentalparameter.Inagro-industrialproductionanddailylife,themeasurementandcontroloftemperaturealwaysoccupyanextremelyimportantposition.Atpresent,atypicaltemperaturemeasurementandcontrolsystemconsistsofthefollowingparts:Analogtemperaturesensor;A/Dconversioncircuit;MCU.However,theanalogsignaloutputbytheanalogtemperaturesensorhastobeconverted.Itcaninterfacewithmicroprocessorssuchassingle-chipmicrocomputersonlyafterobtainingdigitalsignalsthroughtheA/Dconversionlink.Therefore,thehardwarecircuitstructureiscomplicatedandthecostishigh.ButDS18B20canhelpsolvethisproblem.Thenew1wiredigitaltemperaturesensorrepresentedbyDS18B20integratestemperaturemeasurementandA/Dconversion,anddirectlyoutputsdigitalquantities.Thestructureoftheinterfacecircuitwiththesingle-chipmicrocomputerissimple,anditiswidelyusedintheoccasionswithlongdistanceandmanynodes.Therefore,DS18B20hasstrongpromotionandapplicationvalue.IIIDS18B20Overview3.1DS18B20AdvantagesDS18B20type1wireintelligenttemperaturesensorproducedbyDALLASSemiconductorCompany.Itbelongstoanewgenerationofintelligenttemperaturesensorsadaptedtomicroprocessors.Comparedwiththetraditionalthermistor,ithasthefollowingadvantages:Itcandirectlyreadthemeasuredtemperature;Thereadingmodeof9-12digitscanberealizedthroughsimpleprogrammingaccordingtoactualrequirements;Itcanalsocomplete9-bitand12-bitdigitalquantitieswithin93.75msand750ms,respectively,withamaximumresolutionof0.0625C;ToreadorwritetheinformationofDS18B20,onlyoneportline(1wireinterface)isrequiredtoreadandwrite.3.2DS18B20FeaturesUnique1-WireInterfaceRequiresOnlyOnePortPinforCommunicationReduceComponentCountwithIntegratedTemperatureSensorandEEPROMMeasuresTemperaturesfrom-55Cto+125C(-67Fto+257F)0.5CAccuracyfrom-10Cto+85CProgrammableResolutionfrom9Bitsto12BitsNoExternalComponentsRequiredParasiticPowerModeRequiresOnly2PinsforOperation(DQandGND)SimplifiesDistributedTemperature-SensingApplicationswithMultidropCapabilityEachDeviceHasaUnique64-BitSerialCodeStoredinOn-BoardROMFlexibleUser-DefinableNonvolatile(NV)AlarmSettingswithAlarmSearchCommandIdentifiesDeviceswithTemperaturesOutsideProgrammedLimitsAvailablein8-PinSO(150mils),8-PinSOP,and3-PinTO-92Packages3.3DS18B20InternalStructureDS18B20adopts3-pinPR-35packageor8-pinSOICpackage.ItsDS18B20externalshapeandpindiagramareshowninFigure1.TheDS18B20internalstructureblockdiagramisshownasinFigure2.Thestructureof64-bitflashROMisshowninFigure3.Figure1.DS18B20PinoutFigure2.DS18B20InternalStructureFigure3.64bFlashROMStructureIVDS18B20MCUTemperatureMeasurementDevice4.1CompositionofSystemHardwareTheDS18B20single-chipmicrocomputerintelligenttemperaturemeasurementdeviceismainlycomposedofDS18B20temperaturesensor,AT89S52,displaymoduleandpowermodule,asshowninFigure4.Themaintechnicalindicatorsoftheproductare:MeasuringRange(℃):-55.0~+125.0MeasurementAccuracy(℃):0.1ResponseTime(s):1.5Figure4.SystemStructureDiagramThesystemusesDS18B20asatemperaturesensor.Theone-chipcomputerAT89S52ofATMELCompanyservesastheprocessor.Temperaturedisplayandlight-emittingdiodeastemperaturecontroloutputunit.Thewholesystemstrivestohaveasimplestructureandperfectfunctions.Theworkingprincipleofthesystemisasfollows:AfterDS18B20carriesonthefieldtemperaturemeasurement,themeasureddataissenttotheP3.5portofAT89S52.Thetemperaturevalueisdisplayedafterbeingprocessedbythemicrocontroller.Then,thistemperaturevalueiscomparedwiththeupperlimitofthesetalarmtemperature.Ifitishigherthanthesetupperlimit,theyellowLEDlightsup.ThemaincircuitdiagramofthesystemisshownasinFig.5.Figure5.DS18B20TemperatuerMeasurementDevice4.2DesignofInterfaceThereare2waystoconnectDS18B20tothehardwareofthemicrocontroller:Vccisconnectedtoexternalpowersupply,GNDisgrounded,andI/OisconnectedtotheI/Olineofthemicrocontroller;Useparasiticpowersupply,UDDandGNDaregroundedatthistime,andI/OisconnectedtoMCUI/O.Regardlessofthe1stor2ndpowersupplymode,theI/Olinemustbeconnectedtoapull-upresistorofabout4.7k.Figure6showsatypicalconnectionbetweenDS18B20andamicroprocessor.InFigure6(a),DS18B20adoptsparasiticpowersupply,anditsVDDandGNGterminalsarebothgrounded;InFigure6(b),theDS18B20usesanexternalpowersupply,anditsVDDterminalusesa3~5.5Vpowersupply.ThissystemadoptsthewiringmodeshowninFigure6(b),thatis,theworkingmodeofexternalpowersupply.TheactualconnectionpictureofthesystemisshowninFigure6.Figure6.PhysicalDiagramofSystemConnectionVSoftwareDesignItisworthnotingthatDS18B20hasveryhighrequirementsontwoaspects:timingandelectricalparameters.Therefore,theworkflowofthemainCPUaccessingtheDS18B20throughthesingle-businterfacemustfollowastrictoperatingsequence:first,initializetheDS18B20;second,sendROMcommands;andthen,sendfunctioncommands.Wecantakealookatthefollowingpartofthesourceprogramisasfollows:ORG0000HAJMPMAIN;StatementofMCUmemoryallocation!TEMPER_LEQU29H;usedtosavethelower8bitsofthereadtemperatureTEMPER_HEQU28H;usedtosavetheupper8bitsofthereadtemperatureFLAG1EQU38H;WhethertheDS18B20flagisdetectedPNFLAGEQU68H;DatapositiveandnegativeflagA_BITEQU20H;thesingledigitofthedigitaltubestoresthememorylocationB_BITEQU21H;ThetendigitsofthedigitaltubestorethememorylocationC_BITEQU22H;ThedecimalplacesofthedigitaltubestorethememorylocationT_INTEGEREQU26H;TheintegerpartafterFORMAT,whichintegratestwobytesoftemperatureintoonebyteT_DFEQU27H;ThedecimalfractionafterFORMAT,thedecimalfractionofnibbletemperature(therearelowfourdigits)MAIN:LCALLGET_TEMPER;CallthetemperaturereadingsubroutineLCALLT_FORMAT;Formattheread2bytetemperatureLCALLALARM;callthealarmsubroutineLCALLDISPLAY;callthedigitaltubedisplaysubroutineLCALLD1S;testafteradelayof0.5secondsAJMPMAIN;thisistheDS18B20resetinitializationsubroutineINIT_1820:SETBP3.5NOPCLRP3.5;thehostsendsoutaresetlowpulsewithadelayof537microsecondsMOVR1,#2TSR1:MOVR0,#250DJNZR0,$DJNZR1,TSR1SETBP3.5;thenpullupthedatalineNOPNOPNOPMOVR0,#25HTSR2:JNBP3.5,TSR3;waitingforDS18B20responseDJNZR0,TSR2;delayLJMPTSR4TSR3:SETBFLAG1;SettheflagbittoindicatethatDS1820existsLJMPTSR5TSR4:CLRFLAG1;cleartheflagbit,indicatingthatDS1820doesnotexistLJMPTSR7TSR5:MOVR0,#120TSR6:DJNZR0,TSR6;timingrequiresaperiodofdelayTSR7:SETBP3.5RET;readthetemperaturevalueafterconversionGET_TEMPER:;SETBP3.5LCALLINIT_1820;firstresetDS18B20JBFLAG1,TSS2RET;DeterminewhetherDS1820exists?IfDS18B20doesnotexistThenreturnTSS2:MOVA,#0CCH;skipROMmatchingLCALLWRITE_1820MOVA,#44H;IssuetemperatureconversioncommandLCALLWRITE_1820LCALLDISPLAYLCALLINIT_1820;resetbeforereadingtemperatureMOVA,#0CCH;SkipROMmatchingLCALLWRITE_1820MOVA,#0BEH;IssuereadtemperaturecommandLCALLWRITE_1820LCALLREAD_18200;savethereadtemperaturedatato28H/29HRET;WriteDS18B20subroutine(withspecifictimingrequirements)WRITE_1820:MOVR2,#8;atotalof8bitsofdata;CLRCWR1:CLRP3.5MOVR3,#6DJNZR3,$RRCAMOVP3.5,CMOVR3,#23DJNZR3,$SETBP3.5NOPDJNZR2,WR1SETBP3.5RET;readtheprogramofDS18B20,readtwobytesoftemperaturedatafromDS18B20READ_18200:MOV36H,#2;SetthehighandlowtemperatureReadfromDS18B20MOVR1,#29H;thelowbitisstoredin29H(TEMPER_L),thehighbitDeposit28H(TEMPER_H)RE00:MOVR2,#8;Thereare8bitsofdataRE01:;CLRCSETBP3.5NOPNOPCLRP3.5NOPNOPNOPSETBP3.5MOVR3,#9RE10:DJNZR3,RE10MOVC,P3.5MOVR3,#23RE20:DJNZR3,RE20RRCADJNZR2,RE01MOV@R1,ADECR1DJNZ36H,RE00RET;-----Integratethetwo-bytetemperaturereadout(pleaserefertotheinformationaboutthe2-bytetemperatureformatreadoutbyDS18B20)----------T_FORMAT:;AlarmsubroutineALARM:;DisplaysubroutineDISPLAY:;1MSdelay(calculatedby12MHZ)D1MS:MOVR7,#250llmm:nopnopDJNZR7,llmmRET;1MSdelay(calculatedby12MHZ)D1S:MovR6,#4LOOP2:movR5,#125;------------250LOOP1:LCALLD1mSDJNZR5,LOOP1DJNZR6,LOOP2RET;7-segmentdigitaltube0-9digitcommonanodedisplaycodeNUMTAB:DB0C0H,0f9H,0a4H,0b0H,99H,92H,82H,0f8H,80H,90H,0ffHXIAOSHU:DB00H,01H,01H,02H,03H,03H,04H,04H,05H,06H,06H,07H,08H,08H,09H,09HENDVIApplicationinAgriculturalProductionThistemperaturemeasurementsystemcandirectlyoutputdigitalquantities.Inaddition,ithasthecharacteristicsofsimplestructure,convenientuseandlowprice.Therefore,itcanbewidelyusedinagriculturalproduction.6.1TemperatureofMildewModerngrainwarehousescanusethissystemtomonitorthetemperatureofhundredsofpoints.Inthisway,youcaneasilygraspthetemperaturechangesatvariouspointsatdifferenttimes,increasestoragecapacity,andeffectivelyreducetheoccurrenceofmildew.6.2TemperatureofAgriculturalProductsAtpresent,low-temperaturerefrigerationmeasuresarewidelyadoptedforthepreservationoffruitsandvegetables.Thesystemcanbeinstalledinthetemperaturemeasurementpositionoftherefrigeratorcompartment.Inthisway,thetemperaturevaluecanbeconvenientlyobservedatanytimetocheckwhethertheoptimalpreservationtemperatureisreached.6.3TemperatureDetectioninGreenhousesThesystemisusedinplasticgreenhousesforgreenhousevegetablecultivationandflowerproduction.Inthisway,automatictemperaturedisplaycanberealized,andlaborandtimefortemperaturemeasurementcanbesaved.6.4TemperatureofSoilIntheprocessofplantingcropswithstrictrequirementsonsoiltemperature,thesystemcantestthechangesinsoiltemperatureasneededtofacilitatethegraspofaccuratetemperaturevalues.VIIConclusionThesingle-chiptemperaturemeasurementsystemtakesfulladvantageofthesimplicityofthehardwarestructureofDS18B20andAT89S52,using8-segmentdigitaltubedisplay,lowpriceandwideapplication.Accordingtoactualneeds,wecanalsouseLCDasadisplaydeviceorformadistributedtemperaturemeasurementandcontrolsystem.Althoughthedesigniseasytoexpand,italsohasitsshortcomings.Thesimplicityofthehardwarestructurecomesattheexpenseofsoftware.Therefore,specialattentionshouldbepaidtotheworkingsequencerequirementsofDS18B20duringprogramming.Inshort,thesystemcanbewidelyusedintemperaturemeasurementinagriculturalproduction.FAQWhatisDS18B20temperaturesensor?TheDS18B20isa1-wireprogrammabletemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.HowdoestheDS18B20work?Itworksontheprincipleofdirectconversionoftemperatureintoadigitalvalue.IsDS18B20athermistor?Athermistorisathermalresistor-aresistorthatchangesitsresistancewithtemperature....Thermistorshavesomebenefitsoverotherkindsoftemperaturesensorssuchasanalogoutputchips(LM35/TMP36)ordigitaltemperaturesensorchips(DS18B20)orthermocouples.HowaccurateisDS18B20?TheDS18B20readswithanaccuracyof0.5Cfrom-10Cto+85Cand2Caccuracyfrom-55Cto+125C.Whatisds1820?TheDS18B20isonetypeoftemperaturesensoranditsupplies9-bitto12-bitreadingsoftemperature....Thecommunicationofthissensorcanbedonethroughaone-wirebusprotocolwhichusesonedatalinetocommunicatewithaninnermicroprocessor.HowdoIconnectmyDS18B20tomyRaspberryPi?OnceyouveconnectedtheDS18B20,powerupyourPiandlogin,thenfollowthesestepstoenabletheOne-Wireinterface:1.Atthecommandprompt,entersudonano/boot/config.txt,thenaddthistothebottomofthefile:2.dtoverlay=w1-gpio.3.ExitNano,andrebootthePiwithsudoreboot.WhatistheworkingprincipleofDS18B20?TheDS18B20DigitalThermometerprovides9to12-bit(configurable)temperaturereadingswhichindicatethetemperatureofthedevice.Itcommunicatesovera1-Wirebusthatbydefinitionrequiresonlyonedataline(andground)forcommunicationwithacentralmicroprocessor.Inadditionitcanderivepowerdirectlyfromthedataline(parasitepower),eliminatingtheneedforanexternalpowersupply.ThecorefunctionalityoftheDS18B20isitsdirect-to-digitaltemperaturesensor.Theresolutionofthetemperaturesensorisuser-configurableto9,10,11,or12bits,correspondingtoincrementsof0.5C,0.25C,0.125C,and0.0625C,respectively.Thedefaultresolutionatpower-upis12-bit.WheretouseDS18B20Sensor?TheDS18B20isa1-wireprogrammableTemperaturesensorfrommaximintegrated.Itiswidelyusedtomeasuretemperatureinhardenvironmentslikeinchemicalsolutions,minesorsoiletc.Theconstrictionofthesensorisruggedandalsocanbepurchasedwithawaterproofoptionmakingthemountingprocesseasy.Itcanmeasureawiderangeoftemperaturefrom-55Cto+125withadecentaccuracyof5C.EachsensorhasauniqueaddressandrequiresonlyonepinoftheMCUtotransferdatasoitaverygoodchoiceformeasuringtemperatureatmultiplepointswithoutcompromisingmuchofyourdigitalpinsonthemicrocontroller.HowconnectDS18B20toArduino?FirstplugthesensoronthebreadboardtheconnectitspinstotheArduinousingthejumpersinthefollowingorder:pin1toGND;pin2toanydigitalpin(pin2inourcase);pin3to+5Vor+3.3V,attheendputthepull-upresistor.OnanATMega328P,whyisaDS18B20temperaturesensorreturningincorrecttemperaturevalues?Severalpossibilities:1.Ifitisjustreadingalittlehigh,itmightbecausedbyselfheating.Addaheatsinkand/ormakemeasurementslessfrequently.2.Especiallyifthevaluesarereallywhacky,itmightbecodewitherrorsormis-wiring.Useapublishedsketchtocheckoperation.3.TheDS18B20mightbedefective.Tryanother.4.Itsaccurateto0.5C.Areyouexpectingittobemoreaccurate(likedowntotheLSBofthereadvalue)?IDescriptionThisblogintroducesandanalyzes4simpleandeasy74LS00NandGatecircuitdiagrams.Itsincluding:SquareWaveGeneratorCircuit,PulseGeneratorCircuit,LEDLightCircuit.Andintheend,wewillanalyzethecircuitthatturnsthetimerintoacountdowntimerindetail.ThisVideoisAnIntroductionof7400LogicDevicesCatalogIDescriptionIISquareWaveGeneratorCircuitIIIPulseGeneratorCircuitIVLEDLightCircuitVTurnTimerintoCountdownTimer5.1SchemeDesign5.2ImplementationofSchemeDesignOrdering&QuantityIISquareWaveGeneratorCircuitLetstakealookatthefigurebelow.Itsasquarewavegeneratorcircuit.Thiscircuitcontainsa74LS00NandGateintegratedcircuit.Figure1.SquareWaveGeneratorCircuitDiagramAmongthiscircuitdiagram:NANDgates1,2andexternalRCtimeconstantcomponentsformanoscillatorcircuitNANDgate3isabufferoutputstage.AslongasthecapacityofCischanged,squarewaveoutputsofdifferentfrequenciescanbeobtained.IIIPulseGeneratorCircuitFigure2.PulseSignalGeneratorCircuitDiagramThecircuitdiagramisshowninFigure2anditsasimplepulsesignalgeneratorcircuit.ThesignalgeneratormainlyusestwoTTLintegratedcircuits(74LS00and74LS221).Sowhychoosethesetwocircuits?Thatisbecause,thesetwocircuitscanbeusedtogenerateapulsesignalof=4s.Besides,itusesfewercomponentsandisconvenientfordebuggingandmaintenance.IVLEDLightCircuitThiscircuitismadewithNE555,74LS00,74LS154,74LS193andLEDlights,andtheproductionprocessisverysimple.Whenweturnonthepower,hereishowitworksis:WhentheoutputQ0ofthe74LS154decoderislow,the74LS193isapositivecounter.Atthistime,theLEDsareindividuallylitfromD1...D16;WhentheoutputQ15ofthe74LS154decoderislow,the74LS193isacountdowncounter.Atthistime,theLEDsareindividuallylitfromD16...D1.Figure3.LEDLightCircuitDiagramFromtheabovewecanseethat:theLEDlightsturnonfromD1toD16,andthenbacktoD1fromD16,andsoon.VTurnTimerintoCountdownTimerGenerally,therearetwodesignideasforturningatimerintoacountdowntimer:First,changethecountingchipinthetimer;Second,resetthefunctionofthechip.Besides,thereisactuallyanotherwaytoachievethisgoal:Byappliyingthe74LS00and74LS20chipstoreversetheresultsonthedisplay,soastoachievethepurposeofcountingdown.5.1SchemeDesignTheresultdisplayedbyeachdigitofthetimerisanincrementalvalue,suchas0.1.2.3.4.5.6.7.8.9.Yet,thecountdowntimerdisplaysadecreasingvalue,suchas9.8.7.6.5.4.3.2.1.0.Aslongasthedisplayresultconversioniscompletedwithasuitablelogiccircuit,thetimercanbeturnedintoacountdowntimer.Atfirst,weneedtofindthelogicalrelationshipbetweenthetimerdisplayresultandthecountdowntimerdisplayresult.Table1belowliststheBCDcodescorrespondingtoeachdisplayresultofthetimerandcountdowntimer.Fromthistable,youcaneasilyfindtheBCDcodesofthetimerandcountdowntimer:ThelowestbitQ1andY1areopposite;WhileQ2andY2arethesame;RelationshipbetweenQ3andY3:Y3ofthecountdowntimeristheexclusiveORoftimerQ3andQ2;RelationshipbetweenQ4andY4:TheY4bitofthecountdowntimeristheoppositevalueoftheORofQ4,Q3,andQ2ofthetimer,whichisalsoequaltothenon-re-ANDofQ4,Q3,andQ2.Table1.CorrespondingBCDCodeDisplayedby(Down)TimerTheabovelogicalexpressionis:Therefore,aslongasyouchooseacircuitthatcancompletetheabovelogicconversionrelationship,youcanrealizethedesignfromatimertoacountdowntimer.Thefigure?showsatwo-digittimercircuit.Afteraddingtheaboveconversioncircuit,itbecomesthefigure3showsthecountdowncircuit.Figure4.TimerCircuitDisplaying2DigitsFigure5.CountdownCircuitDiagram5.2ImplementationofSchemeDesignTwokindsofchips74LS00and74LS20areuesdhere.Theformerarefourtwo-inputNANDgates,whichareusedtocompletetheconversionofY1andgeneratethenegationofQ4,Q3,andQ2.Thelatteraretwofour-inputNANDgates,whichareusedtoobtainY4fromthenon-reANDofQ4,Q3,andQ2.Insummary,wecanfollowthelogicalrelationshipasfollows:ThelogicdiagramisshowninFigure6.Figure6.LogicDiagramKnowingthattheXORgateoperationcanbecompleted,theY3conversioncanbecompleted.Theconnectioncircuitdiagramoftheabove-mentionedY4,Y3,Y1conversionspecificphysicalobjectsisshowninFigure7.Figure7.Y4,Y3,Y1ConversionSpecificPhysicalConnectionDiagramFigure8showstheactualpictureofthecountdowntimer.Figure8.CountdownTimerSofar,thetimerhasbecomeacountdowntimer.Throughthisdesignmethod,thereisnoneedtochangetheoriginalcountercircuit,isitparticularlytrouble-free?I.IntroductionTDA7294isaveryinnovativeDMOShigh-powerintegratedamplifiercircuitlaunchedbythefamousEuropeanSGS-THOMSONSTMicroelectronicstomainlandChinainthe1990s.Itsweepsawaytheraw,cold,andhardtonesofthepreviouslinearintegratedpoweramplifiersandthickfilmintegration,andiswidelyusedintheHI-FIfield:suchashometheater,activespeakers,etc.Thedesignofthischipfocusesontone,andhastheadvantagesofbipolarsignalprocessingcircuitandpowerMOS.Ithasthecharacteristicsofhighvoltageresistance,lownoise,lowdistortion,andveryaffinityforreplayingsound;andhasasilentstandbyfunction,short-circuitcurrentandoverheatprotectionfunctionstomakeitsperformancemoreperfect.ThisarticlewillintroduceseveralpoweramplifiercircuitdesignsbasedonTDA7294.CatalogI.IntroductionII.OCLCircuitIII.BTLCircuitIV.ConstantCurrentPowerAmplifierV.Hi-FiIntegratedPowerAmplifierVI.ActiveSubwooferAmplifierAddsStandbyFunctionVII.HighFidelityPowerAmplifierVIII.ClassABPowerAmplifierIX.Two-channelPowerAmplifierX.100WPowerAmplifierCircuitOrdering&QuantityII.OCLCircuitTheOCLcircuitdiagramisshowninFigure1.Thiscircuitisadual-channel70WpoweramplifiercomposedoftwoTDA7294.Therearefewexternalcomponentsandsimplecircuit.Whenthepowersupplyvoltageis35V,70Wcontinuousoutputpowercanbeobtainedonan8ohmload.Itisverysuitableforplaybackinanenvironmentbelow30squaremeters.Ifthespeakerimpedanceislessthan8ohms,thepowersupplyvoltageshouldbereducedaccordingly.Figure1OCLCircuitDiagramIII.BTLCircuitTheBTLcircuitisshowninFigure2.ItusestwoTDA7294bridgestoformaBTLpoweramplifiercircuit.Theoutputpowercanreachmorethan150W.Itissuitableforplacesthatrequirehighpowersuchasdancehalls.4TDA7294arerequiredforstereo.Whenthepowersupplyvoltageis25V,acontinuousoutputpowerof150Wcanbeobtainedonan8ohmload.Whenthepowersupplyis35V,acontinuousoutputpowerof180Wcanbeobtainedona16ohmload.WhenuseTDA7294asBTLpoweramplifier,theloadmustnotbelessthan8ohms.Figure2BTLCircuitDiagramIV.ConstantCurrentPowerAmplifierThispoweramplifiercircuitissomewhatdifferentfromtheprevioustwostructures.Itsfeedbackcircuitiscurrentsampling,voltagesummationandnegativefeedback.Thiskindofcircuitstructureistheconstantcurrentpoweramplifierthatpeopleoftensay.Thespecificanalysisofthecircuitwillnotbedetailed,onlythemoreprominentadvantagescomparedwiththetraditionalconstantvoltagepoweramplifierwillbeintroduced.(1)Theoutputcurrentofthepoweramplifierhasnothingtodowiththeloadimpedance.Eveniftheloadisshort-circuited,itwillnotcausetheamplifiertooverheat.(2)Theoutputpowerincreaseswiththeincreaseofloadimpedance.Pushingthespeakerloadwithinacertainpowerreservecanensurethebassstrengthandhighfrequencyresolutionoftheoriginalmusicsignal.(3)Theforceactingonthevoicecoilofthespeakeronlydependsonthecurrent.Theuseoffluid-controlledoscillationtopromotethespeakermustbefasterthanthevoltage-controlledoscillation,sothattheinputandoutputimpedanceofthespeakervibrationsystemcanbeeasilymatched.Theconstantcurrentpoweramplifiercircuitisactuallyacontrolledcurrentsourcecontrolledbytheinputsignalvoltage.Itsinternalfeedbackcircuitiscurrentsampling,voltagesummingnegativefeedback,andithasthecharacteristicsofhighinputandoutputimpedance.Theinputimpedanceishigh,whichisexactlywhatthepreviousstageconstantvoltageamplifiercircuitneeds,whichisbeneficialforthesignalvoltagetobesenttotheinputendofthepoweramplifierwithoutloss.Thehighoutputimpedancecanreducetheshuntoftheinternalresistancetothesignal,whichisconducivetoaddingtheoutputsignalcurrenttotheload.InFigure3,thepowersupplyvoltageisselectedas35V,anditsmagnificationisdeterminedbytheratioofthespeakertoR6.Figure3ConstantcurrentpoweramplifiercircuitdiagramV.Hi-FiIntegratedPowerAmplifierThefamousEuropeanSGS-THOMSONSTMicroelectronicshaslaunchedaHi-Fihigh-powerDMOSintegratedamplifiercircuitTDA7294.ThecircuitisshowninFigure4.Itintegratesthebestdesignofmodernpoweramplifiercircuit,combinestheadvantagesofbipolarsignalprocessingcircuitandpowerMOS,hasthecharacteristicsoflownoiseandlowdistortion;standbyandmutecircuitcompletelyeliminatestheimpactnoisecausedbypoweronandoff,andeliminatesspeakerprotectioncircuitoverheating,short-circuitcurrentprotectionandotherfunctionsmakeitsperformancemoreexcellent.ThisdeviceissuitableforhometheaterandHi-Fiamplifiers.Themainparametersare:VS(powersupplyvoltage)10~40V(maximumvoltagewithoutsignal50V);Io(peakoutputcurrent)10A;Po(RMScontinuousoutputpower)70Wwhenvs=35V8;vs=70Wwhen27V4;(effectivevalueofmusicoutputpower)100WwhenVS=38V8;100WwhenVS=29V4.Figure4Hi-FiIntegratedPowerAmplifierCircuitDiagramTheclosed-loopgainofthecircuitinFigure4is30dB.IncreasingR3canincreasethegain,andviceversa,buttheamplifiergainshouldbe24dB.TheamplifierhasthebestperformancewhenR1=R3.R7,C4andR5+R6,C3determinethestandbyandmutetimeconstants.Thelargerthevalue,thelongerthetime.Whenthecontrolterminalisconnectedtolowpotentialground,itismuteandstandby;whenthecontrolterminalisconnectedtoVS,because(R5+R6)R7,pin⑩risestoahigherpotentialthanpin⑨,andturnstoalowpotentialfirstwhenshuttingdown,whichmakesthestandbyandshutdownprocessesgooninasilentstate,ensuringthattheamplifieristurnedonandoffwithoutnoise.Figure5BTLPoweramplifierfinishedboardForhigh-powerprofessionalapplicationsfiledssuchasdancehalls,youcanchoosetheBTLpoweramplifierfinishedboardshowninFigure5.BothTDA7294areequippedwiththeirownprofessionalradiators.Whenvs=25V8,themaximumcontinuousoutputpowerreaches150W;when35V16,Themaximumcontinuousoutputpowerreaches170W.WeusedTDA7294standardapplicationcircuitandMarantzPM80andYAMAHAA-592tomakealisteningcomparison.Theformerisamid-pricedHi-FimachinewithaClassA,ClassAandBstatusswitch,andthelatterisa439.16dollarsclasswithAc-3inputAVpoweramplifier,audiosourceismusicfaxE60CD,speakerisTannerNo.5.ItturnsoutthatthesoundorientationofTDA7294hasadistinctiveEuropeanstyle,soft,mellow,delicate,andfullofbouncingfeeling.ItissimilartotheMarantzPM-80inClassAandBstatus,butthesoundfieldofPM-80isdeeperwhenworkinginpureClassA.ComparedwithYAMAHAA-592,thedifferenceislarger.ThelowfrequencyofA-592seemstobeslightlyimproved.Itsoundspowerful,butitisharderandthelinesareblurry.TDA7294issweetandnatural,withhigherresolution,reallylikelandscapepaintingdonewithsplashesofinkandfine-brushflowersandbirds(atechniqueofchineseink-painting),eachhasitsinfinitecharm.VI.ActiveSubwooferAmplifierAddsStandbyFunctionThiscircuitisanimprovementontheaudiocircuitusingtheintegratedcircuitTDA7294.ThecircuitdiagramisshowninFigure6.TDA729410pinhasamutefunction.WhentheexternalDCprovideshighlevel,theintegratedblockisintheworkingstate;whenthelowlevelisapplied,theintegratedblockisinthecut-offstate.Atthistime,thecircuitconsumeslittlepowerandIC114pinhasnooutput,thatis,standbyform.Thegeneralcircuitistoprovideahighleveltopin10tomakeitintheconductingstate,infact,thedevelopmentofthispinfunctioncanmeetsomespecialworkrequirements.Thiscircuitisbasedonthistoincreasethestandbyfunctionoftheactivesubwooferpoweramplifier,anditscircuitisreliableandresponsive.Figure6ActivesubwooferamplifieraddsstandbyfunctioncircuitdiagramVII.HighFidelityPowerAmplifierThecircuitisshowninFigure7.ThedrivestageadoptsTDA7294.Theinternaldrivestageandoutputstageofthechipusefieldeffecttubes,whicharepoweredby40V,andtheoutputpowercanreach70W(RL=8;THD=0.005%).Ithasadelicatetoneandanexcellentsenseofhearing.PoweroutputVT1,VT2adoptsShankenhigh-powerpairtube2SA1394,2SC3858.Thecircuitprincipleisasfollows:ThesignalisinputtotheTDA7294non-invertinginputpin③throughC1andR1.R7andR3,C3,C4ofICpin②formanegativefeedbacknetwork,theclosedloopgainofthisamplifierisabout34times.The⑨and⑩pinsarethestandbyandmuteterminalsrespectively.SincetheRCnetworktimeconstantofthe⑩pinislargerthanthatofthe⑨pin,theswitchingmachinesareallperformedundermutesatge,avoidingtheswitchingimpactsound,andC7isabootstrapcapacitor.Figure7High-fidelitypoweramplifierpromotedbyTDA7294Productionpoints:(1)InsulatingmicasheetsshouldbeaddedbetweenthemetalcapandtheheatsinkofTDA7294(themetalcapisconnectedtothepin⑧).(2)Thepowertransformerusesring-shaped300Wdouble20V,four50V/10000Ffiltercapacitors,two50V/100F,andtwo100V/0.1F.Thepowersupplypartshouldbetestedseparately,firstwithoutconnectingthepoweramplifier,measurewhetherthepositiveandnegativeoutputvoltageofthepowersupplyaresymmetrical,theerrorshouldbewithin0.6V.(3)Whentestingthemachine,forsafetyreasons,youshouldfirstusealowervoltagetest(suchas25V)withoutaddingasignal,andmeasuretheDCvoltageoftheoutputterminaltotheground.Normally,itshouldbewithin20mV.(4)R8,R9,R10,D1formthefinalbiascircuit.ThisbiasmakestheoutputtubesVT1andVT2notcutoffduringoperation,sothequiescentcurrentcanbesmall(about5mA).(5)Thepowertubeshouldbestrictlymatched(within3%)andgenuineproductsshouldbeselected.TheoutputresistanceR14isa5Wnon-inductivetype,andtheinductorLisformedbytightlywinding10turnsonR14withadiameterof1.5mmenameledwire.TDA7294uses60mmTimes,85mmTimes,20mm12-slotheatsink,andtheoutputpairtubeneedsaprofessionalheatsink.Thesectionswithhighcurrentontheprintedboardneedtobetin-rolled,whichisextremelybeneficialforthetransparencyandstrengthofthesound.Figure8PoweramplifierPCBpromotedbyTDA7294VIII.ClassABPowerAmplifierTDA7294integratedcircuitcanbeusedasahigh-fidelityaudioclassABpoweramplifier.Itcandrive4ohmor8ohmspeakers,andwhenconnectedtoan8ohmspeaker,itwillprovide50wattsofoutputpowerand0.1%THD.Figure9ClassABpoweramplifiercircuitdiagramYoumustinstallalargeenoughradiatorforTDA7294.Pin10isamuteinput,andpin9providesastandbymode.Muteshouldalwaysoccurwhenselectingstandbymode.TheIChasinternalthermalprotection,whichcausesmutereductionat145C,andtheamplifierentersstandbyat150C.TheTDA7294integratedcircuitheatsinkisinternallyconnectedtothenegativepowerrail.Ifthemoduleisinstalledinagroundedmetalenclosure,thentheICmustbeinsulatedfromtheheatsink.Ifnot,thenegativepowerrailwillbeshortedtoground.IX.Two-channelPowerAmplifierTDA7294high-powerintegratedcircuitICisspeciallydesignedforassemblinghigh-performanceaudioamplifiers.TwoTDA7294piecescanbeusedtomakeapowerfuldual-channelhigh-fidelitypoweramplifier.ThecircuitprincipleisshowninFigure10.TheoverallcircuitiscomposedoftwoTDA7294corecomponents,andtheperipheryincludessomeresistorsandcapacitors.Thecircuitsofthetwochannelsarealmostidenticalindesign.TheyallusethestandardcircuitofficiallyreleasedbyTDA7294,connectedtoanon-invertingamplifiercircuit,withavoltagegainof30.5dB,anoutputpowerofupto70Wperchannel,andadualpowersupplysymmetricalpowersupplyvoltage35V.Amongthem,Cl5andCl6areinputcouplingcapacitors.0.47Fisusedintheoriginalcircuit.Here,ifyouincreaseitto1F,youcanimprovethelow-frequencyresponseofthecircuit.Itisrecommendedtousepolypropylenespecialaudiocapacitors,suchasWIMAsMKT4seriescapacitors,itcangreatlyimprovethesoundresolution.R3andR4areinputresistances,whichdeterminetheinputimpedanceofTDA7294inthein-phaseamplificationstate.Here,22kisrelativelymoderate.Toolargeavaluecanreducetheburdenonthefront-endsignalsource,butitmayaffectthestabilityofTDA7294andmaketheoutputmidpointvoltagedriftincreased,toosmallvaluewillaffecttheresponseabilitytolowfrequency.ThetheoreticalvalueofthefeedbackresistorsR7andR8shouldbeequaltotheinputresistorsR3andR4,whichcanensurethebiascurrentbalanceoftheTDA7294inputdifferentialcircuitandreducesignaldistortion.ThefeedbackgroundresistanceR5,R6cooperateswithR7,R8tosetthecircuitgain.Here,thefeedbackDCblockingcapacitorsCl3andCl4areusedtoformACnegativefeedback,inhibitDCvoltageoutput,andprotectthespeaker.Figure10Two-channelpoweramplifiercircuitdiagramTDA7294hasastartmutefunction,andcooperateswithanexternalcircuittoachieveanon-impactsoundeffectwhenthepoweristurnedonandoff.R9,R1O,R11,Rl2,Cl7,Cl8andVD5,VD6intheschematicdiagramformanexternalmutecontrolcircuit.Delaytheenergizationofpins9and10ofTDA7294toachievethefunctionofsoftstart.Thepowersupplyrectifierfiltercircuitisalsoverysimple.Thefullbridgerectifiercircuitiscomposedof4EuropeanspeedrectifierdiodesVD1-VD4.CapacitorsC1andC2arethemainfiltercapacitors.Large-capacityandhigh-currentaudiofiltercapacitorsarerequired,suchasELNAsFORAUDIOseriesorBHCAerovoxindustrialgradecapacitors.DesignPCBisgenerallyabottleneckinamateurproduction,sothatmanyexcellentschematicdiagramshavenotbeentransformedintofinishedPCBsthatcanbeactuallyassembled.Here,thepopularProtel99sedesignsoftwareisusedtodrawtheprintedcircuitboardagainsttheschematicdiagram10,asshowninFigure11.The2mmthickFR-4board-baseddouble-sidedPCBisused,andthecopperfoilisthickenedto70mm,whichissuitableforhighcurrentpoweramplifiers.ThewholePCBtraceadoptsone-pointgroundingmethod,whicheffectivelyeliminatesgroundwireinterferencenoise.Insomehigh-currenttraces,tinplatingisalsoadoptedtoincreasetheadditionalcurrentcarryingcapacity.Thepowerinputandpoweroutputstructureuseshigh-currentscrewterminalstoensuresufficientover-currentcapabilityanddurabilityofrepeatedwiring.Figure11PrintedcircuitboardX.100WPowerAmplifierCircuitFigure12100WpoweramplifiercircuitdiagramcomposedofTDA7294Figure12isa100WpoweramplifiercomposedofamonolithicaudiopoweramplifierintegratedcircuitTDA7294.TDA7294includespre-opamplifier,finalpoweramplifier,temperatureprotection,shortcircuitprotection,mutecontrolandothercircuits.ThefinalstageadoptsbipolarDMOSpowertransistor,whichhasthecharacteristicsofhighoutputpower,bandwidth,lowdistortion,andgoodversatility.Theintegratedcircuitalsohasperfectanti-overload,anti-shortcircuitandtemperatureprotectioncircuitfunctions.Whenthechiptemperatureistoohigh,itautomaticallycutsofftheaudiosignaltoprotectthechipfromburningThepoweramplifiercircuitcomposedofTDA7294hasthecharacteristicsofsimpleperipheralcircuitandeasyproduction.Thecircuitinputimpedanceis20k,theinputsensitivityis750mV,thevoltagegainis32dB,thepowersupplyvoltagerangeis(25~40)V,andthequiescentcurrentis50mA.Whentheloadimpedanceis8,theoutputpoweris100W;whentheloadimpedanceis4,theoutputpowercanreach180W.Inactualproduction,TDA7294shouldbeequippedwithenoughheatsinks.Thesupportingpowercircuitshouldhavesufficientcapacity.Ifyouneedtoincreasethecircuitvoltagegain,youcanappropriatelychangetheratioofR3toR2,voltagegainA=201g(R3/R2)(dB).However,itisnotadvisabletoone-sidedlypursuethevoltagegainofthisstage.Excessivevoltagegaincaneasilycausecircuitself-excitation.Thesolutionistoincreasethevoltagegainofthepre-stage.

DS28E01P-100+T-MAXIM

I.DescriptionTDA2030Aisoneofthehigh-fidelityintegratedpoweramplifiers,andmanypoweramplifiercircuitsusethisintegrationmethod.TDA2030isalsoaHI-FIpoweramplifierintegratedblockusedbymanycomputeractivespeakers.Ithassimpleconnectionmethodandaffordableprice.Theratedpoweris14W.Thepowersupplyvoltageis6~18V.Theoutputcurrentislarge,theharmonicdistortionandthecrossoverdistortionaresmall(14V/4ohm,THD=0.5%).Ithasexcellentshortcircuitandoverheatprotectioncircuit.Thefollowingdescribesitsconnectionandapplicationcircuit.CatalogI.DescriptionII.Connection2.1SinglePowerConnection2.2DualPowerConnectionIII.ApplicationCircuit3.1OTLFormPowerAmplifier3.2OCLFormPowerAmplifier3.3BTLFormPowerAmplifier3.440WPowerAmplifierCircuit3.5High-fidelityActiveSpeakerCircuit3.625WBridgeLowFrequencyPowerAmplifierCircuitOrdering&QuantityII.ConnectionItsconnectionmethodisdividedintosinglepowersupplyanddualpowersupply:2.1SinglePowerConnectionFigure1TDA2030singlepowerconnectiondiagram2.2DualPowerConnectionFigure2TDA2030dualpowerconnectiondiagramIII.ApplicationCircuit3.1OTLFormPowerAmplifierOTLformpoweramplifier:singlepowersupply,outputcouplingcapacitor.TheR5(150k)andR4(4.7k)resistorsinthecircuitshowninFigure3determinetheclosed-loopgainoftheamplifier.ThesmallertheR4resistor,thegreaterthegain,buttoolargegaincaneasilycausesignaldistortion.Twodiodesareconnectedbetweenthepowersupplyandtheoutputterminaltopreventtheinductiveloadofthespeakerfromkickingbackandaffectingthesoundquality.ThecapacitorofC3(0.22uF)andtheresistanceofR6(1)areusedtocompensatetheinductiveload(speaker)toeliminateself-excitation.Thecircuitusesa36Vsinglepowersupplyandtheoutputpowerisabout20W.Figure3OTLtypepoweramplifiermadewithTDA2030A3.2OCLFormPowerAmplifierTheformoftheOCLpoweramplifieradoptsdualpowersuppliesandhasnooutputcouplingcapacitor.AsshowninFigure4,sincethelowfrequencyresponseoftheoutputcouplingcapacitorisimproved,itisahigh-fidelitycircuit.Thedualpowersupplyusesatransformerwiththemiddlepointoftheprimarycoilgroundedandtheupperandlowervoltagesaresymmetricalandequal.Afterrectificationandfiltering,a18Vdualpowersupplyisformed,andtheoutputpoweris20W.Figure4OCLtypepoweramplifiermadewithTDA20303.3.BTLFormPowerAmplifierThemainfeatureofBTLis:itiscomposedoftwoidenticalpoweramplifiers,andtheinputsignalsareinversetoeachother.Thein-phaseinputandtheinvertedinputoftheamplifierareactuallyusedtoensurethattheinputsignalsareinversetoeachother.Atthesametime,theamplitudesofthetwoinputsignalsshouldbethesame,sothatthebasicrequirementsoftheBTLcircuitformcanbemet.ThecircuitdiagramisshowninFigure5,whereR7(1k)andR8(33)resistorsdividethesignalandtheattenuationfactorisexactlythesameastheamplificationfactorofU1.TheattenuatedsignalisaddedtotheinvertinginputterminalofU2throughR5.Infact,twoopampscompleteasignalamplification,andtheactualmeasuredoutputlevelis1.5timeshigherthanthatofanintegratedcircuit.Thatis,theoriginaloutputpoweroftheopampis20W,andtheoutputpowerisnowabout50W.However,duetothecharacteristicsoftheBTLcircuit,whenchoosinganintegratedcircuit,usetwooperationalamplifiercircuitswiththesameparametersasmuchaspossibletoadjusttheinputsignalamplitude.Youcanuseanoscilloscopetoobservetheamplitudeofthetwoinputsignalsbyinputtingasinewave.Atthistime,adjustR7tomakethetwoinputsignalsTheamplitudeisthesametoensurethatthenonlinearsymmetrydistortionisminimizedwhileincreasingthepower.Figure5BTLtypepoweramplifiermadewithTDA2030A3.440WPowerAmplifierCircuitFigure6isa40WpoweramplifiercircuitmadebyTDA2030poweramplifierintegratedblockandBD907/908:Figure640WpoweramplifiercircuitmadebyTDA20303.5High-fidelityActiveSpeakerCircuitAhigh-fidelityactivespeakercircuitdesignedwithTDA2030,thecircuitdiagramisshowninFigure7.Usingdualpowersupply,addedhighandlowbassandvolumeadjustment.WhendesigningthePCB,thegroundwireshouldnotpassthroughthecomponentpinsasmuchaspossibletoreduceDCnoise.Figure7Highfidelityactivespeakercircuitdiagram3.625WBridgeLowFrequencyPowerAmplifierCircuitFigure825WbridgelowfrequencypoweramplifiercircuitThecircuitinFigure8usestwoTDA2030sconnectedtoformabridgecircuit,withthesamecircuitstructureandparametersonbothsides.Theintegratedcircuitontherightiscontrolledbytheintegratedcircuitontheleftthrougha22knegativefeedbackresistor,andviceversa.Thediode1N4001isusedtopreventthespeakerinductiveloadfromgeneratingovervoltageanddamagingthedevice.Theamplificationfactorofthecircuitcanbeadjustedbychangingthenegativefeedbackvoltageratiobetweentheoutputterminal(pin4)andtheinvertinginputterminal(pin2).IDescriptionThisblogintroducesthepoweramplifierwithNE5532andLM1875Tasthecorecomponents.Thepoweramplifierwearediscussinghereisahigh-fidelitytwo-channelstereosubwooferpoweramplifier.Here,wewilldiscussitsmethodsandprocedures,schematicdesign,assemblyanddebugging,andspeakerproduction.Hopethisblogcanprovideagoodreferenceforbeginners.Figure1.LM1875CatalogIDescriptionIILM1875TandNE5532Overview2.1PowerAmplifierLM1875T2.2Pre-amplificationComponentNE5532IIICompositionofPowerSupplyIVAssemblyandDebuggingSpeaker4.1ElectricalInspection4.2BoxProductionVIntheEndOrdering&QuantityIILM1875TandNE5532OverviewFirst,weintroducethecorecomponentsthatwewilluse.Andthen,thebasiccharacteristicsofthesecomponents.Audiopoweramplifierisgenerallycomposedofthefollowingthreeparts:powersupply,pre-amplifierandpost-amplifier.Here,wewillusehigh-efficiencyHI-FIpowerintegratedchipLM1875Tasthecoreoriginal.LM1875Tadoptsapositiveandnegative15Vdualpowersupply,theleft,andrightchannelsworkinOCLmode,andthebassworksinBTLmode.AsfarasthecharacteristicsofLM1875Tareconcerned,ithasthecharacteristicsofgoodsoundquality,goodfrequencyresponse,lowcostandrelativelysimplecircuit.Inaddition,thepre-amplifierpartusestheNE5532integratedoperationalamplifier.2.1PowerAmplifierLM1875TLM1875Thasexcellentperformance.Manyluxury-lookingactivespeakers,mid-rangepoweramplifiers,andsubwoofersonthemarketuseLM1875T.ThepoweramplifiercircuitcomposedofLM1875Tchiphasthefollowingcharacteristics:Theoutputpowerislarge,themaximumpowercanreachabout20W;Thestaticcurrentissmall,theloadcapacityisstrong,andthedynamiccurrentislarge,whichcandrive4~8speakers;Thecircuitissimple,easytomanufactureandlowcost;Withaninternalprotectioncircuit,itisahigh-fidelitypoweramplifiercomponentwithstableperformance.Theblogdesignofthisarticleisadual-channelstereosubwooferpoweramplifier,butLM1875Tisamono-channelpoweramplifierintegratedcircuit,sothedual-channelOCLworkingmodeusesoneLM1875Tforeachchannel.SincethebassworksinBTLmode,wehavetousetwopieces.LM1875Thas5pins.Theyarepositivepowersupply,negativepowersupply,positiveinput,reverseinput,andoutput.ThecircuitisshowninFigure2.Figure2.LM1875Circuit2.2Pre-amplificationComponentNE5532Beforethepoweramplifiercircuit,itisgenerallynecessarytoaddapreamplifier.Thepurposeofthisistoamplifythevoltageofvariousinputweakelectricalsignals.Inordertoensurethattheoutputelectricalsignalhashighfidelity,thepre-amplifierisNE5532.NE5532isahigh-performance,low-noise,dualoperationalamplifierintegratedcircuit.Comparedwithmanystandardopamps,NE5532hasbettersoundperformance,excellentoutputdrivecapability,relativelyhighsmallsignalbandwidth,andlargepowersupplyvoltagerange.Therefore,itisverysuitableforhigh-qualityandprofessionalaudioequipment,instruments,controlcircuitsandtelephonechannelamplifiers.Whenusedforaudioamplification,thetoneiswarmandhighfidelity.ThefunctionalblockdiagramofNE5532isshownasinFig.3.Figure3.NE5532FunctionalBlockDiagramIIICompositionofPowerSupplyLM1875Tadoptsapositiveandnegative15Vdualpowersupply.TheoperatingvoltageofNE5532isalso15V.Weneedtostepdownthemainspowerto15Vthroughastep-downtransformer,thenrectifyitthroughtherectifierbridgeKBL406,filteritthroughalargecapacitor,anddirectlysupplyittothepoweramplifier.Inthisway,largeroutputpowerisobtained.After7815and7915,theregulatedoutput15VisusedasthepowersupplyofthepreamplifierNE5532.ThecompositionofthepowersupplyisshowninFigure4.Figure4.PowerCircuitFigure5.PowerAmplifierCircuitBoardIVAssemblyandDebuggingSpeakerWhenstartingthecircuitinstallation,firstcheckthecircuitboardagainstthecircuitdiagram.Forexample,checkwhetherthemaincomponentsareinstalledcorrectly,andwhetherthesolderjointshavemissingsolderingorfalsesoldering.Thenturnonthepowertodebugthecircuit,andmakespeakersafterthedebuggingiscompleted.TheactualproductionisshowninFigure6.Figure6.PhysicalShootingPic4.1ElectricalInspectionUseanACsignalgeneratortoaddatinysinusoidalsignaltothesignalinput.Then,usetheoscilloscopetomeasurethethreeoutputsignalsofthepoweramplifierboard.Atthistime,observewhetherthesinemeetstherequirementsandwhethertheparametersinthetestarerelativelystable.Then,connecttwofull-rangespeakerstotheleftandrightchannels,andconnectawoofertothebassoutputport.Atthistime,addthesongsignaltocarefullycheckwhetherthethreespeakersareworkingproperlyandthesoundisgood.Iftheabovestepsarewellexpressed,thenproceedtothenextstep.4.2BoxProductionThekeytomakingspeakersistheselection,sizeandothersteps.Intheexperiment,weusedthelaminatesinthelaboratoryforsplicingandassembly.First,drawasketch.Thepaintingisdividedonthreedifferentsubstrates,andthenmadeintotwopartsrespectively.Afterdrilling,polishing,splicingandbonding,thecompletedcircuitpartsareinstalledintheirrespectiveparts.Then,wedividetheentirepoweramplifierintothreeparts.Twosatellitespeakers,aswellasawooferandpoweramplifierboard.Thesethreepartstogetherformacomplete2.1subwooferpoweramplifier.Here,thereisaplacethatneedsspecialattention.Whenmakingthebasspartofthecabinet,theimpactofvibrationshouldbefullyconsidered.Therefore,wehavetodesigndampingcomponents.VIntheEndAftertheinstallationisnormal,connectthemusicsignalsourceandlistentothemusiceffect.Thesoundreproducedbythiscircuithasastrongsenseofhierarchy,aclearsenseoforientation,andanobvioussenseofspaceanddistance.Inaddition,thesoundimageorientationisclear,thewidthisoutstanding,andthesounddynamicrangeislarge,givingpeoplearealfeeling.

DS28E01P-100+T-MAXIM

IntroductionLM3886isahigh-performanceaudiopoweramplifier.ItexhibitsextremelylowTHD+Nvaluesof0.03%attheratedoutputintotheratedloadovertheaudiospectrum,andprovidesexcellentlinearitywithanIMD(SMPTE)typicalratingof0.004%.Itisverysuitablefortheenthusiastswhopursuebothbeautifulsoundqualityandstrongvolume.ThisarticleintroducesseveralpracticalapplicationsofLM3886inhometheatersystems.ThisisatechnicalexaminationvediooftheLM3886Amplifier.CatalogIntroductionCatalogIHighQualityDual-channelPowerAmplifierIIPowerfulBTLPowerAmplifierIIISubwooferSpeakerOrdering&QuantityIHighQualityDualChannelPowerAmplifierLM3886outputsnearly70Wpoweratratedvoltageandthepeakpoweris150W.Thedualchannelpoweramplifieradoptssimpleandtypicalcircuit,whichcanreplaceavarietyofHI-FIpoweramplifier,andissuitablefortheleftandrightmainchannelofpoweramplifierinhomecinema.ThewholecircuitisinstalledonthesamePCB.EachofthetwoLM3886sisequippedwithaspecialaluminumradiator(length140,thickness50,height75(mm)),whicharefixedonbothsidesofthePCBtofacilitateheatdissipation.Thepowertransformercanchoosedouble24~28V,3~5A.IIPowerfulBTLPowerAmplifierApureBTLbridgeamplifieriscomposedofanoperationalamplifierNE5532,anLM3886in-phaseamplifierandanLM3886invertingamplifier,whichcaneasilyoutputmorethan200Wundistortedpower.Itcanbeusedindancehalls,karaoke,theatersandotheroccasions.Thiscircuitcankeepthesoundqualitynaturalandsmoothwhenplayingatlowvolume.BTLPoweramplifiercircuitisshowninFigure1.Onecircuitboardforeachchannel,withindependentrectification.Thesizeoftworadiatorsis140mminlength,50mminthicknessand100mminheight.Figure1.BTLPowerAmplifierCircuitIIISubwooferSpeakerFigure2isthecircuitofahouseholdsubwooferspeaker.Figure2.circuitofsubwooferspeakerInthepicture,theLinkwitzactivecompensatoraccuratelycontrolsthecenterfrequencyf1ofthecompensationpeakanditsQvalue,sothattheclosedbox(seeFigure3)withanaturalcornerfrequencyabout50Hzandthefrequencyresponsecurve(seeFigure4)extendsdownflatly.Thelowend-3dBpointreaches25Hz.Figure3.ClosedboxFigure4.frequencyresponsecurveInFigure4,curveAisnaturalfrequencyresponse;Biscompensationcurve;andCissystemfrequencyresponse.Theturningfrequencyofthelow-passfilteriscontinuouslyadjustablefrom80Hzto200Hz,sothattheactivesubwoofercanmatchthereadersdualchannelspeakerwithdifferentfrequencylimits.TheloudspeakerusessilverfluteYD310-43.Thebasindiameteris310mm.Themagnetdiameteris158mm.Theresonancefrequencyis25Hz.Q=0.35.Thecontinuouspoweris50W,andthesensitivityisashighas95dB.ComparedwiththeHiviS8unitwithasensitivityof88dB,thesensitivitydifferencebetweenthetwois7dB.Fortheclosedbox,theoutputsoundpressureofYindiYD310-43whenitinput50WisequivalenttotheoutputofHiviS8unitwhenitinput200W.YindicanalsobereplacedbytheBlueWhaleYD310-8XA.Insteadofthebassreflexwithpoortransientperformanceandlowsensitivity,itisbettertousethesimplestclosedbox.Theboxshallbesolidandairtight,filledwithglassfibercottonoracryliccottonforwarmthabsorption,andthesmallcavityatthebottomoftheboxshallbeusedtoinstallthecircuitpart.Forthesakeofsimpleinstallation,allcircuitsareinstalledonthePCB.ThePCB,radiator,switchandI/Oconnectorarefixedonthemetalpanel,andthenfixedonthespeakerwith6screws.Then,itcanworkafterconnectingtohornandtransformer.Connectthesubwooferactivespeakerwiththehomestereospeakertoforma3Dplaybacksystem.

ⅠIntroductionAlinefollowingcardesignedwithLM393VoltageComparatorcapableoftrackingonaspecificrunway.Thelinefollowingcarmainlyincludesasolarpowersupplypartandatrackingcontrolpart.Thecontrolcircuitpartmainlyincludesabattery,aswitch,firstandsecondlightsensitivecircuits,aDCmotor,acomparisoncircuit,andamotordrivecircuit.ThisblogtestshowsthatthelinefollowingcarcontrolledbytheLM393voltagecomparatorhasthecharacteristicsofhighcontrolaccuracy,faststartandstop,etc.,andsolvestheproblemsofthecomplicatedcontrolcircuitstructureofthelinefollowingcarandthelargedeviationofthedrivingtrajectory.CatalogⅠIntroductionⅡWhatisLM393?ⅢWhatisALineFollowingCar?3.1SolarPowerDesign3.2LineFollowingDesignⅣCircuitDesignofLineFollowingCarⅤTestⅥConclusionOrdering&QuantityⅡWhatisLM393?TheLM393offersexceptionalvalueforcost-sensitiveapplicationswithaloweroffsetvoltage,highersupplyvoltagecapability,lowersupplycurrent,lowerinputbiascurrent,shorterpropagationdelay,aswellasimproved2kVESDperformanceandinputrobustnesswithdedicatedESDclamps.TheLM393devicesconsistoftwoindependentvoltagecomparatorsthataredesignedtooperatefromasinglepowersupplyoverawiderangeofvoltages.Thequiescentcurrentisindependentofthesupplyvoltage,andtheoutputscanbeconnectedtootheropen-collectoroutputstoachieveawiredANDrelationship.Figure1.LM393ⅢWhatisALineFollowingCar?Alinefollowingcarisacarthatcantravelalongapresettrajectory.Intheprocessofdrivingthelinefollowing,howtomakethecarcanaccuratelyfollowthetrajectorywithoutlargedeviationsisthefundamentalapplicationofthelinefollowingcar.However,theexistinglinefollowingcargenerallyusestheinfraredreflectionmethodtofeedbackthedrivingtrajectoryofthecar,thecontrolcircuitstructureismorecomplicated,andtheinfraredreflectioniseasilyaffected,sonotonlythecostishigher,butalsothedrivingtrajectoryofthecarispronetodeviation,soitoftendoesnotmatchthedesigntrajectory.UsingLM393voltagecomparatorasthemaincontrolchipofthetrackingcarwillbeabetterway.UsetheresistancechangeofthephotoresistorunderthelightintensityandtheLM393voltagecomparatortocontroltheleftandrightdrivingwheelsofthecartorealizethetrackingdriveofthecar,andcooperatewiththedisplaycircuittounderstandthestatusofthecar.TheprincipleblockdiagramoflinefollowingcarbasedonLM393voltagecomparatorisshowninFigure3.Figure2.LineFollowingCarⅣCircuitDesignofLineFollowingCarThecircuitdesignoflinefollowingcarbasedonLM393voltagecomparatormainlyincludessolarpowersupplyandcartrackingdesign.Themaincomponentsofthelinefollowingcarincludeabatterybox,acontrolcircuitboardattachedtothebottomofthebatteryboxbydouble-sidedadhesive,andseveralwheelassembliesinstalledonbothsidesofthecontrolcircuitboardandasolarbatterypanelinstalledabovethebatterybox.Figure3.BlockDiagramofLineFollowingCar3.1SolarPowerDesignThelinefollowingcaradoptsbatterypowersupplyandstorage.Thesolarbatteryboardprovidespowerforthebattery,thatis,thebatteryinthecarischargedfirst,andonlywhenthebatteryhasenoughpoweroutputvoltage,therequiredvoltagecanbeoutputattheoutputendofthebatterytodrivethetracingcar.ThedesignofthepowersupplypartmentionedinthisblogusesasinglelithiumbatterychargingmanagementchipTP4057withaninputvoltageof4V9V(typicalvalue5V),whichcanbeusedtochangetheresistancetocontrolthechargingcurrent,anditsadjustmentrangeis100mm500mAandthecut-offvoltageis4.2V.Thechargingcircuithassimpleperipherals,noexternalswitchtubeisrequired,andhasfunctionssuchaschargingindicationandfullindication,anti-reversebatterypositiveandnegativepolereverseconnectionprotection,andpowersupplyundervoltageprotection.Inadditiontousingsolarpanelstopowerthecircuit,itcanalsoworkwithUSBpowerandadapterpower.Figure4.SchematicDiagramofChargingCircuit3.2LineFollowingDesignThecartrackingadoptstheLM393voltagecomparatorasthecontrolcenteroftheentiretrackingcircuit.LM393isadualvoltagecomparatorintegratedcircuit,whichiscomposedoftwoindependentprecisionvoltagecomparators.Itsfunctionistocomparetwoinputvoltagesandchangetheleveloftheoutputvoltageaccordingtothelevelofthetwoinputvoltages.TheschematicdiagramusingtheLM393voltagecomparatorasthetrackingcontrolcircuitisshowninFigure5.ThiscarchoosesredLEDlightasitslightsource.Whenthelightsourceshinesonwhiteobjectsandblackobjects(thepredeterminedtrajectoryofthecarisblack),thereflectivityisdifferent.Thelightisreflectedontothephotoresistorthroughtheground.WhentheredLEDlightisprojectedonthewhiteareaandtheblacktrackline,theresistanceofthephotoresistorwillbesignificantlydifferentbecauseofthedifferentreflectance;Bydetectingtheresistancechangeofthephotoresistor,itcanbejudgedwhetherthecarisdrivingontheblacktrackline.ThiscarchoosesredLEDlightasitslightsource.Whenthelightsourceshinesonwhiteobjectsandblackobjects(thepredeterminedtrajectoryofthecarisblack),thereflectivityisdifferent.Thelightisreflectedontothephotoresistorthroughtheground.WhentheredLEDlightisprojectedonthewhiteareaandtheblacktrackline,theresistanceofthephotoresistorwillbesignificantlydifferentbecauseofthedifferentreflectance;Bydetectingtheresistancechangeofthephotoresistor,itcanbejudgedwhetherthecarisdrivingontheblacktrackline.Figure5.SchematicDiagramofTracingIftheresistanceofthephotoresistorchanges,itmeansthatthewhiteareahasbeendetected,andthecarhasdeviated;atthistime,themotoroftheleftorrightwheelofthecarisdeceleratedorevenstoppedtomakethecarreturntotheblacktrack.ThetrackcarrunsonasimilarS-shapedroutetoachievethelinefollowingfunction.Whenthereisanimbalance(forexample,onewheelispressedontheblacktrackline),themotorononesideisstoppedimmediately,andthemotorontheothersideisacceleratedtorotate,sothatthecarcancorrectthedirectionandreturntothecorrectdirection.Thewholeprocessisaclosedloopcontrol,soyoucanquicklyandsensitivelycontrolthemovementofthelinefollowingcar.Atthesametime,thephotoresistorcandetecttheintensityoftheexternallight.Thestrongertheexternallightis,thesmallertheresistancevalueofthephotoresistoris.TheleftandrightwheeldriveofthistrackingcarusesaDCmotorwithareductiongear.TheDCmotordrivesthecartoslowdown,otherwisethecarwillruntoofastifthespeedistoohigh.Moreover,thetorqueistoosmalltorunevenwithoutdeceleration.Themotorusedinthislinefollowingcarhasintegratedareductiongeartogreatlyreducethedifficultyofproductionanddebugging.Comparedwiththeuseofasingle-chipmicrocomputerasthecontrolcircuit,thecontrolcircuitcomposedoftheLM393voltagecomparatorhasasimplerstructure,isconvenientforassemblyanddebugging,andhasalowercost.ⅤTestFirstofall,placethecaronthewhitebackgroundtestfieldoftheblacktrackline(theblackrunwayisthecarspresettrack),andturnontheswitchesS1,S2,solarpanels(orbatteries)toprovideelectricity,sothatthevoltagecomparatorcontrolsthestartoftwoDCmotorstodrivethewheelassembliesonbothsidesofthecar.OurDIYlinefollowingcarbegantodrivealongthedesignedtrack(blackrunway)!Duringthedrivingofthecar,thelight-emittingdiodesD2andD3ontheleftandrightsidesofthecarbothemitredlightsources.Becausethelightsourceirradiatestheblackrunwayandthewhiterunwaywithdifferentreflectivity,andthephotoresistorcandetecttheexternallightintensity,thestrongertheexternallight,thesmallerthephotoresistorresistance,theweakertheexternallight,thegreatertheresistance.Therefore,whentheredLEDlightisprojectedontotheblackandwhiterunway,becauseofthedifferentreflectance,theresistanceofthephotoresistorwillbesignificantlydifferent.Figure6.RedLEDWhenthelightsourceisreflectedbytherunwaytothephotoresistorsR14andR15,thecomparatorcandeterminewhetherthecarisdrivingontheblacktracklineorthewhiteareaaccordingtothechangesintheresistanceofthephotoresistorsonbothsides.Andthroughthediodesandphotoresistorsontheleftandrightsides,wecanalsodeterminewhichsidethecarisdeflectingatthistime.Whenanimbalanceoccurs(forexample,thesideofthecarispressedagainstthewhitearea),theDCmotorononesideisimmediatelystopped,andtheDCmotorontheothersideisacceleratedtorotate,sothatthecarcancorrectthedrivingdirectionandreturntothecorrectdrivingdirection(blacktrackon-line.Actually,wecanseethattheleftandrightdrivingwheelsofthecarrotateinturnandstopdrivingthecarforward;thereisaprocessofdeviation,correction,deviation,andcorrection;butitalwaysadvancesalongtheestablishedblacktrajectory.ⅥConclusionThesolartrackingcardiscussedinthisblog:Passedthetestandsuccessfullyrealizedthecarslinefollowing;Canbepoweredbysolarenergyorbattery;Strongstabilityandanti-interferenceability,highcontrolaccuracy,faststartandstop;Solvedtheproblemsofcomplicatedcontrolcircuitoflinefollowingcarandlargedeviationofdrivingtrajectory.UsingonlytheLM393voltagecomparatorasthecontrollercircuitallowsustoassembleanddebugconvenientlyandatalowercost.Theuseofnon-singlechipcontrolisafeatureofthislinefollowingcar.Figure7.LM393Insummary,thelinefollowingcarbasedonLM393controlissuitablefortechnologicalinnovationandtechnologypromotion.Afterreadingtheblog,haveyoubetterunderstandLM393?Finally,ifyouhaveanyquestionsaboutLM393,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!IIntroductionLM567isatonedecodingphase-lockedloopintegratedcircuit.Itiscompactindesign,simpleincircuit,andhasawiderangeofapplications.However,ifusingimproperly,itwillbringtroublesindebugging.ThisblogintroducestheworkingprincipleandtipsabouthowtouseLM567tonedecoderforreadersreference.Figure1.LM567ToneDecoderCatalogIIntroductionIILM567InternalStructurePinFunctionIIILM567WorkingPrincipleApplicationIVTipsofUsingToneDecoderLM567Ordering&QuantityIILM567InternalStructurePinFunctionThenameofLM567isphase-lockedlooptonedecoder,itspackageformuses8-pindualin-line,itsinternalstructureandpinfunctionsareillustratedinFigure2.Itsinternalcircuitstructureiscomposedofquadraturephase,detector,phase-lockedloop,amplifier,etc.TheoperatingvoltagerangeofLM567is4.75-9V,theoperatingfrequencycanreach500KHz,andthestaticoperatingcurrentisonly8mA.Thepin③isthesignalinputterminal,whichrequirestheinputsignaltobegreaterthan25mV.Thepin⑧isthelogicoutputterminal.Itcanbeseenfromthefigurethatitisanopencollectortransistoroutput,whichallowsamaximumsinkcurrentof100mA.Theexternalresistanceandcapacitanceofpins⑤and⑥determinethecenterfrequencyf01/1.1RCofICinternalvoltagecontrolledoscillator.Pins①and②areusuallyconnectedtothegroundseparatelytoformanoutputfilternetworkandalooplow-passfilternetwork.Thecapacitorconnectedtopin②determinesthecapturebandwidth.Thelargerthevalueofthecapacitor,thenarrowertheloopbandwidthis.Figure2.TopViewofLM567IIILM567WorkingPrincipleApplicationWhenthetonedecoderLM567works,itsphase-lockedloopinternalcurrent-controlledoscillatorgeneratesanoscillationsignalofacertainfrequencyandphase.Thissignalissenttothequadraturephasedetectortogetherwiththesignalinputatpin③forcomparison.Whenthefrequencyofthesignalfallswithinagivenpassband,thephase-lockedlooplocksthissignal,andatthesametimetheinternaltransistoroftheLM567iscontrolledtobepoweredup,andtheoutputterminaloftheLM567outputslowlevel.The⑤pinofLM567outputstherectangularsignaloftheinternaloscillator,andthe⑥pinoutputsthesawtoothpulse.Thefrequencyofbothisthesameasthecenterfrequencyoftheinternaloscillator.The②pinistheoutputofthephase-lockedloopphasedetector.ThevoltageonisthesignalafterF/Vconversion.Ifthetonesignalisinputtothe②pin,thenthe⑤pinoutputstheFMsquarewavesignalmodulatedbythe②pininputsignal.FromthebasicfunctionofLM567,LM567canbeusedasanoscillator,modulatorordemodulator.Therefore,itcanbeusedasabasicdeviceinthecircuit.TheapplicationofLM567hasthefunctionofdecodingaspecificfrequencyintheinputsignal,anditiswidelyusedincommunication,remotecontrol,measurement,frequencymonitoring,etc.Figure3.LM567ToneDecoderIVTipsofUsingToneDecoderLM567AlthoughLM567hasaverywiderangeofapplications,ifitisnothandledproperlyduringdesignandapplication,itstillfailstoachievetheexpectedresults,andevenbringstroubletothedebuggingoraffectsthereliabilityoftheproduct.Therefore,itshouldbeconsideredfromthefollowingaspectswhenusingit:1.SetOperatingFrequencyandBandwidthofLM567AccuratelyandAppropriatelyWeknowthattheinternaloscillationfrequencyf0ofLM567canbepre-setwithintherangeof0.1KHzto500KHz,anditscorrespondingbandwidthcanalsobedeterminedasrequiredwithinthefieldrangeof7%f0to14%f0.Therefore,afterthedetectedsignalisdetermined,theinternaloscillationfrequencyf0ofLM567shouldbesettocoincidewiththecenterfrequencyofthemeasuredsignal,andthetimingcomponentsRandCconnectedwiththe5and6feetofLM567shouldbeusedwithhighprecision.Amongthem,thesettingofthecenterfrequencycanbedeterminedbytheresistancevalueofthetunerR.Whenadjusting,itisnecessarytopreventRshortcircuitoropencircuit,otherwisetheoutputlevelof⑧pinwillbelowlevelwhetherthereisinputsignalornot.Theexternalcapacitanceofthe②pinofLM567determinesthecapturebandwidth.Thesmallerthecapacity,thewiderthecapturebandwidth.However,thecapacitancecannotbereducedblindlytoincreasethebandwidth,soasnottoreducetheanti-interferenceabilityoreventriggerfalsely,whichaffectsthereliabilityoftheproduct.2.MaketheCenterFrequencyofthePassbandCoincidewiththeCenterFrequencyoftheOscillationAsMuchAsPossibleItshouldbenotedthatthecenterfrequencyofthepassbanddoesnotalwayscoincidewiththecenterfrequencyoftheoscillator,andsometimesitwilldeviateseverely.Thiswillinevitablycauseadecreaseinreliabilityandsensitivity.Therefore,measuresshouldbetakentomakethetwocenterscoincideasmuchaspossible.ThecircuitshowninFigure4canminimizethefrequencyoffsetofthetwocenters.Figure4.CircuitofLM5673.WorkingVoltageofLM567ShouldBeStableThestabilityoftheoperatingvoltageoftheLM567hasafixedresponsetothestabilityofthecenterfrequencyofthetonedecoder.4.AvoidMisoperationWhentheOutputTerminalisPoweredOnLM567outputsalowlevelatthemomentwhenthepoweristurnedon.Therefore,forsomeremotecontrolcircuits,itisnecessarytoaddaCRintegrationdelaycircuittotheoutputendtoavoiderroneousoperationwhenthepoweristurnedon.Thisisespeciallyimportantintheon-offcontrolcircuit.Afterreadingtheblog,haveyoubetterunderstandLM567?Finally,ifyouhaveanyquestionsaboutLM567,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!

IIntroductionWhentestingenvironmentalprotection,safety,andeconomicindicatorssuchasnoise,accelerationperformance,maximumspeed,andfuelconsumptionofmotorvehicles,itisnecessarytomeasureandcontrolthevehiclespeed.Mostexistingvehiclespeedmeasurementmethodsuseelectronictimingdevicesorstopwatchestomeasurevehicles.Thetimeittakestotravelafixeddistanceandthenfindtheaveragespeed.Generally,theprocessorandthedisplaypartoftheelectronictimingdevicearebasicallythesame,butthespeedsensorpartisdifferent,andthecharacteristicsofthesensordirectlyaffecttheaccuracyofthemeasurementresult.Atpresent,thecommonlyusedspeedsensorsincludepressuresensitivesensors,COMScamerasandparallellightsources.Theformerhasasimplestructure,butitiscumbersometolay,thesensoriseasilydamaged,andthesensitivityisreducedafterlong-termuse,whichaffectsthemeasurementresults.Thelatterhashighsensitivityandaccuratemeasurement.However,thecostistoohigh,involvesmoreequipment,andhashigherrequirementsfortheplacementofthelightsource.Consideringtheaboveproblems,itisafeasiblemethodtodesignanewinfraredspeedsensorusingLM567.Thesensorissmallinsize,lowincost,simpleinoperation,easytouse,hashighsensitivity,accuracy,stabilityandanti-interferenceability,andissuitableformeasuringtheaveragespeedofavehiclewithinafixeddrivingdistance.Figure1.LM567CatalogIIntroductionIIWorkingPrincipleofTraditionalSpeedMeasuringDevice2.1UsingPressureBeltRoadTester2.2UsingLaserRoadTesterIIIWorkingPrincipleofInfraredSpeedSensorBasedonLM5673.1InternalStructureandFunctionofLM5673.2PrincipleofInfraredSpeedMeasurementBasedonLM567IVConclusionOrdering&QuantityIIWorkingPrincipleofTraditionalSpeedMeasuringDeviceThefollowingusesthemeasurementofmotorcycleaccelerationnoiseasanexample,tointroducetheprinciplesandadvantagesdisadvantagesoftheconventionalspeedmeasuringdevicescurrentlycommonlyused.Figure1isasimplifiedlayoutofmotorcycleaccelerationnoisetest.2.1UsingPressureBeltRoadTesterForthespeedmeasurementmethodusingthepressurebeltroadtester,placethepressurebeltatAA,BB,CC,DDrespectivelyandstickthepressurebelttotheroadsurfacewell.ThedistancebetweenAAandBB,CCandDD(thatis,thespeedmeasurementzone)is1meter,andthepressurebeltandtheroadtesterareconnectedinsequencewithacable.WhenthevehiclepassesthepressurebeltatAA,thepressure-sensitivesensorinthepressurebeltistriggered,andthetriggersignalissenttotheroadtestertostartthetimingofitsinternaltimingdevice;WhenthevehiclepassesBB,atriggersignalisgeneratedagaintostopthetimingdevice.Usingtheinternalprocessoroftheroadtester,thetimetakentopassthedistancebetweenAAandBBisconvertedintovehiclespeedanddisplayedontheLCDscreen.Figure2.LayoutDiagramUsingPressureBeltRoadTesterSimilarly,avehiclespeedvaluecanbemeasuredbetweenCCandDDtomeettherequirementsofnoisemeasurement.Theworkingprincipleofthisspeedmeasurementmethodissimple,buttheequipmentismoretroublesometolay,andthesensoriseasilydamaged.Afterlong-termuse,thesensitivitywillbereduced,whichwillaffectthemeasurementresult.2.2UsingLaserRoadTesterForthespeedmeasurementmethodusingthelaserroadtester,fourparallellaserlightsourcesareplacedatfourpositionsofA,B,C,andD,andfourareplacedatfourpositionsofABCD.CMOScameraforreceivinglasersignals.Thelightsourcecanbeadjustedsothatthelaserlightemittedisalignedwiththecenterofthecamera,andthecameraisconnectedtotheroadtesterinsequence.WhenthevehiclepassesAA,thelightisblocked,andthecamerageneratesatriggersignaltomaketheinternaltimingdeviceoftheroadtesterwork;WhenthevehiclepassesBB,atriggersignalisgeneratedagaintostopthetimingdevice,andtheinternalprocessoroftheroadtesterisusedtoconvertthetimespentthroughthedistancebetweenAAandBBtothevehiclespeedanddisplayitontheLCDscreen.on.Figure3.LayoutDiagramUsingLaserRoadTesterSimilarly,aspeedvaluecanbemeasuredbetweenCCandDD.Thesensitivityandmeasurementaccuracyofthisspeedmeasurementmethodareveryhigh,buttheoperationisextremelyinconvenient.Notonlydoeseachlaserlightsourcerequireanindependentpowersupply,butalsothelasersignalmustbedirectedtothecenterreceivingpointofthecamera,whichplaceshighrequirementsontheplacementofthelightsource,otherwisethesensorwillbedifficulttoworkproperly.IIIWorkingPrincipleofInfraredSpeedSensorBasedonLM567Thisblogusesaphase-lockedloopaudiodecodingchipLM567todesignanewinfraredspeedsensor.Itscircuitdiagramandworkingprincipleareasfollows.3.1InternalStructureandFunctionofLM567LM567isspeciallyusedtodemodulateasingletonefrequencymodulationsignal,anditsoperatingfrequencycanbeashighas500kHz.Itiswidelyusedinindustrialautomaticcontrol,remotecontroltelemetry,securityalarmandotherfields.LM567ismainlycomposedofquadraturephasedetector,phase-lockedloopandamplifier.ItsinternalstructureisshowninFigure2.Pins5and6ofLM567areexternallyconnectedwithtimingresistorsandcapacitorsR,C.RandCdeterminethecenterfrequencyf0ofthephase-lockedloopinternalvoltagecontrolledoscillator,thatis,f0.ResistorRisconnectedbetweenpins5and6,ofwhichpin6isgroundedthroughcapacitorC(Uss).IfRis2~20k,theLM567canextractthetonesignalintherangeof0.01~500kHz.Pins1and2ofLM567arerespectivelyconnectedtothegroundwithacapacitortoformanoutputfilternetworkandaphase-lockedlooplow-passfilternetwork.ThecapacityoftheexternalcapacitorC2onpin2determinesthecapturebandwidthofthephase-lockedloop,anditssizeisBw1070.Uinistheeffectivevalueofthesinewavesignalvoltageinputfrompin3,andrequiresUin25mV,generallybetween100~200mV.TheexternalcapacitorC1ofpin1istheoutputfiltercapacitorofthequadraturephasedetector,anditscapacityismorethantwicethecapacityofthecapacitorC2connectedtopin2,whichshouldsatisfyC12C2.Figure4.TopViewofLM567(1)UsingLM567asFrequencyModulatorPin2isconnectedtotheinputofthelow-passfilterofthephase-lockedloop.Themodulatedsignaladdedfrompin2isfilteredbyalow-passfiltertoremoveout-of-bandnoiseandnoise,andthenaddedtothecenterfrequencyf0ofthevoltage-controlledoscillatorforfrequencymodulation,andthenthepin5outputstheFMsignal.Thecenterfrequencyf0oftheFMsignalisdeterminedbytheparametersoftheRCresistor-capacitornetworkconnectedtopins5and6.WhenLM567isusedasthefrequencymodulationcircuit,onlyitsinternalphase-lockedlooplow-passfilterandvoltage-controlledoscillatorareused.ChangingtheparametervalueoftheRCnetworkcanrealizemodulationtodifferentfrequencies.(2)UsingLM567asFrequencyDemodulatorThemodulatedsignalisinputfrompin3.Whenthecenterfrequencyoftheinputsignalisequaltothecenterfrequencyf0ofthevoltage-controlledoscillatorintheLM567,thelow-passfilter(pin2)oftheloopoutputsthedemodulatedsignal.3.2PrincipleofInfraredSpeedMeasurementBasedonLM567ThecircuitdiagramoftheinfraredspeedsensorbasedonLM567isshowninFigure3.TheinternaloscillatoroftheLM567providesasquarewavesignaltodrivefourLEDstoemitinfraredlight,anditsfrequencyisdeterminedbyR2andC4.Figure5.CircuitDiagramofInfraredSpeedSensorPlacethefoursensorsinthefourpositionsA,B,C,andDinFigure1.Whenthevehiclepassesthesensor,theinfraredraysemittedbytheLEDarereflectedbythevehiclebody.ThephotosensitivetubeQ1receivesthereflectedlight,isamplifiedbythetransistorandconvertedintoavoltagesignal,andissenttotheinternalphasedetectoroftheLM567forsynchronousdemodulation,andthenconvertedintoadigitalsignalbythecomparatorinsidetheLM567andoutputfrompin8.Theoutputsignalistransmittedtotheroadtester,whichtriggersthetimingdeviceintheroadtestertostarttiming.Similarly,whenthevehiclepassesthesensoratpointB,atriggersignalisgeneratedtostopthetimingdeviceandpasstheroadtester.TheinternalprocessoroperatestoobtainthespeedofthevehicleasitpassesAAandBB.LM567isaphase-lockedloopaudiodecodingcircuit.Inthecircuit,itisusedforfrequencyselection,thatis,thecircuitoutputslowlevelonlywhenthefrequencyofthe3-pininputsignalisconsistentwiththefrequencyoftheLM567internaloscillator,otherwisetheoutputishigh.Level.Inotherwords,onlywhenthereflectedinfraredlightreceivedbyQ1comesfromtheLEDinitsowncircuit,theLM567willoutputatriggersignalfromhightolowtotheroadtester.Thebiggestfeatureofthiscircuitistorealizetheautomaticsynchronizationoftheinfraredemissionfrequencyandtheworkingfrequencyofthereceivingcircuit;Thatis,thereisnospecialpulsegeneratingcircuitintheinfraredtransmittingpart,andthepulseisdirectlyintroducedfromthedetectioncircuitofthereceivingpart(LM567phase-lockedcenterfrequencysignal).Inthisway,thewiringanddebuggingworkissimplified,avoidinginconsistenttransmissionandreceptionfrequenciescausedbychangesinthesurroundingenvironmentandcomponentparameters,eliminatingmutualinterferencebetweenadjacentsensors,andgreatlyenhancingcircuitstabilityandanti-interferencecapabilities.IVConclusionTheinfraredspeedsensordesignedbasedontheLM567modulationanddemodulationfunctionrealizestheautomaticsynchronizationoftheinfraredtransmissionfrequencyandtheworkingfrequencyofthereceivingcircuit.Inaddition,ithasthecharacteristicsofstronganti-interferenceabilityandstability,lowcostandsimplestructure.Therefore,itcanbewidelyusedtomeasuretheaveragespeedofvehiclessuchasautomobilesandmotorcycles.Figure6.LM567Afterreadingtheblog,haveyoubetterunderstandLM567?Finally,ifyouhaveanyquestionsaboutLM567,pleasedonothesitatetoleaveamessageinthecommentsectionbelow!TheLM2940isacommonlow-dropout(LDO)linearregulator.ThisisacomprehensiveintroductiontoLM2940voltageregulator,fromitspinout,feature,parametertoitsapplication,itsdifferencebetweenLM7805andmore.CatalogLM2940DescriptionLM2940PinoutLM2940FeaturesLM2940ParametersLM2940EquivalentLM2940VSLM7805LM2940TypicalApplicationLM2940PackageLM2940ApplicationComponentDatasheetLM2940DescriptionTheLM2940isacommonlow-dropout(LDO)linearregulator.Thedropoutvoltageofaregulatoristhevoltagerequiredbetweentheinputandtheregulatedoutputvoltage.Theregulatorwastesthisvoltage(multipliedbycurrent),sothelowerthedropoutonalinearregulator,themoreefficientitis.ThismeansthattheLM2940,witha5Vdropoutat1amp,canbeusedwitha6voltwallwarttoprovidearegulated5Voutput.Thisalsomeansthattheregulatorwilloperateatamuchlowertemperaturethanastandard7805,whichwouldrequireamuchhigherinputvoltage(around7.5volts)foraregulated5Voutput.LM2940PinoutLM2940voltageregulatorLM2940PinoutPinNo.PinNameDescription1VinA(+ve)voltageisgivenasinputtothispin.2GNDCommontobothInputandOutput.3VoutOutputregulated12VistakenatthispinoftheIC.LM2940FeaturesInputVoltageRange=6Vto26VDropoutVoltageTypically0.5VatIOUT=1AOutputCurrentinExcessof1AOutputVoltageTrimmedBeforeAssemblyReverseBatteryProtectionInternalShortCircuitCurrentLimitMirrorImageInsertionProtectionP+ProductEnhancementTestedLM2940ParametersOutputoptionsFixedOutputIout(Max)(A)1Vin(Max)(V)26Vin(Min)(V)6Vout(Max)(V)15Vout(Min)(V)5Fixedoutputoptions(V)5,8,9,10,12,15Noise(uVrms)150Iq(Typ)(mA)10ThermalresistanceJA(C/W)23Loadcapacitance(Min)(F)22RatingCatalogRegulatedoutputs(#)1Features-Accuracy(%)2PSRR@100KHz(dB)48Dropoutvoltage(Vdo)(Typ)(mV)500Operatingtemperaturerange(C)-40to125,-40to85LM2940EquivalentTheequivalentforLM2940isLM7805.LM2940VSLM7805TheLM7805isapopularlinearvoltageregulatorbecauseitrequiresnoadditionalcomponentstooperate.Itisaverylow-costcomponent.Becauseofitscharacteristics,itreducestheoutputvoltageattheexpenseofheatdissipation,makingitinefficient.TheLM7805requiresaminimuminputvoltageof7.3Vtofunctionproperly.Itcanhandleamaximumcurrentof1A.Somemodelscanhandleupto1.5A.Itisrecommended,andinsomecasesrequired,tousecapacitorstoreduceoreliminatetheeffectsofthefrequenciesintroducedbytheotherelementsofthecircuit.Theyalsohelptoreducetheimpactofpeakconsumption.WhiletheLM2940isfromadifferentgeneration,butitspinisstillcompatiblewiththeLM7805.ItisaLow-dropout(LDO)LinearRegulatorthatismoreefficientthantheLM7805,butitwillrequirecapacitors.ThemaindifferencebetweenLM2940andLM7805isthatthemaximumoutputcurrentofLM2940is1A.ThemaximumoutputcurrentofLM7805is1.5A.Othersareveryclose,soifthecircuitonlyrequires1Aorbelow,LM2940canbeusedinsteadofLM7805.Whatsmore,the7805isexpendingtheexcesspowerasheat.Whichisverylossyespecialyifyourprojectusesbatteries.Theotherchipisabuckconverterissoitapproaches90%efficiencybyswitchingsothereisnowasteheat,thatswhyeventhoughLM7805ischeaperandeasiertousebuttheresstillalotofpeoplewouldgoforLM2940.LM2940LM7805SchematicComparisonLM2940SchematicLM7805SchematicLM2940TypicalApplicationLM2940PackageLM2940ApplicationPostregulatorforswitchingsuppliesLogicpowerSuppliesIndustrialInstrumentationComponentDatasheetLM2940Datasheet

S8050isalow-powerNPNsilicontubewithamaximumcollector-base(Vcbo)voltageof40Vandacollectorcurrent(Ic)of0.5A.S8050isoneofthemostcommonlyusedsemiconductortransistormodelsincircuithardwaredesign.Name:S8050Type:NPNDissipatedpower:0.625W(SMD:0.3W)Collectorcurrent:0.5ABasevoltage:40VCatalogS8050PinoutS8050CircuitS8050ApplicationS8050FeaturesS8050AdvantageS8050AlternativesS8050EquivalentsWhereHowtouseS8050HowtoSafelyLongRunS8050inCircuitS8050PinoutPinNumberPinNameSymbolDescription1EmitterECurrentDrainsoutthroughemitter2BaseBControlsthebiasingoftransistor3CollectorCCurrentflowsinthroughcollectorS8050ApplicationAudioamplificationcircuitsClassBamplifiersPushpulltransistorsCircuitswherehighgainisrequiredLowsignalapplicationsS8050FeaturesLowVoltage,HighCurrentNPNTransistorSmallSignalTransistorMaximumPower:2WattsMaximumDCCurrentGain(hFE)is400ContinuousCollectorcurrent(IC)is700mABase-EmitterVoltage(VBE)is5VCollector-EmitterVoltage(VCE)is20VCollector-BaseVoltage(VCB)is30VHighUsedinpush-pullconfigurationdoeClassBamplifiersAvailableinTo-92PackageNote:CompleteTechnicalDetailscanbefoundattheS8050datasheetgivenattheendofthispage.S8050AdvantageS8050npntransistorS8050isaNPNtransistorhencethecollectorandemitterwillbeleftopen(Reversebiased)whenthebasepinisheldatgroundandwillbeclosed(Forwardbiased)whenasignalisprovidedtobasepin.Ithasamaximumgainvalueof400;thisvaluedeterminestheamplificationcapacityofthetransistornormallyS8050.Sinceitisveryhighitisnormallyusedforamplificationpurposes.However,atanormaloperatingcollectorcurrentthetypicalvalueofgainwillbe110.ThemaximumamountofcurrentthatcouldflowthroughtheCollectorpinis700mA,hencewecannotdriveloadsthatconsumemorethan700mAusingthistransistor.Tobiasatransistorwehavetosupplycurrenttobasepin,thiscurrent(IB)shouldbelimitedto5mA.Whenthistransistorisfullybiasedthenitcanallowamaximumof700mAtoflowacrossthecollectorandemitter.ThisstageiscalledSaturationRegionandthetypicalvoltageallowedacrosstheCollector-Emitter(VCE)orCollector-Base(VCB)couldbe20Vand30Vrespectively.Whenbasecurrentisremovedthetransistorbecomesfullyoff,thisstageiscalledastheCut-offRegion.S8050Alternatives2N3904,2N3906,2N2369,2N3055,S9014,MPSA42,SS8050,BC547S8050Equivalents2N5830,S9013S8050CircuitThisisavideointroducingtransistorsstereoamplifierS8050andS8550.WhereHowtouseS8050S8050transistorisageneral-purposetransistor,itisaperfecttransistortoperformsmallandgeneraltasksinelectroniccircuits.Youcanuseitasaswitchinelectroniccircuitstoswitchonloadsunder700mA.700mAisenoughtohandlevarietyofloadsforexamplerelays,LEDs,bulbsetc.Itcanalsobeusedasamplifierinsmallamplificationstagesorasaseparatesmallsignalamplifier.HowtoSafelyLongRunS8050inCircuitTosafelyrunS8050transistorinyourcircuitorelectronicprojectsdonotoperatethistransistorfromvoltagehigherthan20Vanddonotoperateanyloadmorethan700mAor0.7A.Useasuitablebaseresistorwhichwilllimitsthebasecurrenttoitsrequiredlevel.Donotexposeittoheatover150centigradeandbelow-60Centigrade.LM3914isamonolithicicthatsensesanalogvoltagelevelsanddrives10LEDs,providingalinearanalogdisplay.Asinglepinchangesthedisplayfromamovingdottoabargraph.ThisisanoverviewofLM3914dot/bardisplaydriver,wewillprovidetheinformationofitspinout,datasheet,parameter,andwherehowtousethisdeviceandsomuchmore.Top5electronicsProjectsusingLM3914-15IC|lm3914lm3915circuitsCatalogLM3914DescriptionLM3914PinoutLM3914FeaturesLM3914ParameterLM3914EquivalentWheretouseLM3914ICHowtouseLM3914ICLM3914CircuitLM3914PackageLM3914ApplicationComponentDatasheetLM3914DescriptionTheLM3914isamonolithicintegratedcircuitthatsensesanalogvoltagelevelsanddrives10LEDs,providingalinearanalogdisplay.Asinglepinchangesthedisplayfromamovingdottoabargraph.CurrentdrivetotheLEDsisregulatedandprogrammable,eliminatingtheneedforresistors.Thisfeatureisonethatallowsoperationofthewholesystemfromlessthan3V.TheLM3914isveryeasytoapplyasananalogmetercircuit.A1.2Vfull-scalemeterrequiresonly1resistorandasingle3Vto15Vsupplyinadditiontothe10displayLEDs.Ifthe1resistorisapot,itbecomestheLEDbrightnesscontrol.Thesimplifiedblockdiagramillustratesthisextremelysimpleexternalcircuitry.Wheninthedotmode,thereisasmallamountofoverlaporfade(about1mV)betweensegments.ThisassuresthatatnotimewillallLEDsbeOFF,andthusanyambiguousdisplayisavoided.Variousnoveldisplaysarepossible.TheLM3914isratedforoperationfrom0Cto+70C.TheLM3914N-1isavailableinan18-leadPDIP(NFK)package.LM3914PinoutLM3914LM3914PinoutPinNumberPinNameDescription1and10to18LED1,LED2,LED3.....LED10The10LEDswhichhastobecontrolledisconnectedtothesepins2V-/GroundGroundpinoftheIC3V+/VccSupplyVoltage(3-18)V4RLOLowlevelvoltageforpotentialdivider5SignalAnalogsignalInputpinbasedonwhichtheLEDiscontrolled.6RHIHighLevelvoltageforpotentialdivider7REFOUTOutputReferenceVoltageforLEDcurrentlimiting8REFADJAdjustpinforvoltagereference9ModeSelectbetweenDot/BarModeLM3914FeaturesAnalogControlledLEDDriverICNumberofcontrollableLEDs:10OperatingVoltage:3Vto18VInputAnalogvoltagerange:1.2Vto12VLEDsinkcurrent:2mAto30mA(programmable)BothDot/BarmodeavailableCanbecascadedtocontrolupto100LEDsAvailablein18-pinDIP,PLCCpackageItcandriveLCDs,LEDsotherwisevacuumfluorescents.Thedototherwisebotdisplaymodecanbeselectedbytheuserexternally.Itcanbeexpandableupto100displays.LM3914ParameterManufacturer:TexasInstrumentsSeries:-Packaging:TubePartStatus:ObsoleteDisplayType:LEDLCDVacuumFluorescent(VF)Configuration:Dot/BarDisplayInterface:-DigitsorCharacters:10StepsCurrent-Supply:6.1mAVoltage-Supply:3V~20VOperatingTemperature:0C~70CMountingType:ThroughHolePackage/Case:18-DIP(0.3007.62mm)SupplierDevicePackage:18-PDIPBasePartNumber:LM3914LM3914EquivalentLM3914EquivalentLEDDriver:LM3916AlternativeLEDDriverICs:CD4511,MAX7219,CD4054WheretouseLM3914ICTheLM3914isananalogcontrolledLEDdriverIC,whichmeansthatitcancontrol(turnonoroff)10LEDlightsusingananaloginputvoltage.Thisintegratedcircuiteliminatestheneedforamicrocontrollerandprogramming,aswellasthehardwarerequiredtocontroltenLEDs.Theanaloginputvoltagecanrangefrom3Vto18V,andtheLEDcurrentcanbecontrolledwithasingleresistoronpin7.(RefOut).TheICalsohastwooperatingmodes:DOTmodeandBARmode,andupto100LEDscanbecontrolledbycascadingmultipleICs.TheseICsarecommonlyusedinvisualalarmsandothermetering/monitoringapplicationsbecausetheLEDscanbecontrolledwithoutflickeringandflawlesslywithequalbrightness.So,ifyourelookingforanICtopoweryourbarLEDlightsoranother10-LEDsequence,thisICmightbeofinteresttoyou.HowtouseLM3914ICThebenefitofusingLM3914isthatitrequireslittlehardwareandissimpletosetup.Simplyconnectthe10LEDstotheIC,setthereferencevoltagesfortheinputvoltage,andlimitthecurrentthroughtheLED,andweredone.ThecircuitbelowisanexampleofanLM3914applicationcircuit.SimplyconnecttheV+andV-topowertheIC,andtheanalogsignalvoltageisconnectedtopin5.Inthiscase,weused9VtopowertheICandmonitorananalogyvoltagerangingfrom0to5V.AlwayskeepinmindthatthevoltageusedtopowertheIC(inthiscase,9V)shouldbeatleast1.5Vhigherthanthemonitoringvoltage(here5V).Becausewearemonitoring0-5Vhere,wesetthelowreferencevoltage(pin4)to0Vandthehighreferencevoltage(pin6)to5V.Asyoumayhavenoticed,weconnectedalltenLEDsdirectlytotheICwithoutusinganycurrentlimitingresistors.ThisisbecausetheIChasaninternalcurrentlimiterandthecurrentvaluecanbesetusingthepinVRO(pin7).Thecurrentcalculationformulasaregivenbelow,whereIisthecurrentflowingthrougheachLEDandRListheresistorconnectedtopin7.I=12.5/RLIntheprecedingexample,weuseda470ohmresistorasRl,sothecurrentthrougheachLEDwillbearound25mA;youcanchangethevalueasneeded.Also,thecathodeoftheLEDisconnectedtotheIC,whiletheanodeisconnectedto+5V.ThisisduetothefactthattheICoutputpinscanonlysinkcurrentandnotsourceit.Theintegratedcircuit(IC)canoperateintwomodes:dotmodeandbarmode.Indotmode,themodepin(pin9)mustbeleftfloating;inthismode,basedontheinputvoltage,onlyoneLEDwillbeturnedon.InBarmode,connectthemodepin(pin9)toV+,andtheLEDwillturnonandoffsequentiallybasedontheinputvoltage.Boththemodesareshowninthegiffileabove.LM3914CircuitThecircuitdiagramforICLM3914isshownbelow.Thecircuitcanbeconstructedusingbothbasicelectricalandelectroniccomponents.TheICLM3914isacriticalcomponentofthiscircuit.AnalarmdrivingswitchforoverrangecanbeconnectedtoabartypeLMseriesLEDdrivingdisplaycircuitinthefollowingcircuit.Thiscircuitissuitableforbardisplays.LM3914BasedAlarmDriverCircuitThecircuithereemploysaPNPtransistor,denotedbyQ1.ThistransistorcanbeconnectedbetweentheLEDpositiveandnegativeterminals,andthebaseterminalofthetransistorisconnectedtotheICspin-10todrivetheLED10.Inseries,analarmunitisconnectedtothetransistorscollectorterminal.Normally,Q1transistor,LED10,andthealarmunitareallturnedoff;however,ifLED10isactivated,itpullsQ1transistorthroughresistorR2andthusactivatesthealarmunit,indicatingthattheconditionisoutofrange.Intheabovecircuit,analarmunitgeneratesanacousticalarmsoundusingapiezosirenunit,otherwiseagatedastableswitchunitthatcontinuouslyactivatestheLEDbrightnessbetweenhighandlowlevelsbeneaththeover-rangestate,oracombinationofboth.Ifdesired,theunitcanbeswitchedtoanyoftheLEDdisplays,andthealarmwillsoundifthatoranyotherhighLEDisenergized.LM3914PackageLM3914ApplicationBatteryMeterforRobotMonitoringof12VCarBatteryTesterCircuitforSoilMoistureMonitoringofLeadAcidBatteryChargerChargeMonitoringCircuitforAtmosphericKitchenExhaustFanforControllingTemperatureMeterCircuitforTemperatureDigitalgaugesElectronicdisplaysLow-costmonitordevicesCrudeBatterylevelindicatorsFadebarsComponentDatasheetLM3914Datasheet

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