Cov haujlwm tshwj xeeb thiab kev siv ntawm multimeter
Lub multimeter tau dhau los ua cov cuab yeej tseem ceeb rau cov kws tsim hluav taws xob thiab hluav taws xob vim nws muaj ntau yam, yooj yim, thiab siv tau yooj yim. Txawm li cas los xij, yog tias koj xav siv tag nrho nws txoj haujlwm, koj tuaj yeem tau txais cov ntaub ntawv raug thiab nrawm. Tom qab ntawd peb yuav tsum delve tob rau hauv ib co ntawm cov yam ntxwv ntawm ib tug multimeter:
Puas yog digital multimeter yuav tsum zoo dua li analog multimeter?
Kev daws: Digital multimeter tau siv sai heev vim nws qhov zoo heev, xws li siab precision thiab rhiab heev, ntsuas ceev ceev, ntau lub zog, me me, siab input impedance, kev soj ntsuam yooj yim, thiab muaj zog sib txuas lus muaj nuj nqi. Muaj ib qho kev hloov pauv ntawm cov lus analog pointer.
Txawm li cas los xij, hauv qee qhov xwm txheej, xws li thaum electromagnetic cuam tshuam muaj zog heev, cov ntaub ntawv kuaj nrog digital multimeter yuav muaj qhov sib txawv tseem ceeb vim tias cov input impedance ntawm digital multimeter yog siab thiab yooj yim cuam tshuam los ntawm induced electromotive quab yuam.
Thaum lub sij hawm tu, nws xav tias los ntawm kev daws teeb meem tias lub diode lossis transistor hauv Circuit Court yuav puas. Tab sis siv cov 'meter' diode ntau yam los ntsuas nws qhov hluav taws xob conduction ntawm li 0.6V, nrog infinite reverse direction. Tsis muaj teeb meem, tsis muaj qhov yuam kev tom qab kuaj xyuas lub voj voog. Vim li cas?
Kev daws: Qhov ntsuas hluav taws xob tawm los ntawm feem ntau cov meter diodes yog hais txog 3-4. 5 v. Yog hais tias lub transistor kuaj tau me ntsis to los yog tus yam ntxwv nkhaus tau deteriorated, nws tsis tuaj yeem tso tawm ntawm qhov tsis tshua muaj hluav taws xob. Lub sijhawm no, peb yuav tsum siv lub rooj simulation × Hauv 10K tsis kam, qhov ntsuas hluav taws xob tawm los ntawm qhov ntau yog 10V lossis 15V. Ntawm qhov ntsuas hluav taws xob no, nws yuav pom tias qhov xav tias transistor muaj qhov xau hauv qhov rov qab. Ib yam li ntawd, thaum ntsuas qhov tsis kam ntawm qee qhov ntsuas qhov ntsuas qhov ntsuas nrog qhov tsis tshua muaj hluav taws xob, siv lub ntsuas ntsuas analog tuaj yeem ua rau puas tsuaj rau cov khoom rhiab heev. Hauv qhov no, koj yuav tsum siv lub ntsuas ntsuas digital los ntsuas.
3. Siv lub multimeter los ntsuas qhov voltage ntawm high-voltage sojntsuam tom qab attenuation, nws tau pom tias qhov kev xeem DCV yog qhov tseeb dua, tab sis ACV yuam kev yog qhov tseem ceeb. Txawm hais tias siv multimeter nrog high precision, yog vim li cas rau qhov no?
Kev daws: Feem ntau ntawm multimeters ntsuas voltage nyob rau hauv parallel, thiab rau tag nrho cov kev xeem Circuit Court, lub voltmeter nws tus kheej yog sib npaug rau ib tug load yog input impedance. Qhov loj dua qhov load impedance, qhov me me cuam tshuam rau qhov ntsuas hluav taws xob, thiab qhov ntsuas qhov tseeb dua. Tab sis tsis muaj dab tsi tuaj yeem ua tau zoo tag nrho, raws li qhov siab impedance txi lub bandwidth ntawm kev xeem. Tam sim no, cov input impedance ntawm ib tug multimeter nrog ib tug zaus teb ntawm ib ncig ntawm 100KHz nyob rau hauv kev ua lag luam yog hais txog 1.1M, yog li nws yuav muaj kev cuam tshuam loj heev thaum kuaj qhov voltage ntawm ob kawg ntawm ib tug siab load, xws li lub siab kuj. tus nqi ntawm high-voltage sojntsuam nws tus kheej. Nyob rau ntawm lub sijhawm no, koj yuav tsum xaiv lub multimeter uas muaj kev tiv thaiv sab hauv, xws li ESCORT 170/172/176/178/179 handheld digital multimeter, uas muab cov input impedance txog li 10000 Ω thaum kuaj ACV, txhawm rau zam. qhov teeb meem no.
