MN : K THUT O LNG TI: THIT K VOM DNG C CU HIN TH KIM V OPAMP

GVHD:NGUYN CHNG NH SVTH: NHM 51.NGUYN NH C NH 2.NGUYN PHNG V 3.TRN C CHU TON 4.TRN VN V 5.L HUY TUN

TRNH BY :1. 2.

3.

4.

5.

THIT K MCH O P DC BNG OPAMP (L Huy Tun) THIT K MCH DNG DC BNG OPAMP (Nguyn Phng V) THIT K MCH P AC BNG OPAMP (Trn Vn V) THIT K MCH O IN TR BNG OPAMP (Trn c Chu Ton) M PHNG MCH (Nguyn nh c Nh)

TNG THIT K BAN U

Rm = 2000 k

I max = 50 A

THIT K MCH O P DC: TNG: S dng 1 OPAMP in t ngn dng qua c cu,ta thit k sao cho Vo=Vin Khi thit k mt VOM nhiu tm o ta cho tm o nh nht trc tip qua OPAMP xc nh dng Imax qua c cu .Imax s c gi tr c nh vi tt c cc tm o. Khi mun m rng thnh nhiu tm o ta phi dng thm in tr phn p qua nhm cho in p qua OPAMP c nh l in p ca tm o nh nht.

Mch o p 6 tm o dng OPAMP

cc cng thc tnh ton thit k: T hnh v ta c h phng trnh sau1000 .R6 = 0.5 R1 + R2 + R3 + R4 + R5 + R6 250.( R5 + R6 ) = 0 .5 R1 + R2 + R3 + R4 + R5 + R6 50 .( R4 + R5 + R6 ) = 0.5 R1 + R2 + R3 + R4 + R5 + R6 10 .( R3 + R4 + R5 + R6 ) = 0.5 R1 + R2 + R3 + R4 + R5 + R6 2,5.( R2 + R3 + R4 + R5 + R6 ) = 0.5 R1 + R2 + R3 + R4 + R5 + R6

Gii h phng trnh ta c: R1= 1600R6 R2= 300R6 R3= 80R6 R4= 16R6 R5= 3R6 T ta cho R6=1k thit k mch o

THIT K MCH O DNG DC

Mch V.O.M thc t bao gm cc tm o: 100A 2.5mA 25mA 250mA

Cc biu thc suy ra t mch100 *106

0 .5 0 .5 = + R5 R1 + R2 + R3 + R4

R1 + R2 + R3 + R4 0.5 0.5 2.5 *10 = + ( ) R2 + R3 + R4 R2 + R3 + R4 R53

0.5 0.5 R1 + R2 + R3 + R4 25 *10 = + ( ) R3 + R4 R3 + R4 R53

0.5 0.5 R1 + R2 + R3 + R4 250 *10 = + ( ) R4 R4 R53

Kt qu tnh ton Quy

kt qu v bin R4:

R1 = 2400R4

R2 = 90 R4

R3 = 9R4 1250 R4 R5 = (0.25 R4 0.5)

THIT K MCH P AC

V.O.M thc t c cc thang o:10V 50V 250V 1000V

Cc biu thc tnh:0.318 2 *10 * ( R2 + R3 + R4 + R5 ) = 0.5 R1 + R2 + R3 + R4 + R5

0.318 2 * 50 ( R3 + R4 + R5 ) = 0.5 R1 + R2 + R3 + R4 + R50.318 2 * 250 ( R4 + R5 ) = 0.5 R1 + R2 + R3 + R4 + R5

0.318 2 *1000 R5 = 0.5 R1 + R2 + R3 + R4 + R5

Kt qu tnh ton

R1 = (636 2 100 ) R5

R2 = 80R5R3 = 16R5R4 = 3R5

THIT K MCH O IN TR

V.O.M thc t gm cc tm o:X1 X10 X100 X1k X10k

Cch tnh ton in tr Trong

R(o)=R(hin th)*tm o: R(o):l gi tr thc in tr cn o R(hin th):l gi tr kim ch th trn V.O.M Tm o :l cc mc o(X1,X10) n v: Ohm()

Biu thc tnh:

Biu thc tnh chung

i:trong khong 1-6 X1:Rx = 1k =>R1=2k X10: Rx = 10k =>R2=20k X100: Rx = 1M =>R3=200k X1k: Rx = 10 M =>R4=2M X10k: Rx = 100 M =>R5=20M

Rx E= = 0.5V Rx + Ri

KIM HIN TH