gt dien tu co ban

Gio trnh in t c bn

Bi:Phan Kin Nguyn

Gio trnh in t c bn

Bi:Phan Kin Nguyn

Phin bn trc tuyn:< http://voer.vn/content/col10494/1.2/ >

Thu vien Hoc Lieu Mo Viet Nam

Ti liu ny v vic bin tp ni dung c bn quyn thuc v Phan Kin Nguyn. Ti liu ny tun th theo giy

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Ti liu c hiu nh ngy: August 15, 2012

Ngy to PDF: August 15, 2012

bit thng tin v ng gp cho cc module c trong ti liu ny, xem tr. 24.

Ni dung

1 Gii thiu chung . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 C bn v bn dn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Cc linh kin in t c bn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Mt s mch in t ng dng c bn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Ch mc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Tham gia ng gp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Chng 1

Gii thiu chung1

1.1 Khi nim chung

bt u vi khi nim lin quan ti lnh vc in t, chng ta quay li vi nhng khi nim c bn cain hc trc khi cp ti in t v cc linh kin ng dng. tin cho vic tng kt cc khi nim ,phn di s lit k mt lot cc khi nim c bn lin quan ti lnh vc in-in t. Chng bao gm:

1.1.1 Khi nim dng in

Mt dng in l dng chuyn di c hng ca cc ht mang in. chnh l dng chuyn di ca ccelectron qua cc dy dn v cc linh kin in t. Chng ta c th hnh dung s chuyn di ca cc electronny tng t qu trnh chy ca mt dng nc thng qua cc ng dn nc. Nc l qu trnh chuyn dica cc phn t nc trong cc ng dn nc di tc ng ca my bm nc th dng in chuyn ditrong cc dy dn c thc hin di tc ng ca ngun pin.

Vy ngun pin tc ng nh th no to ra dng in? Nh bit cc ht ng du th y nhau,cc ht tri du th ht nhau. C th cc ht mang in tch cng dng hoc cng m s y nhau cn ccht mang in tch tri du th hp dn ln nhau. Chnh nh l do , mt ngun pin s c hai cc. Ccm s y cc electron i vo trong dy dn v cc dng s ht cc electron v pha n. Do , nu tothnh mt vng kn, th cc electron s chuyn di theo mt hng xc nh v chnh l dng in.

Dng in ny c chiu khng i nn c gi l dng mt chiu.Trong trng hp, hai cc ca ngun pin tun t i cc tnh t dng sang m v t m sang dng

th lc ny dng in trong dy dn cng ln lt i chiu tng ng vi s i cc ca cc in cc. Dngin ny chnh l dng xoay chiu.

1.1.2 Khi nim in p (hay hiu in th)

in p hay hiu in th l gi tr chnh lch in th gia hai im. Cng tng t nh dng in, inp c 2 loi in p mt chiu v in p xoay chiu. in p mt chiu l s chnh lch in th gia haiim m ti s chnh lch in th to ra cc dng in mt chiu. in p xoay chiu tng ng vitrng hp s thay i lin tc v cc tnh gia hai im tng ng v iu ny chnh l nguyn nhn tora s thay i chiu dng in v chng ta c dng in xoay chiu.

"Cc linh kin c bn"Trong cc mch in t, cc linh kin c bn c bit n chnh l in tr, t in v cun cm. y

l 3 linh kin c bn ch yu v khng th thiu trong bt k mt mch in t no. Mi linh kin u ccc c trng ring ca n. V d nh in tr l khi nim vt l c trng cho tnh cht cn tr dngin ca mt vt dn in nn linh kin in tr trong mch thng dng hn ch cc dng in trong

1Phin bn trc tuyn ca ni dung ny c .

1

2 CHNG 1. GII THIU CHUNG

mch. Vic s dng in tr trong mch in t nu c dng ng cch v ng cc gi tr in tr thmch in s hot ng mt cch ti u, cn ngc li, nu s dng mt cch tu tin s gy ra nhng sais khng ng c trong mt mch in t. Chnh v th, trong cc mch in t, vic la chn gi tr intr cng l mt vn cn lu tm trong qu trnh thit k mch. Cng tng t i vi cc linh kin tin v cun cm. Chi tit v cch s dng cc linh kin ny s c cp chi tit trong phn sau.

1.1.3 Cc nh lut c bn

Mt trong cc nh lut c bn nht trong in hc chnh l nh lut m v n c biu din bi cngthc U=I.R. trong U l hiu in th gia hai u in tr o bng Vn (k hiu V), I l cng dngin i qua in tr (o bng Ampe (k hiu A) v R l in tr lp trong mch (o bng m, k hiu ).Trong trng hp dng in l xoay chiu th khi nim in tr c gi mt cch tng qut l tng trkhng, trong in tr c gi l tr khng thun, in dung ca t in c gi l dung khng v incm ca cun cm c gi l cm khng.

1.2 Tng quan v cc h thng trang thit b in t

Trong phn ny, s trnh by v cc cu trc chung ca cc h thng trang thit b in t di dng s khi ri t , chng ta c th dnh thi gian i su phn tch thm v cc khi chc nng khc nhautrong mch in t.

Chng 2

C bn v bn dn1

2.1 Cc khi nim c bn v bn dn

Trong qu trnh phn loi vt chn i vi qu trnh dn in, ngi ta chia cc vt liu ra thnh ba loi. chnh l cc vt liu dn in (nh kim loi) v cc vt liu khng dn in/cch in v loi th ba lcc vt liu bn dn. Cc vt liu dn in l cc vt liu cho php cc dng in truyn qua cn cc vtliu cch in hay khng dn in l cc vt liu khng cho dng in truyn qua.

Cht bn dn ch yu c cu to t cc nguyn t c 4 electron lp ngoi trong cu trc nguyn tca chng. Nh vy, v bn cht, cc cht bn dn c 4 electron lp ngoi cng m c trng l 2 cht bndn Ge v Si.

dng rn, cc nguyn t cu to nn cht bn dn c sp xp theo mt cu trc c th t m chngta gi l dng tinh th. Mi nguyn t chia s cc electron ca chng vi cc nguyn t ngay cnh tonn mt cu trc bn vng c 8 electron lp ngoi cho nguyn t nm ti v tr trung tm. Nh vy, minguyn t xung quanh nguyn t trung tm s chia s 1 electron vi nguyn t trung tm to thnh mtcu trc bn vng c 8 electron lp ngoi (i vi nguyn t trung tm). Nh vy c th ni, lin kt gianguyn t trung tm vi 4 nguyn t xung quanh s da trn ch yu 4 lin kt ha tr. Di tc dng canhit, cc nguyn t s to ra cc dao ng xung quanh v tr cn bng v ti mt gi tr xc nh no ,nhit c th ph v cc lin kt ha tr v to ra cc electron t do. Ti v tr ca cc electron t do vabt ra s thiu 1 electron v tr thnh cc l trng. L trng ny c xu hng nhn thm 1 electron nhmto li s cn bng.

2.1.1 Bn cht dng in trong cht bn dn

Nh ni trn, trong cu trc vt liu ca bn thn cht bn dn, di tc dng ca nhit mi trngcng lun tn ti hai dng in tch. Mt l in tch m do electron v hai l in tch dng do l trngto ra. Di tc dng ca in trng, cc electron c xu hng di chuyn v pha pha c nng lng intch cao hn. Do , lc ny, trong bn cht cht bn dn s c 2 thnh phn cn bng. Mt l electron tdo bt ra khi lin kt ha tr v hai l l trng sinh ra do electron bt ra. Electron bt ra khi cu trc tinhth s di chuyn v pha in trng c in th ln. ng thi, l trng cng c xu hng ht cc electron xung quanh in y v i v pha in trng c in th nh hn. Nh vy, bn cht dng in trongcht bn dn c sinh ra bi 2 dng chuyn di: dng chuyn di ca cc electron t do v dng chuyndi ca cc l trng. Cc electron v cc l trng thng c gi chung vi mt ci tn l ht mang inbi chng mang nng lng in tch dch chuyn t im ny n im khc.


3

4 CHNG 2. C BN V BN DN

2.1.2 Bn dn tp cht v bn cht dng in

Nh bit, bn dn tp cht c to ra bi vic cung cp cc cht tp cht thuc nhm 3 v nhm 5bng tun hon Mendelep a vo trong cu trc tinh th cht bn dn thun.

tng s lng cc electron t do, thng thng, ngi ta thm cc tp cht thuc nhm 5 trong bngtun hon Medelep vo. Khi , cc thnh phn tp cht ny s tham gia xy dng cu trc tinh th ca vtcht. Tng t nh gii thch v phn cu to nguyn t, khi 1 nguyn t tp cht ng cnh cc nguynt bn dn thun th chng cng s chia s 1 electron vi nguyn t bn dn thun, do s cn 4 electronti lp ngoi cng phn t. Trong s 4 electron ny ch c 3 electron tip tc tham gia to mng tinh th v1 electron s c xu hng tch ra v tr thnh cc electron t do. Do , khi so snh vi cu trc mng tinhth bn dn thun, cu trc bn dn tp cht loi ny c nhiu cc electron t do hn. Loi bn dn tpcht ny c gi l bn dn loi n (n bn cht ting Anh l negative ch c trng bn cht ca vic thaelectron). Nh vy trong bn dn loi n s tn ti 2 loi ht mang in. Ht a s chnh l cc electron tdo tch in m v ht thiu s l cc l trng (mang in tch dng).

Tng t nhng vi hng ngc li, ngi ta thm tp cht thuc nhm 3 trong bng tun honMendeleep vo trong cu trc tinh th cht bn dn thun. Cc thnh phn tp cht ny cng tham gia xydng cu trc tinh th ca cht bn dn, nhng do ch c 3 electron lp ngoi nn trong cu trc nguynt s c mt v tr khng c electron tham gia xy dng cc lin kt. Cc v tr thiu ny v hnh chung to nn cc l trng. Do , trong cu trc tinh th ca loi bn dn tp cht ny s c nhiu v tr khuytelectron hn hay cn gi l cc l trng hn. Loi bn dn ny c gi l bn dn loi p (p c trng chot positive). Ht a s chnh l cc l trng v ht thiu s s l cc electron. Tm li, bn dn loi n cnhiu electron t do hn v bn dn loi p c nhiu l trng hn. Do , n c kh nng cho electron v pc kh nng nhn electron.

2.1.3 it bn dn- Phn t mt mt ghp p-n

Trong cng ngh ch to phn t 1 mt ghp p-n, ngi ta thc hin pha trn hai loi bn dn tp chtln trn mt phin tinh th bn dn thun vi mt bn l bn dn loi p v 1 bn l bn dn loi n. Dolc ht ln nhau, cc electron t do bn pha bn dn loi n c xu hng khuch tn theo mi hng. Mtvi electron t do khuch tn vt qua b mt ghp p-n. Khi mt electron t do ca bn dn loi n i vovng ca bn dn loi p, n tr thnh ht thiu s. Do c mt lng ln cc l trng nn cc electron nys nhanh chng lin kt vi l trng tinh th tr v trng thi cn bng v ng thi lm l trng binmt.

Mi ln mt electron khuch tn vt qua vng tip gip th n to ra mt cp cc ion. Khi mt electronri khi min n th n li cho cu trc nguyn t tp cht mt (thuc nhm 5 bng tun hon Mendeleep)sang trng thi mi, trng thi thiu mt electron. Nguyn t tp cht lc ny li tr thnh 1 ion dng.Nhng ng thi, khi i sang min p v kt hp vi mt l trng th n v hnh lm nguyn t tp cht(thuc nhm 3 bng tun hon Medeleep) tr thnh ion m.

Qu trnh ny din ra lin tc v lm cho vng tip xc ca cht bn dn ln lt c ngy cng nhiucp ion dng v m tng ng min n v min p. Cc cp ion ny sau khi hnh thnh s to nn mtvng ti min tip xc bn dn m ta gi l min tip xc, c in trng ngc li vi chiu khuch tn tnhin ca cc electron t do v cc l trng. Qu trnh khuch tn s dng khi s lng cc cp ion sinh ra ln cn tr s khuch tn t do ca cc electron t n sang p.

Nh vy, k hiu m v dng ti min tip xc p-n chnh l k hiu ca cc cp ion sinh ra trong qutrnh khuch tn.

52.1.3.1 Phn cc thun

2.1.3.2 Phn cc ngc

2.1.3.3 nh thng

2.1.4 L thuyt v it

2.1.5 Phn loi it

2.1.5.1 Cch kim tra it

kim tra mt it cn kh nng hot ng hay khng, chng ta c th s dng cc ng h o, t ch o in tr o kh nng dn dng in hay hn ch dng in ca it. Thng qua , chng ta sbit c it cn kh nng s dng hay khng.

note:

i vi mt s loi Ohm k c, dng hoc p ca Ohm k c th ph hy 1 s loi diode sdng trong cc mch tn s cao.

Gi tr ca thang o Ohm xc nh kh nng hot ng ca diode thng khong vitrm KiloOhm.

Vi cc ng h Digital Multimeter c chc nng kim tra diode, ta c th s dng chc nngny kim tra.

2.1.5.2 Mt s loi it thng dng

2.2 Bn dn nhiu lp

2.2.1 Transistor

Tn hiu radio hay v tuyn thu c t ng-ten yu n mc n khng chy mt ci loa hay mt nin t tivi. y l l do chng ta phi khuch i tn hiu yu n c nng lng tr nn hudng. Trc nm 1951, ng chn khng l thit b chnh dng trong vic khuch i cc tn hiu yu. Mcd khuch i kh tt, nhng ng chn khng li c mt s nhc im. Th nht, n c c mt si nungbn trong, n i hi nng lng 1 W hoc hn. Th hai, n ch sng c vi nghn gi, trc khi si nunghng. Th ba, n tn nhiu khng gian. Th t, n ta nhit, lm tng nhit ca cc thit b in t.

Nm 1951, Shockley pht minh ra tranzitor c mt tip gip u tin, mt dng c bn dn c khnng khuch i cc tn hiu radio v v tuyn. Cc u im ca tranzito khc phc c cc khuyt imca ng chn khng. Th nht, n khng c si nung hay vt lm nng no, do n cn t nng lng hn.Th hai, do n l dng c bn dn nn c th sng v hn nh. Th ba, do n rt nh nn cn t khnggian. Th t, do n sinh ra t nhit hn, v vy nhit ca cc thit b in t s thp hn.

Tranzito dn ti nhiu pht minh khc, bao gm: mch tch hp (IC), mt thit b nh cha hngngn tranzito. Nh IC m my vi tnh v cc thit b in t k diu khc c th thc hin c.

2.2.2 Hai loi transistor c bn

Transistor c chia lm 2 loi l transistor lng cc (BJT -Bipolar Junction Trasistor) v transistor hiung trng (FET- Field Effect Transistor).

2.2.2.1 Transistor lng cc (BJT)

2.2.2.2 c xong phn ny bn nn c th:

Trnh by nhng hiu bit v mi quan h gia cc dng in baz, emit v collect ca mt transistorlng cc.


V s d ca mch CE v nh du cc cc, in p v in tr. V mt ng cong baz gi thuyt v tp hp cc ng cong emit, ghi tn cc trc. Tho lun v cc c tnh ca transistor l tng v transistor xp x ln hai. K ra vi thng s c trng ca transistor hu dng i vi cc nh k thut.

2.2.2.3 Transistor cha phn cc

Mt transistor c ba min pha tp nh trong hnh 6.1. Min di cng c gi l emit, min gia cgi l baz, min trn cng l collect. Loi transistor c th y l mt thit b npn. Transitor cn c thc sn xut nh cc thit b pnp.

Diode emit v collectTransistor hnh 6.1 c 2 tip gip: mt gia emit v baz v ci kia l gia baz v collect. Do

transistor tng t hai diode. emit v baz to mt diode, baz v collect to thnh mt diode khc. Tgi, chng ta s gi my diode ny l diode emit (ci di) v diode collect (ci trn).

Trc v sau s khuych tnHnh 6.1 ch ra cc min ca transistor trc khi s khuch tn xy ra. Nh ni n phn trc,

electron t do min n khuch tn qua vng tip gip v kt hp vi l trng min p. Hnh dung ccelectron mi min n ngang qua phn tip gip v kt hp vi cc l trng. Kt qu l hai vng ngho nhhnh 6.2, Mi vng ngho ny hng ro th xp x 0.7 V 25 C. Nh ni, chng ta nhn mnh n ccthit b silic v chng c s dng rng ri hn cc thit b bng germani.

2.2.2.4 Transistor phn cc

2.2.2.5 Transistor hiu ng trng ( FET )

Gii thiu chung v FET

a. a.FET hot ng da trn hiu ng trng c ngha l in tr ca bn dn c iu khin bi intrng bn ngoi, dng in trong FET ch do 1 loi ht dn l electron hoc l trng to nn.

b. b.Phn loi: FET c 2 loi chnh:

JFET: Transistor trng iu khin bng tip xc N-P. IGFET:Transistor c cc ca cch in, thng thng lp cch in ny c lm bng 1 lp oxit nn

c tn gi khc l MOSFET ( Metal Oxide Semicondutor FET ).

Mi loi FET u c 2 loi knh N v knh P. FET c 3 cc l cc Ngun ( source - S ), cc Mng ( drain- D ), cc Cng ( gate - G ).

JFETCu toJFET c cu to bi 1 ming bn dn mng ( loi N hoc loi P ) 2 u tung ng l D v S, ming

bn dn ny c gi l knh dn in. 2 ming bn dn 2 bn knh dn c ni vi cc G, lu , c Gc tch ra khi knh nh tip xc N-P.

a phn cc JFET c cu to i xng nn c th i ch cc D v S m tnh cht khng thay i.Nguyn l hot ngMun cho JFET hot ng ta phi cung cp UGS sao cho c 2 tip xc N-P u phn cc ngc, ngun

UDS sao cho dng ht dn dch chuyn t cc S qua knh ti cc D to thnh dng ID.Kh nng iu khin in p I D ca U GS :Gi s vi JFET knh N, UDS = const. Khi t UGS = 0, tip gip PN bt u phn cc ngc mnh

dn, knh hp dn t S v D, nhng lc ny rng knh l ln nht do vy dng qua knh l ln nht khiu l IDo.

7Khi UGS < 0, PN phn cc ngc mnh hn do vy b rng ca knh dn hp dn, ti thi im UGS= Ungt th 2 tip gip PN ph ln nhau, che lp ht knh, dng ID = 0. Dng ID c tnh theo cng thc:ID = IDo (1 UGS/Ungt )

2

Ch : gi tr ca Ungt v IDo ph thuc vo UDS.

2.2.2.6 Cch kim tra transistor

i vi transistor ni chung, do cu to ca transistor gm 2 tip xc P-N nn c th coi l 2 diode ni tipnhau t c th kim tra s hot ng ca transistor tng t nh kim tra diode.

Chng 3

Cc linh kin in t c bn1

Nh cp trong phn trc, cc linh kin in t c bn trong mt mch in t bao gm:in tr, tin, cun cm. Do y l cc linh kin c bn nn vic u tin khi lm quen vi cc linh kin ny lcch nhn bit cc loi linh kin khc nhau, ng thi c c gi tr cc loi linh kin khc nhau.

3.1 Phn loi in tr v cch c in tr

Nh cp,ni mt cch nm na, in tr c trng cho tnh cht cn tr dng in. Chnh v th, khis dng in tr cho mt mch in th mt phn nng lng in s b tiu hao duy tr mc chuyndi ca dng in. Ni mt cch khc th khi in tr cng ln th dng in i qua cng nh v ngc likhi in tr nh th dng in d dng c truyn qua.Khi dng in cng I chy qua mt vt c intr R, in nng c chuyn thnh nhit nng vi cng sut theo phng trnh sau:

P = I2.Rtrong :P l cng sut, o theo WI l cng dng in, o bng AR l in tr, o theo Chnh v l do ny, khi phn loi in tr, ngi ta thng da vo cng sut m phn loi in tr. V

theo cch phn loi da trn cng sut, th in tr thng c chia lm 3 loi:

in tr cng sut nh

in tr cng sut trung bnh

in tr cng sut ln.Tuy nhin, do ng dng thc t v do cu to ring ca cc vt cht to nn in tr nn thng thng,in tr c chia thnh 2 loi:

in tr: l cc loi in tr c cng sut trung bnh v nh hay l cc in tr ch cho php cc dngin nh i qua.

in tr cng sut: l cc in tr dng trong cc mch in t c dng in ln i qua hay ni cchkhc, cc in tr ny khi mch hot ng s to ra mt lng nhit nng kh ln. Chnh v th, chngc cu to nn t cc vt liu chu nhit.


9

10 CHNG 3. CC LINH KIN IN T C BN

tin cho qu trnh theo di trong ti liu ny, cc khi nim in tr v in tr cng sut c s dngtheo cch phn loi trn.

Cch c gi tr cc in tr ny thng thng cng c phn lm 2 cch c, tu theo cc k hiu ctrn in tr. Di y l hnh v cch c in tr theo vch mu trn in tr.

Hnh 3.1

i vi cc in tr c gi tr c nh ngha theo vch mu th chng ta c 3 loi in tr: in tr 4vch mu v in tr 5 vch mu v 6 vch mu. Loi in tr 4 vch mu v 5 vch mu c ch ra trnhnh v. Khi c cc gi tr in tr 5 vch mu v 6 vch mu th chng ta cn phi mt cht v c skhc nhau mt cht v cc gi tr. Tuy nhin, cch c in tr mu u da trn cc gi tr mu sc cghi trn in tr 1 cch tun t:

3.1.1 i vi in tr 4 vch mu

Vch mu th nht: Ch gi tr hng chc trong gi tr in tr

11

Vch mu th hai: Ch gi tr hng n v trong gi tr in tr

Vch mu th ba: Ch h s nhn vi gi tr s m ca 10 dng nhn vi gi tr in tr

Vch mu th 4: Ch gi tr sai s ca in tr

3.1.2 i vi in tr 5 vch mu

Vch mu th nht: Ch gi tr hng trm trong gi tr in tr

Vch mu th hai: Ch gi tr hng chc trong gi tr in tr

Vch mu th ba: Ch gi tr hng n v trong gi tr in tr

Vch mu th 4: Ch h s nhn vi gi tr s m ca 10 dng nhn vi gi tr in tr

Vch mu th 5: Ch gi tr sai s ca in tr

V d nh trn hnh v, in tr 4 vch mu pha trn c gi tr mu ln lt l: xanh l cy/xanh datri/vng/nu s cho ta mt gi tr tng ng nh bng mu ln lt l 5/6/4/1%. Ghp cc gi tr ln ltta c 56x104=560k v sai s in tr l 1%.

Tng t in tr 5 vch mu c cc mu ln lt l: /cam/tm/en/nu s tng ng vi cc gi trln lt l 2/3/7/0/1%. Nh vy gi tr in tr chnh l 237x100=237, sai s 1%.

3.2 Phn loi t in v cch c t in

T in theo ng tn gi chnh l linh kin c chc nng tch t nng lng in, ni mt cch nm na.Chng thng c dng kt hp vi cc in tr trong cc mch nh thi bi kh nng tch t nng lngin trong mt khong thi gian nht nh. ng thi t in cng c s dng trong cc ngun in vichc nng lm gim gn sng ca ngun trong cc ngun xoay chiu, hay trong cc mch lc bi chcnng ca t ni mt cch n gin l t ngn mch (cho dng in i qua) i vi dng in xoay chiuv h mch i vi dng in 1 chiu.

Trong mt s cc mch in n gin, n gin ha trong qu trnh tnh ton hay thay th tngng th chng ta thng thay th mt t in bng mt dy dn khi c dng xoay chiu i qua hay thot ra khi mch khi c dng mt chiu trong mch. iu ny kh l cn thit khi thc hin tnh ton hayxc nh cc s mch tng ng cho cc mch in t thng thng.

Hin nay, trn th gii c rt nhiu loi t in khc nhau nhng v c bn, chng ta c th chia t inthnh hai loi: T c phn cc (c cc xc nh) v t in khng phn cc (khng xc nh cc dng mc th).

c trng cho kh nng tch tr nng lng in ca t in, ngi ta a ra khi nim l in dungca t in. in dung cng cao th kh nng tch tr nng lng ca t in cng ln v ngc li. Gi trin dung c o bng n v Farad (k hiu l F). Gi tr F l rt ln nn thng thng trong cc mchin t, cc gi tr t ch o bng cc gi tr nh hn nh micro fara (F), nano Fara (nF) hay picro Fara(pF).

1F=106F=109nF=1012pF


3.2.1 T ho

Hnh 3.2: K hiu t ho v hnh dng t ho

T ha l mt loi t c phn cc. Chnh v th khi s dng t ha yu cu ngi s dng phi cm ngchn ca t in vi in p cung cp. Thng thng, cc loi t ha thng c k hiu chn c th chongi s dng bng cc k hiu + hoc = tng ng vi chn t.

C hai dng t ha thng thng l t ha c chn ti hai u tr trn ca t (t c ghi 220F trnhnh a) v loi t ha c 2 chn ni ra cng 1 u tr trn (t c ghi gi tr 10F trn hnh a). ng thitrn cc t ha, ngi ta thng ghi km gi tr in p cc i m t c th chu c. Nu trng hpin p ln hn so vi gi tr in p trn t th t s b phng hoc n t ty thuc vo gi tr in pcung cp. Thng thng, khi chn cc loi t ha ny ngi ta thng chn cc loi t c gi tr in pln hn cc gi tr in p i qua t m bo t hot ng tt v m bo tui th ca t ha.

13

3.2.2 T Tantali

Hnh 3.3: T Tantali

T Tantali cng l loi t ha nhng c in p thp hn so vi t ha. Chng kh t nhng nh v chngc dng khi yu cu v t dung ln nhng kch thc nh.

Cc loi t Tantali hin nay thng ghi r trn n gi tr t, in p cng nh cc ca t. Cc loi tTantali ngy xa s dng m mu phn bit. Chng thng c 3 ct mu (biu din gi tr t, mt ctbiu din gi tr in p) v mt chm mu c trng cho s cc s khng sau du phy tnh theo gi trF. Chng cng dng m mu chun cho vic nh ngha cc gi tr nhng i vi cc im mu th immu xm c ngha l gi tr t nhn vi 0,01; trng nhn 0,1 v en l nhn 1. Ct mu nh ngha gi trin p thng nm gn chn ca t v c cc gi tr nh sau:

Hnh 3.4: T thng v k hiu

vng=6,3Ven= 10VXanh l cy= 16V


Xanh da tri= 20VXm= 25VTrng= 30VHng= 35V

3.2.3 T khng phn cc

Cc loi t nh thng khng phn cc. Cc loi t ny thng chu c cc in p cao m thng thngl khong 50V hay 250V. Cc loi t khng phn cc ny c rt nhiu loi v c rt nhiu cc h thngchun c gi tr khc nhau.

Rt nhiu cc loi t c gi tr nh c ghi thng ra ngoi m khng cn c h s nhn no, nhngcng c cc loi t c thm cc gi tr cho h s nhn. V d c cc t ghi 0.1 c ngha gi tr ca n l0,1F=100nF hay c cc t ghi l 4n7 th c ngha gi tr ca t chnh l 4,7nF

Hnh 3.5: T thng

Hnh 3.6: T thng

Cc loi t c dng mM s thng c dng cho cc loi t c gi tr nh trong cc gi tr c nh ngha ln lt nh

sau:

15

Gi tr th 1 l s hng chc

Gi tr th 2 l s hng n v

Gi tr th 3 l s s khng ni tip theo gi tr ca s to t gi tr 1 v 2.Gi tr ca t c ctheo chun l gi tr picro Fara (pF)

Ch s i km sau cng l ch gi tr sai s ca t.

Example 3.1t ghi gi tr 102 th c ngha l 10 v thm 2 s 0 ng sau =1000pF = 1nF ch khng phi102pF

Hoc

Example 3.2t 272J th c ngha l 2700pF=2,7nF v sai s l 5%

T c dng m mu

Hnh 3.7: T dng m mu

S dng ch yu trn cc t loi polyester trong rt nhiu nm. Hin nay cc loi t ny khng cnbn trn th trng na nhng chng vn tn ti trong kh nhiu cc mch in t c. Mu c nh nghacng tng t nh i vi mu trn in tr. 3 mu trn cng ln lt ch gi tr t tnh theo pF, mu th4 l ch dung sai v mu th 5 ch ra gi tr in p.


Example 3.3t c mu nu/en/cam c ngha l 10000pF= 10nF= 0.01uF.

note: Khng c khong trng no gia cc mu nn thc t khi c 2 mu cnh nhau ging nhauth n to ra mt mng mu rng. V d Di rng/vng= 220nF=0.22uF

T PolyesterNgy nay, loi t ny cng him khi c s dng. Gi tr ca cc loi t ny thng c in ngay trn

t theo gi tr pF. T ny c mt nhc im l d b hng do nhit hn nng. Chnh v th khi hn ccloi t ny ngi ta thng c cc k thut ring thc hin hn, trnh lm hng t.

Hnh 3.8: T polyester

3.2.4 T in bin i

T in bin i thng c s dng trong cc mch iu chnh radio v chng thng c gi l t xoay.Chng thng c cc gi tr rt nh, thng thng nm trong khong t 100pF n 500pF.

17

Hnh 3.9: T xoay

Rt nhiu cc t xoay c vng xoay ngn nn chng khng ph hp cho cc di bin i rng nh lin tr hoc cc chuyn mch xoay. Chnh v th trong nhiu ng dng, c bit l trong cc mch nhthi hay cc mch iu chnh thi gian th ngi ta thng thay cc t xoay bng cc in tr xoay v kthp vi 1 gi tr t in xc nh.

T chnT chn l cc t xoay c gi tr rt nh. Chng thng c gn trc tip ln bn mch in t v iu

chnh sau khi mch c ch to xong. Tng t cc bin tr hin ny th khi iu chnh cc t chnny ngi ta cng dng cc tuc n vt loi nh iu chnh. Tuy nhin do gi tr cc t ny kh nh nnkhi iu chnh, ngi ta thng phi rt cn thn v kin tr v trong qu trnh iu chnh c s nh hngca tay v tuc n vt ti gi tr t.


Hnh 3.10: T chn

Cc t chn ny thng c gi tr rt nh, thng thng nh hn khong 100pF. C iu c bit lkhng th gim nh c cc gi tr t chn v 0 nn chng thng c ch nh vi cc gi tr t in tithiu, khong t 2 ti 10 pF.

19

3.3 Cun cm

Hnh 3.11

Tng t nh i vi in tr, trn th gii c mt s loi cun cm c cu trc tng t nh in tr. Quynh mu v cch c mu u tng t nh i vi cc in tr.

Tuy nhin, do cc gi tr ca cc cun cm thng kh linh ng i vi yu cu thit k mch cho nncc cun cm thng c tnh ton v qun theo s vng dy xc nh. Vi mi loi dy, vi mi loi likhc nhau th gi tr cun cm s khc nhau. Trong phn gio trnh ny khng cp c th ti cch tnhton v qun cc cun cm khc nhau. Phn ny s c cp c th trong phn sch sau ny.

Mt s cc phng php kim tra thng thng kim tra cc gi tr t in, cun cm hoc in tr th thng thng mi ngi s dng cc ng

h o a nng. Hin nay, c cc loi ng h o a nng c chc nng o chnh xc cc gi tr cun cm,t in v in tr, in p, dng in, thm ch xc nh transitor v it. Chnh v th, trong phn ny,ti khng cp ti cc phng php kim tra c (khi dng ng h c/kim) nh trc y.


3.4 Tm tt chng

Trong chng ny, cc linh kin in t c bn c trnh by mt cch tng i c th. Yu cu duynht i vi ngi c l sau khi c chng ny c th nm bt c v nhn bit c cc linh kinin t c bn trc khi tm hiu v i su hn vo lnh vc in t. Yu cu nm vng ca phn chngny l phn bit c cc linh kin c bn nh in tr, t in, cc phng php c in tr v caohn na chnh l kh nng c c gi tr ca in tr, t in,...m khng cn phi tra cu. tc iu ny, yu cu i vi ngi c l phi thc hnh so snh v c gi tr cc linh kin thng xuyn.

Chng 4

Mt s mch in t ng dng c bn1

4.1

4.1.1 Mch o cm bin lch quang (Position sensitive detector)

Mch o cm bin lch quang s dng photodiode l mt trong s cc mch in t c ng dng khrng ri trong cc nghin cu v o lc ca t c. Nguyn l c bn ca mch o cm bin quang s dngcho photo diode c ch ra trong hnh di.


21

22 CHNG 4. MT S MCH IN T NG DNG C BN

Hnh 4.1

Theo nh hnh th tu thuc cng chiu sng vo 2 photodiode D1 v D2 m gi tr dng sinh rati cc photodiode tng ng l khc nhau. Sau chng c a qua cc b khuch i s dng khuchi thut ton c di tn rng v nhy cao xc nh cc gi tr tng v hiu ca lch sng gia2 photodiode. Cc tn hiu ny sau c a vo IC AD734 dng lm chc nng xc nh lch hiudng chnh xc gia 2 photodiode. Ngoi ra, tng cng chnh xc cho mch, cc bn c th thm vo cc mch lc nhiu nhm trnh nhiu quang do tc ng t ngun sng bn ngoi nh n in hay nhsng mt tri. Tu thuc vo gi tr o m mch lc c thc hin mt cch tng ng.

INDEX 23

Ch mc T kha v Thut ng

Cc t kha c lit k theo phn mc theo th t ch ci v c dng: t kha, mc (trang). Thutng c tham chiu bi cc trang m chng xut hin.

C Cc linh kin in t c bn, 3(9)C bn v bn dn, 2(3)

G Gii thiu chung, 1(1)

M Mch in t ng dng c bn, 4(21)

24 Tham gia ng gp

Tham gia ng gp

Ti liu: Gio trnh in t c bnBin son bi: Phan Kin NguynURL: http://voer.vn/content/col10494/1.2/Giy php: http://creativecommons.org/licenses/by/3.0/

Module: "Gii thiu chung"Tc gi: Phan Kin NguynURL: http://voer.vn/content/m45005/1.1/Trang: 1-2Bn quyn:Giy php: http://creativecommons.org/licenses/by/3.0/

Module: "C bn v bn dn"Tc gi: Phan Kin NguynURL: http://voer.vn/content/m44997/1.1/Trang: 3-7Bn quyn:Giy php: http://creativecommons.org/licenses/by/3.0/

Module: "Cc linh kin in t c bn"Tc gi: Phan Kin NguynURL: http://voer.vn/content/m44977/1.1/Trang: 9-20Bn quyn:Giy php: http://creativecommons.org/licenses/by/3.0/

Module: "Mt s mch in t ng dng c bn"Tc gi: Phan Kin NguynURL: http://voer.vn/content/m45016/1.1/Trang: 21-22Bn quyn:Giy php: http://creativecommons.org/licenses/by/3.0/

Gio trnh in t c bnGio trnh in t c bn

Thu vien Hoc Lieu Mo Viet NamHc liu m Vit Nam - Vietnam Open Educational Resources (VOER) - l th vin hc liu m c phttrin trn m hnh ba chn, cng ng m, ni dung m v cng ngh m. Hc liu m Vit Nam s dngh thng phm mm Rhaptos (h thng xut bn trc tuyn do i hc Rice pht trin v c nh gi lmt cuc cch mng trong lnh vc xut bn), gip cho vic xy dng, pht trin v lu tr ni dung nhsch, gio trnh, .. tr nn d dng nh m 1-2-3. Tt c cc ti liu trn Hc liu m Vit Nam u tuntheo giy php bn quyn M Create Commons Attribution 3.0 (CC-by 3.0) gip cho vic ti s dng vphn phi tr ln trong sut vi ngi dng. Bt k ai cng c th tham gia Cng ng M ng gp,s dng, phn phi Ni dung M trn th vin Hc liu M Vit Nam. Hc liu m Vit Nam v s phttrin ca cng ng ngi Vit.

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