B CNG THNG

TRNG I HC CNG NGHIP TPHCM

KHOA CNG NGH IN

----

TIU LUN

IN T C BN

TI : Linh kin th ng

GVHD : L Ngc Tun

Tp.HCM, 2013

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DANH SCH NHM

H & Tn MSSV

Nguyn ng c 12021171 ( Nhm trng)

Trn Tin Thnh 12090931

Nguyn Xun Lanh 12024771

Nguyn Vn Tin 12016151

Nguyn Vn Nhon 12034841

L Trn Hng Duy 12011151

inh Anh Tun 12078721

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MC LC

PHN I: IN TR ............................................................................................................................... 4

PHN II: T IN .............................................................................................................................. 13

PHN 3: CUN CM .......................................................................................................................... 24

TI LIU THAM KHO ..................................................................................................................... 29

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PHN I: IN TR

1. Khi nim

in tr l linh ki c tnh cn tr dng in v lm mt s chc nng khc ty thuc vo v

tr ca in tr trong mch in.

in tr l i lng vt l c trng cho tnh cht cn tr dng in ca mt vt th dn

in. N c nh ngha l t s ca hiu in th gia hai u vt th vi cng dng in

i qua n:

URI

Trong :

U : l hiu in th gia hai u vt dn in, o bng vn

I : l cng dng in i qua vt dn in, o bng ampe (A).

R : l in tr ca vt dn in, o bng Ohm ()

n v : ohm ()

1k =10 1M = 10 = 10 2. in tr ca dy dn

2.1 Khi nim

in tr ca dy dn l i in c trng cho tnh cn tr ca dng in ca dy dn

K hiu l : R, n v l :

Tr s in tr ca dy dn in ln hn hay nh hn ty thuc vo vt liu lm nn dy dn,

chiu di dy dn v tit din ca dy dn.

lRS

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: l in tr sut m L : l chiu di ( m ) S : l tit din ()

R : l in tr ()

2.2 in dn l i lng c trng cho tnh dn in ca dy dn . in dn nghch o ca

in tr.

K hiu : G, n v l : S ( siemens)

1GR

2.3 in tr sut

S o in tr ca ay dn lm bng mt cht no v c chiu di 1m , tit din thng

1 c gi l in tr sut ca cht .

Ty cht khc nhau m c in tr sut khc nhau, in tr sut bin i theo nhit v

s bin i ny c xc nh theo cng thc sau.

= (1 + ) Trong :

: in tr sut o 0 t: nhit ()

: h s nhit

: in tr sut nhit t in tr sut ca mt s cht thng gp:

Cht m Cht m

Bc 0,016.106 Km 0,06.106

ng 0,017.106 Thp 0,1.106

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3. Phn loi

in tr c th phn loi da vo cu to hay da vo mc ch s dng m n c nhiu loi

khc nhau .

3.1 Phn loi theo cu to

a. in tr than

Ngi ta trn than v bt t st theo t l nht nh cho ra nhng tr s khc nhau . Sau

, ngi ta p v cho vo mt ng bng bakelite .Kim loi p st hai u v hai dy ra c

hn vo kim loi , bc kim loi bn ngoi gi cu trc bn trong ng thi chng c xt v m.

Ngoi cng ngi ta sn cc vng mu cho bit tr s cc in tr . Loi in tr ny d ch

to, tin cy kh tt nn n r tin v rt thong dng . in tr than c tr s t vi n vi

M.

b. in tr mng kim loi

in tr mng kim loi c ch to theo quy trnh kt lng mng Ni Cr trn than gm c

x rnh xon , sau ph bi mt lp sn. in tr mng kim loi c tr s n nh, khong in

tr t 10 n 5M .Loi ny thng c dng trong cc mch dao ng v n c chnh

xaac1 cao v tui th cao , t ph thuc vo nhit .

c. in tr oxit kim loi in tr oxit kim loi ch to theo quy trnh kt hp oxit thic trn

thanh Si. Loi ny c n nh cao, chng m tt, cng sut danh nh t 0,25W n 2W.

d. in tr dy qun

in tr dy qun lm bng hp kim Ni Cr qun quanh trn mt li cch in snh s. Bn

ngoi c ph mt nha cng v mt lp sn cch in . gim thiu h s t cm L ca dy

qun, ngi ta qun 1 2 s vng theo chiu thun v 1 2 s vng theo chiu nghch. in tr chnh xc dng dy qun c tr s t 0,1 n 1,2 M , cng sut danh nh thp

t 0,125 W n 0,75 W.

Nhm 0,026.106 Photpho 0,11.106

Vonfram 0,055.106 Ch 0,21.106

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in tr dy qun c cng sut danh nh cao cn c gi l in tr cng sut.

3.2 Mc ch s dng

a. Bin tr (VR :Variable Resistor)

L mt loi in tr c tr s thay i c. Cu to gm mt in tr mng than hay dy

qun c dng hnh cung , c gc xoay l 270 . C mt trc xoay gia ni mt con trt lm

bng than hay bng kim loi cho bin tr than. Con trt s p ln mt din tr to kiu ni tip

xc, lm thay di tr s in tr khi xoay trc.

Bin tr dy qun thng c tr s nh t vi n vi chc . Cng sut kh ln, c th

ti vi chc W.

b. Bin tr than : ngi ta trng mt lp than mng ln hnh vng cung bng bakelit. Hai

u lp than ni vi cc dn in. gia l cc ca bin tr v chnh l con chy bng kim loi

tip xc vi lp than. Trc xoay gn lin vi con chy , khi xoay trc con tr chy di ng trn

lp than lm cho tr s bin tr thay i. Bin tr than cn chia lm 2 loi: bin tr tuyn tnh, bin

tr phi tuyn tnh.

c. Nhit tr (TH Thermistor)

L loi in tr m tr s ca n tthay i theo nhit .

Nhit tr m (NCT): l loi nhit tr c tr s in tr gim xung khi nhn nhit cao hn

v ngc li.

Nhit tr dng (PTC): l loi nhit tr c tr s in tr tng ln khi nhn nhit cao hn

v ngc li.

d. in tr ty p

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L loi in tr c tr s thay i theo in p t vo hai cc. Khi in p gia hai cc

di tr s quy nh th VDR c tr s in tr rt ln ,coi nh h mch. Khi in p gia hai cc

tng cao qu mc quy nh th VDR c tr s gim xung cn rt thp, coi nh ngn mch.

VDR thng c mc song song cc cun dy c h s t cm ln dp tt cc in p

cm ng qu cao khi cun dy b mt dng in qu t ngt trnh lm h cc linh kin khc trong

mch.

e. Quang tr (Photoresistor)

L loi in tr ph thuc vo nh sang (LDR light dependent resistor )

Quang tr thng c ch to t sulfur-cadmiun .Quang tr c tr s in tr ln hay nh

ty thuc vo cng chiu sang vo n . chiu sang cng mnh th in tr c tr s cng

nh v ngc li.

Khi b che ti cc in tr vo khong vi trm k n vi M

Khi dc chiu sang th in tr vo khong vi trm n vi k .

f. in tr cu ch (Fusistor)

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in tr cu ch c tc dng bo v qu ti nh cc cu ch ca h thng in nh nhng n

c dng trong cc mch in t bo bo v cho mch ngun hay cc mch c dng ti ln.

Khi c dng in ln hn dng cho php i qua th in tr s b nng v b t.

in tr cu ch c gi tr rt nh , khong vi

4. Cch mc in tr

4.1 Mc ni tip

td 1 2 3R R R R

Nu mc nhiu in tr ni tip th

= + + + 4.2 Mc song song

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1 2td

1 2

R RRR R

5. cch oc tr s in tr

5.1 c tr s in tr theo quy c vng mu

a. in tr 3 vng mu

L loi in tr c chnh xc thp, sai s cao, gi tr R c tnh theo cng thc sau:

R AB C 20% Trong :

Vng A: l s th 1

Vng B: l s th 2

Vng C: l b s

V d: vng A mu nu, vng B: xanh lc,vng C nu th ta s c gi tr in tr tng ng

l: 115 10 ( ) 20%

R 150 20%

b. in tr 4 vng mu

L loi in tr c chnh xc mc trung bnh, gi tr R c tnh theo cng thc:

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R AB C DD 5%

Trong :

Vng A: l s th 1

Vng B: l s th 2

Vng C: l b s

Vng D: l sai s

c. in tr 5 vng mu

L loi in tr c chnh xc cao, sai s l 1%, c xc nh theo cng thc:

R ABC D E Trong :

Vng A: l s th 1

Vng B: l s th 2

Vng C: l s th 3

Vng D: l bi s

Vng E: l sai s (1%)

5.2 c in tr theo quy c chm mu

Trn thn cc in tr, mt u in tr c mu B khc vi mu than in tr A, gia than

c chm mu C.

Cch c tr s vn nh trn : vng A vng B 10 c s m vng C V d: mt in tr c thn mu xanh l cy, mt u mu , c chm vng

Tr s in tr l 520 k

5.3 in tr c ghi s trn thn

i vi in tr c ghi s trn thn th 2 s u c ngha, s th 3 l s nhn

V d : trn thn ghi 103 th tr s in tr l 10 k

Ngoi ra trn thn in tr c ghi con s v ch th con s ch tr s in tr cn ch ch bi

s : R=1, K= 10, M= 10. Cc gi tr tiu biu : 1.0; 1.2; 1.5; 1.8; 2.2; 2.7; 3.3; 3.9; 4.3; 4.7; 5.1; 5.6; 6.8; 7.5; 8.2; 9.1.

Cc linh kin in tr thng c ch to vi gi tr l cc gi tr tiu chun nhn vi bi s ca

10.

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V d: 10 , 100 , 1,5k

6. Cng sut ca in tr

Cng sut ca in tr l tr s ch cng sut tiu tn ti a ca n.

Cng sut chu ng ny do nh sn xut cho bit di dng ghi sn trn thn hoc kch

thc ca in tr. Kch thc ca in tr ln th cng sut ln. Cng sut ca in tr thay i

theo kch thc.

Cng sut 1/4W, chiu di = 0,7 cm

Cng sut 1/2W, chiu di = 1cm

Cng sut 1W, chiu di =1,2cm

Cng sut 2W, chiu di =1,6cm

Cng sut 4W, chiu di= 2,4 cm

Nn chn cng sut chu ng ln hn hai ln cng sut tnh ton

V c tnh theo cng thc: 2P RI

Trong :

I l cng dng din (A)

R l in tr () 7. ng dng ca in tr

in tr c nhiu ng dng trong lnh vc in v in t .

Ta nhit : bp in , bn i

Thp sng: bng n si t

B cm bin nhit , cm bin quang

Hn dng , chia dng

Gim p , chia p

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PHN II: T IN

1. Khi Nim.

T in l linh kin tch ch nng lng in di dng in trng

2. Cu To K Hiu.

T in c cu to gm hai bn cc bng cht dn in t song song gn nhau nhng

cch bi lp in mi gia.

K hiu ca t in

Bao gm:

T khng phn cc

T phn cc

T c ci sn

T bn i c

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3. S dn in ca t in

Xt nh hnh trn, khi kha K m th n tt.kha K ng ta thy n lo sng ln ri tt .

Nu i ngun VDC bng ngum VAC th khi kha K h n tt, khi kha K ng ta thy n

sng lin tc.

4. in dung

in dung ( capacitance ) l i lng c trng cho kh nng tch in ca t.

K hiu: C, n v : Farad (F)

Thng c dng cc c s ca Farad:

Microfarad: 1 F= 10-6 F

Nanofarad: 1n F= 10-9 F

Picofarad: 1p F=10-12 F

Femptofarad: 1f F = 10-15 F

in dung ph thuc vo cht in mi, t l thun vo tit din ca bn t v t l nghch

vi khong cch gia hai bn t (b dy ca lp in mi).

C = .

C: in dung (F)

S: tit din ca bn t 2m

d: l khong gia hai bn t (m)

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Mt s cht in mi thng c dung lm t nh: khng kh kh, giy tm du, gm,

mica.

Hng s in mi ca mt s cht

Cht in mi Hng s in mi

Khng kh kh 1

Gm 3.6

Giy 5.5

Mica 4-:-5

Paraphin 2

Ebonit 2.7-:-2.9

in dung c th o bng t s in tch ca t trn hiu in th gia hai bn t

=

Nng lng tch tr t in

= 12 Trong :

W: nng lng (J)

C: in dung (F)

U: hiu in th gia hai bn t (V)

Q: in tch (C)

5. in th lm vic

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i vi mi loi t in, ch c th t vo n mt in p ln nht no , ty theo kt cu

ca lp in mi. Nu in p t vo qu ln in mi s b nh thng v ch ln dn in , lm

t in b hng khng dung c na.

in th lm vic chnh l in th ln nht cho php p vo hai u t m t chu ng

c, thng in th ny c ghi trn t.

6. Mch tng ng ca t in

Ngoi in dung, mt t in thc t cn c in tr v in cm nh trong mch tng

ng hnh:

Trong :

Rs : l in tr ni tip do dy dn cc u tip xc v cc in cc.

Rp: in tr shunt do in tr sut ca cht in mi v vt liu lm v, do hao in mi.

L: h s t cm tp do dy dn v cc in cc.

in tr tng ng ni tip ESR ( Equyvalent Series Rcsistance ) l in tr AC ca t

in phn nh c in tr ni tip Rs v in tr song song Rp ti tn s cho hao ca cc

phn t ny c th biu th bng hao ca mt in tr R trong mch tng ng.

Dung khng l i lng c trng cho sc cn in ca t.

K hiu : XC hoc ZC, n v : Ohm ()

Biu thc : X = = XC l dung khng ()

W l tn s gc (rad/s)

C in dung (F)

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F tn s (Hz)

Tng tr ( tr khng ) : khi lm vic tn s cao th phi tnh thm in cm u ra: Z = R + (X + X) Z: tng tr ()

R: in tr ()

XC: dung khng ()

XL: cm khng ()

L: h s t cm (H)

H s cng sut PF ch hao in trong khi t lm vic vi in p AC. t in l tng,

dng s sm pha hn in p gia hai u t in l 900. T thc t, do tn hao cht in mi,

in cc v cc u tip xc nn gc pha nh hn 900 . PF c nh ngha l t s in tr tng

ng ni tip R v tng tr Z . PF c n v : %.

H s tiu tn DF l t s in tr tng ng ni tip R v dung khng XC. DF c n v:

%. DF xp s bng PF khi PF

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in c np vo t theo cng thc:

Q = Q1 = Q2

Q = CU1 = CU2 =>U = ; U = Mt khc ta c:

Q = Ctd U => U =

M : U = U1+U2

=>

=

+

+ +

7.1. Mc song song

Hiu in th gia hai u t : U=U1=U2.

in tch np vo t C1: Q1=C1U.

in tch np vo t C2: Q2=C2U.

in tch np vo t Ctd: Q=CtdU.

in tch np vo t C1,C2 bng in tch np vo t Ctd nn:

Q=Q1+Q2

Ctd.U=C1U+C2U=(C1+C2)U

= > Ctd=C1+C2

Nu c nhiu t mc song song th :

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Ctd=C1+C2++Cn

8. Hin tng np x ca t

Xt mch nh hnh trn, gi s t cha tch in, ta bt kha K sang v tr s 1 th t bt u

np in, lng in tch trn hai bn t tng dn n khi in th gia hai bn t gn bng ngun

VDC (99% VDC) th qu trnh np in ca t chm dt . T c xem nh np y, nu khng

c tc ng khc th hin tng vn khng thay i.

Khi cha tch in th hiu in th gia hai u t bng khng. Trong qu trnh np in th

hiu in th gia hai u t thay i theo dng hm s m: V(t) = V(1 e ) Trong :

e=2,71828

RC

R : in tr ()

C : in dung (F)

: thi gian hng np x ca t

t : thi gian t np in (S)

Trong qu trnh np in , t c dng in np thay i theo dng hm s m:

i(t) = VR e Theo l thuyt, thi gian t np y l v hn (VC(t)=VDC). Trn thc t, sau thi gian

5 t np c 99%VDC, lc ngi ta xem nh t np y.

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Khi t np y, ta bt K qua v tr s 2, t C x in qua R, hiu in th gia hai u t

thay i theo biu thc :

V(t) = Ve Trong :

e=2,71828

C : in dung (F)

RC

: thi gian hng np x ca t (s)

t : thi gian t x (s)

Dng x ca t thay i theo biu thc:

() = 9. Phn loi

9.1. Theo mc ch s dng

T c nh: l t c tr s nh dung c nh. Tr s ny c nh sn xut n nh c sai s

trong phm vi cho php. N dc chia lm hai dng:

T c cc:

T c phn cc tnh m dng.

T khng: phn cc : t c hai cc nh nhau.

T bin i c: l loi t c in dung dc iu chnh theo yu cu s dng.

9.2 Da theo cht in mi

T ha: l loi t c tnh phn cc. t ha c bn cc l nhng l nhm, in mi l lp oxit

nhm rt mng c to bng phng php in phn. in dung ca t kh ln.

Khi dng phi rp ng cc tnh m v dng. in th lm vic thng nh hn 500V.

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T ha tantalum : l t c phn cc tnh, c cu to tng t t ha nhng dng tantalum

thay v dng nhm. T tantalum c kch thc nh nhng in dung ln. in th lm vic ch

vi chc volt.

T giy : l loi t khng c phn cc tnh. T giy c hai bn cc l nhng l nhm hoc

thic, gia c lp cch in l giy tm du v cun li thnh ng.

T mng: l t khng phn cc tnh. T mng c cht in mi l cht mng do nh:

polypropylene, polystyrene, polycarbonate, polyethelene. C hai loi t mng chnh: loi foil v

loi c kim loi ha.

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T gm: l loi t khng phn cc tnh. T gm dc ch ta gm cht in mi l gm,

trng ln b mt n lp bc lm bn cc.

T mica: l loi t khng phn cc tnh. T mica c ch to gm nhiu ming mica

mng, trnags bc, t chng ln nhau hoc ming mica c xp xen k vi cc ming thic. Cc

ming thic l ni vi nhau to thnh mt bn cc. Sau bao ph bi lp chng m bng sp

hoc nha cng .Thng t mica c dng hnh khi ch nht.

10. Cch c tr s in dung

T c ghi s trn thn: .1 c ngha l t c in dung 0.1; .01 ngha l t c in dung

0.01

T c ghi s trn thn: 103K ngha l t c in dung: C 10000 pF 10%

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Hai s u l s th nht v s th 2, s th 3 l s nhn: 10 , ch ch sai s J=5%, K= 10%, 20%

T c ghi hai ch s trn thn, vd: 47/50 th s u l in dung, n v , s th hai l in p lm vic, n v l Volt

10. ng dng

T thng c dng lm t lc trong cc mch lc ngun, lc chn tn s hay cho qua cc

tn s no . T c mt trong mch lc th ng, mch lc tch cc, t lin lc ni gia cc

tng khuch i. T kt hp vi mt s linh kin khc to nhng mch dao ng, ngy nay,

cn c t nano tng cng nng lng b nh nhm p ng nhu cu ngy cng cao ca con

ngi.

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PHN 3: CUN CM

1. Cu to k hiu

Cun cm (cun cm)l nhiu vng dy in t qun lin tip nhau trn mt li.

Li ca cun dy c th l mt ng rng (li khng kh),li st bi ,hay li st l.

Cun dy li st l dng cho cc dng in xoay chiu tn s thp.

Cun dy li st bi dng cho dng in xoay chiu tn s cao .

Cun dy li khng kh cho dng in xoay chiu c tn s rt cao.

H s t thm tng i ca vt liu lm li()l t s gia t trng ca cun dy khi c li

v khi khng c li(li l khng kh)

2. H s t cm

H s t cm l i lng c trng cho kh nng tch tr nng lng t trng ca cun

cm.

K hiu : L

n v o : Henri (H)

Milihenri: 1mH=10-3 H

Mcrohenri : 1 H =10-6 H

H s t cm ph thuc vo s vng dy,tit din ,chiu di v vt liu lm cun cm.

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2 2

o r o r

7o

n dL Sl 4

4 .10 H / m

r : h s t thm tng i ca vt liu lm li i vi chn khng.

n: s vng dy

S: tit din li (m2)

l: chiu di li (m)

d: ng knh li (m)

Nng lng np vo cun cm

Dng in chy qua cun cm v tch tr di dng t trng:

21W Li2

3.Mch tng ng ca cun cm

Ngoi h s t cm L, mt cun cm thc t cn c in tr tn hao (in tr ni tip RS, c

khi k n in dung k sinh C nh mch tng ng hnh di

4. Hin tng t cm

Nu dng in I chy trong mt cun cm thay i theo thi gian, th cun cm s t cm

ng v sinh ra mt sc in ng cm ng

Ie n Lt t

Trong :

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I : vin thin dng in (A)

: bin thin t thng (wb)

t : khong thi gian bin thin (s)

5. H cm

Khi c hai hay nhiu cun cm th s thay i dng in trong mt cun cm s lm t thng

thay di ,cc cun cm cn li phn ng bng cch sinh ra cc sc in ng cm ng khi ngi

ta gi l hin tng h cm.

K hiu : M

n v o : H

6. Cch mc cun cm

a. Mc ni tip

td 1 2L L L

b. Mc song song

5. Hin tng np x ca cun cm

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Xt c tuyn np x ca cun cm:

Gi s cun cm cha tch tr nng lng in bt kha K sang v tr s mt cun cm pht

sinh sc in ng cm ng bng ngun VDC cung cp, do lc u dng in chy qua cun

cm bng bng khng. Sau dng in qua cun cm tng ln theo biu thc sau:

t

DCL

Vi t (1 e )R

LR

l thi gian hng np x ca cun cm

Ngc vi dng in, hiu in th gia hai u cun cm lc u bng ngun VDC nhng

sau gim dn theo biu thc:

t

L DCv t V e

Sau thi gian 5 th cun cm xem nh c np y, nu khng c tc ng khc th hin

tng vn khng thay i.

Khi cun cm np y ta bt kha K sang v tr s 2. Dng in x thay i theo hm s m:

t

DCL

Vi t eR

Trong qu trnh x nng lng in th hiu in th gia hai u cun cm thay i theo

biu thc:

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t

L DCv t V e

Sau thi gian 5 th cun cm s x ht nng lng tch tr trong n.

8. Phn loi

8.1 Cun cm mt lp li khng kh

Cu to :gm mt s vng dy qun vng n st vng kia hoc cch nhau vi ln ng knh

si dy. Dy c th cun trn khung bng vt liu cch in cao tn (gm,thy tinh,nha)

8.2 Cun cm nhiu lp li khng kh

Cu to : tng t nh cun cm mt lp li khng kh nhng c nhiu vng qun hn, v

cun cc vng dy thnh nhiu lp xp chng ln nhau theo kiu t ong.

8.3 Cun cm c li st bi (bt st t)

Cu to :cng tng t nh hai loi trn nhng li dng qun l ferit, thn li c rng

xon c, hai u c kha hai rnh.

8.4 Cun cm c li st ming (st l)

Cu to : cng tng t nh trn nhng li c lm t l thp Si,thp Si ht nh hng.hnh

dng li thng l E,I,U,TMi l thp c cch in bi lp ph rt mng oxit st ,thp Si

hoc vamis.

9. ng dng

Hin nay nh sn xut ch to nhiu loi cun cm c sn di dng linh kin d tr

ta c th dng ngay hoc p ng nhu cu ring ta thit k qun dy, chn li cho cun cm

Cun cm c ng dng lm micro in ng, loa in ng, bin p, cun dy trong u

c aTrong mch in t, cun cm c th mch lc tn s, mch dao ng cng hng,

mch to dng sng, dng xung

Linh kin th ng

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TI LIU THAM KHO

1. PHM TH C L MINH CNG TRNG TRNG TUN M, mch in 1,

NXB HQG TP.HCM, 2013

2. L TH HNG THM, linh kin in t, NXB HCN TP.HCM, 2011

3. TRNG VN TM, linh kin in t, H CN TH

4. Ngun internet