Lesson16TheuseofmultimeterKeywords■multimeter萬用表

■physically物理地■mode模式

■probe探測■display顯示屏

■upperlight高亮■nominal額定的

■over-range超量程■drift漂流

■工作任務：如何檢測鍵盤是否串建？如何測試常用電池的電壓？■學習目標：掌握萬用表的功能和使用方法，以及在日常生活和電路檢測中的應用?！鲋攸c難點：萬用表在電路檢測中的應用■推薦學時：6學時工作任務：任務1：Howtodetectwhetherthekey“w”andthekey“e”arephysicallyconnectedwithamultimeter?GetintothemodeTouchandgoExample1:Thismeterisverysimple.Whentheprobesarenottouching,thedisplayshows"1",Whenyoutouchthetipstogether,thedisplaychangestoathreedigitmode(it'sdisplayingresistance,whichwewillcoverlater)Italsoemitsabeep.Example2:Thismeterisdual-modebutstillveryeasytouse.Turnthedialtothesymbol.Whentheprobesarenottouchingthedisplayshows"OL"whichstandsforOpenLoop.Whenyoutouchtheprobes,thesoundwaveiconshowsupinthedisplay(upperright)anditalsoshowsanumber.Thenumberisnottheresistance,actuallyit’sthevoltage.ProbingaPCBExample:HereisanexampleoftestingaPCBforcontinuity.Thefirsttestshowsthatthetwopointsarenotconnected;thesecondtestshowsthatthesetwopointsareconnected.任務2：Howtomeasurethevoltageofdailybatterieswithamultimeter?VoltagetestingExample1:Thefirstbatterywe'lltestisanew1.5Valkaline.ThisoneisaAAAbutaAA,CorDcellwillbethesamevoltage.Settherangeto2VDC.Example2:Wemeasurea9Valkalinebattery.Ifwestillhavetherangesetto2VDCwewillgetamysterious"1"display,indicatingisitover-range.Questions1:Howtoselectanappropriatemeasuringrange?2:Couldyouexchangetheblackprobeandtheredprobewhenyou