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1.C bn: Ngun mt chiu DC14-02-2009 |lqv77 | 62 phn hi

1 Khi nim c bn v dng in

1. Cu trc nguyn t : hiu v bn cht dng in ta bit rng ( kin thc PTTH) tt c cc nguyn t u ccu to ln t cc nguyn t v mi nguyn t ca mt cht c cu to bi hai phn l- Mt ht nhn gia cc ht mang in tch dng gi l Proton v cc ht trung ho ingi l Neutron.- Cc Electron (in t ) mang in tch m chuyn ng xung quanh ht nhn.- Bnh thng cc nguyn t c trng thi trung ho v in ngha l s Proton ht nhn bngs electron bn ngoi nhng khi c tc nhn bn ngoi nh p sut, nhit , ma st tnhin, tc ng ca t trng .. th cc in t electron lp ngoi cng c th tch khi quo tr thnh cc in t t do.- Khi mt nguyn t b mt i mt hay nhiu in t, chng b thiu in t v tr thnh iondng v ngc li khi mt nguyn t nhn thm mt hay nhiu in t th chng tr thnhion m.

2 . Bn cht dng in v chiu dng in .Khi cc in t tp trung vi mt cao chng to ln hiu ng tch in- Dng in chnh l dng chuyn ng ca cc ht mang in nh in t , ion.- Chiu dng in c quy c i t dng sang m ( ngc vi chiu chuyn ng ca ccin t i t m sang dng )

3. Tc dng ca dng in :Khi c mt dng in chy qua dy dn in nh th nghim sau :

Ta thy rng dng in to ra mt t trng xung quanh lm lch hng ca nam chm,khi i chiu dng in th t trng cng i hng => lm nam chm lch theo hngngc li.- Dng in chy qua bng n lm bng n pht sng v sing nhit nng- Dng in chy qua ng c lm quay ng c quay sinh ra c nng

- Khi ta np c quy cc cc ca c quy b bin i v dng in c tc dng ho nng..
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Nh vy dng in c cc tc dng l tc dng v nhit , tc dng v c nng , tc dng v ttrng v tc dng v ho nng.

2 Dng in v in p mt chiu

1. Cng dng in :L i lng c trng cho mnh yu ca dng in hay c trng cho s lng cc int i qua tit din ca vt dn trong mt n v thi gian K hiu l I- Dng in mt chiu l dng chuyn ng theo mt hng nht nh t dng sang m theoquy c hay l dng chuyn ng theo mt hng ca cc in t t do.

n v ca cng dng in l Ampe v c cc bi s :

Kilo Ampe = 1000 Ampe Mega Ampe = 1000.000 Ampe Mili Ampe = 1/1000 Ampe Micro Ampe = 1/1000.000 Ampe

2. in p :Khi mt cc in t tp trung khng u ti hai im A v B nu ta ni mt dy dn t Asang B s xut hin dng chuyn ng ca cc in tch t ni c mt cao sang ni c mt thp, nh vy ngi ta gi hai im A v B c chnh lch v in p v p chnh lch

chnh l hiu in th.- in p ti im A gi l UA- in p ti im B gi l UB.- Chnh lch in p gia hai im A v B gi l hiu in th UABUAB = UA UB- n v ca in p l Vol k hiu l U hoc E, n v in p c cc bi s l

Kilo Vol ( KV) = 1000 Vol Mili Vol (mV) = 1/1000 Vol Micro Vol = 1/1000.000 Vol

in p c th v nh cao ca mt bnh nc, nu hai bnh nc c cao khc nhau thkhi ni mt ng dn s c dng nc chy qua t bnh cao sang bnh thp hn, khi hai bnhnc c cao bng nhau th khng c dng nc chy qua ng dn. Dng in cng nhvy nu hai im c in p chn lch s sinh ra dng in chy qua dy dn ni vi hai im

t in p cao sang in p thp v nu hai im c in p bng nhau th dng in trongdy dn s = 0


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3 Cc nh lut c bn

1. nh lut mnh lut m l nh lut quan trng m ta cn phi nghi nh

Cng dng in trong mt on mch t l thun vi in p hai u on mch v tl nghch vi in tr ca on mch .

Cng thc : I = U / R trong

I l cng dng in , tnh bng Ampe (A) U l in p hai u on mch , tnh bng Vol (V) R l in tr ca on mch , tnh bng m

2. nh lut m cho on mchon mch mc ni tip:Trong mt on mch c nhiu in tr mc ni tip th in p hai u on mch bngtng st p trn cc in tr .

Nh s trn th U = U1 + U2 + U3 Theo nh lut m ta li c U1 =I1 x R1 , U2 = I2 x R2,

U3 = I3 x R3 nhng on mch mc ni tip th I1 = I2 = I3 St p trn cc in tr => t l thun vi cc in tr .

on mch mc song songTrong on mch c nhiu in tr mc song song th cng dng in chnh bngtng cc dng in i qua cc in tr v st p trn cc in tr l nh nhau:

Mch trn c U1 = U2 = U3 = E I = I1 + I2 + I3 v U1 = I1 x R1 = I2 x R2 = I3 x R3


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Cng dng in t l nghch vi in tr .

3. in nng v cng sut :* in nng.Khi dng in chy qua cc thit b nh bng n => lm bng n sng, chy qua ng c

=> lm ng c quay nh vy dng in sinh ra cng. Cng ca dng in gi l innng, k hiu l W, trong thc t ta thng dng Wh, KWh ( Kilo wat gi)

Cng thc tnh in nng l :

W = U x I x t

Trong W l in nng tnh bng June (J) U l in p tnh bng Vol (V) I l dng in tnh bng Ampe (A) t l thi gian tnh bng giy (s)

* Cng sut .Cng sut ca dng in l in nng tiu th trong mt giy , cng sut c tnh bi cngthc

P = W / t = (U. I .t ) / t = U .I

Theo nh lut m ta c P = U.I = U2 / R = R.I2

2. C bn: in t trng15-02-2009 | lqv77.com | 7 phn hi

1 - Khi nim v t trng.

* Nam chm v t tnh .Trong t nhin c mt s cht c th ht c st gi l nam chm t nhin.Trong cng nghim ngi ta luyn thp hoc hp cht thp to thnh nam chm nhn to.

Nam chm lun lun c hai cc l cc bc North (N) v cc nam South (S) , nu cht thanhnam chm ra lm 2 th ta li c hai nam chm mi cng c hai cc N v S l nam

chm c tnh cht khng phn chia..Nam chm thng c ng dng sn xut loa in ng, micro hoc m t DC.

* T trngT trng l vng khng gian xung quanh nam chm c tnh cht truyn lc t ln cc vtliu c t tnh, t trng l tp hp ca cc ng sc i t Bc n cc nam.
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* Cng t trngL i lng c trng cho mnh yu ca t trng, k hiu l H n v l A/m

* t cmL i lng c trng cho vt c t tnh chu tc ng ca t trng, t cm ph thucvo vt liu . VD St c t cm mnh hn ng nhiu ln . t cm c tnh bi cngthc

B = .H

Trong B : l t cm : l t thm

H : l cng t trng

* T thngL s ng sc i qua mt n v din tch, t thng t l thut vi cng t trng.

* ng dng ca Nam chm vnh cu.Nam chm vnh cu c ng dng nhiu trong thit b in t, chng c dng sn xutLoa, Micro v cc loi M t DC.

2 T trng ca dng in i qua dy dn thng.
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Th nghim trn cho thy, khi cng tc bn ngoi ng, dng in i qua bng n lm bngn sng ng thi dng in i qua dy dn sinh ra t trng lm lch hng kim nam chm.

Khi i chiu dng in, ta thy kim nam chm lch theo hng ngc li , nh vy dngin i chiu s to ra t trng cng i chiu.

2. T trng ca dng in i qua cun dy.

Khi ta cho dng in chy qua cun dy, trong lng cun dy xut hin t trng lcc ng sc song song, nu li cun dy c thay bng li thp th t trng tptrung trn li thp v li thp tr thnh mt chic nam chm in, nu ta i chiudng in th t trng cng i hng

Dng in mt chiu c nh i qua cun dy s to ra t trng c nh, dng inbin i i qua cun dy s to ra t trng bin thin.

T trng bin thin c c im l s to ra in p cm ng trn cc cun dy ttrong vng nh hng ca t trng , t trng c nh khng c c im trn.

ng dng:T trng do cun dy sinh ra c rt nhiu ng dng trong thc t, mt ng dng m

ta thng gp trong thit b in t l R le in t.
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R le in t

Khi cho dng in chy qua cun dy, li cun dy tr thnh mt nam chm in ht thanhst v cng tc oc ng li, tc dng ca r le l dng mt dng in nh iu khinng mch cho dng in ln gp nhiu ln.

3. Lc in tNu c mt dy dn t trong mt t trng, khi cho dng in chy qua th dy dn c mtlc y => l lc in t, nu dy dn t do chng s chuyn ng trong t trng,nguyn l ny c ng dng khi sn xut loa in ng.
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Nguyn l hot ng ca Loa ( Speaker )

Cun dy c gn vi mng loa v t trong t trng mnh gia 2 cc ca nam chm , ccS l li , cc N l phn xung quanh, khi cho dng in xoay chiu chy qua cun dy , ditc dng ca lc in t cun dy s chuyn ng, tc ng chuyn ng ca cun dy ph

thuc vo tn s ca dng in xoay chiu, cun dy chuyn ng c gng vo mng loalm mng loa chuyn ng theo, nu chuyn ng tn s > 20 Hz chng s to ra sng mtn trong di tn s tai ngi nghe c.

4. Cm ng in t .Cm ng in t l hin tng xut hin in p cm ng ca cun dy c t trong mt ttrng bin thin.V d : mt cun dy qun quanh mt li thp , khi cho dng in xoay chiu chay qua, trnli thp xut hin mt t trng bin thin, nu ta qun mt cun dy khc ln cng li thpth hai u cun dy mi s xut hin in p cm ng. Bn thn cun dy c dng in chyqua cng sinh ra in p cm ng v c chiu ngc vi chiu dng in i vo.

3. C bn: Dng in xoay chiu15-02-2009 |lqv77 | 10 phn hi

1 Khi nim v dng in xoay chiu

Dng in xoay chiu l dng in c chiu v gi tr bin i theo thi gian, nhng thay iny thng tun hon theo mt chu k nht nh.

trn l cc dng in xoay chiu hnh sin, xung vung v xung nhn.

Chu k v tn s ca dng in xoay chiu.Chu k ca dng in xoay chiu k hiu l T l khong thi gian m in xoay chiu lp liv tr c , chu k c tnh bng giy (s)

Tn s in xoay chiu : l s ln lp li trang thi c ca dng in xoay chiu trong mtgiy k hiu l F n v l Hz
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F = 1 / T

Pha ca dng in xoay chiu :Ni n pha ca dng xoay chiu ta thng ni ti s so snh gia 2 dng in xoay chiu ccng tn s .

* Hai dng in xoay chiu cng pha l hai dng in c cc thi im in p cng tng vcng gim nh nhau:

Hai dng in xoay chiu cng pha

* Hai dng in xoay chiu lch pha : l hai dng in c cc thi im in p tng gimlch nhau .

Hai dng in xoay chiu lch pha

* Hai dng in xoay chiu ngc pha : l hai dng in lch pha 180 , khi dng in nytng th dng in kia gim v ngc li.

Hai dng in xoay chiu ngc pha

Bin ca dng in xoay chiuBin ca dng xoay chiu l gi tr in p nh ca dng in.xoay chiu, bin ny

thng cao hn in p m ta o c t cc ng h
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Gi tr hiu dng ca dng in xoay chiuThng l gi tr o c t cc ng h v cng l gi tr in p c ghi trn zc cmngun ca cc thit b in t., V d ngun 220V AC m ta ang s dng chnh l ch gi trhiu dng, thc t bin nh ca in p 220V AC khong 220V x 1,4 ln = khong 300V

Cng xut ca dng in xoay chiu .Cng xut dng in xoay chiu ph thuc vo cng , in p v lch pha gia hai ilng trn , cng xut c tnh bi cng thc :

P = U.I.cos

Trong U : l in p I l dng in l gc lch pha gia U v I

=> Nu dng xoay chiu i qua in tr th lch pha ga U v I l = 0 khi cos =

1 v P = U.I

=> Nu dng xoay chiu i qua cun dy hoc t in th lch pha gia U v I l +90 hoc -90, khi cos = 0 v P = 0 ( cng xut ca dng in xoay chiu khi i qua t inhoc cun dy l = 0 )

2 Dng in xoay chiu i qua R, C, L

1. Dng in xoay chiu i qua in trDng in xoay chiu i qua in tr th dng in v in p cng pha vi nhau , ngha l

khi in p tng cc i th dng in qua tr cng tng cc i. nh vy dng xoay chiu ctnh cht nh dng mt chiu khi i qua tr thun.do c th p dng cc cng thc cadng mt chiu cho dng xoay chiu i qua in tr

I = U / R hay R = U/I Cng thc nh lut ohm

P = U.I Cng thc tnh cng xut

2 . Dng in xoay chiu i qua t in .Dng in xoay chiu i qua t in th dng in s sm pha hn in p 90

Dng xoay chiu c dng in smpha hn in p 90 khi i qua t

* Dng xoay chiu i qua t s b t cn li vi mt tr khng gi l Zc, v Zc c tnh bicng thc
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Zc = 1/ ( 2 x 3,14 x F x C )

Trong Zc l dung khng ( n v l Ohm ) F l tn s dng in xoay chiu ( n v l Hz) C l in dung ca t in ( n v l Fara)

Cng thc trn cho thy dung khng ca t in t l nghch vi tn s dng xoay chiu(ngha l tn s cng cao cng i qua t d dng) v t l nghc vi in dung ca t ( ngha lt c in dung cng ln th dng xoay chiu i qua cng d dng)

=> Dng mt chiu l dng c tn s F = 0 do Zc = v vy dng mt chiu khng i quac t.

3. Dng in xoay chiu i qua cun dy.Khi dng in xoay chiu i qua cun dy s to ra t trng bin thin v t trng binthin ny li cm ng ln chnh cun dy mt in p cm ng c chiu ngc li , do

cun dy c xu hng chng li dng in xoay chiu khi i qua n, s chng li ny chnh lcm khng ca cun dy k hiu l ZL

ZL = 2 x 3,14 x F x L

Trong ZL l cm khng ( n v l Ohm) L l h s t cm ca cun dy ( n v l Henry) L ph thuc vo s vng dy qun

v cht liu li . F l tn s dng in xoay chiu ( n v l Hz)

T cng thc trn ta thy, cm khng ca cun dy t l thun vi tn s v h s t cm cacun dy, tn s cng cao th i qua cun dy cng kh khn => tnh cht ny ca cun dyngc vi t in.

=> Vi dng mt chiu th ZL ca cun dy = 0 ohm, d dng mt chiu i qua cun dych chu tc dng ca in tr thun R m thi ( tr thun ca cun dy l in tr o c

bng ng h vn nng ), nu tr thun ca cun dy kh nh th dng mt chiu qua cundy s b on mch.

* Dng in xoay chiu i qua cun dy th dng in b chm pha so vi in p 90 nghal in p tng nhanh hn dng in khi qua cun dy .

Dng xoay chiu c dng in chmpha hn in p 90 khi i qua cun dy
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=>> Do tnh cht lch pha gia dng in v in p khi i qua t in v cun dy, nn takhng p dng c nh lut Ohm vo mch in xoay chiu khi c s tham gia ca L v Cc.

=>> V cng xut th dng xoay chiu khng sinh cng khi chng i qua L v C mc d c U

> 0 v I >0.

4. Tng hp hai dng in xoay chiu trn cng mt mch in* Trn cng mt mch in , nu xut hin hai dng in xoay chiu cng pha th bin in p s bng tng hai in p thnh phn.

Hai dng in cng pha bin s tng.

* Nu trn cng mt mch in , nu xut hin hai dng in xoay chiu ngc pha th bin in p s bng hiu hai in p thnh phn.

Hai dng in ngc pha, bin gim

4. C bn: S dng ng h VOM15-02-2009 |lqv77 | 44 phn hi

Hng dn o bng ng h (VOM)

1) Gii thiu v ng h vn nng ( VOM)
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ng h vn nng ( VOM ) l thit b o khng th thiu c vi bt k mt k thut vinin t no, ng h vn nng c 4 chc nng chnh l o in tr, o in p DC, o in pAC v o dng in.

u im ca ng h l o nhanh, kim tra c nhiu loi linh kin, thy c s phng npca t in , tuy nhin ng h ny c hn ch v chnh xc v c tr khng thp khong20K/Vol do vy khi o vo cc mch cho dng thp chng b st p.

2) Hng dn o in p xoay chiu.

S dng ng h vn nng o p AC

Khi o in p xoay chiu ta chuyn thang o v cc thang AC, thang AC cao hn in pcn o mt nc, V d nu o in p AC220V ta thang AC 250V, nu ta thang thphn in p cn o th ng h bo kch kim, nu thanh qu cao th kim bo thiu chnhxc.

* Ch ch :


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Tuyt i khng thang o in tr hay thang o dng in khi o vo in p xoay chiu=> Nu nhm ng h s b hng ngay lp tc !

nhm thang o dng in, o vongun AC => s hng ng h

nhm thang o in tr, o vo ngun AC=> s hng cc in tr trong ng h


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* Nu thang o p DC m o vo ngun AC th kim ng h khng bo , nhng ng hkhng nh hng .

thang DC o p AC ng h khng ln kimtuy nhin ng h khng hng

3) Hng dn o in p mt chiu DC bng ng h vn nng.

Khi o in p mt chiu DC, ta nh chuyn thang o v thang DC, khi o ta t que vocc dng (+) ngun, que en vo cc m (-) ngun, thang o cao hn in p cn o mtnc. V d nu o p DC 110V ta thang DC 250V, trng hp thang o thp hn inp cn o => kim bo kch kim, trng hp thang qu cao => kim bo thiu chnh xc.


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Dng ng h vn nng o in p mt chiu DC

* Trng hp sai thang o :

Nu ta sai thang o, o p mt chiu nhng ta ng h thang xoay chiu th ng h sbo sai, thng thng gi tr bo sai cao gp 2 ln gi tr thc ca in p DC, tuy nhin ngh cng khng b hng .


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sai thang o khi o in p mt chiu => bo sai gi tr.

* Trng hp nhm thang o

Ch ch : Tuyt i khng nhm ng h vo thang o dng in hoc thang o

in tr khi ta o in p mt chiu (DC) , nu nhm ng h s b hng ngay !!

Trng hp nhm thang o dng inkhi o in p DC => ng h s b hng !


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Trng hp nhm thang o in tr khi o inp DC => ng h s b hng cc in tr bn trong!

4) Hng dn o in tr v tr khng.

Vi thang o in tr ca ng h vn nng ta c th o c rt nhiu th. o kim tra gi tr ca in tr o kim tra s thng mch ca mt on dy dn o kim tra s thng mch ca mt on mch in o kim tra cc cun dy bin p c thng mch khng o kim tra s phng np ca t in o kim tra xem t c b d, b chp khng. o kim tra tr khng ca mt mch in o kim tra i t v bng bn dn.

* s dng c cc thang o ny ng h phi c lp 2 Pn tiu 1,5V bn trong, xdng cc thang o 1Kohm hoc 10Kohm ta phi lp Pin 9V.

4.1 o in tr :


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o kim tra in tr bng ng h vn nng

o tri s in tr ta thc hin theo cc bc sau : Bc 1 : thang ng h v cc thang o tr, nu in tr nh th thang x1 ohm

hoc x10 ohm, nu in tr ln th thang x1Kohm hoc 10Kohm. => sau chphai que o v chnh trit o kim ng h bo v tr 0 ohm.

Bc 2 : Chun b o . Bc 3 : t que o vo hai u in tr, c tr s trn thang o , Gi tr o c =

ch s thang o X thang oV d : nu thang x 100 ohm v ch s bo l 27 th gi tr l = 100 x 27 = 2700ohm = 2,7 K ohm

Bc 4 : Nu ta thang o qu cao th kim ch ln mt cht , nh vy c tr s s

khng chnh xc. Bc 5 : Nu ta thang o qu thp , kim ln qu nhiu, v c tr s cng khng

chnh xc. Khi o in tr ta chn thang o sao cho kim bo gn v tr gia vch ch s s cho

chnh xc cao nht.

4.2 Dng thang in tr o kim tra t in

Ta c th dng thang in tr kim tra phng np v h hng ca t in , khi o tin , nu l t gm ta dng thang o x1K ohm hoc 10K ohm, nu l t ho ta dng thang x1 ohm hoc x 10 ohm.


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Dng thang x 1K ohm kim tra t gm

Php o t gm trn cho ta bit :

T C1 cn tt => kim phng np khi ta o T C2 b d => ln kim nhng khng tr v v tr c T C3 b chp => kim ng h ln = 0 ohm v khng tr v.

Dng thang x 10 ohm kim tra t ho


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trn l php o kim tra cc t ho, t ho rt t khi b d hoc chp m ch yu l b kh( gim in dung) khi o t ho bit chnh xc mc hng ca t ta cn o so snh vimt t mi c cng in dung.

trn l php o so snh hai t ho cng in dung, trong t C1 l t mi cn C2

l t c, ta thy t C2 c phng np yu hn t C1 => chng t t C2 b kh ( gimin dung ) Ch khi o t phng np, ta phi o chiu que o vi ln xem phng np.

5 Hng dn o dng in bng ng h vn nng.

Cch 1 : Dng thang o dng

o dng in bng ng h vn nng, ta o ng h ni tip vi ti tiu th v ch l cho c dng in nh hn gi tr ca thang o cho php, ta thc hin theo cc bc sau

Bc 1 : t ng h vo thang o dng cao nht . Bc 2: t que ng h ni tip vi ti, que v chiu dng, que en v chiu

m . Nu kim ln thp qu th gim thang o Nu kim ln kch kim th tng thang o, nu thang o thang cao nht th ng h

khng o c dng in ny. Ch s kim bo s cho ta bit gi tr dng in .

Cch 2 : Dng thang o p DC

Ta c th o dng in qua ti bng cch o st p trn in tr hn dng mc ni vi ti,in p o c chia cho gi tr tr hn dng s cho bit gi tr dng in, phng php nyc th o c cc dng in ln hn kh nng cho php ca ng h v ng h cmg anton hn.

Cch c tr s dng in v in p khi o nh th no ?

* c gi tr in p AC v DCKhi o in p DC th ta c gi tr trn vch ch s DCV.A

Nu ta thang o 250V th ta c trn vch c gi tr cao nht l 250, tng t thang 10V th c trn vch c gi tr cao nht l 10. trng hp thang 1000Vnhng khng c vch no ghi cho gi tr 1000 th c trn vch gi tr Max = 10, gi

tr o c nhn vi 100 ln


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Khi o in p AC th c gi tr cng tng t. c trn vch AC.10V, nu o thang c gi tr khc th ta tnh theo t l. V d nu thang 250V th mi ch s cavch 10 s tng ng vi 25V.

Khi o dng in th c gi tr tng t c gi tr khi o in p

5. C bn: S dng ng h Digital15-02-2009 |lqv77 | 7 phn hi

Hng dn s dng ng h Digital

1) Gii thiu v ng h s DIGITAL

ng h s Digital c mt s u im so vi ng h c kh, l chnh xc cao hn, trkhng ca ng h cao hn do khng gy st p khi o vo dng in yu, o c tn sin xoay chiu, tuy nhin ng h ny c mt s nhc im l chy bng mch in t lnhay hng, kh nhn kt qu trong trng hp cn o nhanh, khng o c phng np cat.
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ng h vn nng s Digital

Hng dn s dng :

2) o in p mt chiu ( hoc xoay chiu )
http://lqv77.com/wp-content/uploads/2009/02/donghodigital3.jpg


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t ng h vo thang o in p DC hoc AC

que ng h vo l cm V mA que en vo l cm COM Bm nt DC/AC chn thang o l DC nu o p mt chiu hoc AC nu o p

xoay chiu. Xoay chuyn mch v v tr V hy thang o cao nht nu cha bit r in p,

nu gi tr bo dng thp phn th ta gim thang o sau. t thang o vo in p cn o v c gi tr trn mn hnh LCD ca ng h. Nu t ngc que o(vi in mt chiu) ng h s bo gi tr m (-)

3) o dng in DC (AC)

Chuyn que ng h v thang mA nu o dng nh, hoc 20A nu o dng ln. Xoay chuyn mch v v tr A Bm nt DC/AC chn o dng mt chiu DC hay xoay chiu AC t que o ni tip vi mch cn o c gi tr hin th trn mn hnh.

4) o in tr

Tr li v tr dy cm nh khi o in p . Xoay chuyn mch v v tr o , nu cha bit gi tr in tr th chn thang o

cao nht , nu kt qu l s thp phn th ta gim xung. t que o vo hai u in tr. c gi tr trn mn hnh. Chc nng o in tr cn c th o s thng mch, gi s o mt on dy dn bng

thang o tr, nu thng mch th ng h pht ra tin ku

5) o tn s

Xoay chuyn mch v v tr FREQ hoc Hz thang o nh khi o in p . t que o vo cc im cn o

c tr s trn mn hnh.
http://lqv77.com/wp-content/uploads/2009/02/thangdoap.jpg


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6) o Logic

o Logic l o vo cc mch s ( Digital) hoc o cc chn ln ca vi x l, o Logicthc cht l o trng thi c in K hiu 1 hay khng c in 0, cch o nhsau:

Xoay chuyn mch v v tr LOGIC t que vo v tr cn o que en vo mass Mn hnh ch l bo mc logic mc cao, ch l bo logic mc thp

7) o cc chc nng khc

ng h vn nng s Digital cn mt s chc nng o khc nh o i t, o t in,o Transistor nhng nu ta o cc linh kin trn, ta ln dng ng h c kh s chokt qu tt hn v o nhanh hn

6. C bn: in tr15-02-2009 |lqv77 | 27 phn hi

1. Khi nim v in tr.

in tr l g ? Ta hiu mt cch n gin in tr l s cn tr dng in ca mt vt dnin, nu mt vt dn in tt th in tr nh, vt dn in km th in tr ln, vt cch inth in tr l v cng ln.

in tr ca dy dn :in tr ca dy dn ph thc vo cht liu, di v tit din ca dy. c tnh theo cngthc sau:

R = .L / S

Trong l in tr xut ph thuc vo cht liu L l chiu di dy dn S l tit din dy dn R l in tr n v l Ohm

2. in tr trong thit b in t.

a) Hnh dng v k hiu : Trong thit b in t in tr l mt linh kin quan trng,chng c lm t hp cht cacbon v kim loi tu theo t l pha trn m ngi ta to rac cc loi in tr c tr s khc nhau.
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Hnh dng ca in tr trong thit b in t.

K hiu ca in tr trn cc s nguyn l.b) n v ca in tr

n v in tr l (Ohm) , K , M 1K = 1000 1M = 1000 K = 1000.000

b) Cch ghi tr s ca in tr

Cc in tr c kch thc nh c ghi tr s bng cc vch mu theo mt quy c

chung ca th gii.( xem hnh trn ) Cc in tr c kch thc ln hn t 2W tr ln thng c ghi tr s trc tip trn

thn. V d nh cc in tr cng xut, in tr s.

Tr s cng xut ln , tr s c ghi trc tip.

3. Cch c tr s in tr .

Quy c mu Quc t

Mu sc Gi tr Mu sc Gi tren 0 Xanh l 5

Nu 1 Xanh l 6 2 Tm 7

Cam 3 Xm 8Vng 4 Trng 9

Nh vng -1Nh bc -2


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in tr thng c k hiu bng 4 vng mu , in tr chnh xc th k hiu bng 5

vng mu.

* Cch c tr s in tr 4 vng mu :

Cch c in tr 4 vng mu

Vng s 4 l vng cui lun lun c mu nh vng hay nh bc, y l vng ch sais ca in tr, khi c tr s ta b qua vng ny.

i din vi vng cui l vng s 1, tip theo n vng s 2, s 3 Vng s 1 v vng s 2 l hng chc v hng n v Vng s 3 l bi s ca c s 10. Tr s = (vng 1)(vng 2) x 10 ( m vng 3)

C th tnh vng s 3 l s con s khng 0 thm vo Mu nh ch c vng sai s hoc vng s 3, nu vng s 3 l nh th s m ca c

s 10 l s m.


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* Cch c tr s in tr 5 vng mu : (in tr chnh xc )

Vng s 5 l vng cui cng , l vng ghi sai s, tr 5 vng mu th mu sai s cnhiu mu, do gy kh khn cho ta khi xc inh u l vng cui cng, tuy nhinvng cui lun c khong cch xa hn mt cht.

i din vng cui l vng s 1

Tng t cch c tr s ca tr 4 vng mu nhng y vng s 4 l bi s ca cs 10, vng s 1, s 2, s 3 ln lt l hng trm, hng chc v hng n v. Tr s = (vng 1)(vng 2)(vng 3) x 10 ( m vng 4)

C th tnh vng s 4 l s con s khng 0 thm vo

4 Thc hnh c tr s in tr.

Cc in tr khc nhau vng mu th 3

Khi cc in tr khc nhau vng mu th 3, th ta thy vng mu bi s ny thngthay i t mu nh bc cho n mu xanh l , tng ng vi in tr < 1 nhng M.


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Cc in tr c vng mu s 1 v s 2 thay i .

hnh trn l cc gi tr in tr ta thng gp trong thc t, khi vng mu s 3 thayi th cc gi tr in tr trn tng gim 10 ln.

Bi tp - Bn hy on nhanh tr s trc khi p n xut hin, khi no tt c cc tr s m

bn on ng trc khi kt qu xut hin l kin thc ca bn phn ny n ri !

Bi tp on nhanh kt qu tr s in tr.

5 Cc tr s in tr thng dng.

Ta khng th kim c mt in tr c tr s bt k, cc nh sn xut ch a ra khong 150loi tr s in tr thng dng , bng di y l mu sc v tr s ca cc in tr thngdng.


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Cc gi tr in tr thng dng.

6 -. Phn loi in tr.


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in tr thng : in tr thng l cc in tr c cng xut nh t 0,125W n0,5W

in tr cng xut: L cc in tr c cng xut ln hn t 1W, 2W, 5W, 10W. in tr s, in tr nhit : L cch gi khc ca cc in tr cng xut , in tr

ny c v bc s, khi hot ng chng to nhit.

Cc in tr : 2W 1W 0,5W 0,25W

in tr s hay tr nhit

7 Cng xut ca in tr.Khi mc in tr vo mt on mch, bn thn in tr tiu th mt cng xut P tnh ctheo cng thc

P = U . I = U2 / R = I2.R

Theo cng thc trn ta thy, cng xut tiu th ca in tr ph thuc vo dng ini qua in tr hoc ph thuc vo in p trn hai u in tr.

Cng xut tiu th ca in tr l hon ton tnh c trc khi lp in tr vo mch. Nu em mt in tr c cng xut danh nh nh hn cng xut n s tiu th th

in tr s b chy. Thng thng ngi ta lp in tr vo mch c cng xut danh nh > = 2 ln cng

xut m n s tiu th.


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in tr chy do qu cng xut

s trn cho ta thy : Ngun Vcc l 12V, cc in tr u c tr s l 120 nhngc cng xut khc nhau, khi cc cng tc K1 v K2 ng, cc in tr u tiu th mtcng xut l

P = U2 / R = (12 x 12) / 120 = 1,2W

Khi K1 ng, do in tr c cng xut ln hn cng xut tiu th , nn in tr khngchy.

Khi K2 ng, in tr c cng xut nh hn cng xut tiu th , nn in tr b chy .

8 Bin tr, trit p :Bin trL in tr c th chnh thay i gi tr, c k hiu l VR chng c hnh dngnh sau :

Hnh dng bin tr K hiu trn s

Bin tr thng rp trong my phc v cho qu trnh sa cha, cn chnh ca k thut vin,

bin tr c cu to nh hnh bn di.

Cu to ca bin tr

Trit p : Trit p cng tng t bin tr nhng c thm cn chnh v thng b tr phatrc mt my cho ngi s dng iu chnh. V d nh Trit p Volume, trit p Bass,Treec v.v.. , trit p ngha l trit ra mt phn in p t u vo tu theo mc chnh.


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K hiu trit p trn s nguyn l.

Hnh dng trit p Cu to trong trit p

9 in tr mc ni tip .

in tr mc ni tip.

Cc in tr mc ni tip c gi tr tng ng bng tng cc in tr thnh phncng li. Rtd = R1 + R2 + R3

Dng in chy qua cc in tr mc ni tip c gi tr bng nhau v bng I I = ( U1 /R1) = ( U2 / R2) = ( U3 / R3 )

T cng thc trn ta thy rng , st p trn cc in tr mc ni tip t l thun vi gitr int tr .

10 in tr mc song song.


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in tr mc song song

Cc in tr mc song song c gi tr tng ng Rtd c tnh bi cng thc (1 /Rtd) = (1 / R1) + (1 / R2) + (1 / R3) Nu mch ch c 2 in tr song song th

Rtd = R1.R2 / ( R1 + R2) Dng in chy qua cc in tr mc song song t l nghch vi gi tr in tr .

I1 = ( U / R1) , I2 = ( U / R2) , I3 =( U / R3 ) in p trn cc in tr mc song song lun bng nhau

11 in tr mc hn hp

in tr mc hn hp.

Mc hn hp cc in tr to ra in tr ti u hn . V d: nu ta cn mt in tr 9K ta c th mc 2 in tr 15K song song sau mc

ni tip vi in tr 1,5K .

12 ng dng ca in trin tr c mt mi ni trong thit b in t v nh vy in tr l linh kin quan trngkhng th thiu c , trong mch in , in tr c nhng tc dng sau :

Khng ch dng in qua ti cho ph hp, V d c mt bng n 9V, nhng ta chc ngun 12V, ta c th u ni tip bng n vi in tr st p bt 3V trn in

tr.


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u ni tip vi bng n mt in tr.

- Nh hnh trn ta c th tnh c tr s v cng xut ca in tr cho ph hp nh sau:Bng n c in p 9V v cng xut 2W vy dng tiu th l I = P / U = (2 / 9 ) = Ampe cng chnh l dng in i qua in tr.- V ngun l 12V, bng n 9V nn cn st p trn R l 3V vy ta suy ra in tr cn tm lR = U/ I = 3 / (2/9) = 27 / 2 = 13,5 - Cng xut tiu th trn in tr l : P = U.I = 3.(2/9) = 6/9 W v vy ta phi dng in tr c

cng xut P > 6/9 W

Mc in tr thnh cu phn p c c mt in p theo mun t mt in pcho trc.

Cu phn p ly ra p U1 tu .

T ngun 12V trn thng qua cu phn p R1 v R2 ta ly ra in p U1, p U1 ph thucvo gi tr hai in tr R1 v R2.theo cng thc .

U1 / U = R1 / (R1 + R2) => U1 = U.R1/(R1 + R2)

Thay i gi tr R1 hoc R2 ta s thu c in p U1 theo mun.

Phn cc cho bng bn dn hot ng .


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Mch phn cc cho Transistor

Tham gia vo cc mch to dao ng R C

Mch to dao ng s dng IC 555

7. C bn: T in15-02-2009 |lqv77 | 45 phn hi

T in :T in l linh kin in t th ng c s dng rt rng ri trong cc mchin t, chng c s dng trong cc mch lc ngun, lc nhiu, mch truyn tn hiu xoaychiu, mch to dao ng .vv

1. Cu to ca t in .

Cu to ca t in gm hai bn cc t song song, gia c mt lp cch in gi l inmi.

Ngi ta thng dng giy, gm , mica, giy tm ho cht lm cht in mi v t in cngc phn loi theo tn gi ca cc cht in mi ny nh T giy, T gm, T ho.
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Cu to t gm Cu to t ho

2. Hnh dng thc t ca t in.

Hnh dng ca t gm.

Hnh dng ca t ho

3. in dung , n v v k hiu ca t in.

* in dung : L i lng ni ln kh nng tch in trn hai bn cc ca t in, in dungca t in ph thuc vo din tch bn cc, vt liu lm cht in mi v khong cch gi

hai bn cc theo cng thc

C = . S / d

Trong C : l in dung t in , n v l Fara (F) : L hng s in mi ca lp cch in. d : l chiu dy ca lp cch in. S : l din tch bn cc ca t in.

* n v in dung ca t: n v l Fara (F) , 1Fara l rt ln do trong thc t thng

dng cc n v nh hn nh MicroFara (F) , NanoFara (nF), PicoFara (pF). 1 Fara = 1.000.000 Fara = 1.000.000.000 n F = 1.000.000.000.000 p F


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1 Fara = 1.000 n Fara 1 n Fara = 1.000 p Fara

* K hiu : T in c k hiu l C (Capacitor)

K hiu ca t in trn s nguyn l.

4 . S phng np ca t in .

Mt tnh cht quan trng ca t in l tnh cht phng np ca t , nh tnh cht ny m t ckh nng dn in xoay chiu.

Minh ho v tnh cht phng np ca t in.

* T np in :Nh hnh nh trn ta thy rng , khi cng tc K1 ng, dng in t ngun Ui qua bng n np vo t, dng np ny lm bng n lo sng, khi t np y th dngnp gim bng 0 v vy bng n tt.

* T phng in :Khi t np y, nu cng tc K1 m, cng tc K2 ng th dng in tcc dng (+) ca t phng qua bng n v cc m (-) lm bng n lo sng, khi t phng

ht in th bng n tt.


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=> Nu in dung t cng ln th bng n lo sng cng lu hay thi gian phng np cnglu.

5 . Cch c gi tr in dung trn t in.

* Vi t ho : Gi tr in dung ca t ho c ghi trc tip trn thn t

=> T ho l t c phn cc (-) , (+) v lun lun c hnh tr .

T ho ghi in dung l 185 F / 320 V

* Vi t giy , t gm : T giy v t gm c tr s ghi bng k hiu

T gm ghi tr s bng k hiu. Cch c : Ly hai ch s u nhn vi 10(M s th 3 ) V d t gm bn phi hnh nh trn ghi 474K ngha l

Gi tr = 47 x 10 4 = 470000p ( Ly n v l pic Fara)= 470 n Fara = 0,47 F

Ch K hoc J cui l ch sai s 5% hay 10% ca t in .

* Thc hnh c tr s ca t in.


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Cch c tr s t git v t gm .Ch : ch K l sai s ca t .

50V l in p cc i m t chu c.

* T giy v t gm cn c mt cch ghi tr s khc l ghi theo s thp phn v ly n v lMicroFara

Mt cch ghi tr s khc ca t giy v t gm.

6. ngh ca gi tr in p ghi trn thn t :

Ta thy rng bt k t in no cng c ghi tr s in p ngay sau gi tr in dung,

y chnh l gi tr in p cc i m t chu c, qu in p ny t s b n. Khi lp t vo trong mt mch in c in p l U th bao gi ngi ta cng lp t

in c gi tr in p Max cao gp khong 1,4 ln. V d mch 12V phi lp t 16V, mch 24V phi lp t 35V. vv..

7 Phn loi t in

7.1) T giy, T gm, T mica. (T khng phn cc )Cc loi t ny khng phn bit m dng v thng c in dung nh t 0,47 F tr xung,cc t ny thng c s dng trong cc mch in c tn s cao hoc mch lc nhiu.

T gm l t khng phn cc.


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7.2) T ho ( T c phn cc )T ho l t c phn cc m dng , t ho c tr s ln hn v gi tr t 0,47F n khong4.700 F , t ho thng c s dng trong cc mch c tn s thp hoc dng lcngun, t ho lun lun c hnh tr..

T ho L t c phn cc m dng.

7.3) T xoay .T xoay l t c th xoay thay i gi tr in dung, t ny thng c lp trong Radio thay i tn s cng hng khi ta d i.

T xoay s dng trong Radio

8 Phng php kim tra t in

8.1) o kim tra t giy v t gm.

T giy v t gm thng hng dng b d r hoc b chp, pht hin t d r hoc bchp ta quan st hnh nh sau y .


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o kim tra t giy hoc t gm .

hnh nh trn l php o kim tra t gm, c ba t C1 , C2 v C3 c in dung bngnhau, trong C1 l t tt, C2 l t b d v C3 l t b chp.

Khi o t C1 ( T tt ) kim phng ln 1 cht ri tr v v tr c. ( Lu cc t nh qu< 1nF th kim s khng phng np )

Khi o t C2 ( T b d ) ta thy kim ln lng chng thang o v dng li khng tr

v v tr c. Khi o t C3 ( T b chp ) ta thy kim ln = 0 v khng tr v. Lu : Khi o kim tra t giy hoc t gm ta phi ng h thang x1K hoc

x10K, v phi o chiu kim ng h vi ln khi o.

8.2) o kim tra t ho

T ho t khi b d hay b chp nh t giy, nhng chng li hay hng dng b kh ( kh hocht bn trong lp in mi ) lm in dung ca t b gim , kim tra t ho , ta thng sosnh phng np ca t vi mt t cn tt c cng in dung, hnh nh di y minh hocc bc kim tra t ho.


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o kim tra t ho

kim tra t ho C2 c tr s 100F c b gim in dung hay khng, ta dng t C1cn mi c cng in dung v o so snh.

ng h thang t x1 n x100 ( in dung cng ln th thang cng thp ) o vo hai t v so snh phng np , khi o ta o chiu que o vi ln. Nu hai t phng np bng nhau l t cn kim tra cn tt, trn ta thy t C2 phng

np km hn do t C2 trn b kh.

Trng hp kim ln m khng tr v l t b d.

Ch : Nu kim tra t in trc tip trn mch , ta cn phi ht rng mt chn t khimch in, sau kim tra nh trn.

9 Cc kiu mc v ng dng

9.1 . T in mc ni tip .

Cc t in mc ni tip c in dung tng ng C t c tnh bi cng thc : 1 /C t = (1 / C1 ) + ( 1 / C2 ) + ( 1 / C3 )

Trng hp ch c 2 t mc ni tip th C t = C1.C2 / ( C1 + C2 ) Khi mc ni tip th in p chu ng ca t tng ng bng tng in p ca cc

t cng li. U t = U1 + U2 + U3 Khi mc ni tip cc t in, nu l cc t ho ta cn ch chiu ca t in, cc m

t trc phi ni vi cc dng t sau:


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T in mc ni tip T in mc song song

9.2 T in mc song song.

Cc t in mc song song th c in dung tng ng bng tng in dung ca cct cng li . C = C1 + C2 + C3

in p chu ng ca t in tng tng bng in p ca t c in p thp nht. Nu l t ho th cc t phi c u cng chiu m dng.

9.3 ng dng ca t in .

T in c s dng rt nhiu trong k thut in v in t, trong cc thit b in t, t

in l mt linh kin khng th thiu c, mi mch in t u c mt cng dng nht nhnh truyn dn tn hiu , lc nhiu, lc in ngun, to dao ng ..vv

Di y l mt s nhng hnh nh minh ho v ng dng ca t in.

* T in trong mch lc ngun.

T ho trong mch lc ngun.

Trong mch lc ngun nh hnh trn , t ho c tc dng lc cho in p mt chiu

sau khi chnh lu c bng phng cung cp cho ti tiu th, ta thy nu khng


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c t th p DC sau i t l in p nhp nh, khi c t in p ny c lc tng iphng, t in cng ln th in p DC ny cng phng.

* T in trong mch dao ng a hi to xung vung.

Mch dao ng a hi s dng 2 Transistor

Bn c th lp mch trn vi cc thng s cho trn s . Hai n bo sng s dng n Led du song song vi cc CE ca hai Transistor, ch

u ng chiu m dng.

8. C bn: Cun dy15-02-2009 |lqv77 | 12 phn hi

1 Cun cm

1.1 - Cu to ca cun cm.

Cun cm gm mt s vng dy qun li thnh nhiu vng, dy qun c sn emay cchin, li cun dy c th l khng kh, hoc l vt liu dn t nh Ferrite hay li thp k thut.

Cun dy li khng kh Cun dy li Ferit

K hiu cun dy trn s : L1 l cun dy li khng kh, L2 l cun dy li ferit, L3 lcun dy c li chnh, L4 l cun dy li thp k thut
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1.2 - Cc i lng c trng ca cun cm.

a) H s t cm ( nh lut Faraday)H s t cm l i lng c trng cho sc in ng cm ng ca cun dy khi c dngin bin thin chy qua.

L = ( r.4.3,14.n2.S.10-7 ) / l

o L : l h s t cm ca cun dy, n v l Henrry (H)o n : l s vng dy ca cun dy.o l : l chiu di ca cun dy tnh bng mt (m)o S : l tit din ca li, tnh bng m2

o r : l h s t thm ca vt liu lm li .

b) Cm khngCm khng ca cun dy l i lng c trng cho s cn tr dng in ca cun dy ivi dng in xoay chiu .

ZL = 2.3,14.f.L

o Trong : ZL l cm khng, n v l o f : l tn s n v l Hzo L : l h s t cm , n v l Henry

Th nghim v cm khng ca cundy vi dng in xoay chiu

* Th nghim trn minh ha:Cun dy ni tip vi bng n sau c u vo cc ngun in 12Vnhng c tn s khc nhau thng qua cc cng tc K1, K2 , K3 , khi K1ng dng in mt chiu i qua cun dy mnh nht ( V ZL= 0 ) => do bng n sngnht, khi K2 ng dng in xoay chu 50Hz i qua cun dy yy hn ( do ZL tng ) =>

bng n sng yu i, khi K3 ng , dng in xoay chiu 200Hz i qua cun dy yu nht( do ZL tng cao nht) => bng n sng yu nht.

=> Kt lun : Cm khng ca cun dy t l vi h s t cm ca cun dy v t l vi tn

s dng in xoay chiu, ngha l dng in xoay chiu c tn s cng cao th i qua cundy cng kh, dng in mt chiu c tn s f = 0 Hz v vy vi dng mt chiu cun dy ccm khng ZL = 0


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c) in tr thun ca cun dy.

in tr thun ca cun dy l in tr m ta c th o c bng ngh vn nng, thng thng cun dy c phm cht tt th in tr thun

phi tng i nh so vi cm khng, in tr thun cn gi l in tr

tn hao v chnh in tr ny sinh ra nhit khi cun dy hot ng.

1.3 - Tnh cht np , x ca cun cm* Cun dy np nng lng : Khi cho mt dng in chy qua cun dy, cun dy np mtnng lng di dng t trng c tnh theo cng thc

W = L.I 2 / 2

W : nng lng ( June ) L : H s t cm ( H ) I dng in.

Th nghim v tnh np x ca cun dy.

th nghim trn : Khi K1 ng, dng in qua cun dy tng dn ( do cun dy sinh ra cmkhng chng li dng in tng t ngt ) v vy bng n sng t t, khi K1 va ngt v K2ng , nng lng np trong cun dy to thnh in p cm ng phng ngc li qua bngn lm bng n lo sng

=> l hin tng cun dy x in.

2 Loa v Micro

2.1 - Loa ( Speaker )

Loa l mt ng dng ca cun dy v t trng.


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Loa 4 20W ( Speaker )

Cu to v hot ng ca Loa ( Speaker )

Cu to ca loa :

Loa gm mt nam chm hnh tr c hai cc lng vo nhau , cc N giav cc S xung quanh, gia hai cc to thnh mt khe t c t trngkh mnh, mt cun dy c gn vi mng loa v c t trong khe t,mng loa c bng gn cao su mm gip cho mng loa c th d dngdao ng ra vo.

Hot ng :Khi ta cho dng in m tn ( in xoay chiu t 20 Hz => 20.000Hz )

chy qua cun dy, cun dy to ra t trng bin thin v b t trng


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c nh ca nam chm y ra, y vo lm cun dy dao ng =>mng loa dao ng theo v pht ra m thanh.

Ch : Tuyti ta khng c a dng in mt chiu vo loa , v dng in mt

chiu ch to ra t trng c nh v cun dy ca loa ch lch v mthng ri dng li, khi dng mt chiu qua cun dy tng mnh ( dokhng c in p cm ng theo chiu ngc lai ) v vy cun dy s bchy .

2.2 Micro

Micro

Thc cht cu to Micro l mt chic loa thu nh, v cu to Micro ging loa nhng Micro cs vng qun trn cun dy ln hn loa rt nhiu v vy tr khng ca cun dy micro l rtln khong 600 (tr khng loa t 4 16) ngoi ra mng micro cng c cu to rtmng d dng dao ng khi c m thanh tc ng vo.Loa l thit b chuyn dng in thnh m thanh cn micro th ngc

li , Micro i m thanh thnh dng in m tn.

2.3 R le ( Relay)

R le

R le cng l mt ng dng ca cun dy trong sn xut thit b in t, nguyn l hot ngca Rle l bin i dng in thnh t trng thng qua qun dy, t trng li to thnhlc c hc thng qua lc ht thc hin mt ng tc v c kh nh ng m cng tc, ngm cc hnh trnh ca mt thit b t ng vv


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Cu to v nguyn l hot ng ca R le

3 Bin p

3.1 Cu to ca bin p.

Bin p l thit b bin i in p xoay chiu, cu to bao gm mt cun s cp ( a inp vo ) v mt hay nhiu cun th cp ( ly in p ra s dng) cng qun trn mt li t cth l l thp hoc li ferit .

K hiu ca bin p

3.2 - T s vng / vol ca bin p .

Gi n1 v n2 l s vng ca qun s cp v th cp. U1 v I1 l in p v dng in i vo cun s cp U2 v I2 l in p v dng in i ra t cun th cp.

Ta c cc h thc nh sau :

U1 / U2 = n1 / n2 in p trn hai cun dy s cp v th cp t l thun vi s vng dyqun.

U1 / U2 = I2 / I1Dng in trn hai u cun dy t l nghch vi in p, ngha lnu ta ly ra in p cng cao th cho dng cng nh.

3. 3 Cng xut ca bin p .


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Cng xut ca bin p ph thuc tit din cali t, v ph thuc vo tn s ca dng in xoay chiu, bin p hotng tn s cng cao th cho cng xut cng ln.

3.4 Phn loi bin p .

* Bin p ngun v bin p m tn:

Bin p ngun Bin p ngun hnh xuynBin p ngun thng gp trong Cassete, mply .. , bin p ny hot ng tn s in li50Hz , li bin p s dng cc l Tnsilic hnh ch E v I ghp li, bin p ny c t svng / vol ln.

Bin p m tn s dng lm bin p o pha v bin p ra loa trong cc mch khuych icng xut m tn,bin p cng s dng l Tnsilic lm li t nh bin p ngun, nhng ltnsilic trong bin p m tn mng hn trnh tn hao, bin p m tn hot ng tn scao hn , v vy c s vng vol thp hn, khi thit k bin p m tn ngi ta thng ly gitr tn s trung bnh khong 1KHz n 3KHz.

* Bin p xung & Cao p .

Bin p xung Cao p

Bin p xung l bin p hot ng tn s cao khong vi chc KHz nh bin p trong ccb ngun xung , bin p cao p . li bin p xung lm bng ferit , do hot ng tn s caonn bin p xung cho cng xut rt mnh, so vi bin p ngun thng thng c cng trnglng th bin p xung c th cho cng xut mnh gp hng chc

9. C bn: i t Diode

15-02-2009 |lqv77 | 38 phn hi
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1 Cht bn dn

1.1 - Cht bn dn l g ?Cht

bn dn l nguyn liu sn xut ra cc loi linh kin bn dn nh

Diode, Transistor, IC m ta thy trong cc thit b in t ngynay.

Cht bn dn l nhng cht c c im trung gian giacht dn in v cht cch in, v phng din ho hc th bn dn lnhng cht c 4 in t lp ngoi cng ca nguyn t. l cc chtGermanium ( Ge) v Silicium (Si)

T cc cht bn dn ban u ( tinh khit) ngi ta phito ra hai loi bn dn l bn dn loi N v bn dn loi P, sau ghp cc ming bn dn loi N v P li ta thu c Diode hay Transistor.

Si v Ge u c ho tr 4, tc l lp ngoi cng c 4in t, th tinh khit cc nguyn t Si (Ge) lin kt vi nhau theolin kt cng ho tr nh hnh di.

Cht bn dn tinh khit .

1.2 - Cht bn dn loi N

* Khi ta pha mt lng nh cht c ho tr 5 nh Phospho (P) vo chtbn dn Si th mt nguyn t P lin kt vi 4 nguyn t Si theo linkt cng ho tr, nguyn t Phospho ch c 4 in t tham gia lin ktv cn d mt in t v tr thnh in t t do => Cht bn dn lcny tr thnh tha in t ( mang in m) v c gi l bn dn N (

Negative : m ).


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Cht bn dn N

1.3 - Cht bn dn loi P

Ngc li khi ta pha thm mt lng nh cht c ho tr 3 nh Indium(In) vo cht bn dn Si th 1 nguyn t Indium s lin ktvi 4 nguyn t Si theo lin kt cng ho tr v lin kt b thiu mtin t => tr thnh l trng ( mang in dng) v cgi l cht bn dn P.

Cht bn dn P

2 Diode (i t) Bn dn

2.1 Tip gip P N v Cu to ca Diode bn dn.Khi c c hai cht bn dn l P v N , nu ghp hai cht bn dn theomt tip gip P N ta c mt Diode, tip gip P -N c c im: Ti b mt tip xc, cc in t d tha trong bn dn N khuych tnsang vng bn dn P lp vo cc l trng => to thnh mt lp Iontrung ho v in => lp Ion ny to thnh min cch in giahai cht bn dn.


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Mi tip xc P N => Cu to ca Diode .

* hnh trn l mi tip xc P N v cng chnh l cu to ca Diode bn dn.

K hiu v hnh dng ca Diode bn dn.

2.2 - Phn cc thun cho Diode.Khita cp in p dng (+) vo Ant ( vng bn dn P ) v in p m (-)vo Katt ( vng bn dn N ) , khi di tc dng tng tc ca inp, min cch in thu hp li, khi in p chnh lch gi hai cc t0,6V ( vi Diode loi Si ) hoc 0,2V ( vi Diode loi Ge ) th dintch min cch in gim bng khng => Diode bt u dn in. Nutip tc tng in p ngun th dng qua Diode tng nhanh nhng chnhlch in p gia hai cc ca Diode khng tng (vn gi mc 0,6V )

Diode (Si) phn cc thun Khi Dode dnin p thun c gim mc 0,6V


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ng c tuyn ca in p thun qua Diode

* Kt lun : Khi Diode (loi Si)c phn cc thun, nu in p phn cc thun < 0,6V th cha cdng i qua Diode, Nu p phn cc thun t = 0,6V th c dng i quaDiode sau dng in qua Diode tng nhanh nhng st p thun vn gi gi tr 0,6V .

2.3 Phn cc ngc cho Diode.

Khi phn cc ngc cho Diode tc l cp ngun (+) vo Katt (bndn N), ngun (-) vo Ant (bn dn P), di s tng tc ca in pngc, min cch in cng rng ra v ngn cn dng in i quami tip gip, Diode c th chiu c in p ngc rt lnkhong 1000V th diode mi b nh thng.

Diode ch b chy khi p phn cc ngc tng > = 1000V

2.4 Phng php o kim tra Diode


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o kim tra Diode

t ng h thang x 1 , t hai que o vo hai u Diode, nu : o chiu thun que en vo Ant, que vo Katt => kim ln, o chiu o kim

khng ln l => Diode tt Nu o c hai chiu kim ln = 0 => l Diode b chp.

Nu o thun chiu m kim khng ln => l Diode b t. php o trn th Diode D1 tt , Diode D2 b chp v D3 b t Nu thang 1K m o ngc vo Diode kim vn ln mt cht l Diode b d.

2.5 ng dng ca Diode bn dn .

* Do tnh cht dn in mt chiu nn Diodethng c s dng trong cc mch chnh lu ngun xoay chiu thnh mtchiu, cc mch tch sng, mch gim p phn cc cho transistor hotng . trong mch chnh lu Diode c th c tch hp thnh Diode cuc dng .

Diode cu trong mch chnh lu in xoay chiu .


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3 Cc loi Diode

3.1 - Diode Zener* Cu to :Diode Zener c cu to tng t Diode thng nhng c hai lp bn dn P

- N ghp vi nhau, Diode Zener c ng dng trong ch phn ccngc, khi phn cc thun Diode zener nh diode thng nhng khi phncc ngc Diode zener s gim li mt mc in p c nh bng gi trghi trn diode.

Hnh dng Diode Zener ( Dz )

K hiu v ng dng ca Diode zener trong mch.

S trn minh ho ng dng ca Dz, ngun U1 l ngun c in p thay i, Dz ldiode n p, R1 l tr hn dng.

Ta thy rng khi ngun U1 > Dz th p trn Dz lun lun c nh cho d ngun U1thay i.

Khi ngun U1 thay i th dng ngc qua Dz thay i, dng ngc qua Dz c gi trgii hn khong 30mA.

Thng thng ngi ta s dng ngun U1 > 1,5 => 2ln Dz v lp tr hn dng R1 sao cho dng ngc ln nht qua Dz< 30mA.


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Nu U1 < Dz th khi U1 thay i p trn Dz cng thay iNu U1 > Dz th khi U1 thay i => p trn Dz khng i.

3.2 - Diode Thu quang. ( Photo Diode )Diode

thu quang hot ng ch phn cc nghch, v diode c mt mingthu tinh nh sng chiu vo mi P N , dng in ngc qua diodet l thun vi cng nh sng chiu vo diode.

K hiu ca Photo Diode

Minh ho s hot ng ca Photo Diode

3.3 - Diode Pht quang ( Light Emiting Diode : LED )Diode

pht phang l Diode pht ra nh sng khi c phn cc thun, in plm vic ca LED khong 1,7 => 2,2V dng qua Led khong t 5mA n20mA

Led c s dng lm n bo ngun, n nhy trang tr, bo trng thi c in . vv

Diode pht quang LED

3.4 Diode Varicap ( Diode bin dung )Diode bin dung l Diode c in dung nh t in, v in dung bin i khi ta thay i inp ngc t vo Diode.


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n dng ca Diode bin dung Varicap ( VD )trong mch cng hng

hnh trn khi ta chnh trit p VR, in pngc t vo Diode Varicap thay i , in dung ca diode thay i=> lm thay i tn s cng hng ca mch.

Diode bin dung c s dng trong cc b knh Ti vi mu, trong cc mch iuchnh tn s cng hng bng in p.

3.5 - Diode xungTrongcc b ngun xung th u ra ca bin p xung , ta phi dng Diodexung chnh lu. diode xung l diode lm vic tn s cao khong vichc KHz , diode nn in thng thng khng th thay th vo v trdiode xung c, nhng ngc li diode xung c th thay th cho v trdiode thng, diode xung c gi thnh cao hn diode thng nhiu ln.

V c im , hnh dng th Diode xung khng c g khc bit vi Diodethng, tuy nhin Diode xung thng c vng dnh du t nt hocnh du bng hai vng

K hiu ca Diode xung

3.6 Diode tch sng.

L loi Diode nh v bng thu tinh v cn gi l diode tip im vmt tip xc gia hai cht bn dn P N ti mt im trnh indung k sinh, diode tch sng thng dng trong cc mch cao tn dng

tch sng tn hiu.

3.7 Diode nn in.

L Diode tip mt dng nn in trong cc b chnh lu ngun AC 50Hz, Diode ny thng c 3 loi l 1A, 2A v 5A.

Diode nn in 5A


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10. C bn: Transistor15-02-2009 |lqv77 | 30 phn hi

1 Gii thiu v Transistor

1.1 Cu to ca Transistor. ( Bng bn dn )

Transistor gm ba lp bn dn ghp vi nhau hnh thnh hai mitip gip P-N , nu ghp theo th t PNP ta c Transistor thun , nughp theo th t NPN ta c Transistor ngc. v phng din cu toTransistor tng ng vi hai Diode u ngc chiu nhau .

Cu to Transistor

Ba lp bn dn c ni ra thnh ba cc , lp gia gil cc gc k hiu l B ( Base ), lp bn dn B rt mng v c nng tp cht thp.

Hai lp bn dn bn ngoi c ni ra thnh cc pht (Emitter ) vit tt l E, v cc thu hay cc gp ( Collector )vit tt l C, vng bn dn E v C c cng loi bn dn (loi N hay P )nhng c kch thc v nng tp cht khc nhau nn khng hon v chonhau c.

1.2 - Nguyn tc hot ng ca Transistor.

* Xt hot ng ca Transistor NPN .
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Mch kho st v nguyn tc hotng ca transistor NPN

Ta cp mt ngun mt chiu UCE vo hai cc C v E trong (+) ngun vo cc C v(-) ngun vo cc E.

Cp ngun mt chiu UBE i qua cng tc v tr hn dng vo hai cc B v E , trong cc (+) vo chn B, cc (-) vo chn E.

Khi cng tc m , ta thy rng, mc d hai cc C v E c cp in nhng vn khng c dng in chy qua mi C E ( lcny dng IC = 0 )

Khi cng tc ng, mi P-N c phn cc thun do c mt dng in chy t (+)ngun UBE qua cng tc => qua R hn dng => qua mi BE v cc (-) to thnh dngIB

Ngay khi dng IB xut hin => lp tc cng c dng IC chy qua mi CE lm bng npht sng, v dng IC mnh gp nhiu ln dng IB

Nh vy r rng dng IC hon ton ph thuc vo dng IB v ph thuc theo mt cngthc .

IC = .IB

Trong IC l dng chy qua mi CE IB l dng chy qua mi BE

l h s khuych i ca Transistor

Gii thch : Khi c in p UCE nhng cc in t v l trng khng th vt qua mi tipgip P-N to thnh dng in, khi xut hin dng IBEdo lp bn dn P ti cc B rt mng v nng pha tp thp, v vy sin t t do t lp bn dn N ( cc E ) vt qua tip gip sang lp

bn dn P( cc B ) ln hn s lng l trng rt nhiu, mt phn nhtrong s cc in t th vo l trng to thnh dng IB cn phn ln s in t b ht v

pha cc C di tc dng ca in p UCE => to thnh dng ICE chy qua Transistor.


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* Xt hot ng ca Transistor PNP .

S hot ng ca Transistor PNP hon ton tng t Transistor NPN nhng cc tnh ca ccngun in UCE v UBE ngc li . Dng IC i t E sang C cn dng IB i t E sang B.

2 K hiu v hnh dng ca Transistor

2.1 - K hiu & hnh dng Transistor .

K hiu ca Transistor

Transistor cng xut nh Transistor cng xut ln

2.2 - K hiu ( trn thn Transistor )*Hin nay trn th trng c nhiu loi Transistor ca nhiu nc snxut nhng thng dng nht l cc transistor ca Nht bn, M v Trungquc.

Transistor Nht bn : thng k hiu l A, B, C, D V d A564, B733,C828, D1555

trong cc Transistor k hiu l A v B l Transistor thun PNP cnk hiu l C v D l Transistor ngc NPN. ccTransistor A v C thng c cng xut nh v tn s lm vic caocn cc Transistor B v D thng c cng xut ln v tn s lm victhp hn.

Transistor do M sn xut. thng k hiu l 2N v d 2N3055, 2N4073 vv Transistor do Trung quc sn xut :

Bt u bng s 3, tip theo l hai ch ci. Ch ci thc nht cho bitloi bng : Ch A v B l bng thun , ch C v D l bng ngc, chth hai cho bit c im : X v P l bng m tn, A v G l bng caotn. Cc ch s sau ch th t sn phm. Th d : 3CP25 ,

3AP20 vv..


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2.3 - Cch xc nh chn E, B, C ca Transistor.

Vi cc loi Transistor cng xut nh th th t chn C v B tu theo bng ca ncno s xut , nhng chn E lun bn tri nu ta Transistor nh hnh di

Nu l Transistor do Nht sn xut : th d Transistor C828, A564 th chn C

gia , chn B bn phi. Nu l Transistor Trung quc sn xut th chn B gia , chn C bn phi. Tuy nhin mt s Transistor c sn xut nhi th

khng theo th t ny => bit chnh xc ta dng phng php obng ng h vn nng.

Transistor cng xut nh.

Vi loi Transistor cng xut ln (nh hnh di ) th hu ht u c chung th tchn l : Bn tri l cc B, gia l cc C v bn phi l cc E.

Transistor cng xut ln thngc th t chn nh trn.

* o xc nh chn B v C

Vi Transistor cng xut nh th thng thng chn E bn tri nh vy ta ch xc nh chn B v suy ra chn C l chn cnli.

ng h thang x1 , t c nh mt que o vo tng

chn , que kia chuyn sang hai chn cn li, nu kim ln = nhau


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th chn c que t c nh l chn B, nu que ng h c nh l queen th l Transistor ngc, l que th l Transistor thun..

3- Phng php kim tra Transistor

Transistorkhi hot ng c th h hng do nhiu nguyn nhn, nh hng do nhit, m, do in p ngun tng cao hoc do cht lng ca bn thnTransistor, kim tra Transistor bn hy nh cu to ca chng.

Cu to ca Transistor

Kim tra Transistor ngc NPN tng t kim tra

hai Diode u chung cc Ant, im chung l cc B, nu o t B sang Cv B sang E ( que en vo B ) th tng ng nh o hai diode thunchiu => kim ln , tt c cc trng hp o khc kim khng ln.

Kim tra Transistor thun PNP tng t kim trahai Diode u chung cc Katt, im chung l cc B ca Transistor, nuo t B sang C v B sang E ( que vo B ) th tng ng nh o haidiode thun chiu => kim ln , tt c cc trng hp o khc kimkhng ln.

Tri vi cc iu trn l Transistor b hng. Transistor c th b hng cc trng hp .

* o thun chiu t B sang E hoc t B sang C => kimkhng ln l transistor t BE hoc t BC* o t B sang E hoc t B sang C kim ln c hai chiu l chp hay d BE hoc BC.* o gia C v E kim ln l b chp CE.

* Cc hnh nh minh ho khi o kim tra Transistor.


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Php o cho bit Transistor cn tt .

Minh ho php o trn : Trc ht nhn vok hiu ta bit c Transistor trn l bng ngc, v ccchn ca Transistor ln lt l ECB ( da vo tn Transistor ). < xem li phn xc

nh chn Transistor > Bc 1 : Chun b o ng h thang x1 Bc 2 v bc 3 : o thun chiu BE v BC => kim ln . Bc 4 v bc 5 : o ngc chiu BE v BC => kim khng ln. Bc 6 : o gia C v E kim khng ln => Bng tt.

-


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Php o cho bit Transistor b chp BE

Bc 1 : Chun b . Bc 2 : o thun gia B v E kim ln = 0 Bc 3: o ngc gia B v E kim ln = 0

=> Bng chp BE


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Php o cho bit bng b t BE

Bc 1 : Chun b . Bc 2 v 3 : o c hai chiu gia B v E kim khng ln. => Bng t BE


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Php o cho thy bng b chp CE

Bc 1 : Chun b . Bc 2 v 4 : o c hai chiu gia C v E kim ln = 0 => Bng chp CE

Trng hp o gia C v E kim ln mt cht l b d CE.

4 Cc thng s k thut ca Transistor

4.1 Cc thng s k thut ca Transistor

Dng in cc i : L dng in gii hn ca transistor, vt qua dng gii hn nyTransistor s b hng.

in p cc i : L in p gii hn ca transistor t vo cc CE , vt qua inp gii hn ny Transistor s b nh thng.

Tn s ct : L tn s gii hn m Transistor lm vic bnh thng, vt qu tn sny th khuych i ca Transistor b gim .

H s khuych i : L t l bin i ca dng ICE ln gp bao nhiu ln dng IBE Cng xut cc i : Khi hoat ng Transistor tiu tn mt cng xut P = UCE . ICE nu

cng xut ny vt qu cng xut cc i ca Transistor th Transistor s b hng .

4.2 - Mt s Transistor c bit .

* Transistor s ( Digital Transistor ): Transistor s c cu to nh Transistor thng nhngchn B c u thm mt in tr vi chc K

Transistor s thng c sdng trong cc mch cng tc , mch logic, mch iu khin , khi hotng ngi ta c th a trc tip p lnh 5V vo chn B iu khinn ngt m.


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Minh ho ng dng ca Transistor Digital

* K hiu : TransistorDigital thng c cc k hiu l DTA( dn thun ),

DTC( n ngc ) , KRC( n ngc ) KRA( nthun), RN12( n ngc ), RN22(n thun ), UN., KSR. Th d : DTA132 , DTC 124 vv

* Transistor cng xut dng ( cng xut ngang )

Transistor cng xut lnthng c gi l s. S dng, S ngun vv..cc s ny c thit k iu khin b cao p hoc bin p ngun xung hot ng , Chngthng c in p hot ng cao v cho dng chu ng ln.Cc s cng xut dng( Ti vi mu) thng c u thm cc diode

m trong song song vi cc CE.

S cng xut dng trong Ti vi mu

5 Phn cc cho Transistor

5.1 Cp in cho Transistor ( Vcc in p cung cp )

s dng Transistor trong mch ta cn phi cpcho n mt ngun in, tu theo mc ch s dng m ngun in c cp

trc tip vo Transistor hay i qua in tr, cun dy v v ngunin Vcc cho Transistor c quy c l ngun cp cho cc CE.


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Cp ngun Vcc cho Transistor ngc v thun

Ta thy rng : Nu Transistor l ngc NPN th Vcc phi l ngun dng (+), nuTransistor l thun PNP th Vcc l ngun m (-)

5.2 nh thin ( phn cc ) cho Transistor .

* nh thin : l cpmt ngun in vo chn B ( qua tr nh thin) t Transistor votrng thi sn sng hot ng, sn sng khuych i cc tn hiucho d rt nh.

* Ti sao phi nh thin cho Transistor n mi sn sng hot ng ? : hiu ciu ny ta hy xt hai s trn :

trn l hai mch s dng transistor khuych itn hiu, mt mch chn B khng c nh thin v mt mch chn B cnh thin thng qua Rt.

Cc ngun tn hiu a vo khuych i thng c bin

rt nh ( t 0,05V n 0,5V ) khi a vo chn B( n cha cnh thin) cc tn hiu ny khng to ra dng IBE ( c im mi P-N pha c


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0,6V mi c dng chy qua ) => v vy cng khng c dng ICE => st p trn Rg =0V v in p ra chn C = Vcc

s th 2 , Transistor c Rt nh thin => c dng IBE, khi a tn hiu nh vochn B => lm cho dng IBE tng hoc gim => dng ICE cngtng hoc gim , st p trn Rg cng thay i => v kt qu u ra

ta thu c mt tn hiu tng t u vo nhng c bin ln hn.

=> Kt lun : nh thin ( hay phn cc) ngha l to mt dng in IBE ban u, mt st ptrn Rg ban u khi c mt ngun tn hiu yu i vo cc B , dng IBE s tng hoc gim=> dng ICE cng tng hoc gim => dn n st p trn Rg cng tng hoc gim => v st pny chnh l tn hiu ta cn ly ra .

5.3 - Mt s mach nh thin khc .

* Mch nh thin dng hai ngun in khc nhau .

Mch nh thin dng hai ngun in khc nhau

* Mach nh thin c in tr phn p

c th khuch i c nhiu ngun tn hiu mnh yu khc nhau, thmch nh thin thng s dng thm in tr phn p Rpa u t B xungMass.

Mch nh thin c in tr phn p Rpa

* Mch nh thin c hi tip .Lmch c in tr nh thin u t u ra (cc C ) n u vo ( cc B)mch ny c tc dng tng n nh cho mch khuych i khi hot ng.


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11. C bn: Mosfet15-02-2009 |lqv77 | 81 phn hi

1. Gii thiu v Mosfet

Mosfet l Transistor hiu ng trng ( Metal Oxide SemiconductorField Effect Transistor )l mt Transistor c bit c cu to v hot ng khc vi Transistor thng thng m ta

bit, Mosfet c nguyn tc hot ng da trn hiu ng t trng to ra dng in, l linh

kin c tr khng u vo ln thch hn cho khuych i cc ngun tn hiu yu, Mosfet cs dng nhiu trong cc mch ngun Monitor, ngun my tnh .

Transistor hiu ng trng Mosfet

2. Cu to v k hiu ca Mosfet.
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K hiu v s chn tng nggia Mosfet v Transistor

* Cu to ca Mosfet.

Cu to ca Mosfet ngc Knh P

G : Gate gi l cc cng S : Source gi l cc ngun D : Drain gi l cc mng Mosfet kn N c hai ming bn dn loi P t trn nn bn dn N, gia hai lp P-N

c cch in bi lp SiO2 hai ming bn dn P c ni ra thnh cc D v cc S,nn bn dn N c ni vi lp mng mng trn sau c du ra thnh cc G.

Mosfet c in tr gia cc G vi cc S v gia cc G vi cc D l v cng ln ,

cn in tr gia cc D v cc S ph thuc vo in p chnh lch gia cc G v ccS ( UGS )


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Khi in p UGS = 0 th in tr RDS rt ln, khi in p UGS > 0 => do hiu ng ttrng lm cho in tr RDS gim, in p UGS cng ln th in tr RDS cng nh.

3. Nguyn tc hot ng ca Mosfet

Mch in th nghim.

Mch th nghim s hot ng ca Mosfet

Th nghim : Cp ngun mt chiu UD qua mt bng n D vo hai cc D v S caMosfet Q (Phn cc thun cho Mosfet ngc) ta thy bng n khng sng ngha lkhng c dng in i qua cc DS khi chn G khng c cp in.

Khi cng tc K1 ng, ngun UG cp vo hai cc GS lm in p UGS > 0V => n Q1dn => bng n D sng.

Khi cng tc K1 ngt, in p tch trn t C1 (t gm) vn duy tr cho n Q dn =>chng t khng c dng in i qua cc GS. Khi cng tc K2 ng, in p tch trn t C1 gim bng 0 => UGS= 0V => n tt => T thc nghim trn ta thy rng : in p t vo chn G khng to ra dng GS

nh trong Transistor thng thng m in p ny ch to ra t trng => lm choin tr RDS gim xung .

4. o kim tra Mosfet

Mt Mosfet cn tt : L khi o tr khng gia G vi S v gia G vi D c in trbng v cng ( kim khng ln c hai chiu o) v khi G c thot in th tr

khng gia D v S phi l v cng.

Cc bc kim tra nh sau :


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o kim tra Mosfet ngc thy cn tt.

Bc 1 : Chun b thang x1K Bc 2 : Np cho G mt in tch ( que en vo G que vo S hoc D ) Bc 3 : Sau khi np cho G mt in tch ta o gia D v S ( que en vo D que

vo S ) => kim s ln. Bc 4 : Chp G vo D hoc G vo S thot in chn G. Bc 5 : Sau khi thot in chn G o li DS nh bc 3 kim khng ln. => Kt qu nh vy l Mosfet tt.


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o kim tra Mosfet ngc thy b chp

Bc 1 : ng h thang x 1K o gia G v S hoc gia G v D nu kim ln = 0 l chp o gia D v S m c hai chiu o kim ln = 0 l chp D S

5. ng dung ca Mosfet trong thc t

Mosfet trong ngun xung ca Monitor

Mosfet c s dng lm n cng xut ngun Monitor


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Trong b ngun xung ca Monitor hoc my vi tnh, ngi ta thng dng cp linh kin l ICto dao ng v n Mosfet, dao ng to ra t IC c dng xung vung c a n chn Gca Mosfet, ti thi im xung c in p > 0V => n Mosfet dn, khi xung dao ng = 0VMosfet ngt => nh vy dao ng to ra s iu khin cho Mosfet lin tc ng ngt tothnh dng in bin thin lin tc chy qua cun s cp => sinh ra t trng bin thin cm

ng ln cc cun th cp => cho ta in p ra.

* o kim tra Mosfet trong mch .Khi kim tra Mosfet trong mch , ta ch cn thang x1 v o gia D v S => Nu 1 chiukim ln o chiu o kim khng ln => l Mosfet bnh thng, Nu c hai chiu kim ln = 0 l Mosfet b chp DS.

6. Bng tra cu Mosfet thng dng

Hng dn :

Loi knh dn : P-Channel : l Mosfet thun , N-Channel l Mosfet ngc. c im k thut : Th d: 3A, 25W : l dng D-S cc i v cng xut cc i.

STT K hiu Loi knh dn c im k thut1 2SJ306 P-Channel 3A , 25W2 2SJ307 P-Channel 6A, 30W3 2SJ308 P-Channel 9A, 40W4 2SK1038 N-Channel 5A, 50W5 2SK1117 N-Channel 6A, 100W

6 2SK1118 N-Channel 6A, 45W7 2SK1507 N-Channel 9A, 50W8 2SK1531 N-Channel 15A, 150W9 2SK1794 N-Channel 6A,100W

10 2SK2038 N-Channel 5A,125W11 2SK2039 N-Channel 5A,150W12 2SK2134 N-Channel 13A,70W13 2SK2136 N-Channel 20A,75W14 2SK2141 N-Channel 6A,35W

15 2SK2161 N-Channel 9A,25W16 2SK2333 N-FET 6A,50W17 2SK400 N-Channel 8A,100W18 2SK525 N-Channel 10A,40W19 2SK526 N-Channel 10A,40W20 2SK527 N-Channel 10A,40W21 2SK555 N-Channel 7A,60W22 2SK556 N-Channel 12A,100W23 2SK557 N-Channel 12A,100W

24 2SK727 N-Channel 5A,125W25 2SK791 N-Channel 3A,100W


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26 2SK792 N-Channel 3A,100W27 2SK793 N-Channel 5A,150W28 2SK794 N-Channel 5A,150W29 BUZ90 N-Channel 5A,70W

30 BUZ90A N-Channel 4A,70W31 BUZ91 N-Channel 8A,150W32 BUZ 91A N-Channel 8A,150W33 BUZ 92 N-Channel 3A,80W34 BUZ 93 N-Channel 3A,80W35 BUZ 94 N-Channel 8A,125W36 IRF 510 N-Channel 5A,43W37 IRF 520 N-Channel 9A,60W38 IRF 530 N-Channel 14A,88W

39 IRF 540 N-Channel 28A,150W40 IRF 610 N-Channel 3A,26W41 IRF 620 N-Channel 5A,50W42 IRF 630 N-Channel 9A,74W43 IRF 634 N-Channel 8A,74W44 IRF 640 N-Channel 18A,125W45 IRF 710 N-Channel 2A,36W46 IRF 720 N-Channel 3A,50W47 IRF 730 N-Channel 5A,74W

48 IRF 740 N-Channel 10A,125W49 IRF 820 N-Channel 2A,50W50 IRF 830 N-Channel 4A,74W51 IRF 840 N-Channel 8A,125W52 IRF 841 N-Channel 8A,125W53 IRF 842 N-Channel 7A,125W54 IRF 843 N-Channel 7A,125W55 IRF 9610 P-Channel 2A,20W56 IRF 9620 P-Channel 3A,40W

57 IRF 9630 P-Channel 6A,74W58 IRF 9640 P-Channel 11A,125W59 IRFI 510G N-Channel 4A,27W60 IRFI 520G N-Channel 7A,37W61 IRFI 530G N-Channel 10A,42W62 IRFI 540G N-Channel 17A,48W63 IRFI 620G N-Channel 4A,30W64 IRFI 630G N-Channel 6A,35W65 IRFI 634G N-Channel 6A,35W

66 IRFI 640G N-Channel 10A,40W67 IRFI 720G N-Channel 3A,30W


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68 IRFI 730G N-Channel 4A,35W69 IRFI 740G N-Channel 5A,40W70 IRFI 820G N-Channel 2A,30W71 IRFI 830G N-Channel 3A,35W

72 IRFI 840G N-Channel 4A,40W73 IRFI 9620G P-Channel 2A,30W74 IRFI 9630G P-Channel 4A,30W75 IRFI 9640G P-Channel 6A,40W76 IRFS 520 N-Channel 7A,30W77 IRFS 530 N-Channel 9A,35W78 IRFS 540 N-Channel 15A,40W79 IRFS 620 N-Channel 4A,30W80 IRFS 630 N-Channel 6A,35W

81 IRFS 634 N-Channel 5A,35W82 IRFS 640 N-Channel 10A,40W83 IRFS 720 N-Channel 2A,30W84 IRFS 730 N-Channel 3A,35W85 IRFS 740 N-Channel 3A,40W86 IRFS 820 N-Channel 2A-30W87 IRFS 830 N-Channel 3A-35W88 IRFS 840 N-Channel 4A-40W89 IRFS 9620 P-Channel 3A-30W

90 IRFS 9630 P-Channel 4A-35W91 IRFS 9640 P-Channel 6A-40W92 J177(2SJ177) P-Channel 0.5A-30W93 J109(2SJ109) P-Channel 20mA,0.2W94 J113(2SK113) P-Channel 10A-100W95 J114(2SJ114) P-Channel 8A-100W96 J118(2SJ118) P-Channel 8A97 J162(2SJ162) P-Channel 7A-100W98 J339(2SJ339) P-Channel 25A-40W

99 K30A/2SK304/2SK30R N-Channel 10mA,1W

100 K214/2SK214 N-Channel 0.5A,1W101 K389/2SK389 N-Channel 20mA,1W102 K399/2SK399 N-Channel 10-100103 K413/2SK413 N-Channel 8A104 K1058/2SK1058 N-Channel105 K2221/2SK2221 N-Channel 8A-100W106 MTP6N10 N-Channel 6A-50W107 MTP6N55 N-Channel 6A-125W108 MTP6N60 N-Channel 6A-125W


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109 MTP7N20 N-Channel 7A-75W110 MTP8N10 N-Channel 8A-75W111 MTP8N12 N-Channel 8A-75W112 MTP8N13 N-Channel 8A-75W

113 MTP8N14 N-Channel 8A-75W114 MTP8N15 N-Channel 8A-75W115 MTP8N18 N-Channel 8A-75W116 MTP8N19 N-Channel 8A-75W117 MTP8N20 N-Channel 8A-75W118 MTP8N45 N-Channel 8A-125W119 MTP8N46 N-Channel 8A-125W120 MTP8N47 N-Channel 8A-125W121 MTP8N48 N-Channel 8A-125W

122 MTP8N49 N-Channel 8A-125W123 MTP8N50 N-Channel 8A-125W124 MTP8N80 N-Channel 8A-75W

12. C bn: Thyristor15-02-2009 |lqv77 | 17 phn hi

1. Cu to v nguyn l hot ng ca Thyristor

Cu to Thyristor K hiu ca Thyristor S tng tng

Thyristor c cu to gm 4 lp bn dn ghp li to thnh hai Transistor mc ni tip, mtTransistor thun v mt Transistor ngc ( nh s tng ng trn ) . Thyristor c 3cc l Anot, Katot v Gate gi l A-K-G, Thyristor l Diode c iu khin , bnh thng khic phn cc thun, Thyristor cha dn in, khi c mt in p kch vo chn G =>

Thyristor dn cho n khi in p o chiu hoc ct in p ngun Thyristor mi ngngdn..
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Th nghim sau y minh ho s hot ng ca Thyristor

Th nghim minh ho s hot ng ca Thyristor.

Ban u cng tc K2 ng, Thyristor mc d c phn cc thun nhng vn khngc dng in chy qua, n khng sng.

Khi cng tc K1 ng, in p U1 cp vo chn G lm n Q2 dn => ko theo nQ1 dn => dng in t ngun U2 i qua Thyristor lm n sng.

Tip theo ta thy cng tc K1 ngt nhng n vn sng, v khi Q1 dn, in p chn Bn Q2 tng lm Q2 dn, khi Q2 dn lm p chn B n Q1 gim lm n Q1 dn ,nh vy hai n nh thin cho nhau v duy tr trang thi dn in.

n sng duy tr cho n khi K2 ngt => Thyristor khng c cp in v ngngtrang thi hot ng.

Khi Thyristor ngng dn, ta ng K2 nhng n vn khng sng nh trng hpban u.

Hnh dng Thyristor

o kim tra Thyristor


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o kim tra Thyristor

t ng h thang x1 , t que en vo Anot, que vo Katot ban u kim khng ln ,dng Tovit chp chn A vo chn G => thy ng h ln kim , sau b Tovit ra => ng hvn ln kim => nh vy l Thyristor tt .

ng dng ca Thyristor

Thyristor thng c s dng trong cc mch chnh lu nhn i t ng ca ngun xungTi vi mu .

Th d mch chnh lu nhn 2 trong ngun Ti vi mu JVC 1490 c s nh sau :

ng dng ca Thyristor trong mch chnh lu nhn 2 t ng ca ngun xung Tivi mu JVC

13. C bn: Mch khuych i


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15-02-2009 |lqv77 | 8 phn hi

1 Mch khuch i

1.1 Khi nim v mch khuyh i .

Mch khuych i c s dng trong hu ht cc thit b in t, nh mch khuych i mtn trong Cassete, mply, Khuych i tn hiu video trong Ti vi mu v.v

C ba loi mch khuych i chnh l :

Khuych i v in p : L mch khi ta a mt tn hiu c bin nh vo, u rata s thu c mt tn hiu c bin ln hn nhiu ln.

Mch khuych i v dng in :L mch khi ta a mt tn hiu c cng yu vo, u ra ta s thu c mt tnhiu cho cng dng in mnh hn nhiu ln.

Mch khuych i cng xut : L mch khi ta a mt tn hiu c cng xut yu vo ,u ra ta thu c tn hiu c cng xut mnh hn nhiu ln, thc ra mch khuychi cng xut l kt hp c hai mch khuych i in p v khuych i dng inlm mt.

1.2 Cc ch hot ng ca mch khuych i.

Cc ch hot ng ca mch khuych i l ph thuc vo ch phn cc cho Transistor,tu theo mc ch s dng m mch khuych i c phn cc K ch A, ch B , ch AB hoc ch C

a) Mch khuych i ch A.L cc mch khuych i cn ly ra tn hiu hon ton gin vi tn hiu ng vo.

Mch khuych i ch A khuych i c hai bn chu k tn hiu ng vo
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* Transistor hot ng ch A, ta phi nh thin sao cho in p UCE ~ 60% 70%Vcc.

* Mch khuych i ch A c s dng trong cc mch trung gian nh khuych i caotn, khuych i trung tn, tin khuych i vv..

b) Mach khuych i ch B.

Mch khuych i ch B l mch ch khuych i mt na chu k ca tn hiu, nukhuych i bn k dng ta dng transistor NPN, nu khuych i bn k m ta dngtransistor PNP, mch khuych i ch B khng c nh thin.

Mch khuych i ch B ch khuych i mt bn chu k ca tn hiu ng vo.* Mch khuych i ch B thng c s dng trong cc mch khuch i cng xut yko nh cng xut m tn, cng xut mnh ca Ti vi, trong cc mch cng xut y ko ,ngi ta dng hai n NPN v PNP mc ni tip , mi n skhuych i mt bn chu k ca tn hiu, hai n trong mch khuych i y ko phi c ccthng s k thut nh nhau:

* Mch khuych i cng xut kt hp c hai ch A v B .


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Mch khuych i cng xut mply c : Q1 khuych i ch A, Q2 v Q3 khuych i ch B, Q2 khuych i

cho bn chu k dng, Q3 khuych i cho bn chu k m.

c) Mch khuych i ch AB.Mch khuych i ch AB l mch tng t khuych i ch B , nhng c nhthin sao cho in p UBE sp s 0,6 V, mch cng ch khuych i mt na chu k tn hiu vkhc phc hin tng mo giao im ca mch khuych i ch B, mch ny cng c

s dng trong cc mch cng xut y ko .

d) Mch khuych i ch CL mch khuych i c in p UBE c phn c ngc vi mc ch ch ly tn hiu u ral mt phn nh ca tn hiu u vo, mch ny thng s dng trong cc mch tch tnhiu : Th d mch tch xung ng b trong ti vi mu.

ng dng mch khuych i ch C trong mch tch xung ng b Ti vi mu.


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2 Cc kiu mc ca Transistor

2.1 Transistor mc theo kiu E chung.

Mch mc theo kiu E chung c cc E u trc tip xung mass hoc u qua t xung mass

thot thnh phnxoay chiu, tn hiu a vo cc B v ly ra trn cc C, mch c s nh sau :

Mch khuych i in p mc kiu E chung , Tn hiu a vo cc B v ly ra trn cc C

Rg: l in tr ghnh ,Rt: L in tr nh thin,Rpa : L in tr phn p .

c im ca mch khuych i E chung.

Mch khuych i E chung thng c nh thin sao cho in p UCE khong 60% 70 % Vcc.

Bin tn hiu ra thu c ln hn bin tn hiu vo nhiu ln, nh vy mchkhuych i v in p.

Dng in tn hiu ra ln hn dng tn hiu vo nhng khng ng k. Tn hiu u ra ngc pha vi tn hiu u vo : v khi in p tn hiu vo tng =>

dng IBE tng => dng ICEtng => st p trn Rg tng => kt qu l in p chn C gim, v ngc li khi inp u vo gim th in p chn C li tng => v vy in p u ra ngc pha vi tnhiu u vo.

Mch mc theo kiu E chung nh trn c ng dng nhiu nht trong thit b in t.

2.2 Transistor mc theo kiu C chung.

Mch mc theo kiu C chung c chn C u vo mass hoc dng ngun (Lu : v phngdin xoay chiu th dngngun tng ng vi mass), Tn hiu c a vo cc B v ly ra trn cc E, mch c s nh sau :


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Mch mc kiu C chung , tn hiu a vo cc B v ly ra trn cc E

c im ca mch khuych i C chung .

Tn hiu a vo cc B v ly ra trn cc E Bin tn hiu ra bng bin tn hiu vo : V mi BE lun lun c gi tr khong

0,6V do khi in p chn B tng bao nhiu th p chn C cng tng by nhiu => vvy bin tn hiu ra bng bin tn hiu vo .

Tn hiu ra cng pha vi tn hiu vo : V khi in p vo tng => th in p ra cngtng, in p vo gim th in p ra cng gim.

Cng ca tn hiu ra mnh hn cng ca tn hiu vo nhiu ln : V khi tnhiu vo c bin tng => dng IBE s tng => dng ICE cng tng gp ln dng IBEv ICE = .IBE gi s Transistor c h s khuych i = 50 ln th khi dng IBE tng1mA => dng ICE s tng 50mA, dng ICE chnh l dng ca tn hiu u ra, nh vy

tn hiu u ra c cng dng in mnh hn nhiu ln so vi tn hiu vo. Mch trn c ng dng nhiu trong cc mch khuych i m (Damper), trc khi

chia tn hiu lm nhiu nhnh, ngi ta thng dng mch Damper khuych icho tn hiu kho hn. Ngoi ra mch cn c ng dng rt nhiu trong cc mch np ngun (ta s tm hiu trong phn sau)

2.3 Transistor mc theo kiu B chung.

Mch mc theo kiu B chung c tn hiu a vo chn E v ly ra trn chn C , chn Bc thot mass thng qua t.

Mach mc kiu B chung rt t khi c s dng trong thc t.


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Mch khuych i kiu B chung, khuych i v in p v khng khuych i v dng in.

3 Cc kiu ghp tng

3.1 Ghp tng qua t in.* S mch ghp tng qua t in

Mch khuych i u t c hai tng khuych i c ghp vi nhau qua t in.

trn l s mch khuych i u t trong i Cassette, mch gm hai tngkhuych i mc theo kiu E chung, cc tng c ghp tn hiu thng qua t in,ngi ta s dng cc t C1 , C3 , C5lm t ni tng cho tn hiu xoay chiu i qua vngn p mt chiu li, cc t C2 v C4 c tc dng thot thnh phn xoay chiu tchn E xungmass, C6 l t lc ngun.

u im ca mch l n gin, d lp do mch c s dng rt nhiu trong thitb in t, nhc im l khng khai thc c ht kh nng khuych i ca

Transistor do h s khuych i khng ln. trn l mch khuych i m tn, do cc t ni tng thng dng t ho c tr st 1F 10F.


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Trong cc mch khuych i cao tn th t ni tng c tr s nh khong vi nanFara.

3.2 Ghp tng qua bin p .* S mch trung tn ting trong Radio s dng bin p ghp tng

Tng Trung tn ting ca Radio s dng bin p ghp tng.

trn l s mch trung tn Radio s dng cc bin p ghp tng, tn hiu u raca tng ny c ghp qua bin p i vo tng pha sau.

u im ca mch l phi hp c tr khng gia cc tng do khai thc c tiu h s khuych i , hn na cun s cp bin p c th u song song vi t cng hng khi mch khuych i mt tn s c nh.

Nhc im : nu mch hot ng di tn s rng th gy mo tn s, mch ch tophc tp v chim nhiu din tch.

3.3 Ghp tng trc tip .

* Kiu ghp tng trc tip thng c dng trong cc mch khuych i cng xut m tn.


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Mch khuych i cng xut m tn c n o pha Q1 c ghp trc tip vi hai n cngxut Q2 v Q3.

4 Phng php kim tra mt tng khuch i

4.1 Trong cc mch khuych i ( ch A ) th phn cc nh th no l ng.

Mch khuych i c phn cc ng.

Mch khuych i ( ch A) c phn cc ng l mch cUBE ~ 0,6V ; UCE ~ 60% 70% Vcc

Khi mch c phn cc ng ta thy , tn hiu ra c bin ln nht v khng b

mo tn hiu .


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4.2 Mch khuych i ( ch A ) b phn cc sai.

Mch khuych i b phn cc sai, in p UCEqu thp .

Mch khuych i b phn cc sai, in p UCEqu cao .

Khi mch b phn cc sai ( tc l UCE qu thp hoc qu cao ) ta thy rng tn hiu rab mo dng, h s khuych i ca mch b gim mnh.

Hin tng mo dng trn s gy hin tng m thanh b r hay b nght cc mchkhuych i m tn.

Phng php kim tra mt tng khuych i.

Mt tng khuych i nu ta kim tra thy UCE qu thp so vi ngun hoc qu cao

sp s bng ngun => th tng khuych i c vn . Nu UCE qu thp th c th do chp CE( hng Transistor) , hoc t Rg.


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gim mo bin v mo tn s khi tn s, bin ca tn hiu vo thay i.- R7-C4 : Hp thnh mch hi tip m dng in c tc dng n nh h s k/ dng in choQ1, gim nh hin tng mo bin . Khi /chnh gi tr ca C4 s thay i h s k/ caQ1, ni cch khc /c C4 s lm mch ku to_ku nh.- Q1 : K/i tn hiu vo, c mc theo kiu E chung.

- Q2 : ng vai tr k/ tin cng sut c mc kiu C chung. Tn hiu ra chn E cp cho 2BJT cng sut. y, thc cht ko c tn hiu xoay chiu no ht, ch c in p mt chiuthay i (ln xung) quanh mc tnh ban u. Tn hiu ra chn E Q2 c dng kch thch(thng qua thay i in p) cho Q3, Q4.- Q3, Q3 : Cp BJT cng sut c mc theo kiu y ko ni tip. Hai BJT ny thay nhaung/m tng na chu k ca tn hiu t vo. Lu l Q3 dng PNP, Q4 dng NPNnhng phi c thng s tng ng nhau. Kiu mc Q2, Q3, Q4 nh trn gi l y koni tip t o pha- R9, R10 : in tr cu ch, bo v Q3, Q4 khi b cht khi c 1 trong 2 BJT b chp.- D1, D2 : n nh nhit, bo v trnh cho Q3, Q4 b nng. C ch bo v ti ko gii thch y, cc bn t xem li l thuyt mch BJT c bn.

- PR1 : iu chnh phn cc Q4, thng qua chnh cn bng cho in p trung imNguyn l hot ng :Ch tnh : Khi tn hiu vo bng 0.- Mch c thit k Q1, Q2 hot ng ch A. Q3, Q4 c th ch A hoc AB.- PR1 c /chnh Q3, Q4 c in p chn B bng nhau, nh vy m ca Q3=Q4 vkt qu l in p ti im C bng 1/2 in p ngun cp (theo s mch c cp 15V thin p im C l 7.V), in p ti im C gi l in p trung im.- T C5 c ni vo im C. in p ban u trn t chnh bng in p im C (7.5V)Khi tn hiu vo bn k dng (+):- in p chn B Q1 tng Q1 m thm, dng IcQ1 tng st p trn R4 (UR4 =R4xIcQ1) tng lm cho UcQ1 gim. gim ca UcQ1 t l thun vi bin tn hiu vo.- V chn CQ1 ni trc tip chn BQ2 nn khi UcQ1 gim th UbQ2 gim theo lm cho Q2kha bt, nh vy dng IcQ2 gim xung dn n in p ti im A(UA) v im B(UB)u gim.- Cc bn : Q3 l PNP, Q4 l NPN do vy khi UA gim th m Q3 tng (m thm),UB gim th m Q4 gim (kha bt).- V Q3 m thm, Q4 kha bt lm cho in p ti im C tng ln dn ti t C5 (ban u l7.5V) np, dng np cho C5 i t (+) ngun 15V CEQ3 R9 C5 loa mass.Dng np qua loa l i xung. in p trn t C5 lc ny ln hn 7.5V.Khi tn hiu vo bn k m (-)- in p chn B Q1 gim Q1 kha bt, dng IcQ1 gim st p trn R4 (UR4 =

R4xIcQ1) gim lm cho UcQ1 tng. tng ca UcQ1 t l thun vi bin tn hiu vo.- V chn CQ1 ni trc tip chn BQ2 nn khi UcQ1 tng th UbQ2 tng theo lm cho Q2 mthm, nh vy dng IcQ2 tng ln dn n in p ti im A(UA) v im B(UB) u tng.- Cc bn : Q3 l PNP, Q4 l NPN do vy khi UA tng th m Q3 gim (kha bt),UB tng th m Q4 tng (m thm).- V Q3 kha bt, Q4 m thm lm cho in p ti im C gim ln dn ti t C5 phng,dng phng ca C5 i t (+) t R10 CQ4 mass loa (-)C5. Dng phng qua loal i ln.Kt lun :Nh vy, vi c chu k ca tn hiu vo ta thu c 2 dng in lin tc i

xung/i ln loa, chnh l tn hiu xoay chiu ra loa. Cng 2 dng ny t l thunvi bin tn hiu xoay chiu vo mch.

th thi gian :


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15. C bn: Mch chnh lu v n p15-02-2009 |lqv77 | 39 phn hi

1 Mch chnh lu in xoay chiu

1.1 B ngun trong cc mch in t .

Trong cc mch in t ca cc thit b nh Radio -Cassette, mlpy, Ti vi mu, u VCD vv chng s dng ngun mt chiu DC cc mc in p khc nhau, nhng ngoi zccm ca cc thit b ny li cm trc tip vo ngun in AC 220V 50Hz, nh vy cc thit bin t cn c mt b phn chuyn i t ngun xoay chiu ra in p mt chiu , cungcp cho cc mch trn, b phn chuyn i bao gm :

Bin p ngun : H th t 220V xung cc in p thp hn nh 6V, 9V, 12V, 24V vv

Mch chnh lu : i in AC thnh DC. Mch lc Lc gn xoay chiu sau chnh lu cho ngun DC phng hn. Mch n p : Gi mt in p c nh cung cp cho ti tiu th
http://lqv77.com/author/lqv77/http://lqv77.com/author/lqv77/http://lqv77.com/2009/02/15/co-ban-mach-chinh-luu-va-on-ap/#respondhttp://lqv77.com/wp-content/uploads/2009/05/bieu-do-thoi-gian.jpghttp://lqv77.com/author/lqv77/http://lqv77.com/2009/02/15/co-ban-mach-chinh-luu-va-on-ap/#respond


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S tng qut ca mch cp ngun.

1.2 Mch chnh lu bn chu k .

Mch chnh lu bn chu k s dng mt Diode mc ni tip vi ti tiu th, chu k dng=> Diode c phn cc thun do c dng in i qua diode v i qua ti, chu k m ,

Diode b phn cc ngc do khng c dng qua ti.

Dng in p u ra ca mch chnh lu bn chu k.

1.3 Mch chnh lu c chu k

Mch chnh lu c chu k thng dng 4 Diode mc theo hnh cu (cn gi l mch chnh lucu) nh hnh di.

Mch chnh lu c chu k .

chu k dng ( u dy pha trn dng, pha di m) dng in i qua diode D1=> qua Rti => qua diode D4 v u dy m


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chu k m, in p trn cun th cp o chiu ( u dy trn m, di dng)dng in i qua D2 => qua Rti => qua D3 v u dy m.

Nh vy c hai chu k u c dng in chy qua ti.

2 Mch lc v mch chnh lu bi p

2.1 Mch lc dng t in.

Sau khi chnh lu ta thu c in p mt chiu nhp nh, nu khng c t lc th in pnhp nh ny cha th dng c vo cc mch in t , do trong cc mch ngun, ta philp thm cc t lc c tr s t vi trm F n vi ngn F vo sau cu Diode chnh lu.

Dng in p DC ca mch chnh lu trong hai trng hp c t v khng c t

S trn minh ho cc trng hp mch ngun c t lc v khng c t lc. Khi cng tc K m, mch chnh lu khng c t lc tham gia , v vy in p thu c

c dng nhp nh. Khi cng tc K ng, mch chnh lu c t C1 tham gia lc ngun , kt qu l in p

u ra c lc tng i phng, nu t C1 c in dung cng ln th in p u racng bng phng, t C1 trong cc b ngun thng c tr s khong vi ngn F .

Minh ho : in dng ca t lc cng ln th in p u ra cng bng phng.

Trong cc mch chnh lu, nu c t lc m khng c ti hoc ti tiu th mt cngxut khng ng k so vi cng xut ca bin p th in p DC thu c l DC =

1,4.AC


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2.2 Mch chnh lu nhn 2 .

S mch ngun chnh lu nhn 2

tr thnh mch chnh lu nhn 2 ta phi dng hai t ho cng tr s mc ni tip,sau u 1 u ca in p xoau chiu vo im gia hai t => ta s thu c inp tng gp 2 ln.

mch trn, khi cng tc K m, mch tr v dng chnh lu thng thng . Khi cng tc K ng, mch tr thnh mch chnh lu nhn 2, v kt qu l ta thu c

in p ra tng gp 2 ln.

3 Mch n p c nh

3.1 Mch n p c nh dng Diode Zener.

.

Mch n p to p 33V c nh cung cp cho mch d knh trong Ti vi mu

T ngun 110V khng c nh thng qua in tr hn dng R1 v gim trn Dz 33V ly ra mt in p c nh cung cp cho mch d knh

Khi thit k mt mch n p nh trn ta cn tnh ton in tr hn dng sao cho dngin ngc cc i qua Dz phi nh hn dng m Dz chu c, dng cc i qua Dzl khi dng qua R2 = 0

Nh s trn th dng cc i qua Dz bng st p trn R1 chia cho gi tr R1 , gidng in ny l I1 ta c


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I1 = (110 33 ) / 7500 = 77 / 7500 ~ 10mA

Thng thng ta nn dng ngc qua Dz 25 mA

3.2 Mch n p c nh dng Transistor, IC n p .

Mch n p dng Diode Zener nh trn c u im l n gin nhng nhc im l chodng in nh ( 20mA). c th to ra mt in p c nh nhng cho dng in mnh hn nhiu ln ngi ta mc thmTransistor khuych i v dng nh s di y.

Mch n p c Transistor khuych i

mch trn in p ti im A c th thay i v cn gn xoay chiu nhng in pti im B khng thay i v tng i phng.

Nguyn l n p : Thng qua in tr R1 v Dz gim c nh in p chn B caTransistor Q1, gi s khi in p chnE n Q1 gim => khi in p UBE tng => dng qua n Q1 tng => lm in pchn E ca n tng , v ngc li

Mch n p trn n gin v hiu qu nn c s dng rt rng di v ngi ta sn xut cc loi IC h LA78.. thay th cho mch n p trn, IC LA78.. c s mch nh phn mch c mu xanh ca s trn.


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IC n p h LA78.. IC n p LA7805

LA7805 IC n p 5V LA7808 IC n p 8V LA7809 IC n p 9V

LA7812 IC n p 12V

Lu :H IC78.. ch cho dng tiu th khong 1A tr xung, khi rp IC trong mch th U in > Uoutt 3 n 5V khi IC mi pht huy tc dng.

3.3 ng dng ca IC n p h 78..

IC n p h 78.. c dng rng ri trong cc b ngun , nh B ngun ca u VCD, trongTi vi mu, trong my tnh

ng dng ca IC n p LA7805 v LA7808 trong b ngun u VCD

4 Mch n p tuyn tnh (c hi tip)

4.1 S khi ca mch n p c hi tip .


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S khi ca mch n p c hi tip .

* Mt s c im ca mch n p c hi tip :

Cung cp in p mt chiu u ra khng i trong hai trng hp in p u vothay i hoc dng tiu th ca ti thay i, tuy nhin s thay i ny phi c giihn.

Cho in p mt chiu u ra c cht lng cao, gim thiu c hin tng gn xoaychiu.

* Nguyn tc hot ng ca mch.

Mch ly mu s theo di in p u ra thng qua mt cu phn p to ra ( Ulm : ply mu)

Mch to p chun => gim ly mt mc in p c nh (Uc : p chun ) Mch so snh s so snh hai in p ly mu Ulm v p chun Uc to thnh in p

iu khin. Mch khuch i sa sai s khuch i p iu khin, sau a v iu chnh s

hot ng ca n cng xut theo hng ngc li, nu in p ra tng => thng quamch hi tip iu chnh => n cng xut dn gim =>in p ra gim xung.

Ngc li nu in p ra gim => thng qua mch hi tip iu chnh => n cngxut li dn tng => v in p ra tng ln =>> kt qu in p u ra khng thay i.

4.2 Phn tch hot ng ca mch ngun c hi tip trong Ti vi en trng Samsung

in p u vo cn gn xoay chiu in p u ra bng phng


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Mch n p tuyn tnh trong Ti vi Samsung en trng .

* ngha cc linh kin trn s .

T 2200F l t lc ngun chnh, lc in p sau chnh lu 18V , y cng l in pu vo ca mch n p, in p ny c th tng gim khong 15%.

Q1 l n cng xut ngun cung cp dng in chnh

giao trinh dien tu

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