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TRNG I HC
CNG NGHIP THC PHM
TIU LUN MN IN T C BN
Ch : Linh kin Opto
I. CU TO:
Trong in-in t, opto cn gi l b cch
ly quang (opto-isolator), l mt linh kin
dng truyn tn hiu in bng cch
chuyn tn hiu sang nh sng v sau mi
truyn i.
Cu to ca opto gm mt LED pht v
mt LED thu l photo diot hay photo
transitor, c hai c tch hp nm bn
trong mt v bc kn.
II. K HIU:
Trn mch nguyn l n c k hiu nh
sau :
Cch b tr LED pht v LED thu bn trong ca opto-coupler:
III. NGUYN L HOT
NG:
Khi c dng nh i qua 2 u ca
led c trong opto lm cho LED pht
sng. Khi LED pht sng lm thng
hai cc ca photo transitor hay photo
diot m cho dng in chy qua.
IV. C TUYN VOLT AMPE:
c tuyn v-i ca LED:
c tuyn volt ampe ca LED tng t c
tuyn volt ampe ca diode thng: n biu
din mi quan h gia dng in quang vi in
p t ln LED.
Nhng khong mc ngng cho php ca LED
ty loi LED v mc ngng ny ln hn mc
ngng ca diode thng. in p nghch ti
a ca LED tng i thp.
c tuyn v-i ca Photo diode :
c tuyn V-I ca quang diod vi quang
thng l thng s cho thy quang thng nh
khi in th phn cc nghch nh, dng in
tng theo in th phn cc,nhng khi in
th phn cc ln hn vi volt, dng in gn
nh bo ha (khng i khi in th phn
cc nghch tng).
Khi quang thng ln, dng in thay
i theo in th phn cc nghch.
Tn s hot ng ca quang diode c
th ln n hnh MHz. Quang diode
cng nh quang in tr thng
c dng trong cc mch iu
khin ng - m mch in (dn
in khi c nh sng chiu vo v
ngng khi ti).
c tuyn v-i ca photo transistor
V. KIM TRA H HNG:
S dng ng h o VOM kim tra h
hng cho OPTO :
Cho hai que th chn vo Anode(chn s 1)
cn chn en vo Kathode(chn s 2 )ca
DIODE trong OPTO v o nh mt diode bnh
thng chn 1 v 2 dn th 3 v 4 cng
dn.Chn 3 v 4 chnh l chn CE ca
transistor loi NPN, ta thang o X10K ri
o, Kim nhch ln mt t, tm s 100 n 150
l tt, khng ln l t, ln gn v cng l b
r CE, ln ht n 0 l b chp CE.
VI. Hnh dng Opto: Bn di l cc hnh dng thc t ca opto v
ng dng ca n trong in-in t cng
nghip:
Cc Opto thng dng hin nay:
a. Opto P521:
L linh kin 4 chn v c k hiu
Cch xc nh chn ca opto 521:
Chn 1 l gn du chm trn mt opto ( du chm
nh lm xung), gn chn 1 l chn 2, i din
chn 1 l chn 3, bn chn 3 l chn 4.
Trong :
1 l Anode
2 l Cathode
3 l Emitter (b pht)
4 collector (b thu)
Opto 521-2:
L kinh kin 8 chn:
b. Cch xc nh chn ca P521-2 tng t nh
P521
Trong :
1, 3 l Anode
2, 4 l Cathode
5, 7 l Emitter
6, 8 l Collector
c. Ngoi ra cn c P521-4:
Xc nh tng t nh P521, P521-2. V c 16
chn.
1,3,5,7 l Anode
2,4,6,8 l Cathode
9,11,13,15 l Emitter
10,12,14,16 l Collector
d. Opto 4N35:
l linh kin c 6 chn, cch xc nh chn tng t nh P521
1 l Anode
2 l Cathode
3 l NC
4 l Emitter
5 l Collector
6 l Base
V. ng dng:
OKhi s c t tng ng dng
nh chy, chp, tng p,...th
cng khng lm nh hng
n tng iu khin