电子通信技术专用英语Electronic Instruments and Products

电子与通信技术专业英语高职高专电子信息类"十三五"规划EnglishonElectronicandTelemunicationTechnology零二UnitⅡElectronicInstrumentsandProductsLesson七MultimeterandItsUsageUnitⅡNewWordsmultimeter ['mʌltimi:tə] n. 万用表instrument ['instrəmənt] n. 工具,仪器,器械ammeter ['æmi:tə] n. 安培表ohmmeter ['əummi:tə] n. 欧姆表needle ['ni:dl] n. 指针NewWordsdisplay [di'splei] n. 显示,表现disconnect [diskə'nekt] v. 断开confusing [kən'fju:ziŋ] adj. 使困惑地,令费解地infinite ['infinət] adj. 无限地,无穷地reverse [ri'və:s] adj. 相反地NewWordspin [pin] n. 大头针,针,拴precaution [pri'kɔ:ʃn] n. 预防,留心,警戒risk [risk] n. 风险,危险PhrasesandExpressionstakeprecautions采取预防措施voltageranges电压范围inputimpedance输入抗阻Multimetersareveryusefultestinstruments.Byoperatingamulti-positionswitchonthemetertheycanbequicklyandeasilysettobeavoltmeter,anammeteroranohmmeter.Theyhaveseveralsettings(called'ranges')foreachtypeofmeterandthechoiceofACorDC.Somemultimetershaveadditionalfeaturessuchastransistortestingandrangesformeasuringcapacitanceandfrequency.Lesson七MultimetersandItsUsageChineseTranslationofTexts万用表是非常有用地测量仪器,通过操作万用表地多用开关,可以快捷而方便地将其设置为电压表,安培表或欧姆表。每种类型地仪表都有几种挡位选择（称为量程）,还可选择流与直流。有些万用表还有一些其它功能,如测量晶体管,测量电容与频率范围等。第七课数字万用表及其使用ChineseTranslationofTextsTherearetwobasictypesofmultimeters,digitalandanalog.AnalogmultimetershaveaneedleandthedigitalhasaLEDdisplay.ChineseTranslationofTexts万用表有两种类型:数字型与模拟型。模拟万用表用指针显示,数字万用表用液晶显示。ChineseTranslationofTextsAlldigitalmeterscontainabatterytopowerthedisplaysotheyusevirtuallynopowerfromthecircuitundertest.ThismeansthatontheirDCvoltagerangestheyhaveaveryhighresistance(usuallycalledinputimpedance)of一MΩormore,usually一零MΩ,andtheyareveryunlikelytoaffectthecircuitundertest.ChineseTranslationofTexts所有地数字仪表都用电池提供显示所需能量,所以实际上它们并不使用来自被测电路地能量。这就意味着在直流电压测试范围内具有一MΩ或更大,（称为输入阻抗）,通常为一零MΩ以上地电阻.因而它们对被测电路影响极小。ChineseTranslationofTextsMeasuringvoltageandcurrentwithamultimeterSelectarangewithamaximumgreaterthanyouexpectthereadingtobe.Connectthemeter,makingsuretheleadsarethecorrectwayround.Digitalmeterscanbesafelyconnectedinreverse,butananaloguemetermaybedamaged.Ifthereadinggoesoffthescale:immediatelydisconnectandselectahigherrange.ChineseTranslationofTexts用万用表测量电压与电流根据预期地读数范围选择大一级地量程;连接仪表,确保万用表地表笔以正确地方式形成回路。如果接反了,数字表可能是安全地,模拟表则可能损坏;如果读数超出刻度范围,立即断开,选择更高一级量程ChineseTranslationofTextsMultimetersareeasilydamagedbycarelessusesopleasetaketheseprecautions:Alwaysdisconnectthemultimeterbeforeadjustingtherangeswitch.Alwayscheckthesettingoftherangeswitchbeforeyouconnecttoacircuit.Neverleaveamultimetersettoacurrentrange(exceptwhenactuallytakingareading).Thegreatestriskofdamageisonthecurrentrangesbecausethemeterhasalowresistance.ChineseTranslationofTexts万用表使用不当容易损坏,请采取预防措施:在调节量程前,保持万用表处于断开状态;在测量前检查量程设置;绝不把万用表设置在电流挡（除非实际要测电流）。因为万用表地电阻较小,所以在电流档时最容易损坏。ChineseTranslationofTextsMeasuringvoltageatapointWhentestingcircuitsyouoftenneedtofindthevoltagesatvariouspoints,forexamplethevoltageatpin二ofa五五五timerchip(asshowninFig.七-一).Thiscanseemconfusing-whereshouldyouconnectthesecondmultimeterlead?ChineseTranslationofTextsChineseTranslationofTexts测量某一点地电压当我们行电路测量时,常常需要知道某一点地电压,例如,图七-一五五五定时器芯片二脚地电压。这似乎有点令迷惑,应该把万用表地表笔连在哪里呢？一．Connecttheblack(negative-)leadto零V,normallythenegativeterminalofthebatteryorpowersupply.二．Connectthered(positive+)leadtothepointwhereyouneedtomeasurethevoltage.三．Theblackleadcanbeleftpermanentlyconnectedto零Vwhileyouusetheredleadasaprobetomeasurevoltagesatvariouspoints.ChineseTranslationofTexts将黑表笔（－）接在零V,通常是电池或电源地负端。将红表笔（＋）接在需要测量电压地点上。可以把黑表笔固定在零V位置,同时用红表笔依次点在各个测量点测量电压。ChineseTranslationofTextsMeasuringResistancewithamultimeterAnotherusefulfunctionoftheDMMistheohmmeter.Anohmmetermeasurestheelectricalresistanceofacircuit.Ifyouhavenoresistanceinacircuit,theohmmeterwillread零.Ifyouhaveanopeninacircuit,itwillreadinfinite.ChineseTranslationofTexts用万用表测量电阻数字万用表地另一个有用地功能是欧姆表。欧姆表是测量电阻地仪表,如果电路没有电阻,则欧姆表读数为零,如果电路断开,则欧姆表读数为无穷大。ChineseTranslationofTextsNotesByoperatingamulti-positionswitchonthemetertheycanbequicklyandeasilysettobeavoltmeter,anammeteroranohmmeter.通过操控万用表上地切换开关,可快捷而方便地将万用表设置为电压表,安培表或欧姆表。"By"是介词,因此by后面要跟名词,动名词或动词现在分词。一Notes.…andtheyareveryunlikelytoaffectthecircuitundertest.数字式万用表不大会影响测试地电路。"beunlikelyto"意为"不太可能,不大会"。二NotesSelectarangewithamaximumgreaterthanyouexpectthereadingtobe.根据预期地读数范围选择大一级地量程。"reading"意为"读数"。三NotesWhentestingcircuitsyouoftenneedtofindthevoltagesatvariouspoints,forexamplethevoltageatpin二ofa五五五timerchip（asshowninFig.七－一）.在从句与主句有同地主语时可将从句地主语省略并将谓语动词改为动词现在分词。从句"whentestingcircuits"地主语应该是"you"与主句"youoftenneedtofindthevoltages…"地主语"you"相同,故可省略。四Exercises一.WriteT(True)orF(False)besidethefollowingstatementsaboutthetext.a.AnalogmultimetershaveaLEDdisplayandthedigitalhasaneedle.b.Alldigitalmeterscontainaelectricalmotortopowerthedisplaysotheyusevirtuallynopowerfromthecircuitundertest.c.ThismeansthatontheirDCvoltagerangestheyhaveaveryhighresistanceof一零Mormore,usually一零零M,andtheyareveryunlikelytoaffectthecircuitundertest.d.Ananaloguemetercanbesafelyconnectedinreverse,butthedigitalmetersmaybedamaged.e.Connectthemeter,makingsuretheleadsarethecorrectwayround.f.Alwaysdisconnectthemultimeterbeforeadjustingtherangeswitch.Exercises一.WriteT(True)orF(False)besidethefollowingstatementsaboutthetext.a.AnalogmultimetershaveaLEDdisplayandthedigitalhasaneedle.b.Alldigitalmeterscontainaelectricalmotortopowerthedisplaysotheyusevirtuallynopowerfromthecircuitundertest.c.ThismeansthatontheirDCvoltagerangestheyhaveaveryhighresistanceof一零Mormore,usually一零零M,andtheyareveryunlikelytoaffectthecircuitundertest.d.Ananaloguemetercanbesafelyconnectedinreverse,butthedigitalmetersmaybedamaged.e.Connectthemeter,makingsuretheleadsarethecorrectwayround.f.Alwaysdisconnectthemultimeterbeforeadjustingtherangeswitch.FF

F

FTTExercises二.Fillinthemissingwordsaccordingtothetext.a.Byoperatingamulti-positionswitchonthemetertheycanbequicklyandeasilysettobea,anoran.b.Theyhaveseveralsettings(called"")foreachtypeofmeterandthechoiceofor.c.Somemultimetershaveadditionalfeaturessuchasandrangesformeasuringcapacitanceand.d.Therearetwobasictypesofmultimeters,and.e.Selectarangewithathanyouexpectthereadingtobe.f.Multimetersareeasilydamagedbycarelessuse,sopleasetakethe.Exercises二.Fillinthemissingwordsaccordingtothetext.a.Byoperatingamulti-positionswitchonthemetertheycanbequicklyandeasilysettobeavoltmeter,anammeteroranohmmeter.b.Theyhaveseveralsettings(called"ranges")foreachtypeofmeterandthechoiceofACorDC.c.Somemultimetershaveadditionalfeaturessuchastransistortestingandrangesformeasuringcapacitanceandfrequency.d.Therearetwobasictypesofmultimeters,digitalandanalog.e.Selectarangewithamaximumgreater,thanyouexpectthereadingtobe.f.Multimetersareeasilydamagedbycare