UY BAN NHAN DAN QU4N 5
TRUONG TRUNG CAP NGHE

,

KY THU4T CONG NGH:¢ HUNG VUONG

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GIAOTRINH

Ky thuit di~n - di~ n tfr
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Nghe:
Quan trj m~ng may tinh

TRINH DO• TRUNG CAP

TPHCM-2019


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LOI GIOI THl¢U
Ho?t d9ng bien SO?n giao trinh la m9t ho?t d(:mg nghien cuu khoa h9c . M6i
giao vien, giang vien tren ca sa cac phuang phap va nguyen tic chung se c6 SlJ v~n
d\,lng sang t?O vao diSu ki~n C\l thS cua minh dS sang t?O ra cac n9i dung giang d?y
h~p dfui, thu hut nguai h9c.
Nh&m giup d9i ngil giao vien c6 tai li~u

C(J

sa dS tiSn hanh cac bu6i len lop

duqc hi?u qua cilng nhu vi?c cung d.p tai li?u giup cho sinh vien n6i chung, d~c bi~t
la sinh vien chuyen nganh Quan tri ID?ng. DS dap ung nhu c§.u thvc tiSn nay khoa
Cong ngh~ thong tin da t6 chuc bien so~ cu6n giao trinh "Ky thu~t di~n tu" do
nh6m giao vien thu9c chuyen nganh Quan tri m~mg dang cong tac t?i truang TCN
KTCN Hung Vuang bien so~n.
Day la cong trinh duqc viSt bai d9i ngil giao vien da va dang cong tac t?i nha
truang cung v&i SlJ g6p

y va phan bi?n cua cac doanh nghi?p trong linh VlJC lien

quan, tuy v~y, cu6n sach chic chin vlln khong tranh khoi nhilng khiSm khuySt.
Chung toi mong nh~n duqc


y kiSn dong g6p cua b?n d9c dS cu6n sach duqc hoan

thi~n han trong 1§.n tai ban.
Xin tran tr9ng gi&i thi~u cung b?n d9c !
Qu~n 5, ngay

thang

nam201J;

Tham gia bien SO{ln

1. Chu bien Ngo Dinh Th&ng
2.D8NhuHao



MlJCLlJC
DEMUC
TRANG
GIOI THI¢U VE MON HQC KY THU~T Dit,N TU .................................... 1
I. Vl TRI, TINH CHA.T CUA MON HQC: .......................................................... 1
II. M{JC TIEU MON HQC .................................................................................... l
III. NQI DUNG MON HOC .................................................................................. 1
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BAI MO DAU TONG QUAN ··············••eo••••e:1••····················································2
1. Cac d:;ii 1uqn_g CC? ban .......................................................................................... 2
, h."
" tin
. ......................................................................................... . 3
2 .T1n
lyU va' truyen
CHUONG 1: LINH KI¥N THV D()NG ........................................................... 5
1.E>i~n tr&: .............................................................................................................. 5
1. l.C§.u t:;io, ki hi~u, phan lo:;ii cua di~n tr& ........................................................... 5
1.2. Cach d9c tri s6 di~n tr& ................................................................................. 10
1.3. Nhfrng thong s6 ca ban cua di~n tra ............................................................. 12
1.4. Cach mic ....................................................................................................... 13
1.5. Cac lo:;ii linh ki~n khac cung lo:;ii: ................................................................. 14
2.Tu dien .............................................................................................................. 15
2.1 .· C§.~ t:;io, ky hi~u, phan lo:;ii: .......................................................................... 15
2.2. Cac thong s6kythu~t, tinh chĐ.t cong dàng .................................................... 18
2.3 . Cach d9c gia tri di~n dung tren tµ di~n ........................................................ 18
2.4 Cach mic tµ di~n ............................................................................................ 19
2.5. Cac linh ki~n khac cung lo:;ii ......................................................................... 20
3.Cu9n day ........................................................................................................... 21
3.1. C§.u t:;io, ky hi~u, phan lo:;ii: .......................................................................... 21
3.2. Cac thong s6 ky thu~t, tinh ch§.t cong d1,mg .................................................. 22
3.3. Cach mic cu9n cam: ..................................................................................... 22
n
, d.nh
4 .u9c
3 ..

ma~ k,y tlJ dAe xac
i tri. so-"- cua d."
Iyn cam ............................................. . 23
4.BiSn ap .............................................................................................................. 23
CHUONG 2 : LINH KIEN Ti CH CUC
. .......................................................... 29
l .Ch§.t ban d§n .................................................................................-.................... 29
1.1.Ch§.t ban d~n nguyen ch§.t va t:;ip ch§.t ........................................................... 29
1.2.Nguyen ly ho:;it d9ng cua ban d~n .................................................................. 32
2.Diod ................................................................................................................... 33
2.1.C§.u t:;io, nguyen ly, d~c tuySn cua m~tghep m~t P-N ................................... 33
2.2.Tinh phan ClJC cua Diod ................................................................................. 36
2.3.Vng dvng diod ............................................................................................... 36
3.Transistor luong cvc BJT .............................................................. ~ .................. 38
3.1.C§.u t:;io, nguyen ly, d~c tuySn cua BJT ......................................................... 38
3.2.lJng dvng ca ban cua BJT ............................................................................. 43
4.Transistor JFET ................................................................................................. 46
4.1.C§_u t:;io, nguyen ly, d~c tuySn cua JFET ....................................................... 46
4.2.Vng dµng caban cua JFET ............................................................................ 49
5.Transistor MOSFET ......................................................................................... 49
5.1.C§.u t:;io, nguyen ly, d~c tuySn cua MOSFET ............................................... .49
5.2.Vng dvng caban cua MOSFET ..................................................................... 51
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6.Transistor don n6i UJT ..................................................................................... 51

6.1.Cfiu t?o, nguyen ly, d~c tuySn cua UJT ......................................................... 51
CHUONG 3 : M4-CH KHUECH 1>4-1 TIN HI¢U NHO ............................... 59
1.M?ch khuSch d?i E chung ................................................................................. 59
1.1.Sa d6 m?ch .................................................................................................... 59
2.Mach
dai
. khuSch
'
. C chung ................................................................................ 61
2.1.Sa do ID?Ch ......... ........... .. ................................... ...... ............. ..... ........ ........... 61
2.2.Tinh toan phan C\IC ... ........... ................................... .. ..................................... 62
2.3.Tinh cong sufit khuSch d?i va d9 lgi .............. ....... .......... .......... .............. ....... 63
3 .Mach khuSch dai B chung ............................. ... ................................... .......... ... 63
3.1.Sa d6m?ch ... :................................................................................................. 63
CHUONG 4: M4-CH KHUECH 1>4-1 CONG SUAT ..................................... 66
1.M?ch khuSch d?i d§.y keo ................................................................................. 66
1.1.Sa d6 m?ch .................................................................................... ............. ... 66
1.2.Tinh toan cong sufit ....... ........ ..... .................................................................... 66
2.M?ch khuSch d?i OCL ......... .- ...... ,...................................................................... 67
2.1.Sa d6m?ch ..................................................................................................... 67
2.2.Tinh toan cong sufit ........................................................................................ 68
3 .M?ch khuSch d?i OTL ...................................................................................... 70
3.1.Sa d6 m?ch ........... ...... ........................................ ............................ ..... .......... 70
3.2.Tinh toan cong sufit ......................................................................................... 70
CHUONG 5: M4-CH KHUECH 1>4-1 VI SAi. ................................................ 73
1.M?ch khuSch d?i vi sai caban ........................................................................... 73
1.1. Sa d6nguyen ly .............................................................................................. 73
1.2.Phuang phap dua tin hi~u vao ....................................................................... 73
2.Cac lo?i ID?Ch vi sai .......................................................................................... 73
2.1.KhuSch d?i vi sai c6 tai kiSu guang dong di~n .................... ........ ................. 73

2.2.Khu1ch d?~ vi Asai d.~ng t;a~~ito \~uong ····:···················· ······················· ····· ···· 75
2.3.Khuech d?I m9t ch1eu co bien d01 trung g1an ................................................ 75
3.Vi ID?Ch thu~t toan ............................................................................................ 76
3 .1.Khai ni~m chung ............................................................................................ 7 6
3.2.BQ khuSch d?i dao ........................................................................................... 76
3 .3 .BQ khuSch d?i khong dao .............................................................................. 77
3.4.M?ch c9ng ...... ................................... ..... .... ............ ............................ ............ 78
3 .5 M?ch tru ......................................................................................................... 79
CHUONG 6: THYRISTOR .............................................................................. 81
l.SCR ................................................................................................................... 81
2.DIAC ................................................................................................................. 83
3.TRIAC ............................................................................................................... 85
TAI LI]j:U THAM KHA0 ................................................................................. 88
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Trang 1

Glffi THIEU VE MON HOC
KYTHUATDIENTU.
.
.
I. VJ TRI, TiNH CHAT CUA MON HQC:
- Vi trf cua mon h9c: Mon h9c duqc b6 tri sau khi h9c sinh h9c xong cac mon
h9c chung, tru&c cac mon h9c/ mo dun dao t9-o ca sa nghS.
- Tinh chfit cua mon h9c : La mon h9c ly thuySt chuyen nganh ti;r ch9n.

II. MVC TIEU MON HQC
- Trinh bay chinh xac cac k:hai ni~m, ki hi~u qui UO'C, tinh chfit, nguyen ly lam
vi~c va hi~n tuqng vS di~n va di~n tu va ph9-m vi su d\ill-g cua cac linh ki~n di~n tu
thong di;mg.
- Trinh bay chinh xac cac dinh lu~t, cac d9-i luqng ca ban cua m9-ch di~n.
- Nh~n di~n, kiSm tra va hi@u nguyen ly ho9-t d9ng cua cac linh ki~n di~n tu.
- Ch9n li;ra, su dvng dung chung 109-i mo han va thi;rc hi~n han duqc m6i han t6t
khong gay hu hong linh ki~n di~n tu.
- L~p duqc cac m~ch di~n, di~n tu ca ban
III. N(H DUNG MON HQC
BAI MO DAU TONG QUAN
CHUONG 1: LINH KI$N TH(J DONG
CHUONG 2 : LINH KI$N TICH C1JC
CHUONG 3 : Mh.CH KHlJECH DAI TIN HI$U NHO
CHUONG 4: Mh.CH KHlJECH DAI CONG SUAT
CHUONG 5: Mh.CH KHlJECH DAI VI SAI
CHUONG 6: THYRISTOR


Trang 2

BAI MO DAU TONG QUAN
1.Cac d~i hrqng CO' ban
Khi xu ly s6 li~u do hay phan tich cac d6i tuqng ng~u nhien nhu dc;ti luqng
ng~u nhien, tin hi~u ng~u nhien, tin hi~u ng~u nhien phuc va truong ng~u nhien ta
phai su d\lng cong C\l toan h9c hi~n dc;ti la toan h9c th6ng ke. V oi toan h9c th6ng ke
ap d\lng cho cac d6i tuqng ng~u nhien ta phai do cac d~c tinh s6 la k:y v9ng toan h9c,
phuang sai, ham tuang quan va m?t d9ph6 nang luqng. Day chinh la cac dc;ti luqng
do phi V?t ly. DS do duqc cac dc;ti luqng nay truoc day nguai ta SU d\lng ky thu?t
analog dS tc;to ra thiSt bi do (vi d\l: tuang quan kS), nhung ngay nay nha c6 may tinh

va SU d\lng ky thu?t s6 lfiy m~u cac tin hi~u V?t ly tu d6 tinh theo angorit da dinh s~
dS tim ra cac dc;ti luqng phi V?t ly nay. M9t trong nhung nhuqc diSm cua vi~c do cac
dc;ti luqng phi v?t ly theo phuang phap th6ng ke la t6c d9 tinh rfit ch?m d~c bi~t khi
c6 yeu cfiu d9 chinh xac cao. DS khic ph\lC nhuqc diSm nay, nguai ta SU d\lng cac
thS h~ may tinh c6 t6c d9 cao hay cac thiSt bi d~c chung c6 c6 t6c d9nhanh cho vi~c
xul y th6ng ke nay (vi d\l: DSP ch~ng hc;tn). M9t phuang phap khac la nghien cuu
cac angorit nhanh dS XU ly th6ng ke, vi d\l thu?t toan biSn df>i Furie nhanh FFT
dSphan tich phf> ch~ng hc;tn, hay thu?t toan thich nghi tinh nhanh ham tuang quan
cua tin hi~u ng~u nhien.
Trong linh vvc truySn, thu nh?n va xuly thong tin chung ta cfing g~p rfit nhiSu
dc;ti luqng phi v?t ly d6 la: luqng thong tin do, t6c d9truySn thong tin, h~ s6 16i bit,
h~ s6 cit giam thong tin thua, dung luqng thong tin cua kenh lien lc;tc va kha nang
truySn cua kenh.
Nhu V?Y trong linh vvc thong tin ta c6 nhiSu dc;ti luqng phi V?t ly.
Vi~c d6 chung duqc thong qua vi~c tinh toan theo m9t angorit da dinh s~n. Vi d\l:
dS do luqng thong tin cua m9t ban tin mang dSn ta phai xac dinh duqc xac sufit xufit
hi~n cua sv ki~n trong ban tin va d9 khong xac dinh cua n6; hay mu6n xac
dinh d9truySn ta phai xac dinh duqc luqng thong tin truySn trong m9t dan vi thai
gian; hay mu6n tinh h~ s6 16i bit ta phai xac dinh duqc tf>ng s6 bit truySn di va s6
bit bi 16i sau khi nh?n duqc.
Ro rang dS xac dinh duqc cac dc;ti luqng phi V?t ly trong linh V\IC thong tin
cung phai dva vao ky thu?t s6va phai tim ra cac angorit t6i uu sao cho thai gian tinh
la it nhfit va c6 d9 chinh xac cao nhfit.
Trong linh vvc xa h9i cung c6 rfit nhiSu dc;ti luqng phi V?t ly cfin do nhu: chi
s6 tang truong GDP cua m9t qu6c gia, chi s6 IQ cua m9t nguai, chi s6 tang dan s6
cua m9t nuoc ... la nhfrng dc;ti luqng phi V?t ly rfit phf> biSn cfin phai do. DS do duqc
chung cfin phai c6 nhung quy tic (angorit) theo quy dinh cua xa h9i. DS c6 duqc s6
li~u dS tinh cac dc;ti luqng phi V?t ly nay phai c6 qua trinh th6ng ke theo thai gian
ho~c theo m9t linh vvc nao d6. Vi d\l: dS dv bao nhu cfiu tieu dung di~n cho
tung nganh trong thang cfin phai c6 nhung th6ng ke vS tieu dung di~n trong qua khu,

hi~n tc;ti va su d\lng phuang phap h6i quy c6 thS dv bao nhu ciu tieu dung di~n cho
1 ngay, 1 tu1n, 1 thang hay 1 nam.
Linh V\IC tam sinh ly cung c6 nhiSu dc;ti luqng phi V?t ly c1n do d6 la: do muc
d9 bi stress, may phat hi~n n6i d6i, may do tinh cam, tv d9ng chu~n doan


Trang 3

b~nh ... Tr?ng thai tam ly cua m6i nguai thuCYng lien quan dt ch~t che d@n nhung
ho?t d9ng cua cac caquan ben trong cathS. Vi dw khi h6i h9p thi nhip tim se tang
len. M9t nguai khi yeu se c6 m9t lo?i h6a ch~t d~c bi~t g9i la h6a ch~t tinh yeu se
xu§t hi~n trong mau. NSu ta do n6ng d9 cua n6 se biSt duqc muc d9 yeu c§.u cua
nguai d6; Hay muc d9 oi thiu cua thit c6 thSxac dinh nha xac dinh n6ng d9khi H2S
sinh ra khi thit bi oi. Nhu v~y vi~c do cac d?i luqng trong linh vvc tam sinh ly
thuCYng phai thong qua vi~c do m9t s6 d?i luqng v~t ly lien quan nao d6. S6 cac
d?i luqng v~t ly d6 c6 thSit hay nhiSu tuy vao svbiSu hi~n cua con nguai vSsvlien
quan d6.
Trong tuang lai g§.n chung ta se c6 chuang trinh chu~n doan b~nh. DS
lam duqc vi~c d6, nhiSu khi phai do nhiSu thong s6v~t ly khac nhau thong qua cac
xet nghi~m va may sequySt dinh la ta da m~c phai b~nh gi thong qua h~chuyen gia
da duqc cai d~t trong may.
Nhuv~y ta cung th~y ring, cac d?i luqng phi v~t ly t6n t?i &nhiSu linh vvc
khac nhau. Trong khuon kh6 bai viSt nay, tac gia khong thS li~t ke hSt duqc
cac linh VlJC c6 cac d?i luqng phi v~t ly cfin do. C6 diSu day la m9t linh VlJC m6i
me d§.y triSn v9ng trong nganh ky thu~t do luCYng hi~n d?i su d-i,mg ky thu~t s6c6
lien quan d@n m9t phuang phap do m6i d6 la do luCYng angorit.
2. Tin hi~u va truy~n tin

Tin hi~u la s6 do di~n ap ho~c dong di~n cu.a m9t qua trinh la sv thay d6i
cua tin hi~u theo thai gian t?o ra tin hi~u huu ich.

Cac d~ng tin hi~u:
,
Tin hi~u duqc chia lam 2 lo?i la tin hi~u tuang tv anolog va tin hi~u so
digital.
Tin hi~u tuang tv la tin hi~u biSn thien lien t1,1c theo thai gian va c6 thS nh~n
m9i gia tri trong khoang biSn thien cua n6.
Tin hi~u s6: la tin hi~u da duqcrai r?c hoa vS m~t thai gian va luqng tu
hoa vS m~t bien d9 n6 duqc biSu di@n b&i t~p hqp xung t?i nhung diSm do rai
f?C.

Tin hi~u c6 thS duqc khu@ch d?i, diSu ch@, tach song, chinh luu, nh6, do,
truySn d?t, diSu khiSn, bi@n d?ng tinh toan b&ng cac m?ch di~n tu.
DS gia cong 2 lo?i tin hi~u s6 va tuang tv dung 2 lo?i m?ch CCY ban: ill?Ch
tuang tv va m?ch
Kenh truy~n tin xac djnh
Mo hinh: tu t~p hqp cac gia tri c6 thS truySn & dfiu truySn duqc phan thanh
L nh6m Bj tuang ung v6i cac gia tri c6 thS nh~ duqc (J d§.u nh~n va xac su~t dS
nh~n yj v6i diSu ki~n da truySn xi la p(Y=ylX=x1 Bj)=I


Trang4

D~c tnmg: cua kenh truySn xac dinh la H(Y/X)=O. C6 nghia la lugng tin chua
biSt vS Y khi truySn X b~ng Ohay khi truySn X thi ta biSt se nh~ duqc Y.
Dung lugng: C=log2L
Kenh truy~n khong nhi~u
Mo hinh: la S\1 kSt hqp cua kenh truySn xac dinh va kenh truySn khong
m§.t thong tin, truySn ky t\1 nao se nh?n duqc dung ky t\1 d6.

D~c tnmg: H(XN)=H(Y/X)=O. Dung lugng: C= log2L= log2M

Vi dµ: ma tr?n truySn tin cua kenh truySn khong nhiSu v6i M=L=3:

.· [1 0I 00
2

.

O O I

x

Y, Y, Y1

Mo hinh: la kenh truySn ma khi truySn gia trjnao thi m§.t gia tri d6 ho~c xac
su§.t nhiSu thong tin tren kenh truySn 16n hon xac su§.t nh~ duqc.
D~c trung: H(X/Y)=H(YIX)= max
Dung lugng: C=O
Vi d\l: kenh truySn c6 ma tr?n truySn tin nhu sau:
A

(B

l-&

&

I- &

Kenh truy~n dBi xung
Mo hinh: la kenh truySn ma ma tr?n truySn tin c6 d~c diSm sau:

+ oi d n a ma tran A 1 m th an i c a pMn ph6i P={p 1 p' , ... , p'L}

i ❖t ua ma~ Ai m t hoan i ua Q=(q J q 2 .•• q' }
Vi d\l: cho kenh truySn d6i xung c6 ma tr?n truySn tin nhu sau:

+

= ; •[: I
x, 1/ 6

:;
II

~

:

I:]

1/ 3


Trang 5

CHUONG 1: LINH KIEN
. THU. DONG
.
1.Di~n tr&:

Di?n tr& la m9t trong nhfrng linh ki?n di?n tu dung trong cac me:lch di?n tu

dS de:lt cac gia tri dong di~n va di~n ap theo yeu c~u cu.a me:lch. Chung c6 tac dàng
nhu nhau trong ca me:lch di~n m<)t chiSu 1Đ.n xoay chiSu va ch@ de) lam vi~c cu.a di~n
tr& khong bi anh huang b&i t~n s6 cu.a ngu6n xoay chiSu.
1.1.C,u t~o, ki hi~u, phan lo~i cu.a di~n tr&

Tuy theo k@t du cu.a di~n tr& ma nguai ta phan loe:li:
- Di?n tr& hgp chfit cacbon:
Di~n tr& c6 cfiu te:lo b~ng b<)t cacbon tan tr<)n v&i chfit each di~n va keo k@t
dinh r6i ep le:li, n6i thanh tung thoi hai d~u c6 day d§.n ra dS han. Loe:li di?n tr& nay
re tiSn, dS lam nhung c6 nhugc diSm la khong 6n dinh, d9 chinh xac thfip, muc de)
te:lp am cao. M<)t d~u tren than di~n tr& co nhfrng Ve:lCh mau ho~c co chfim mau. Do
la nhung quy dinh mau dung dS biSu thi tri s6 di~n tr& va cfip chinh xac.
Cac loe:li di~n tr& hgp chfit b<)t than nay c6 tri s6 tulO d@n hang chµc megom,
cong sufit tul/4 W t&i vai W.
- Di?n tr& mang cacbon:
Cac di?n tr& c6 cfiu te:lo mang cacbon dugc gi&i thi~u tren Hinh 1.1. Cac di~n
tr& mang cacbon da thay th@ h~u hSt cac di~n tr& hgp chfit cacbon trong cac me:lch
di~n tu. Dang le lfip d~y cac hgp chfit cacbon, di~n tr& mang cacbon g6m m<)t lap
chuftn xac mang cacbon bao quanh m<)t 6ng phu g6m mong. De) day cu.a lap mang
bao nay t?O nen tri s6 di~n tr&, mang cang day, tri s6 di~n tr& cang nhova ngugc
l?i. Cac day d§.n kim lo?i dugc k@t n6i v&i cac nip a ca hai d~u di~n tr&.
Toan be) di~n tr& dugc bao b~ng m<)t lap keo epoxi, ho~c b~ng m<)t lap g6m.
Cac di~n tramang cacbon c6 d9chinh xac cao hon cac di~n tr& hgp chfit cacbon, vi
lap mang dugc lang m9t lap cacbon chinh xac trong qua trinh san xufit. Lo?i di~n
tranay dugc dung ph6 bi@n trong cac may tang am, thu thanh, td s6 tu 1 n t&i vai
chµc megom, cong sufit tieu tan tu 1/8 W t&i hang chµc W; c6 tinh 6n dinh cao, ti;ip
am nho, nhung co nhugc diSm la dS va.

Hinh 1.1: M~t cit cu.a di?n tramang cacbon
- Di~n tr& day qufin:

Di~n tr& nay g6m m<)t 6ng hinh trµ b~ng g6m each di~n, tren d6 qufin day kim
loi;ii co di~n tr& sufit cao, h~ s6 nhi~t nho nhu constantan mangani. Day di~n tr& c6
thS trang men, ho~c khong trang men va c6 thS qu~n cac vong sat nhau ho~c qufin
theo nhfrng ranh tren than 6ng. Ngoai cung c6 thS phun m<)t lap men bong va a hai


Trang 6

d~u c6 day ra dShan. Cung c6 th@ tren lap men phu ngoai c6 chua ra m9t khoang dS
c6 th@ chuySn dich m9t con ch~y tren than di~n tr& diSu chinh tri sfJ.
Do di~n tr& day qufin g6m nhiSu vong day nen c6 m9t tri sfJ di~n cam.
BS giam thi@u di~n cam nay, nguoi ta thuang qufin cac vong day tren m9t la each
di~n dyt ho~c qufin hai day ch~p m9t d~u dS cho hai vong day liSn sat nhau c6 dong
dien ch~y nguqc chiSu nhau.
Lo~i di~n tr& day qufin c6 uu diSm la bSn, chinh xac, chiu nhi~t cao do d6
c6 cong sufit tieu tan 16n va c6 muc t?p am nho. Tuy nhien, di~n tr& lo~i nay c6 gia
thanh cao.
- Di~n tr& mang kim lo~i:
Di~n tr& mang kim lo?i duqc chS t?o theo each kSt Hing mang niken-crom tren
than gfJm chfit luqng cao, c6 xe ranh hinh xoiln fJc, hai d~u duqc lilp day nfJi va than
duqc phu m9t lap san. Di~n tr& mang kim lo~i 6n dinh han di~n tr& than nhung gia
thanh dilt gfip khoang 41~. Cong sufit danh dinh khoang 1/l0W tr& len. Ph~n nhiSu
nguoi ta dung lo~i di~n tr& mang kim lo~i v6i cong sufit danh dinh 1/2W tr& len,
dung sai ± 1% va di~n ap qrc d~i 200 V.
- Di?n tr& oxyt kim lo?i:
Di~n tr& oxyt kim lo?i duqc chS t~o bing each kSt lilng mang oxyt thiSc tren
thanh thuy tinh d~c bi~t. Lo?i di~n tr& nay c6 d9 Jm rfit cao, khong bi hu hong do
qua n6ng va cung khong bi anh huang do Jm u6t. Cong sufit danh dinh thuang la
1/2W v6i dung sai ± 2%.
R


-cJ· nt tr" a om.
1.2.
- BiSn tr&:
BiSn tr& dung dS thay d6i gia tri cua di?n tr&, qua d6 thay d6i duqc S\I can
tr& di?n tren m~ch di?n. Hinh 1.3 minh ho? biSn tr&.
IOI• p

O

>---.

VR

IOI pra

Hin 1.3. C·
Ki hieu cua biSn tr&:
- Ki hi?u cua biSn tr& tren sa d6 nguyen ly duqc minh ho? tren Hinh 2.4.

~

2

r-1
~
.
~
.
~

VR
YR
VA
.

a) J i tinh hi h t

.

1

2 -3

1

3


Trang 7

c) Lo,i tich hqp chung, nhung rieng tn.1c di~u chinh

L

3

1

- ~...---2


➔--•UU

O•

---o,,...!

<·i-,· - -

•"•U"'";

d) ~ bi~n tro c6 cong t!c

ffinh 1.4: Cac loti bl@n tra
b) Lo~ hai bi~n tra chinh cthng be} (d
:·..-- . . -·· I!:)· : .......:
I 2 - ~ - !i
:
~

i

l
:

::.

=

tt\lC)


1

31

773
2

I

;;

i
..................................................... ........
,

Hinh d,;mg thi;rc tS:
- BiSn tra than: khi v~n trgc chinh biSn tr&, thanh truqt la m(>t la kim lo~i quet
len do~ m~t than gifra hai chan 1 - 3, lam di~n tr& 1§.y ra a chan 1 - 2 va 2 - 3 thay
d6i theo.
+ Tren Hinh 1.5, khi v~n trgc chinh theo chiSu kim d6ng h6, di~n tr& 1 - 2
giam va di~n tr& 2 - 3 tang.
1

2 3

IDnh 1.5: IDnh inh cua bign tra

+ Tren Hinh 1.6 khi thanh g~t dugc g~t qua, g~t l~i lam cho di~n tr& a
c~p chan 1 - 2 va 2 - 3 se thay d6i tuang ung.
a


mnh 1.6: m1lh inh ciia biln trit tba.nh gft
- Lo~i biSn tr& day qu§.n:
Hinh 1. 7 minh ho~ lo~i biSn tr& day qu§.n.


Trang 8

/Wmo
..-..-"""'-.'-

.lit t

Oay

~n lr
mnh 1.7: IIlnh

n

- Lo~i biSn tr& d6ng tn,1c:
Hinh 1.8 minh ho~ lo~i biSn tr& d6ng tn;c. Lo~i nay g6m hai biSn troVRl va
VR2 duqc d~t chung trong m(>t kh6i va thiSt kS 2 tn,ic chinh rieng d(>c l~p nhau: khi
ta chinh VRl v~n khong lam anh huang dSn VR2 va nguqc l~i .
• I - -

wll- -. a

~

1vn,- i ,

T11,1c chlnh

,

!l~•a·.
!- - ·1 ?.' .!

c' m t
cnhung "eu c
mnh 1.s: nh
C
fcl.P
- Lo~i biSn t;o d6ng chinh:
Hinh 1.9 minh ho~ lo~i · biSn tr& d6ng chinh. Lo~i nay g6m 2 biSn tr&
d~t chung trong m(>t kh6i va c6 chung m(>t tn,ic chinh, vi v~y m6i 1§.n chinh VRl thi
VR2 cung anh huang theo.

Hlnh 1.9: mnh oh c
- Lo~i biSn tr& c6 cong tic:
Lo~i nay gf>m c6 biSn tr& va cong tac; khi ta v~n tn,ic chinh nguqc chiSu kim
d6ng hf> vS dich cu6i cung cong tac se lam ho m~ch, khi ta v~n tn,ic chinh theo chiSu
kim d6ng hf> cong tac se lam dong m~ch. Lo~i biSn tr& c6 cong tac nay thucmg g~p
nhiSu a nut chinh am luqng (volume) cua cac may tang am, radio, cassette dai cu.

b)

a

m
a) Bi n

1.1

lro

mi

6 c"'n
- E>i~n tr& nhi~t (thermistor):

nh ciia · n trlt.
C b BiSn tro tinh chloh


Trang 9

Di?n tr& nhi?t (thuong g9i la themisto) duqc chS t9-o tu ch~t ban d~n, c6 chuc
nang nh9-y cam v6i nhi?t d9. Themisto c6 hai lo~i:
+ Lo~i themisto khi nhi?t d9 tang lam tang gia trj s6 di?n tr& (nhi?t tr&
duong):
+ Lo~i themisto khi nhi?t d9tang lam giam gia tri di?n tr& (nhi?t tr& am).
Hinh 1.11 la cac ky hi?u cua di?n tr& nhi?t.
Th+

----e--Th-

--@,--

Hinh 1.11: Ky hi~u cua cac di~n tr&nhi~t (themisto)
Themisto duqc dung a cac m~ch cong su~t cao nhilm mvc dich can bilng l~i
dong di?n qua m~ch khi m~ch ho~t d9ng trong thai gian dai. Thuong trong cac may
tang am, khi may ho~t d9ng lau, cac tranzito khuSch d~i cong su~t (thuong g9i la
so) bi n6ng, lam tang nhi?t d9 cua m9-ch, nhung nha c6 themisto c6 tri s6 di?n tr&
thay d6i theo nhi?t d9, nen hi?u chinh l~i dong di?n qua so cong su~t, lam cho so
bat n6ng. Themisto con duqc ung dvng r~t nhiSu trong cac m9-ch diSu khiSn nhi~t
d9 a nhiSu IInh V\l'C, vi dv diSu khiSn nhi?t d9 trong phong m6 (giu nhi?t d9phong
m6 khong d6i); diSu khiSn nhi?t d9trong kho vu khi (gifrnhi?t d9 trong kho vil khi
khong d6i), diSu khiSn nhi?t d9 trong cac phan ung hoa h9c (giu nhi?t d9phan ung
kh6ng d6i).
- Di?n tr& quang
Di?n tr& quang (con g9i la quang tr&) la di?n tr& c6 cfiu t~o d~c bi?t dS khi
c6 chum anh sang r9i vao lam thay df>i tri s6 cua di~n tr&. Hinh 1.12 la ky hi~u cua
di?n tr&quang.

-'6)--©

~~

IDnh 1.12: Ky hifn 4ifn tro q11ang
- Lo~i di~n tr& tich hqp:
Bi?n tr& tich hqp la di?n tr& duqc chS t~o g6m nhiSu di?n tr& trong m9t kh6i,
cac di?n tr& tuong ung v6i cac chan. Hinh 1.13 la ky hi~u di?n tr& tich hqp.

ffinb 1.13: Ky hifu cua tti~n trci tfch hqp
- Dien tr& han bS mat:
Di?~ tr& han bS m~t· duqc mo ta tren hinh 1.14. Cung nhu cac di?n tr& mang
cacbon, di?n tr& han bS m~t duqc chS t~o bilng each lang m9t lap mang cacbon len
lap nSn mong bilng g6m. Dai kim lo~i duqc giin vao hai d§.u di~n tr&. Di?n tr& han

Trang 10

b€ m?t dugc han tn,rc tiSp vao phfui m?t tren ho?c m?t du6i cua phiSn m:;ich in, thay
vi phai dung day d~n xuyen qua phi Sn. Cac di~n tr& han b€ m?t la linh ki~n kha nho,
di~n tich chi khoang vai milimet vuong, tuy nhien sai s6 cua di~n tr& l:;ii d.t nho,
chung dugc dung r(mg rai trong cac m:;ich di~n tu hi~n d:;ii nhu may vi tinh, TV
ho?c cac d~u Video, radio, may in laser ...

L p

t,6

p , g to
- Bi~n tr& thuong: Bi~n tr& thuong la cac di~n tr& c6 cong xuit nho tu 0,125W
dSn 0,5W
- Bi~n tr& cong xuit: La cac di~n tr& c6 cong xmit 16n hon tul W, 2W, 5W,
IOW.
- Bi~n tr& su, di~n tr& nhi~t : La each g9i khac cua cac di~n tr& cong xuit ,
di~n tr& nay c6 VO b9c SU, khi ho:;it d9ng chung toa nhi~t.
IIlnb 1.1 : Di

D·

a ....,..,.

1.2. Cach d9c tri s6 di~n tr&

a. B9c tri s6 tren than di~n tr&

M9t s6 di~n tr& thuong la di~n tr& cong suit 16n dugc nha san xuit ghi gia tri
di~n tr& va cong suit tieu tan cho phep tn,rc ti@p len than di~n tr&.

0 7'1

Ngoai cac ki hi~u cong suit, hang san xuit ... c6 ho?c khong dugc ghi
b. Cach d9c tri s6 di~n tr& ghi bfuig vong mau:
- Qui u6c gia tri cac mau :


Trang 11
,

Vong s6
1

Mau

,,
-

Vong s6
,

l.

Vong so
3

Vong s~

4 (sai so)

(s6 bqi)

(s6 thu
nhit)

(SC> th(r

:Den

0

0

X

10°

NAu

1

l

X

lOi

±l%

Do

2

2

X

)02

±2%

Cain

3

3

X

103

Vang

4

4

X

104

5

5

x

lif

6

6

X

106

Tfm

11

7

X

10

Xam

8

8

X

la8

9

9

X

1<>9

Nbfi vang.

X

JO•I

Nhil b~c

X

10-2

Xanh

hai)

l'\IC

Xanh
dtrong

~

Trang_

7

±5%

±10%

- Cach d9c tri s6 di~n tr&
+ Di~n tr& ba vong mau: Dung cho cac di~n tr& du6i 10 0.
- Vong mau thu nh~t: Chi s6 thu nh~t.
- Vong mau thu hai: Chi s6 thu hai.
- Vong mau thu ba:
+ NSu la nhuvang thi nhan v6i 0,1.
+ NSu la nhub9-c thi nhan v6i 0,01.

Vong thlt I

~!~:S
Vong thir 2

Vong thti' 3

+ Di~n tr& 4 vong mau: Day la di~n tr& thuong g~p nh~t.
- Vong s6 4 la vong &cu6i luon luon c6 m~u nhu vang hay nhu b9-c, day la
vong chi sai s6 cua di~n tr&, khi d9c tri s6 ta bo qua vong nay.
- D6i di~n v6i vong cu6i la vong s61, tiSp theo dSn vong s6 2, s6 3


Trang 12

V

D

thli l

n tbu

D

th '

n lb '

- Vong s61 ;a vong s62 la hang chvc va hang don vi
- Vong s6 3 la b9i s6 cua ca s610.
- Tris6= (vong 1)(vong 2) X 1oc mu vong 3)
- C6 thS tinh vong s63 la s6 con s6 khong "O" them vao
- M~u nhii chi c6 a vong sai s6 ho~c vong s63, nSu vong s63 la nhii thi s6

Mu cua co s610 la s6 am.
+ Di~n tra 5 vong mau : ( di~n tra chinh xac )

V

uni

- Vong s6 5 la vong cufJi cung , la vong ghi sai s6, tra 5 vong mau thi mau sai
s6 c6 nhiSu mau, do d6 gay kh6 khan cho ta khi xac dinh dau la vong cu6i cung, tuy
nhien vong cu6i luon c6 khoang each xa hon m9t chut.
- DfJi di~n vong cu6i la vong s61
,
- Tuong tv each d9c tri s6 cua tra 4 vong mau nhung a day vong s64 la b9i
socua
Co s610, vong s61, s6 2, s6 3 l~n luqt la hang tram, hang chvc va hang don
- TfisfJ= (vong l )(vong 2)(vong 3) x 10Cmuvong 4)
- C6 thStinh vong s64 la con s6khong "0" them vao
* Cac tri s6 di~n tra tieu chufin: Nguai ta khong thS chS t:;io di~n tra c6 du
t§.t ca cac tri s6 tu nho nh§.t dSn 16n nh§.t ma chi chS t:;io cac di~n tra c6 tri s6
theo
tieu chufin v6i vong mau s6m9t va vong mau s6 hai c6 gia tri nhu sau:

10

12

15

18

22

27

33

49

43

47

51

56

6

75

82

91

1.3. Nhfrng thong s6 cO' ban cua di~n tr&
a. Di~n tr& danh dinh
- Tren di~n tra khong ghi gia tri thvc cua di~n tr& ma chi ghi gia tri g~n dung
, lam tron , d6 la di~n tr& danh djnh .

Trang 13

- Don vi di~n tra: om(O),kiloom(KO),megaom(MO),gigaom(GO)
- IGO= 1000 MO=l000.000 KO= 1000.000.000 n
b. Sai s6
Di~n tra danh dinh khong hoan toan dung ma c6 sai s6. Sai s6 tinh theo ph~n
tram(%) va·chia thanh ba cfip chinh xac: cfip I c6 sai s6 ± 5%, cfip II la± 10%, cfip
III la± 20%.
C. Cong sufit dinh muc
Cong sufit dinh muc la cong sufit t6n hao Ion nhftt ma di~n tra chiu duqc m9t
thai gian dai lam vi~c ma khong anh huang dSn tri s6 cua di~n tra.
d. H~ s6 nhi~t cua di~n tra
Khi nhi~t d9 lam vi~c thay d6i tho tri s6 di~n tra cung thay d6i. Sv thay d6i
tri s6 tuong d6i khi nhi~t d9thay d6i 1°C g9i la h~ s6nhi~t cua di~n tra. Khi tang 1°C
tri s6 tang khoang 0.2%( tru lo~i di~n tra nhi~t)
1.4. Cach m~c

a. f)i~n tra miic n6i tiSp.
tn

u2

ua

R1

R2

R3

u

mnh 1.1S Difn tr« mi.c n6i ti~.
- Cac di~n tra miic n6i tiSp co gia tri tuong duong bing t6ng cac di~n tra
thanh ph~n c9ng lc;ii. Rtd = Rl + R2 + R3
- Dong di~n chc;ty qua cac di~n tra miic n6i tiSp c6 gia tri bing nhau va bing
I
I= ( Ul / Rl) = ( U2 / R2) = ( U3 / R3)
Tu cong thuc tren ta thfiy ring' S\lt ap tren cac di~n tra miic n6i tiSp ty 1~
thu~n v6i gia tri di~nt tra.
b. Di~n tra miic song song.
ll

·•-·····--

=-1 ~-

··-··

u

ffinh 1..16 Difn trit niic song song
- Cac di~n tra m§.c song song c6 gia tri tuong duong Rtd duqc tinh bai cong
thuc (1 / Rtd) = (1 / Rl) + (1 / R2) +(1 / R3)
- NSu mc;ich chi c6 2 di~n tr& song song thi Rtd= Rl .R2 / ( Rl + R2)


Trang 14

- Dong di~n ch~y qua cac di~n tra mic song song ty 1~ nghich v6i gia tri di~n

I1 = ( U / RI) , 12 = ( U / R2) , I3 =( U / R3 )
- Di~n ap tren cac di~n tra mic song song luon b~ng nhau
c. Di~n tra mic h6n hqp
11

13

1

2

u

Hinh 1.1 7 Di~n tr&mic h6n hqp.
- Mic h6n hqp cac di~n tra dS t~o ra di~n tra t6i lill hon .
Vi d\l: nSu ta c§.n m9t di~n tra 9K ta c6 thS mic 2 di~n tra 15K song song sau
d6 mic n6i tiSp v6i di~n tral,5K.
1.5. Cac lo~i linh ki~n khac cung lo~i:

a. BiSn tra
La di~n tra c6 thS chinh dS thay d6i gia tri, c6 ky hi~u la VR chung c6 hinh
d~ng nhu sau.

K

I

r"n o-d

BiSn tra thuong rap trong may ph\lC V\l cho qua trinh sua chfra, can chinh cua

ky thu~t vien, biSn tra c6 c~u t~o nhu hinh ben du6i.

ffinh 1.19 Ciu t.

tr

*Llill y
D6i v6i VR loai than, thvc t€ c6 2 lo~i: Ava B


Trang 15

- Lo~i A: Chinh thay d6i ch~m dSu, dugc su d\lng dS thay d6i am lu()'Ilg Ian
nho trong Ampli, Cassette, Radio, TV, ho~c chinh d9 tuang phan (Contrass), chinh
d9 sang t6i (Brightness) &TV, ... BiSn tra lo~i A con c6 ten g9i la biSn tro tuySn tinh.
- Lo~i B: Chinh thay d6i d9t bi Sn nhanh, su d\lng chinh am sic tr~m
b6ng ()' Apmli. BiSn tra lo~i B cung c6 ten g9i la biSn tro phi tuySn hay biSn tro
loga.
b. TriSt ap:
TriSt ap cung tuang tv biSn tro nhung c6 them c~n chinh va thuang b6tri phia
tru6c m~t may cho nguai su d\lng diSu chinh. Vi d\l nhu- TriSt ap Volume,
triSt ap Bass, Treec v.v .. , triSt ap nghfa la triSt ra m9t ph~n di~n ap tu d~u
vao tuy
theo muc d9 chinh.

IDnh 1.20 Ky hifu triit ap tren s« d6 nguyen ly~

Hlnb 1..21 mnh dfng trik ap
c. Bi~n tro nhi~t (Thermitor).
- Lo~i nay dugc chS t~o tu chit ban d~n, nen c6 kha nang nh~y cam v6i nhi~t

- Nhi~t d9 tang lam tang gia tri cua di~n tro(Nhi~t troduang).
- Nhi~t d9 tang lam giam gia tri cua di~n tro(Nhi~t troam).
d. Bien tro cam nhan do fim.
- B9 1m tang lam ting gia tri cua di~n tro (duang).
- B9 fim tang lam giam gia tri cua di~n tro (am).
e. Quang tro(Light Dependent Resistor):
Bugc chS t~o c6 d~c diSm la khi anh sang chiSu vao se lam thay d6i gia tri
di~n tro.
2.T\J. di~n
2.1. Cftu t~o,

ky hi~u, phan lo~i:


Trang 16

T\l . di~n la linh ki~n di~n tu th\l d9ng duqc su dl,lng rfit r9ng rai trong cac
m<;1ch di~n tu, chung duqc su dl,lng trong cac m<;1ch l9c ngu6n, l9c nhiSu,
m<;1ch truySn tin hi~u xoay chiSu, m<;1ch t<;10 dao d9ng .vv ...
a. Cfiu t<;10:
G6m hai ban C\l'C d~t song song, ogifra c6 m9t lap each di~n g9i la di~n moi.
Nguai ta thuang dung gifiy, g6m, mica, gifiy t§.m hoa chfit lam chfit di~n moi
va t\l di~n cung duqc phan lo<;1i theo ten g9i cua cac chfit di~n moi nay nhu T\l gifiy,
T\l g6m,_T\l kp~ng khi, T\l h6a . ..

cAn

Hinh 1.22 Ciu t. o t. gGm
b.

o

hoa

Ky hi~u:
Tl,l di~n c6 ky hi~u la C (Capacitor)

T\lho4

1\lkh6ng

Ph n

vc

.1ho

C6 phftn
\1

C6ph§n

T\lhot
kh6ngphln

C\?C

C\lC

1\1 biSn

dungvl
t\l vi
chinh

Phan lo<;1i tl,l di~n
Tl,l di~n duqc chia lam hai lo<;1i chinh la:
- Tl,l di~n c6 phan C\l'C tinh am va duong.
- T\l di~n khong phan eve tinh duqc chia ra nhiSu d,;mg.
* Tl,l gifiy, Tl,l g6m, Tl,l mica. (T\l khong phan C\l'C)
Cac lo<;1i tl,l nay khong phan bi~t am duong va thuang c6 di~n dung nho tu
0,47 µF tro xu6ng, cac t\l nay thuang duqc su dl,lng trong cac m<;1ch di~n c6
t§.n s6cao ho~c m<;1ch l9c nhiSu.
C.


Trang 17

IIlnh l.ZJ Ty g@m .. la ty. kh6ng phan CIJC..
* Tv oxid hoa: Thuong g9i la tv h6a
Tv h6a la tl;l c6 phan C\IC am duang ' tv hoa c6 tri s6 16n han va gia tri tu
0,47µF dSn khoang 4.700 µF, Tv duqc chS t~o v6i ban C\IC nhom lam C\IC duang
c6 b@ m~t hinh thanh lop oxid nhom v6i lop b9t khi c6 tinh each di~n dS lam chit
di~n moi. :Lop oxid nhom r§.t mong nen nen di~n dung cua tl;l l6n, khi su dvng phai
l~p dung ca cj tinh am duang, di~n thS lam vi~c thuong nhohan 500v.
Tv hoa thuong duqc SU d\lllg trong cac m~ch c6 dn s6 thfip ho~c dung dS l9c
ngu6n, tv hoa luon }uon c6 hinh trv ..

ffinh 1.24 T\J.hOa - La tl}.CO phan ClfC am dtrO'ng.
* Tvxoay.
Tv xoay la tv c6 th@ xoay dS thay d6i gia tri di~n dung,

l~p trong Radio dS thay d6i tful s6 c(mg huang khi ta do dai

ffinh 1.25 Ty xoay su dyng trong Radio
* Cac td s6 di~n dung tieu chu~n:

tv nay thuong duqc


Trang 18

Tu.ang tv nhu di~n tra, nguai ta ch@ t?o cac tµ di~n c6 tri s6 di~n dung theo
tieu chu~n v6i cac s6 thu nh§.t va s6 thu hai nhu sau:
10 - 12 - 15 - 18 - 22 - 27 - 33 - 39 - 47 -5 6 - 68.- 75 - 82.

2.2. Cac thong s6kythuit, tinh ch,t cong d\}ng
a. Cac thong s6 ky thu~t
- Di~n ap cong tac la di~n ap ma tµ c6 th@ chiu d\fllg duqc a hai d~u khi
lam vi~c lau dai tren 10.000 gia.
- Di~n ap danh thung la di~n ap ma qua di~n ap d6 thi chfit di~n moi cua tµ
bi danh thung.
- Di~n dung:
La d?i luqng n6i len kha nang tich di~n tren hai ban eve cua tµ di~n, di~n
dung cua tv di~n ph\l thu(>c vao di~n tich ban eve, v~t li~u lam chfit di~n moi
va khoang each gifr
C = s. S / d
Trong d6:
C: la di~n dung tµ di~n, dan vi la Fara (F)
s: La h~ng s6 di~n moi cua lap each di~n.
d: la chiSu day cua lap each di~n.
s: la di~n tich ban C\fC cua tv di~n.

- Dan vi di~n dung cua tµ:
Dan vi la Fara (F), !Fara la rfit 16n do d6 trong thvc tS thuang dung cac dan
vi nho han nhu MicroFara (µF), NanoFara (nF), PicoFara (pF).
1 Fara = I 000 µFara = I 000.000 n F = 1000.000.000p F
1 µFara = 1000 n Fara
1 n Fara = 1000 p Fara
- Tinh chfit cong dvng
Dung d@ (tich) n?p, ph6ng (xa) di~n.
* N?p = gom di~n l?i, tich tµ l?i.
* Xa= ph6ng, thoat.

2.3 . Cach dqc gia trj di~n dung tren t\l di~n.
- Cung tuang tv nhu di~n tra, tuytheo kich thu6c cua tv ma nguai ta c6 th@
ghi trvc tiSp gia tri cua tv va di~n ap chiu d\fllg len than tv.
- NSu tv nho nguai ta c6 th@ ghi theo quy UO'C :Vi dv
- V 6i tv I 04 thi tuang ung la I 0. I 04 dan vi tinh la pF.
- V6i tv ky hi~u bing 2 s6 thi d9c tf\IC tiSp dan vi la nF: 68 tuang ung 68nF
- V6i tv.01 thi tuang ung la 0,01 va dan vi tinh la µF.


Trang 19

Hinh. l.26 Ty boa. ghi difn d1mg la 185 pF / 3:20 V
- V &i tµ hoa : Gia tri di~n dung cua t\l hoa dugc ghi trvc tiSp tren than tµ
=> Tg hoa la tg c6 phan C\l'C ( -) , ( +) va luon luon c6 hinh tn_i.
- V &i tt;L gi~y , tv g6m : Tv gifiy va t\l g6m c6 tri s6 ghi bing ky hi~u

ffinh 1.27 TggBm ghi trjsBbing ky hi~u.
,
Cach d9c : Lfiy hai chu s6 d~u nhan v&i 1oCMusoth(r3 )

Vi dv tµ g6m ben phai hinh anh tren ghi 474K nghia la
Gio tri= 47 x 104= 470000 p ( Lfiy don vi la pico Fara)
= 470 n Fara= 0,47 µF
Chu K ho~c J a cu6i la chi sai s6 5% hay 10% cua tv di~n
2.4 Cach mile t\l di~n

a. Tv di~n mic n6i tiSp.
- Cac tv di~n mic n6i tiSp c6 di~n dung tuang duong C td dugc tinh bai cong
thuc: 1 / C td= (1 / Cl ) + ( 1 / C2) + ( 1 / C3 )
- Truong hgp chi c6 2 tµ mic n6i tiSp thi C td= Cl.C2 / (Cl+ C2)
- Khi mic n6i tiSp thi di~n ap chiu d\l'llg cua tv tuong duong bing t6ng di~n
ap cua cac tv c(mg l~i. U td= Ul + U2 + U3
- Khi mic n6i tiSp cac tv di~n, nSu la cac t\lhoa ta c~n chu y chi@u cua tv di~n,
C\IC am tv !rn&c p~ai n6i v&i C\-1'~ duong ~\l ~au:

,-,-~ããã11f0Ơ"'

...

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ffinh 1..28 Cach mic ty difn
a.T\1 dien rnic n6i ti~p
b. T1,1 di~n mic song song