1234ABCD4321DCBATitleNumberRevisionSizeADate:13-Jul-2011Sheet of File:d:\我的文档\桌面\201 1年春\MF47万用表原理图.ddbDrawn By:WH2 500-1KR2120KR222.69KD4D346.2μAC110μFWH110KR25R350.5R4555R10.47R280.025DC maDCV0.55505000.5A+*一、直流电流档 1、50μA 的电流档由 46.2μA 表头、电位器 WH1、电位器 WH2、R21 组成。 2、0.25V 的电压档由 50μA 的电流档串联 R22 组成。 VVAIVVAIgggg25.01345.0115.026901050115.0508.32.4630000115.02.46115.02500102.462.466611 图一 MF-47 型直流电流档工作原理 1234ABCD4321DCBATitleNumberRevisionSizeADate:17-Jul-2011Sheet of File:d:\我的文档\桌面\201 1年春\MF47万用表原理图.ddbDrawn By:WH2 500-1KR2120KR222.69KD4D346.2μAC110μFWH110KR7150KR630kR8800KR515KDCV12.510502505000.5A+R122.25MR111.8MR134.5MR10360KR984KACV10502505001k1K*R204.15K 图二 MF-47 型直流电压档工作原理 VVVVVVAIVVVVVVVVK1.9918994102.11010)45002250180036084(102.1102.4954494102.11010)2250180036084(102.1102.2472244102.11010)180036084(102.1102.1102.60504150250000505075.4925.010)8001503015(105025.01075.925.010)1503015(105025.05.225.225.010)3015(105025.0175.025.01015105025.0336133650033625025036503610365.2361 VVVVVVAIK76.100089941027.11110)45002250180036084(1027.11104.50044941027.11110)2250180036084(1027.11168.24922441027.11110)180036084(1027.11127.11127.61504080250000503361336500336250250 二、电阻档(欧姆档) 万用表的欧姆档,其原理实质是用伏安法测电阻。它是将测量时用的电压固定,以电流值的大小去反映被测电阻值的大小, 图三是 M F-47 型直流电阻档工作原理电路图 23456ABCD65432TitleNumberRevisionSizeBDate:23-Apr-2012Sheet of File:G:\MF47万用表原理图.ddbDrawn By:WH2 500-1KR2120KD4D346.2μAC110μFWH110KR1555.4KR161.78KR17165(1/2)R1815.3(1/2)R1417.3KX100.5A+...