Mch gm cc linh kin sau: -LDR:Quang tr cm bin nh sng. -R1:To thin p cho Q1.Chn gi tr R1 iu chnh ngng bt sng ca n.R1 thp th mch cng nhy sng tc n tt sm hn khi tri dn sng nhng n cng bt sm hn khi tri dn ti.R1 chn t 470k tr ln. -R2:Hn dng cc B cho Q1,n cng c tc dng l ti C4 x to thi gian tr. -R3:n nh nhit cho Q1. -R4,R5(gm 2 in tr 1k mc song song):To thin p cho Q2. nhy ca mch ty thuc vo R5,R5 cng thp mch cng km nhy,vi mch ny R5 di 470 m th mch khng lm vic. -Q1:Phi hp vi Q2 to thnh 1 swich in t iu khin role. -Q2:Tran lm vic ch bo ha,c tc dng nh mt swich ng ct rle . -D1:it mui.Ngn t C1 x qua LDR khi in tr ca LDR t ngt st xung khi gp nh sng bt thng (ca chp,n chiu,...). -D2:Trit tiu dng cm ng do cun dy rle sinh ra khi n ng ct,bo v tran.

-C1:To thi gian tr ngn n b tt t ngt khi gp ngun sng bt thng trong thi gian ngn. -C2:Chng rung cho rowle . -C3:.Dp tia la in cho tip im ca role khi n ng ct. -Role:C in p lm vic 9 n 12V. +Nguyn l lm vic: Mch lm vic vi ngun DC12V c tc dng t ng bt n khi tri ti,tt n khi tri sng,c th dng cho n ng hoc n phng. -Tri sng,LDR c in tr thp,cc B ca Q1 c p thp nn Q1 kha lm p chn C ca Q1 mc cao,cc B Q2 cng mc cao=>Q2 cng kha,khng c dng qua role,tip im K h n tt. -Tri ti,in tr ca LDR tng cao=>p chn B Q1 tng ln=>Q1 dn=>p chn C Q1 st=>p chn B Q2 st theo=>Q2 dn,c dng qua cun dy Role lm ng tip im K,n sng. -Trng hp LDR gp ngun sng bt thng nh tia chp chng hn,lc in tr ca LDR st xung t ngt nhng c t C1 np sn 1 in tch lc ny s x qua R2,tip gip BE Q1 xung mass gi cho p chn B Q1 khng b t ngt tt xung theo m bo Q1 vn dn trong khong gn chc giy.Vi ngun sng tc ng thi gian ngn nh tia chp th khong thi gian n vn c chiu sng lin tc. -Do c C2 chng rung nn mc d p chn B Q2 c thay i tuyn tnh role cng khng b nhp nhy.Thc t role c rung nhng cc k t,cc bn c th hon ton yn tm role vn ng ct dt khot. -Thay i gi tr linh kin mch c th lm vic vi ngun thp hn.

y l relay 5 chn

Chn 1,2 l ngun ( chn no m dng g cng c, v nh l trong mch c relay th mc con diode 4007 nha) cp chn 3 - 4 l thng m chn 3 - 5 l thng ng chn 4 u vo n hay g . cn chn 3 u vi 1 dy ngun cho bng n Sau khi hc bi cm bin (MT 2) mnh v th kim s mch v lm th thnh 1 ci mch cm bin nh sng. S v cng n gin:

Nguyn l da trn s so snh in p ng vo cng v tr ca LM741, khi tri ti, quang tr tng s ohm, p trn ng tr gim n khi nh hn ng vo cng th ng ra = +Vcc, lm Q1 dn v kch relay hot ng. L do phi dng ti 2 con R5 + R6 l v khi bo ha m V_out ca 741 l xp x 2 V(ci ny vn ch gii thch c, mai ln hi thy Hng), VR iu chnh nhy ca quang tr, R4 hi tip dng, diode D1 c tc dng dp tt dng in ngc do

cun coil trong relay gy ra.

My linh kin ny ra Nht To u c ht ch tr khng c con BC109, thay con ny bng C1815 vn chy tt.