Cov yam ntxwv tseem ceeb ntawm Standard Digital Multimeters thiab Dual-Impedance Digital Multimeters
Cov qauv yooj yim ntawm ib txwm digital multimeter yog qhia hauv daim duab. Lub dual kev koom ua ke A / D converter yog "lub siab" ntawm ib tug digital multimeter, uas enables kev hloov pauv ntawm analog rau cov teeb liab. Cov kab hluav taws xob peripheral feem ntau suav nrog kev hloov pauv kev ua haujlwm, kev ua haujlwm thiab ntau yam kev xaiv hloov, LCD lossis LED cov lus qhia, nrog rau buzzer oscillation circuits, tsav circuits, nrhiav pom Circuit Court on / off circuits, low voltage indication circuits, decimal point and symbol (polarity symbol, etc.) tsav circuits.
Lub A/D converter yog lub hauv paus ntawm ib tug digital multimeter, siv ib zaug xwb -chip loj-scale integrated circuit 7106. 7106 txais yuav ib tug internal XOR rooj tso zis, uas yuav tsav LCD zaub thiab txuag electrode noj. Nws cov yam ntxwv tseem ceeb yog: ib qho fais fab mov, qhov ntau qhov hluav taws xob, siv 9V stacked roj teeb kom ua tiav cov cuab yeej siv me me, siab input impedance, thiab siv cov keyboards hauv analog kom ua tiav tsis siv neeg zeroing thiab polarity conversion. Qhov tsis zoo yog qhov kev hloov pauv A / D qeeb, tab sis nws tuaj yeem ua tau raws li cov kev xav tau ntawm cov qauv ntsuas hluav taws xob.
Basic paub txog impedance
Niaj hnub no, feem ntau ntawm digital multimeters muag nyob rau hauv kev ua lag luam rau kev ntsuas kev lag luam, hluav taws xob, thiab hluav taws xob tshuab muaj cov input Circuit Court impedances siab heev, feem ntau ntau dua 1 megohm. Cias muab, thaum DMM ntsuas lub voj voog, nws yuav luag tsis muaj kev cuam tshuam rau kev ua haujlwm ntawm lub voj voog. Thiab qhov no yog qhov feem ntau ntawm kev ntsuas xav tau, tshwj xeeb tshaj yog rau cov khoom siv hluav taws xob lossis hluav taws xob tswj hluav taws xob. Yav dhau los siv cov cuab yeej daws teeb meem, xws li analog multimeters thiab solenoid valve testers, feem ntau muaj cov input circuit impedances tsawg, nyob ib ncig ntawm 10 kiloohms lossis qis dua. Txawm hais tias cov cuab yeej no tsis cuam tshuam los ntawm cov hluav taws xob tsis zoo, lawv tsuas yog tsim nyog rau kev ntsuas hluav taws xob hluav taws xob lossis lwm yam xwm txheej uas cov tswv yim impedance qis tsis cuam tshuam lossis hloov pauv kev ua haujlwm ntawm lub zog.
Ib qho piv txwv ua ke ntawm ob lub tswv yim impedance
Los ntawm kev siv cov cuab yeej impedance dual, cov kws tshaj lij tuaj yeem daws cov teeb meem hauv hluav taws xob lossis kev tswj xyuas hluav taws xob, nrog rau cov kev ua txhaum uas yuav suav nrog cov hluav taws xob tsis zoo, thiab tuaj yeem txiav txim siab ntau dua seb puas muaj hluav taws xob hauv Circuit Court.
Rau cov qauv ntsuas hluav taws xob, feem ntau nws yog qhov zoo dua los siv cov twj paj nruag siab impedance tshwj tsis yog tias muaj qhov tsis muaj zog tam sim no.
Hauv Fluke114, 116, thiab 117DMM, muaj qhov cuam tshuam tseem ceeb hauv kev siv Vac thiab Vdc hloov txoj haujlwm ntawm cov cuab yeej, uas tuaj yeem siv los daws cov haujlwm hauv feem ntau, tshwj xeeb tshaj yog rau cov khoom siv hluav taws xob rhiab heev. Qhov qis impedance muaj nuj nqi ntawm Fluke hu ua Auto-V/LoZ. Ntawm lawv, Auto-V sawv cev rau qhov tsis siv neeg qhov hluav taws xob, uas tuaj yeem txiav txim siab seb lub teeb liab ntsuas puas yog AC voltage lossis DC voltage, thiab tom qab ntawd xaiv cov haujlwm raug thiab ntau yam los tso saib cov ntaub ntawv raug. LoZ sawv cev rau qis impedance (Z). Qhov kev ua tau zoo no yog qhov tsis tshua muaj impedance input rau qhov ntsuas hluav taws xob, uas tuaj yeem txo qhov muaj peev xwm ntawm kev nyeem ntawv yuam kev tshwm sim los ntawm cov hluav taws xob tsis zoo thiab txhim kho qhov tseeb ntawm kev txiav txim siab muaj lossis tsis muaj qhov hluav taws xob. Thaum muaj kev ua xyem xyav txog kev nyeem ntawv (tejzaum nws yog vim muaj qhov tsis txaus ntseeg) lossis thaum ntsuas qhov muaj qhov hluav taws xob, Auto-V / LoZ hloov txoj haujlwm ntawm DMM tuaj yeem siv.
