1. Cai Ban cn cotrc tin trn ban th la hp ngun DC. co th cho chay th cac kiu mach in ma Ban a rap trn ban th, vic trc tin la Ban phai cp ngun nui thich hp cho mach. Do o, mach in d rap u tinma chung ta se noi n lahp ngun DC.(1) Mach ngun n ap dung transistor.Trn ban th cua Ban lun phai co hp ngun DC, nu thich Ban co th t rap mach ngun DC theo s mach in trn. nga vao, Ban co bin ap T1, cng dung cua bin ap nay la giam ap AC va tao tinh cach ly board mach vi ng ngun AC, nh vy gi an toan cho ngi s dung. Cu chi F1 dung ngt dong khi trong machbi qua dong. in ap 12V ly ra trn cun th cp cho qua cu 4 diode D1...D4 nn dong toan ky, dong in xoay chiu dang Sin c i ra dong in mt pha dang xung. Dong nay cho nap vao mt tu hoa ln C1, cng dung cua tu la lam giam dn song, nng cao mc ngun DC va n inh dong in cp cho tai. Chung ta dung Led o D5 lam Led chi thi va ly mc ap 2V trn Leddung lam mc ap mu cp cho cu o. in tr R1 co cng dung han dong. Transistor Q1, Q2 la 2 transistor ghep dang phc hp co cng sut u ln va co nhy u cao. Q3 la transistor khuch ai tin hiu cua cu o. Cu o dung theo doi mc ap bin ng trn tai, cu o gm co in tr R3, chit ap R5, va R4, y la cu chia volt ly mt phn mc volt trn tai cp cho chn B cua Q3, trong khi o chn E cua Q3 cho ly mc ap mu khng i. Tu hoa C2 tao n ap nga ra va trn nga ra chung ta dung Led xanh D6 vi in tr inh dong R6 bao co ngun ra.Nguyn ly n ap cua mach nh sau:* Khi tai nng, mc ap trn tai co chiu hng giam xung, iu nay se lam cho mc ap trn chn B cua Q3 giam theo, trong khi o mc ap trn chn E khng thay i, vy transistor Q3 se dn yu, mc volt trn chn C cua Q3 se tng ln, vy mc ap trn chn B cua Q2 bi y ln, iu nay se khng cho mc ap trn tai giam xung, chung ta bit mc ap trn tai cung la mc ap trn chn E cua Q1, mc ap nay lun tng giam theo mc ap cua chn B cua Q2.* Ly lun ngc lai, khi tai nhe, mc ap trn tai co chiu hng tng cao, iu nay lam tng mc ap trn chn B cua Q3, transistor Q3 se dn in manh hn, mc ap trn chn C cua Q3 se giam xung, no keo mc ap trn chn B cua Q2 xung va nh vy se khng cho mc ap trn tai tng ln.Khi Ban chinh chit ap R5, Ban a lam thay i mc volt trn chn B cua Q3, nh vy se lam thay i mc volt trn chn C cua Q3 hay thay i mc volt trn chn B cua Q2, va iu nay se lam thay i mc ap trn chn E cua Q1,va a lam thay i mc ap DC trn nga ra. Trong vn hanh, khng transistor Q1 qua nong, Ban nn gn Q1 trn ming nhm lam ngui.

(2) Ngun 5V co mc n inh tt vi ic 7805 rt thng dung vi cac mach s.Chung ta bit trn thi trng lun co ban cac ic n ap 3 chn ho 78xx, ho 79xx. Vy nu mun co mc ap DC nga ra n inh, Ban tim va dung cac ic n ap nay. Vi ic n ap 7805, mc ap ra la 5V, vi ic n ap 7809, mc ap ra se la 9V, vi ic n ap 7812, mc ap ra se la 12V...IC n ap ho 79xx dung tao n ap trn ng ngun volt m.Trong mach, chung ta dung tu hoa ln C1 tao n ap trn ng ngun DC, y la dang n ap thu ng, chung ta dung ic n ap 7805 co mc ap ra 5V co n inh rt tt, y la dang n ap tich cc. Khi dung ic n ap ho 78xx, ho 79xx, trn nga ra Ban nh gn thmtu hoa dung tranh hin tng phat sinh dao ng t kich, khi mach n ap trong ic bi dao ng, Ban se thy mc ap DC trn nga ra chp chn luc ln luc xung. Trng hp ng ngun 5Vnay dung cp in cho cac mach in lam vic vung tn s cao, luc o Ban phai gn thm tu nho C3, cng dung cua cac tu nho la loc bo cac tin hiu tn s cao rt tt, trong khi o do cu truc bn trong cua cac tu hoa lnco tim n tinh ng dy, cun camnn khng loc tt cac dong in tin hiu tn s cao nhim trn ng ngun. Trong mach chung ta cung dung Led o, Led xanh lam Led chi thi

(3) Co th rap ngun co tinh n ap va mc ap ra chinh c vi ic LM317.Khac vi ic n ap ho 78xx, ic n ap LM317 co chn Adjusment, iu nay tao ra tinh iu chinh mc ap nga ra. Trong mach, C1 la tu hoa ln dung n inh mc ap s khi, k o dung mach n ap tich cc vi ic LM317. IC nay co 3 chn, chn 2 cho ly ngun DC trn tu C1, Chn 3 la nga ra, trn nga ra lp cu chia ap vi in tr R2 va bin tr R5, mc ap ly ra cho iu chinh mc ap trn chn 1 inh mc ap nga ra. C2 la tu gi cho mach n ap khng phat sinh dao ng t kich. Dung cac led chi thi theo doi hoat ng cua mach ngun. Chung ta co h thc cho thy mc ap ra phu thuc vao tri cac in tr R2, R5.Ban dung t liu sau hiu ro hn v cach dung ic LM317

Khi trong mach co dung cac tu hoa, bao v ic LM317, Ban tao ng xa in cho cac tu hoa khi ngt ngun. Khng dong xa cua tu qua icLM317. Trong mach khi ngt ngun, tu C1 se xadong qua D1 va tu C2 se xa dong qua tu C2. Cng thc tinh in ap nga ra cho thy, khi R2 = 0 ohm, luc o mc ap nga ra se la 1.2V.

2. Mun th machcn co ngun tin hiu dung kich thich mach.(1) Mach phat xung vi ic Timer 555Khi hoan thanh mt mach in, nhiu khi Ban cn co ngun tin hiu a vao th mach. Nu Ban cn co ngun tin hiu dang xung, Ban co th dung ic 555 tao ra cac dang tin hiu nay. Trong mach:* Mach inh tn s cua xung phu thuc vao tri cac in tr RV1, R1, R2va cac tu C1, C2. Vy khi Ban dung tu nho C2, Ban se tao ra tin hiu dang xung co tn s cao, luc nay bin tr RV1 dung chinh chon tn. Khi Ban i qua dung tu hoa C1 co tri in dung ln hn, Ban se tao ra xung co tn s thp hn, va cung chinh tn vi bin tr RV1.* Xung ra ly trn chn s 3. Khi chn 3 mc ap thp, 0V, thi Led xanh D1 sang va khi chn 3 mc ap cao gn bng 12V thi Led o D2 sang. in tr R3, R4 dung han dong lam vic cua cac Led, Ban nh khng dong qua Led qua ln d lam h Led. Xung ra trn chn 3 la dang xung vung vi b ln va b xung rt thng,dung dang xung nay kich thich cac mach s la rt tt.* Xung ly ra trn chn 2 va 6 co dang rng ca, khi chn 7 luc h masse, thi tu C1 hay tu C2 se nap in ngun, dong nap qua RV1, R1, R2, mc ap trn chn 2, 6 tng dn ln, khi mc ap nay bng 2/3 mc ngun thi chn 7 se cho ni masse, luc nay tu C1, hay C2 se cho xa in, dong xa qua R2. Vy cng dung cua R2 la han ch khng dong xa qua ln se lam h ic 555, va khi mc ap trn chn 2, 6 xung bng 1/3 mc ap ngun thi chn 7 lai h masse, tu lai chuyn qua thi ky nap in.... tin hiu ra co dang xung vung vi h s duty = 50%, Ban ly tri R2 u nho so vi tri cua RV1 + R1.Ghi chu: Khi ly xung rng ca trn chn 2, 6 lam tin hiu th mach, Ban phai chu y n anh hng cua mach ngoai ln mach inh tn vi RV1, R1, R2 va cac tu C1, C2,ni tr cua mach ngoaise lam thay i tn s cua tin hiu, cach hay nht la Ban dung thm tng khuch ai m cach ly tr khang cua mach th vi mach inh tn cua ic 555.T liu noi v cac cach dung ic 555 a c ti cprt nhiu trong cac bai vit trc y. Nu mun hiu ro hn v ic 555, Ban hay tim oc lai cac bai vit nay.

(2) Ngun tin hiu nhacvi ic UM66IC UM66 la mt ic phat tin hiu nhac dang xung iu bin rng, hinh dang cua no ging nh transistor 2SC1815, kiu chn TO92. No co 3 chn, chn 3 cho ni masse, chn 2 ni vao ngun khoang 3V va chn 1 cho ra tin hiu xung nhac. Trong mach chungta dung 2 Led o tao ra mc ap khoang 4V, dung mc ap nay ghim c inh mc ap chn B cua transistor Q1, nh vy trn chn E cua Q1, chung ta cokhoang 3.4V va dung thm tu hoa C1 tng mc n ap ng ngun, mc ap nay cp cho chn 2 cua ic UM66. Tin hiu nhac ra trn chn 1cua UM66 cho qua mach khuch ai tng bin vi Q2, chung ta ly tin hiu trnchn C cua Q2 dung lam tin hiu th mach. Khia tin hiu nay vao cac mach in th mach, Ban nn dung tu lin lac, tri in dung khoang 1uF, dung tu lin lac nhm tranh tac dungcua cac mc ap phn cc DC se coth lam sai lchtrang thai phn cc vn co cua cac machin,chung ta bit cac tu lin lac chi bt cu cho tin hiu i qua va khng lam thay i trang thai phn cc DC vn co cua cac mach in.

(3) Mach dao ng tao song Sin dung ng hi tip qua cu 2TChung ta bit, ngi ta chia tin hiu ra lam 2 dang: Dang Sin va dang phi Sin.* Cac tin hiu dang phi Sin, nh cac tin hiu dang xung, vi cac tin hiu nay, cac tinh toan v mc ap khao sat trn cac mach in se ly theo truc thi gian t. Do vy,khi phai tinh toan vi cactu in C, cac cun cam Lcuamach se phai dung n toan cao cp vi-tich-phn, iu nay lam tng tinh phc tap cuacng vic thit k mach.* Khi dung ngun tin hiu dang sin, cac mc ap trn cac mach in khao sat se chi tinh theo truc tn s f. Vy vai tro cua cac tu in C c xem la dung khang XCva vai tro cua cac cun cam L c xem la cam khang XL. y chung ta chi gp cac bai toan s cp dung tinh bin va goc pha cua tin hiu, do o cng vic thit k mach n gian hn rt nhiu. co ngun tin hiu dang Sin, Ban co th rap theo s mach in trn. Mach dung tinh khuch ai cua transistor Q1, tin hiu cho vao chn B va ly ra trn chn C, hai tin hiu nay co tinh ao pha. Chung ta dung mach loc tn dang 2T ly tin hiu hi tip, chung ta bit mach loc tn 2T va co tinh chon tn va va co th ao pha tin hiu tao ra danghi tip thunva nh vy mach se thoa iu kin dao ng, y chung ta hiu mach dao ng la mach t no khuch ai chinh tin hiu cua no, khng cn ly tin hiu t ngoai vao. Trong mach dung bin tr RV1 chongoc pha cho phu hp vi iu kin dao ng. Tin hiu ly ra qua tu C4 a vao cac mach th. Cung nn nhc lai, ni tr cua cac mach th khng anh hng vao iu kin hoat ng cua mach dao ng, Ban nn dung thm tngkhuch ai m. Tng khuch ai m la cac tng khuch ai, tin hiu a vao trn chn B va ly ra trn chn E.Ngi ta thng dung tin hiu dang Sin kim tra va tinh toan iu kin hoat ng cua cac mach in m thanh.3. Noi n in t la noi ntinh khuch ai tin hiu cua cac transistor.Transistor la linh kin thuc nhom tich cc, no co tinh khuch ai,khi noi n tinh khuch ai phai hiu latinh lam chocng sut nga racua mt tin hiuphai ln hncng sut nga vao. Chung ta bit, cng sut cua tin hiu tinh theo cng thc: P = V x I.* Vy cng sut nga vao se la: Pin= Vinx Iin* Va cng sut nga ra se la: Pout= Voutx IoutMach khuch ai se lun phai cho: Pout >> Pin. y chung ta thy co 3 trng hp:Trng hp 1: Pout >> Pinla do: Vout>> Vin va Iout >> Iin. y la kiu khuch ai va cho li in ap va cho li dong in. Vi transistor, kiu mach khuch ai ma tin hiu cho vao chn B ly ra trn chn C se thuc trng hp nay.Trng hp 2: Pout>> Pinla do: Vout >> VinvaIout gn bng Iin. y la kiu khuch ai co li in ap, khng co li v dong in. Vi transistor, kiu mach khuch ai ma tin hiu cho vao chn E va ly tin hiu ra trn chn C thuc trng hp nay.Trng hp 3: Pout>>Pinla do:Voutgn bng Vin, trong khi Iout >> Iin. y la kiu khuch ai co li v dong khng co li v in ap. Vi transistor, kiu mach khuch ai ma tin hiu cho vao chn B va ly tin hiu ra trn chn E thuc trng hp nay.Ban co th hoi lam sao bit c mach khuch ai dung transistor lam vic theo kiu chn nao chung. Ban c nhin tin hiu vao va tin hiu ra la se bit chn con lai c dung lam chn chung. Va hn na chn chung thng co dung tu in cho ni masse.* Nu tin hiu cho vao chn B va ly ra trn chn C, chung ta co kiu khuch ai E chung.Kiu khuch ai E chung, cho li cng sut rt tt. No co li in ap va ca li dong in. Tin hiu nga vao va nga ra ao pha. Tr khang nga vao trung binh, tr khang nga ra ln. Kiu khuch ai c dung rt ph bin.* Nu tin hiu cho vao chnB va ly ra trn chn E, chung ta co kiu khuch aiC chung.Kiu khuch aiC chung, con quen goi la tng m, cho li cng sut tt. No co li dong in, khng co li in ap. Tin hiu nga vao va nga ra cung pha. Tr khang nga vao rtln nn it gy nng tai ln cac ngun tin hiu, tr khang nga ra nho nn co kha nng mang tai ln.Quan h nga vao nga ra khng co tinh cach ly.* Nu tin hiu cho vao chnE va ly ra trn chn C, chung ta co kiu khuch aiB chung.Kiu khuch aiB chung,cho li cng sut tt. No cho liin ap, khng co li dong in. Tin hiu nga vao va nga ra cung pha. Tr khang nga vao rt nho va tr khang nga ra ln. Kiu khuch ai nay co tn s lam vic rt cao, no thng dung lam mach dao ng, vi ng hi tip thun, cho ly tin hiu trn chn Cqua tu in tra v chn E.

(1) Khuch ai dung cho ng noi dang in dung.ng noi dung chuyn i song m thanh ra dang tin hiu in, ng noi dang in dung trong o co mt transistor FET, trn chn cng (chn Gate), ngi ta t man rung tinh in trng, quen goi la man in chm, khi song m thanh lam rung man tinh in, no se lam thay i rng cua knh dn dong nm bn trong transistor FET va tao ra tin hiu xut hin trn mt in tr t trn chn dn (chn Drain).Trong mach: X1 la microphone, la ng noi dang in dung, no c phn cc vi chn vo cho ni masse va chn con lai qua in tr R5 ni ln ngun dng. Khi Ban noi vao micro, man tinh in bi lam rung, no se lam "co gian" knh dn in trong transistor FET, dong chay ra trn chn Drain qua in tr R5 v ngun, luc nay trn chn Drain se xut hin tin hiu m thanh.Mach khuch ai dung transistor Q1, vi R2 la in tr inh mc ap cho chn C va in tr R1 dung cp phn cc cho chnB va in tr R3 dung ly tin hiu cho chn E tao tac dung hi tip nghich. mach lam vic trong vung khuch ai, mc ap trn chn B phai cao hn chn E khoang 0.6V (mi ni BE phai cho phn cc thun)va mc ap chn C cao hn mc ap chn B (mi ni CB phai cho phn cc nghich), thng mc ap trn chn C ly khoang 1/2 mc ap cua ngun nui. Dong lam vic cua transistor ly khoang 0.5mA la u. Trong mach nay, tin hiu m thanh phat ra t ng noi in dung cho qua tu lin lac1uF a vao chn B va sau khi c khuch ai tin hiu ly ra trn chn C va cho qua tu lin lac 10uF cp cho tai R6. Trn ng ngun t thm mach loc ngun vi in tr R4 va tu C1.

(2) Khuch ai dung cho ng noi dang in ngMicrophone inng gm co mt cundyrt nhe gn trn manrun va t bn trong la mt nam chm vinh cu kha manh. Khi Ban noi vao micro in ng, man rung se lam cho cun dychuyn ng vao ra trn mt nam chm, va theo inh lutFaraday, trn hai u cua cun dy se xut hin in ap tin hiu.Vy micro in ngtao ra tin hiu m thanh bng s rung cua mt cun dy t gn mtnam chm vinh ca. Tinhiu nay con rt nho (nho hn loai micro in dung), nn cn khuch ai.Trong mach: Q1 la transistor khuch ai cho lam vic theokiuly chn B lam chn chung, Ban thy chn B cho ni masse quatu C4. Kiu khuch ainay co cac c im sau:* Trkhang nga vao trn chn E nho, nn rt phu hp vi loai micro in ng, d tao c sphi hp ung tr khang, nh vy cng sut tin hiu ly vao se cc ai. Tr khang nga ra ln, nn cho li in ap cao.* Mach khuch ai ly chn B lam chn chung cho li in ap, khng cho li dong in. in ap tin hiu ly ra trn chn C ln hn in ap tin hiu a vao chnE, nhng dong nga vaola IEthi gn bng dong nga ra ICnn khng co li v dong in.* Mach khuch aikhng ao pha.Khitin hiu lam in ap chnE tng thi in ap tng ng trn chnC cung tng va ngclai, khi in ap trn chn E giam thi in ap trn chn C cung giam theo.Trong mach: R2, R3 va tu C4 cp mc volt phn cc cho chn B. in tr R1 dung inh mc dong lam vic IEcho transistor. in tr R4 dung inh mc ap phn cc cho chn C. Tin hiu qua tu lin lac C5 a vao chn E va tin hiu ly ra trn chn C qua tu lin lac C6 a n chit ap RV1. T y tin hiu se cho qua tng khuch ai tng bin vi Q2, va tng khuch ai m vi Q3.Ghi chu: Do tr khang nga vao trn chn E rt nho, nn tri cua tu lin lac trn chn nay, tu C5,Ban phai ly ln tranh lam mt cac tin hiu vung tn s thp.Transistor Q2latng khuch ai ly chn E lam chn chung, nn tin hiu cho vao chn B va tin hiu ly ra trn chn C. Trong mach: R5 la in tr inh mc ap trn chn C, R6 la in tr inh mc dong lam vic chay vao trn chn E va R8 la in tr cp mc ap phn cc cho chn B. Q3 la tng khuch ai m vi tin hiu vao trn chn B va ly ra trn chn E. Kiu mach khuchai nay ly chn C lam chn chung, chn C cho ni vao ng ngun DC, mach khuch ai C chung co cac c im sau:* Mach cho li dong in, dong tin hiu nga ra IEln hn dong tin hiu nga vao IB, khng cho li in ap, in ap tin hiu nga ra VEgn bng in ap tin hiu nga vao VB.* Tr khang nga vao rt ln, tr khang nga ra nho nn kha nng mang tai cua no tt hn.* Mach khuch ai khng co tinh ao pha. in ap tin hiu vao trn chn B tng thi in ap tin hiu ra trn chn E cung tng theo, va ngc lai tin hiu vao giam thi tin hiu nga ra cung giam theo.Ngi ta ly tin hiu ra trn chn E cua Q3 trn in tr R7, cho qua tu lin lac C9 tip tuc i vao cac tng khuch ai chon tn hay khuch ai cng sut. Trn ng ngun cung t mach loc vi in tr R9 va tu C8.

(3) Tin khuch ai, dung khuch ai cac tin hiu nho.Kiu mach khuch ai nay hin rt thng dung, mach dung 2 transistor lin lac thng. Khi Ban phn tich mt mach khuch ai, trc ht hay xet n iu kin phn cc tinh. cac transistor lam vic trong vung khuch ai, mi ni BE phai cho phn cc thun va mi ni CB phai cho phn cc nghich, luc o donghat tai in phun ra t chn E se chay gn ht vao chn C va chy ra trn chn C, va luc nay, chung ta se dung mc volt bin i trn chn B lam tng giam dong in nay. Trong mach: R1 la in tr inh mc ap trn chn C cua Q1, va R2 la in tr inh mc dong chay vao chn E cua Q1. R5 la in tr cp mc ap phn cc cho chn B cua Q1. R3 la in tr inh mc ap trn chn C cua Q2 va R4 la in tr inh mc dong chay vao chn E cua Q2. Khi kim tra mc ap DC trn mach, chung ta thy Q1, Q2 ac cho phn cc lam victrong vung khuch ai. Tin hiu cho qua tu lin lac C1vao chn B cua Q1, sau khi c khuch ai, tin hiu ly ra trn chn C cua Q2 qua tu lin lac C2 n tai. Trong mach dung tu C3 lam tng li cua Q2. tranh hin tng dao ng boating, chung ta t mach loc R6, C4 trn ng ngun. Do 2 tng khuch ai rap theo kiuE chung, nn mach nay cho li rt ln, nh vy chung ta co th dung ng hi tip nghich cai thin cht lng cua machkhuch ai.

(4) Khuch ai m sc, con goi la khuch ai chinh Bass - Treble.Tin hiu m thanh tai ngi nghe c nm trong day tn st 20Hz n 20000Hz. Ngi ta chia day tn nay ra lam 3 oan:* oan t20Hz n 400Hz goi la m trm, hayBass*oan t400Hzn 3000Hz goi la m trung, hayMedium* oan t 3000Hz n 20000Hz goi la m bng,hayTrebleKhi nghe nhac hay khi nghe li thoai, co ngi thich nghe m trm, lai co ngi thich nghe m bng, mi ngi mi y, do vy ngi ta rap mach khuch ai co chc nngiu chinh bin cua cac tin hiu m thanh theo tn s. Mach ph bin nht la dung mach loc Baxandal dung iu chinh bin tin hiu m thanh vung tn s thp, goi la nutchinh Bassva iu chinh tin hiu vung tn s cao, goi lanut chinh Treble. S mach in nh hinh sau:Trong mach: Q1la tng khuch ai tng bin, rap theo kiu chn E chung, Q1 c phn cc vi in tr R2 dung inh mc ap cho chn C, in tr R1 cp mc ap phn cc cho chn B vain tr inh donh R3,con dung ly tin hiu trn chn E tao tac dung hi tip nghich nhmn inh mach khuch ai. Tin hiu a vao chn B qua tu lin lac C1 vacho ly ra trn chn C qua tu C2 vao mach loc, tai y ngi ta t mach loc tn Baxandal. Mach loc gm 2 nhanh:* Nhanh loc ly tin hiu co tn s cao,gm tu C4, RV1 va tu C5. Cac tin hiu co tn s cao d qua nhanh nay, cac tin hiu tn s thp bi "chn lai".Nh vy chung ta dung chit ap RV1chi chon bin cho cac tin hiu co tn s cao,RV1 thng goi la nut chinh ting bng.* Nhanh loc ly tin hiu tn s thp,gm R10, RV2, R11 va cac tu C6, C7.Mach cho thy chi co cac tin hiu tn s thp cho qua chit ap RV2, cac tin hiutn s cao u cho"i tt ngang qua"chit ap nay. Trong nhanhnay, chung ta dung chit ap RV2 chi chonbin cho cac tin hiu co tn s thp,RV2 thng goi la nut chinh ting trm. in tr R12 tao phn cach gia cac nhanh loc tn.

Sau khi ra khoi 2 nhanh loc tn, mt cho tn s cao va mt cho tn s thp, thanh phn tin hiu m trm va m bng c cho "cng lai" va cho qua tu lin lac C8 a vao chn B cua tng khuch ai vi Q2. Transistor Q2 c phn cc vi in tr R5 inh mc aptrn chn C, in tr R4 cp ap phn cc cho chn B, va in tr R6 tao tac ng hi tip nghich trn chn E. Sau cung tin hiu ly ra trn chn C cua Q2 cho qua tu lin lac C3 n tai, hay i tip vao cac tng khuch ai khac.

tranh "anh hng qua lai gia cac tng do cung dung chung ng ngun", trn ng ngun DC chung ta t mach loc ngun vi in tr R7 va tu C9. Mach loc nay se loc sach cac tin hiu cua cac tng nhim vao ng ngun, tranh c hin tng dao ng ngoai y mun.(5) Khuch ai cng sut m tn, cp tin hiu bin ln cho tai. tin hiu co cng sut u ln dung cp cho cac loai tai nhcac loa trong ng nghe hayloa inng, ngi ta lp rap cac mach khuch ai cng sut lam vic vitin hiu bin ln. Sau y la vai mach thngdung, d rap, c hi rap thanh cng cao.(a)Khuch ai nga ra dung cho ng nghe co cng sut tin hiu u ln cp cho cac loa nho t trong cac ngnghe, chung taco th rap mach theo s trn. Trong mach: Q1 la transistor pnp rap theo kiu chn E chung, tin hiu m thanh t ngoai qua tu lin lac C1 va in tr giam bin R9 a vao chn B cua Q1 va ly ra trn chn C a thng vao chn B cua Q3, y transistor Q2 dung nh mt ngun cp dong hng,no cp dong phn cc u ln cho Q3 nhng lai co trkhang AC rt ln, nn khng gy tn tht tin hiu trn chn C cua Q3. Sau cung tin hiu qua tulin lac C4 ncac loa nho t trong ng nghe.Mach c phncc nh sau: Cac in tr R1, R2, R3 cp ap phn cc cho chn B cua Q1. R6 la in tr inhmc dong lam vic choQ1. Tu C3, va in tr R3 dung lam mach hi tip t c nhm tng tr khang nga vaocho Q1. Cac diode D1, D2 va in tr inh dong R7 dung tao ra mc in ap cinh gi cho mc ap trn chn B cua Q2 khng thay i va dung Q2 lam ngun cp dong hng vi R8 la in tr inh mc dong hng. Q3 la tng khuch ai nga ra,ly thng tin hiu trn chn C cua Q1, y in trR4 dung tng h s ninh nhit cho Q3. Tu C4 la tu nga ra, vi R10 la in tr dung n inh hoat ng cua tu C4, tranh cho mt chn cua tu C4 khng bo trng khi mach khng cm ng nghe. tranh anh hng qua lai gia cac tng khuch ai do dung ng ngun chung, chung ta cung t mach loc nhiu R5, C2 trn ng ngun DC.

(b)Khuch ai nga ra dung cho LoaCo rt nhiu kin mach khuch ai cng sut m tn. Sau y chungta th rap mt kiu mach Ampli rt ph dung.Mach c rap vi 6 transistor, cng dung cua mi transistor nh sau:* Q1 latransistor pnp, dung lamtng khuch ai nga vao. Ngi ta dung2 in tr R1, R2ly ap cp cho chn B phn cc, chn E inh dong lam vic vi in tr R5, loc ngun dung in tr R4 va tu C2. Tin hiu cho qua tu lin lac C1 vao chn B cua Q1, tin hiu ly ra trn chn C cho ghep thng vao tng khuch ai thuc Q2. Trn chn E t tu C3 va in tr R11 dung ly tin hiu hi tip nghich nhm inh li toan phn cua mach tng m.* Q2 la transistor npn,dung lamtng thuc, no c thit k cho lam vic theo dang cng sut nho hang A. Tin hiu cho vao chn B, chn E cho ni masse ly dong. Trn chn C t 2 diode 1N4148 ly ra mc ap DC cp phn cccho cac tng keo y, tranh tac dung cua rao ap,nhm sa meo tai giao im tin hiu. R6, R7 la 2 in tr inh mc dong lam vic cho Q2, mc ap phn cc trn chn C cua Q2 ly khoang na mc ap ngun nui. Tu C4 ly tin hiu nga ra hi tip t c v tng thuc nhm lam cn bng bin tin hiu trn va di nga ra. Dung tu nho C6 tao hi tip nghich chi i vi cac tin hiu vung tn s cao nhm tranh cho mach khng phat sinh dao ng t kich. Khi mach dao ng t kich vung tn s cao, cac transistor cng sut se bi rt nong va bi h.* Q3, Q4 la 2 transistor h b npn va pnp dung lamtng khuch ai keo y. Cp transistor nay co moi tham s u ging nhau, no chi khac la mt npn va mt kia la pnp. Vi cp transistor h b ngi ta khng cn dung thm machao pha. Khi tin hiu ra trn chn C cua Q2 tng ln, no se lam cho Q3 dn in va luc nayQ4 tt, va ngc lai khi tin hiu ra trn chn C cua Q2 giam xung, no se lam cho Q4 dn in va luc nay Q3 tt.R8 va R9 la 2 in tr co tri s bng nhau va dung lam tng h s n inh nhit cho tng cng sut rap theo kiu phc hp.* Q5, Q6 la 2 transistor npn dung lamtng cng sut. co dong in tin hiu u manh ngi ta dung transistor cng sut Q5 cho ghep phc hp vi Q3 va dung transistor cng sut Q6 cho ghep phc hp vi Q4. Khi Q3 dn, Q5 se dn manh hn va tao iu kin cho tu ra loa C5 nap dong in cua ngun nui, dong nay co th dung keo man loa vao. Khi n Q4 dn, Q6 se dn manh hn va tao iu kin cho tu ra loa C5 xa dong in qua loa, dong nay se y man loa ra. Tu C5 la tu cp dong keo y cho loa, tu ny phai ly tu hoa co tri in dung ln. Ngang loa ngi ta t mach loc zobel n inh tr khang cua loa trong day tn tin hiu m thanh nhm tranh dang meo cng sut.Trong mach nay, co 2 h thc Ban cn nh:* H thc dung inh li toan mach:Trong o: KFla litoan phn. R5 la in tr inh dong trn chn E cua Q1, R11 la in tr ly tin hiu hi tip nghich* H thc dung tinh cng sut ly c trn loa: Trong o: Vccla mc ap ngun nui. RL la tr khang cua loa.(c) Khuch ai cng sut m tn dung mach tich hp IC.Trn phngdin thc dung, khi cn co cac mach tng mcng sut ln, ngay nay ngi ta it dung transistor va cac linh kinphn lp rap mach.Vi sao? Vi trn thi trng hin co v s cac IC cng sut m tn,dung cac ICnay cng vic lp rap mach tng m se rt nhanh, gon nhe. Di y ti gii thiu vai mach in Ban tham khao va lam thc hanh cho quen tay.Mach rap vi mt ic tng m nho,co kich c nh ic 555, nhng trong ic co 2 mach tng m oc lp co th rap dang mach tng mstereo hay rap theo kiu mach mono BTL. Khi rapmtic tng m, Banco thlam theo 3 bc:Bc1: Tim chn cp ngun.Thng co mt chn ni masse, mt chn ni vi ngun dng va thng khi con co mt chn dung mc tu loc cho tng ngun tin khuch ai.Bc 2: Tim chn nga vao vanga ra. Trn chn nga vao Ban dung chit ap iu chinh mc tinhiu. Co nhiu IC nga vao phai dung tu lin lac bao toan mc volt phn cc DC, co IC cho ni thng, vi mc ap phn cc nga acho mc0V.Tim chn nga ra, nga ra thngco mc ap phn cc cho bng na mc ap ngun nui. Tin hiu cp cho Loa thng qua mt tu in hoa hoc ln.Bc 3: Chu y n cac mach hi tip,cac mach in phu khac, thng co cacmach sau:* Mach hi tip nghich, tin hiu nga ra tra tr lai nga vao ao. Tri in tr ly tin hiu hi tip nghich cung dung inh li cho toan mach.* Mach hi tip t c. Dung tu hi tip t c ly tinhiu nga ra tra v tng thuc co th lam cn bng bin tin hiu ln xung nga ra.*Dung tu tri nho hitip bu pha hay hi tipnghich gi chomach khng t phat sinh dao ng t kich.* Dung mach loc zobel n inh tr khang cua loa tranh hin tng meo cng sut do tr khang cua loa thay i theo tn s.Trong mach:* C1 la tu lin lac nga vao, RV1 la chit ap dung lam nut chinh mc m lng, tin hiu a vao chn 4 cho knh 1 va chn 6 cho knh 2.* Tin hiu ra trnchn 1 cho knh 1 va chn 3 cho knh 2, tai y tin hiu choqua tu ra loa C4 cp dongin keo y lam rungman loa. Tu C5 va in tr R3 dung lam mach loc zobel n inh tr khang cua loa nhm tranh hin tng sai cng sut. Mc ap phn cc trn cac chn nga ra phai bng 1/2 mc ap ngun nui Vcc.* Ngi ta dung cuchia volt vi in tr R2 va R3 ly mt phn tin hiu nga raqua tu lin lac C2 cho hi tipnghich v chn s 8 cho knh 1 va chn s 5 cho knh 2. ng hi tip nghich co tac dung cai thin cht lng cua tin hiu m thanh.* IC lam vicvi chn s 4 ni masse va chn s 8 noi vao ngun nui Vcc. IC co th lam vic vi mc ngun nui t 3V n 12V.

Trong mach: Chit ap R1 dung lam nut chinh Volume, C1 la tu lin lac nga vao, tin hiua vao IC qua chn s 1. Tin hiu cho ra trn chns 4 qua tu hoa ln C3 cp dong in keo y lam rung man loa.Ngang loa dung mach loc zobel tranh hin tng meo cng sut do tr khang cua loa thay i theo tn s. Dung cu chia volt R2, R3 ly mt phn tin hiu ngara qua tu lin lac C2 cho hi tip nghich v chn s 2 cai thin cht lng cua m thanh. IC lam vic vi chn s 3 cho ni masse va chn s 5 ni vaong ngun Vcc. IC coth lam vic vi mcngun thay i t6V n 18V, chung tabit cp mc ngun nui cang cao cng sut ly ra cang ln.Chu y: Khi kim tra mach,o mc ap phn cctrn chn s 4 cua IC phai co mcap trung im, nghia labng na mc ap cua ngun nui. Tri cua in tr R3 dung inh mc hi tip nghich, ly tri R3 cang nho, mc hi tip nghich cang it, li se ln, cng sut ra lnnhng cht lng m thanh kem hn, khi ly triR3 ln, ngc lai cng sut ra yu hn nhngcht lng m thanh senghe hay hn.

Trn xe hi Ban co th dung ic HA13118 rap mach tngm 2 knh ra 2 loahay kiu mach mono BTL ra 1 loa ly cngsut ra ln khi IC lam vic vimc ngun nui thp.Trong mach: Tin hiu m thanh c ly ra trn nut chinh mc m lng cho qua tu lin lac C10 a vao chn s 3, y gntu nho C11 loc bonhiu tn s cao. Trnnga vao ao cho gn tu loc C1 ly li ln.Tin hiu knh 1 cho ra trn chns 15, trong IC co ng cp tin hiu cho knh 2va tin hiu cho ra cua knh 2 trn chn s 8. Chung ta gn loalytin hiu ra dang BTL trn chn s 15 va chn 8.Tu C5va C6 la cac tu hi tip t c dung cn bng bin keo y nga ra, no ly tin hiu nga ra cho hi tip v chn 14 va chn 10. nga ra cung t cac mach loc zobel vi tu C7, R1 va tu C8, R2, cng dung cua mach loc zobel la n inh tr khangcua loa, tranh hintng meo cng sut do tr khang cua loa thay i theo tn s.IClam vic vichn 12 cho ni masse, chn 13 ni vao ng ngun Vcc, t 8V n 18V. Trn cac chn 2, chn 5 gn tu loc C4 va C3. Trn chn s 4 cua nga vao knh 2 cho ni masse vachn 6 gn tu ni masse C2.Trong mach IC phai cho gn trn ming nhm lam ngui gi cho IC khng qua nong.

S trn cho thy cac dung IC TDA7209 rap mach tng m co cng sut ra 50W. IC nay lam vic vi dangng ngun i xng. congun nui dang i xng, Ban dung bin ap ngun trncun th cp phai co ra dy giadung lam dy masse, k odung cu nn dongvi 4 diode congngun V+ va ng ngun V-. n inh cacmc volt ngun ra, chungta gn cac tu hoa ln dung lam kho cha in va n ap.ICTDA7209 lam vic vi cac chn 7, 13 ni vao ng ngun dng,cac chn 1, 8, 15 cho ni vao ng ngun m va chn s 4 cho ni vao ng masse.Tinhiu qua chit ap chinh bin cho qua tu lin lacC1 va in tr giam bin R1 sa meo ting a vao chn s 3. in tr R2 dung n inh tr khang nga vao va tu nho C2 dung locbo tin hiu nhiu tn s cao. Tin hiu ly ra trn chn s 14 cho cp thng vao loa, chung ta bit khi dungkiu mach tng m chay ngun nui i xng thi trn nga ra khng cn dung tu hoa lam tu xut m. y tu C6 dung ly tin hiu hi tipt c lam cn bng bin tin hiu keo y nga ra.in tr R3, R4 va tu C3 dung ly mt phn tin hiu nga ra cho ng hi tip nghich sa meoting va cai thin cht lng m thanh. IC nay co chn s 10 dung tam lam cm loa va chn s 9 cho IC vao trang thai tt ch. y l nhng mch ng dng tham kho trong thit k mch ngun cho mch nh ngun 5V,12V.., n nh nh, ngun ngun i xng...Mch ngun n nh 12V - 15A

y l dng mch ngun n nh in p u ra vi cng sut ln. S dng IC n p h 78XX v transitor cng sut.. i vi nhng mch ch s dng 78 th cng sut rt b do vy nng cng sut ln ngi ta kt hp vi cc transitor hay cc linh kin khc nng cng sut ca b ngun!Nhim v ca 7812 trong mch dng n nh gi tr in p u ra l 12V c nh. Vi dng u ra ca 7812 l 1ANhim v ca transitor Tip2955 l mt transitor cng sut vi dng Iec ln dng cp dng u ra cho ti. Xem datasheet bit dng Ice l bao nhiu?Nguyn l ca mch : Nhn trn mch chng ta thy c in p u ra lun mc 12V do IC 7812 n p mc in p n nh. Cc transitor TIP2955 lun c m v cp dng ra ti tc l tng thm dng ra ti do 7812 c dng u ra thp.in p nh sau b chnh lu khong Ud = 12*sqrt(2) -1.5V tc l khong Ud = 15VDo cc in tr cng sut R4, R3, R2 nn in p t trn cc in trl Ur = 15V - (12V-0.6V) = 2.4V ( 0.6 l in p st trn transitor v in p ti chn E ca transitor l 12V do 7812 to ra) in p t trn cc con tr R4,R3, R2 khi mch hot ng khong 2.4V nh vy ta phi tnh cng sut hp l dng qua tr nm trong khong cho php nh hnh trn ( Ir = 2.4/R) tc l mt phn cng sut s tiu tn trn in tr. Nn vy 7812 lun n nh in p u ral 12Vv cc TIP2955 mc song song nn kch dng cho u ra t c 15A. Dng u ra bao gm cc dng u ra ca 7812 v dng ra ca 3 con TIP2955Cu ch 15A bo v qu ti v 1A bo v cho 7812M rng ca mch :+Nh i vi mch ny th mun tng cng sut u ra ch cn thay i con TIP2955 ln hn c dng Ice ln.+ Mun n nh in p u ra no ch cn tnh ton gi tr in tr cng sut R2,R3,R4 l c.Ch : i vi mch ny cn ch n ngun cung cp u vo. Bin p h p phi c dng u ra ln hn 15A v in p 12VAC. Chng ta nn chn 20A v cu diode phi l 20A.Cn tn nhit cho TIP2955 v 7812. Khi chy cng sut th cc linh kin ny rt nng.Ngun cung cp in p +- 5V bng +-12VDC dng Lm317 v Lm337

Mch ny c ng dng rt nhiu trong cc b ngun cung cp

Ngun cung cp 20V/15A v 12V/3A

Ngun c hai mc u ra l t 4.5V n 25V vi dng 15A v 1.25V n 25V vi dng 3A

Linh kin:R1-2-3=0.1R 5W C3-5-8-10=100nF 100V MKT IC1-2-3=LM338 [TO-3 case] on HeatsinkR4=100R 0.5W C4=220pF 100V ceramic IC4=LM308R5=150R 0.5W C6-11=47uF 63V IC5=LM350 [TO-220 or TO-3 case] on HeatsinkR6-8=330R 0.5W C7=4700uF 63V J1=3 terminal block computer typeR7-9=4K70.5W C9=10uF 40V J2-3-4-5=2pin Connector 3.96mm step pinR10-13=1K5 0.5W D1-2=Led Red 5mm F1=Fuse 5A slow blockR11-12=220R 0.5W D3=1N4007 T1=230Vac/22Vac 600VA transformerTR1=1K5 trimmer BR1=Bridge Rectifier >250V 35A on HeatsinkTR2=4K7 trimmer BR2=Bridge Rectifier >250V 3A C-2=10000uF 63V Q1=2N2905Ngun cung cp 13.8V 5A dng LM338Linh kin :R1=270R 1/4W 2% C4-5=10uF 25V T1=220Vac/15VAC - 8A Mains TransformerTR1=4k7 (Multiturn) D1-2=1N4002 (1A/100V) S1=2 Pole Single Throw Mains SwitchC1=10000uF 40V B1=25A Bridge Rectifier F1=250mA FuseC2-3=100 nF 100V Polyester IC1=LM338

Ngun in cung cp i xng

Mch ny to ngun i xng!Linh kin:R1-2-4=22Kohm C1=100uF 63V C5=220nF 100V MKTR3=1Kohm C2=100nF 100V MKT IC1=L165R5=1ohm 1W C3-4=10uF 40V

Nhng in p ra khc nhau t 12V

Linh kin :R1=6.8Kohms C19-20-21-22-23=220uF 25V IC2=7912C1-4-8-12-18=100nF 100V C13-24-25-29=100nF 100V IC3=7805C2=220uF 25V C28=3.3nF 63V D1....9=1N4001C3-9-=680nF 63V Q1-3=TIP31 BATT=BATTERY 12V >3AhC5-11-26=4.7uF 16V Q2-4=TIP32 L1-2=VK200Ngun cung cp in p ra 50V 3A n nh v iu chnh.

Mch ny c th cho in p ra t 40 n 60 V. nhng c th ln ti 70V.Linh kin:R1=10Kohm R8=1.8Kohm0.5W Q3=BC303 or BC461R2=1 ohm 5W R9=3.3Kohm0.5W D1....4=Bridge 15AR3=3.9 ohms 1W RV1=470 ohms pot. D5=LED RED 5mmR4=6.8Kohm 1W C1-2-4=4700uF 100V D6-7=10V 1W ZenerR5=390 ohms 1W C3-5=100nF 250VMKT D8-9-10=1N4007Ngun cung cp iu chnh c t 0 - 30VDC ,2A

Ngun ny c ng dng rt nhiu trong thc t. V n iu chnh c gii in p u ra.

Linh kin:R1=1.2Kohm C1=4700uF/63V IC1=LM723 V1=0-30V DCR2=680ohm C2=100nF63V MKT Q1=2N3055 TR1=220VAC/ 27V 4AR3=0.33ohm/5W C3=4.7nF63V MKT B1=Brindge 100V 5A S1=2x10A SWR4=15Kohm C4=220uF/63V F1=0.5A Fast Fuse R5=3.9Kohm P1=4K7 LOG. POT. F2=2A Slow Fuse

Ngun iu chnh c in p u ra i xng t 1.25 - 30VDC ,1A

Mch ny tao ra gii in p i xng rng!

Linh kin :R1-2=270ohms C6-10=100uF/63V D1-2=1N4001R3-4=2.2Kohms C7-9=100nF/100V D3-4=1N4001R5-6=10Kohms RV1-2=10Kohms Lin. L1-2=LED 3mmC1-5=100uF/63V RV3=2X10Kohms Lin. F1-2=1A slow Blow FuseC2-4=100nF/100V IC 1=LM 317T S1-2=2X ON-ON SWC3-8=10uF/25V IC 2=LM 337T V1=0-30V DC Voltmeter

Ngun cung cp di in t 0 -15V , 1A

Tng t nh mch trn nhng gii in p l 0 n 15V, 1ALinh kin :R1= 56ohm 2W Q1= 2N3055R2= 330ohm Lin. pot. T1=220V@18V 1.5AC1= 2200uF 35VC2= 100uF 35V D1= 18V 1.5WzenerC3= 10uF 25VC4= 220uF 25V C5= 100nF 100V GR1= 4 X 1N4007B ngun tng in p 5V - 12V dng Lm2577Ta ch cn thay th con Lm2577-xx th c th cho in p ra l gn bng 40V

LM2577-12 (12Vdc output)

- LM2577-15 (15Vdc output)

- LM2577-ADJ (1.23Vdc to 37Vdc output)Ngun cung cp iu chnh c t 0-300V DC

Mch to in p 1 chiu t 0 - 300VDC t in p u vo 300VDC. in p u ra c iu chnh bi bin tr R3.

iu chnh in p ra t 0 - 30V 1A dng LM317T

Mch s dng IC bin i in p LM317 cho in p u ra t 1.25V n 30VDC vi u vo l 24VDC. in p u ra c iu chnh bi bin tr VR1. Mch ny c th dng trong mch ngun c iu chnh gii rng tc l cn nhiu in p u ra khc nhau. Mch c dng u ra kh nh ln nht l 1.5ANgun Tch hp LM317IC n p LM 317 l loi IC c 3 chn cng gn ging nh h n p 78xx hoc 79xx. Tuy nhin, gia chng c nhiu c tnh k thut khc nhau. Chc nng ca cc chn c m t di y:oH IC n p LM317Chn 1:Chn hi tip iu chnh in p ra;Chn 2:in p ra c gi n nh cp cho ti;Chn 3:in p vo cung cp cho mch hot ng.

Nh vy, khc nhau c bn gia 78xx vi LM317 in p ra ca 78xx c xc nh theo mt in p chun ng vi gi tr ca 2 ch s cui xx c ghi ngay pha sau 2 ch s u qui c ca h 78xx v d nh 7805 l n p 5 V hoc 7812 l n p cho ra in p 12V th LM317 c gi mc in p ra c nh thp nht l 1,5V. Mun to ra in p ln hn 1,5V th cn phi lp thm mch hi tip hiu chnh nh c m t cc ng dng di y:Mch ngun c in p ra gi c nh (mch trn y)Mch ngun trn y hot ng theo nguyn l n gin nh sau: Nu R1c gi vi gi tr c nh l 100 v R2cng ln th in p phn hi t ng ra(cp cho ti)thng qua mch phn p c to bi R1R2s cng ln tc l hiu s in p so snh c to bi h thc di y:UError= UOut UR1R2Trong : UOutl in p ra trn ti v UR1R2l in p phn hi c to ra trn R2so vi cc m chung ca ngun cung cp.Nu UErrorc xc nh theo h thc ni trn cng thp th in p ra UOutphi cng ln tng UErrorn mc gii hn xc nh th lc y in p ra mi c gi n nh.Bng tra cc tham s c gii thiu ni trn cho thy rng nu gi nguyn R1m thay i R2th in p ra(Out)s thay i theo mt cch tng ng.Mch ngun iu chnh c in p raMch di y m t mt cch n gin rng thay v thay i gi tr ca R2, hon ton c th gi nguyn gi tr ca R1nhng R2c th thay bng mt bin tr c th iu chnh c in p ra trong khong t 1,5V n 22V(in p vo ti a l 24V xoay chiu c chnh lu thnh dng mt chiu c th bin thin trong khong t 24 n 35VDC).

Ch :Nh m t i vi H IC 78xx hoc 79xx th vi mt IC 78xx hoc 79xx bt k nu to ra mt mch phn p R1R2 phn hi in p ra v chn GND ca IC n p th cng c th lm thay i c in p ra ging nh i vi LM317 hoc LM337.Tuy nhin v H IC 78xx v 79xx c ch to thnh cc loi c gi tr in p ra nh mc theo nhng yu cu c th l 5V, 9V, 12V, 18V v 24V rt thng dng v ph bin nn vic s dng cc IC 78xx hoc 79xx cho cc mch n p c th thay i c in p ra l vic khng cn thit v khng hiu qu.Ngun lng cc m dng gi n nh

c th to ra c mt B ngun hai cc tnh m v dng hon ton c th thc hin c nh hai IC LM 317 v LM337(LM337 v LM317 hot ng i nghch nhau tng t nh 78xx v 79xx)nh hnh bn y:Trong , cc bin tr VR1v VR2c s dng iu chnh c lp cho tng in p ra sao cho c th t c +5V ng ngun ra dng v 5V ng ngun ra m.Mch Ngun Lng cc iu chnh c in p raon ton c th to ra mt mch ngun hai cc tnh m v dng c in p ra iu chnh c bng cch s dng Chit p kp VR1Av VR1Bl loi Chit p ng chnh c th iu chnh c ng thi c VR1Av VR1Bkhi vn nm ca chit p c th thay i ng thi gi tr in p phn hi ca c 2 ng ngun ra th khi c 2 ng ngun ra s cng thay i gi tr in p nh yu cu.

Ch :c hai loi IC LM337 v LM317 u c 3 chn nhng ch c chn phn hi Adj l cng chung chn 1. in p ra ca LM337 l chn 3(trong lc in p ra ca LM317 l chn 2 theo s trn cng ch r th t cc chn ca cc IC tng ng)v ngc li in p vo ca LM337 l chn 2(in p vo ca LM317 l chn 3)ging nhau.Mch ngun Cng sut lnBi v LM317 v LM337 ch c th cho php to ra mt Cng dng in cung cp cho ti ti a l 1,5A nn c th to ra c mt Cng dng in ti ln th cn phi phi hp vi nhiu Transistor vi chn ra ca LM317.Hnh trn y cho thy rng cn phi c mt bin p to mt ng ngun 10VDC nui IC LM317 v mt ng ngun 12VAC wc chnh lu vi kh nng cung c mt Cng dng in rt ln cp cho ti thng qua cc Transistor 2N3055(hoc 2SC2335 hoc 2SC1061 tc l H1061)c mc song song vi nhau tng cng dng ti.

Transitor 2N3904 c s dng to ra cng dng in phn hi mc cho IC LM317 c th so snh c(c th thay Transistor ny bng 2SC458 hoc 2SC828 rt thng dng trn Th trng).Chn B ca cc Transistor Cng sut 2N3055 s c u chung vi nhau v c u vo chn cp in p ra(Chn s 2)ca LM317 to ra in p n nh cho ti thng qua chn E ca cc Transistor cng c ni chung vi nhau nh vy c th to ra Cng dng in cung cp cho ti ln ti 5A hoc ln hn nu lp nhiu Transistor Cng sut song song vi nhau.Phn 1:Trnh by cc kiu mch khuch i m tn kinh in.Hy ni qua v cc mch khuch i lm vic vi tn hiu nhNgi ta a ra 5 kiu mch kinh in dng khuch i tn hiu c bin nh. Cc mch in c s mch nh sau:Kiu 1:Kiu ny rt thng dng tng khuch i ng vo, khuch i trung gian. Mch dng linh kin t, ph hp vi mc ngun nui thp.Mch in hon chnh: Transistor c 3 chn.

Trn chn E thng c in tr nh mc dng lm vic cho transistor v n cng cn dng ly tn hiu hi tip nghch sa mo (khi ngang in tr khng gn t lc ha hc).Trn chn C c in tr nh mc p phn cc cho chn C (gi l in tr ly p) v n cng dng ly tn hiu ra trn chn C. Tn hiu ny qua t lin lc ng ra n ti hay vo cc tng khuch i tip theo.Trn chn B c in tr cp p phn cc cho chn B, n dng dn dng IB chy v ngun (dng IB rt nh nn cc in tr trn chn B thng c tr ln). Trn chn B c t lin lc dng ly tn hiu t ngun a vo mch khuch i. gii hn dy bin tn lm vic ca mch khuch i (ch gii hn cho lm vic trong vng m tn), ngi ta dng t hi tip nghch, cho ly tn hiu tn cao trn chn C tr v chn B, nn t hi tip trn chn CB c tr thng rt nh.iu kin phn cc DC: Khi thit k mt mch khuch i, bc u tin Bn phi lm l ly c iu kin phn cc DC ng cho transistor.

S trn cho thy cch phn phi in p phn cc tnh trn cc chn C, B, E ca transistor.Mc p trn chn B thng cao hn chn E khong 0.6V ( l do tnh ghim p ca cc mi ni BE).Mc p trn chn B nn ly thp m rng phm vi lm vic cho mc p ca chn C (nn ly di 1.5V).Mc p trn chn C phi cao hn chn B ( to phn cc nghch cho mi ni CB, nh vy dng phun ra t chn E mi b ht v chy gn ht vo vng C v chy ra trn chn C, ch c mt t rt t chy ra trn chn B). Do tn hiu cho ly ra trn chn C, m tn hiu chnh l s bin i ca mc volt trn chn C, nn chng ta phi sp xp mc volt phn cc trn chn C sao cho hp l.Th no l hp l?* Khng t mc volt phn cc trn chn C qu cao, v khong cch t mc volt phn cc n mc ngun b thu hp ( y mc p chn C khng th ln cao hn mc p ca ngun, khi transistor b ngng dn).* Khng t mc volt phn cc trn chn C qu thp, v khong cch t mc volt phn cc n mc volt chn B s b thu hp ( y mc p trn chn C khng th xung thp hn mc p ca chn B, khi transistor b bo ha)..Vi cc transistor lm vic vi tn hiu nh, Bn khng nn chn dng lm vic IC qu ln.V sao?V dng phn cc chy qua transistor s to ra ting n (nghe dng ting si), ting n ny s lm gim cht lng ca mch khuch i, do vy nhiu khi tng ny ngi ta cn dng cc linh kin Low Noise ( LN ngha l tm cc linh kin khi hot ng khng pht ra ting n ln). Theo ngh, dng lm vic ca transistor tng ny ly trong khong t 300uA n 1.2mA l hp l (chng ta bit dng lm vic ca transistor ly cng ln, li ca mch cng cao).T cc hiu bit trn, Bn thy PSpice tnh ra mc p trn cc ng mch (s c mu nu) v cng dng in chy ra vo trn cc chn linh kin (s c mu ), Bn xem hnh trn, qua cc con s ny chng ta thy mch c phn cc kh hp l. Nh vy chng ta ly ng phn cc DC cho mch khuch i kiu 1.Tm li, khi phn tch mt mch khuch i, Bn lun nhn n theo cc 3 trnh t:Trnh t1: Trc ht l iu kin phn cc DC. Lc ny cc t in trong mch hon ton khng c tc dng, v iu kin DC tt c cc t in u xem nh lm h mch.Trnh t 2: K kho st mch vi ngun tn hiu chun c dng sin, c tn s chun l 1KHz, c bin ty theo ngun tn hiu ng vo. Cc ng ni (microphone) thng cho bin tn hiu trung bnh l 10mV.Trnh t 3: Sau cng l s dng cc ng hi tip nghch hon thin mch khuch i. Hi tip nghch tng tnh n nh cho mch, sa mo, thay i tr khng ng vo ng ra cho ph hp v nht l lm cho mch t ph thuc vo cc linh kin c tham s qu phn tn nh transistor.Trong chuyn mc ny, chng ta s lun trnh by cc mch khuch i theo th t ca 3 trnh t ny.Hy tm hiu tnh khuch i ca mch in kiu 1. Chng ta s a mt tn hiu dng sin chun vo v kho st tn hiu ny khi n i qua cc im ca mch in qua hiu r hn cng vic ca nh thit k mch:

Kiu 2:Kiu khuch i dng cu chia volt vi R1-R2 cp p phn cc cho chn B, nn n nh cao hn kiu 1, cc tham s ca mch ny t ph thuc vo tham s ca transistor. y l s hon chnh.

Trong mch R1-R2 dng lm cu chia volt, ly mt phn in p ca ngun cp cho chn B. y R2 l in tr ly p. Tr R2 khng nn chn qu nh v n gy tn hao tn hiu ng vo.in tr R4 c cng dng nh dng. N nh mc dng chy vo chn E ca transistor. Dng lm vic ca transistor nn ly trong khong t 300uA n 1.2mA. Ngang R4 mc t lc ha C3, n lm mt tn hiu trn R4 b tc dng hi tip nghch gy ra do R4. in tr R5 dng ly tn hiu hi tip nghch, n c tc dng sa mo v tng tr khng ng vo.in tr R3dng nh mc p trn chn C v cng l in tr ly tn hiu ra trn chn C. in tr ny khng nn chn tr qu nh v n lm tn tht tn hiu ng ra.T C1 lm t lin lc ng vo v t C2 lm t lin lc ng ra. Tr s ca cc t lin lc c nh hng n bin tn hiu vng tn s thp. Cc t ny khng nn ly tr qu nh v s lm mt tn hiu vng tn thp. Cng khng nn chn qu ln, v dng r ca cc t ha ln s lm mch mt n nh.S cho thy cch ly phn cc DC cho kiu 2.

Trong mch (Khi ni n phn cc, vai tr ca cc t in xem nh h mch):* R1 (39K), R2 (10K) l cu chia volt, dng ly ra in p VB = 1.78V cp cho chn B.* R4 (1K) dng nh dng, dng lm vic chy vo chn E l IE = 963uA.Dng ny mt phn rt nh chy ra trn chn B (IB = 6.48uA) v phn ln chy ra trn chn C (957,4uA). in tr R5 (100), y l in tr nh t nh hng n tnh nh dng, cng dng ca n l ly tn hiu to hi tip nghch trn chn E, gip cho mch lm vic vi tn hiu ln nhng t mo, lm tng tr khng ng vo.* R3 l in tr nh mc p trn chn C, vi R3 = 4.7K, mc p trn chn C s l 4.5V.Ghi nhn: Vi cch phn cc ny, transistor c cho lm vic trong vng khuch i, by gi Bn a tn hiu vo v kho st mch trng thi ng. Tm li, Bn xem hnh gii thich tm lt nh sau:Vi cc mch tng m, ngi ta thng dng ngun tn hiu dng sin, c tn s 1KHz xc nh cc tham s ca mch. Do vy trong PSpice Bn s chn ngun tn hiu dng sin kho st mch.a tn hiu chn chn B (qua t lin lc C1).Xem tn hiu ng ra trn in tr ti. T kt qu ny Bn s bit c:* Tn hiu ra c b mo khng?* li ca mch l bao nhiu?* Bit c cng sut ca tn hiu tc dng trn ti.* Tnh c tr khng ng vo, ng ra.Kho st vai tr ca in tr hi tip trn chn E.R5 (100) gn trn chn E dng ly ra tn hiu trn chn E v tn hiu ny c tc dng hi tip nghch, hi tip nghch tuy lm gim li nhng n c tnh sa mo v lm tng tr khng ng vo. Bn thy khi chng ta cho ni tt in tr RE, iu kin phn cc DC khng c g thay i ln nhng hnh v ca PSpicecho thy tn hiu ng ra b mo bin, do , khi dng kiu mch khuch i ny Bn nn gn mt in tr nh trn chn E, cht lng ca mch khuch i s c ci thin tt hn rt nhiu.Kho st tc dng ca t lc trn chn E.R4 (1K) l in tr nh dng IE (dng lm vic ca tng ny thng ly trn di 1mA), R4 c tc dng to hi tip nghich rt mnh, ngi ta dng R4 tng tnh n nh nhit cho mch, nhng iu ny khin cho li ca mch rt nh, bin tn hiu ra s rt thp, kh tc dng hi tip nghch AC ca R4, ngang R4 chng ta mc t lc ln, vy nu t ny h mch, tuy mch vn hot ng nhng c li rt nh. Dng PSpice chng ta thy rt r bin tn hiu ng ra gim xung rt thp.Ghi ch:Do vy nhiu th in t, khi mun tng li ampli ln tinghnthng mc t ha vo chn E ca cc tng tin khuch i, lm vy l b tc dng hi tip nghch vi tn hiu trn chn E.Kho mch theo ng cong bin tn thy dy tn lm vic ca mch.PSpice cho chng ta cch kho st mch theo ng cong bin tn v pha tn. Dng cch kho st ny, chng ta s bit c mch khuch i lm vic tt vng tn s no ca tn hiu. Vi ng cong bin tn v pha tn, chng ta s bit c:* Mch khuch i c lm sai pha khng, sai bao nhiu /* Cho bit mt tn s chn th mch cho li l bao nhiu?* Chng ta xc nh c dy tn lm vic ca mch, qua tm cch sa li dng ng cong theo ng yu cu mnh mun. Th d:Vi cc mch tng m, chng ta ch cho mch lm vic tt trong vng tn hiu m thanh l tt, mch lm vic vi cc tn hiu vng tn cao khin cho mch d pht sinh dao ng t kch.Kiu 3:Kiu mch khuch i dng 2 transistor cng loi lin lc thng.Kiu mch khuch i 2 transistor lin lc thng ny hin rt thng dng, v n c nhiu u im, nh:* n nh nhit rt tt.* H s khuch i cao, cho php dng ng hi tip nghch xu.* p ng bin tn tt.* Tr khng ng vo ln, nn t gy nng ti ln ngun tn hiu.Chng ta th tm hiu kiu mch khuch i ny. Trong mch:* Q1 lm tng khuch i 1. Trn chn C c in tr nh p R1 (ly ln 22K). Trn chn E c in tr nh dng R2 (1K). Chn B c cp dng phn cc qua R5 (56K), mc p phn cc ly t chn E ca Q2 nn c tc dng hi tip nghch dng tng n nh nhit. T C1 (10uF) dng ly tn hiu cho chn B.* Q2 l tng khuch i 2. Trn chn C c in tr nh p R3 (3.9K). Trn chn E c in tr nh dng R4 (1K). Ngang R4 mc t lc ln C4 (220uF) b tc dng hi tip nghch AC trn chn E nhm tng cao li. Tn hiu ra ly trn chn C (vi R3), qua t lin lc C3 (10uF) cp cho ti l R6 (20K). Ngi ta dng t hi tip nghch AC C5 (5.6pF) nn bin tn hiu vng tn cao, gi cho mch khng b t kch vng tn cao.Cch ly phn cc DC cho mch khuch i tn hiu nh kiu 3.Dng trnh PSpice ca OrCAD. chng ta xc nh c d dng cc mc p phn cc DC trn cc chn C B E ca transistor v nh c mc dng chy qua cc linh kin, v xc nh c mc dng lm vic IC ca cc transistor.* Khi cp volt phn cc chng ta ch :Mc volt chn Cphi ly cao hn chn B, mi ni CB phn cc nghch, nh vy dng phun ra t chn E (chn pht) s b ht vo vng C v chy ra trn chn C, mc p ny s "nhp nh" chnh l tn hiu xut hin trn chn C. Mc volt phn cc cp cho chn B khng ly qu cao, v n s hn ch bin tn hiu ra (mc volt chn C khng th xung thp hn mc volt chn B, v nh vy transistor vo vng bo ha v mt tnh khuch i). Mi ni BE phi cho phn cc thun, nh vy chn E mi phun dng vo vng B v ri b ht vo vng C, cng do vy tr khng ng vo ca cc transistor nh, thng ch khong trn di 2K.* Khi cp dng lm vic cho cc transistor, Bn ch : Dng lm vic Ic ly nh th li km nhng t n v ngc li dng lm vic Ic ly ln th li ln nhng ting n, do dng chy pht ra, ln. Vi cc tng transistor lm vic vi tn hiu bin nh, dng lm vic thng ly trn di 1mA l hp l.

Kiu 4:Kiu mch khuch i dng 2 transistor khc loi lin lc thng.

y l kiu khuch i dng 2 transistor khc loi, mt npn v mt pnp cho ghp thng. c im ca mch khuch i ny l mch c tc dng hi tip nghch rt mch nn cho li nh, nhng b li tn hiu t b mo, d cho bin tn hiu vo ln. Trong mch:* R1- R2 ly p ngun cp cho chn B ca Q1 to phn cc thun cho mi ni BE, nh vy t chn E phun ra dng v dng ny chy vo vng B ri s b ht qua vng C v chy ra trn chn C, to ra dng lm vic ca transistor.* R4 l in tr dng nh dng lm vic cho Q1, n c tc dng hi tip nghch nn lm tng tr khng ng vo v sa mo.* R3 in tr chia dng, c tc dng tng h s n nh nhit cho Q2. Dng chy ra trn chn C to dng IB cho Q2.* R5 l in tr nh dng cho Q2. Ngang R5 mc t lc C3 kh tc dng hi tip nghch tng li.* R6 l in tr nh p chn C ca Q2.* C1 l t lin lc ng vo, C2 l t lin lc ng ra. R7 l in tr ti.Cch ly phn cc DC cho mch khuch i kiu 4.

Kiu 5:Kiu mch khuch i vi sai dng ngun bm dng hng.u im ca mch khuch i vi sai l c kh nng khng nhiu cng sai rt mnh. Trong mch:* Q1, Q2 rp thnh mch khuch i vi sai. Kiu khuch i ny c 4 dng:(1) Dng tn hiu vo trn 2 chn B, v ly ra trn 2 chn C (dng i xng ton phn).(2) Dng tn hiu vo trn 1 chn B v ly ra trn 2 chn C.(3) Dng tn hiu vo trn 2 chn B v ly ra trn 1 chn C.(4) Dng tn hiu vo trn 1 chn B v ly ra trn 1 chn C.c im ca kiu mch khuch i vi sai l mch ch khuch i cc tn hiu sai pha a vo 2 ng vo, vi cc tn hiu vo cng pha, mc volt bin i trn 2 chn C cng cng pha (cng ln hay cng xung) nn khng to dng in cp cho ti, ngoi ra vi mch bm dng hng (rp vi Q3), tr khng trn chn E chung ca Q1, Q2 rt ln, n to tc dng hi tip nghch rt mnh, cng lm tng kh nng khng nhiu tt hn.* R4, R6 l cc in tr cp phn cc cho chn B ca Q1, Q2, hai in tr ny thng ly tr bng nhau* R1, R2 l cc in tr nh p chn C v cng l in tr dng ly tn hiu ra trn chn C.* D1 l diode zener dng n ghim p v R3 l in tr nh dng lm vic cho D1.* R5 l in tr dng nh mc dng hng cp cho Q1, Q2.* C1, C2, C3 l cc t lin lc.Trong mch ny, chng ta kho st tn hiu vo trn 1 chn B v ly ra trn 1 chn C. Kiu khuch i ny thng c dng lm tng khuch i u ca mch khuch i cng sut ln (rp theo kiu 3, Bn xem phn bn di).

Cch ly phn cc DC cho mch khuch i vi sai.

Bn dng Pspice xc nh cc mc p phn cc v dng lm vic ca cc transistor trong mch, mun thay i cc mc p v dng phn cc, Bn thay i tr cc in tr trong mch. Kt qu phn tch ca Pspice cho thy iu kin phn cc tt. Ngha l mc p chn C phi cao hn chn B mi ni CB phn cc nghch v mc p chn B phi cao hn chn E mi ni BE phn cc thunKho st mch khuch i vi sai vi ngun tn hiu sin, c tn s chun l 1KHz.

Kiu 1: Khuch i cng sut m thanh, tng tin khuch i lin lc qua t (Mch lm vic vi bin tn hiu ln)Trong mch:* Q1 l tng tin khuch i vi R1-R2 l cu chia volt, ly p phn cc cho chn B ca Q1. R4 l in tr nh dng lm vic cho Q1. R5 l in tr ly tn hiu hi tip nghch v R3 l in tr nh p cho chn C. Tn hiu qua t lin lc ng vo C1 vo trn chn B v qua t lin lc ng ra C3 ra trn chn C. C4 l t ha ln dng lc b tn hiu trn R4 lm mt tc dng hi tip nghch gy ra do R4. Tng tin khuch i c cp ngun nui qua in tr gim p R6 v t lc C2.* Q2 l tng thc, n l tng khuch i cng sut nh hng A, nn dng lm vic IC ly khong 10mA. R13 l in tr ly mc p trung im cp phn cc cho chn B ca Q2. R14 l in tr lm tng n nh nhit cho Q2. R7 v R8 dng nh p chn C v cng dng nh dng cho Q2. Cc diode D1, D2, D3 dng ly p phn cc DC cp cho cc transistor tng cng sut sa mo ti giao im ca tn hiu. Tn hiu ly ra trn chn C cp cho tng ko y rp vi Q3, Q4. T C5 to tc dng hi tip t c dng lm cn bng bin ca tn hiu ng ra (bin tn hiu phn ln v phn xung bng nhau ). * Q3, Q4 l 2 transistor h b (h tng b tc cho nhau). Q3 l loi transistor npn v Q4 l loi transistor pnp. Nh vy khi tn hiu ra trn chn C ca Q2 tng ln s lm Q3 dn in th Q4 ngng dn v ngc li, khi tn hiu trn chn C ca Q2 gim xung, th Q4 dn in v Q3 ngng dn. c cng sut ra loa ln, mch dng 2 transistor cng sut (gn trn l nhm gii nhit).* Q5 ghp phc hp vi Q3 v Q6 ghp phc hp vi Q4. Vi cc transistor ghp phc hp thng c n nh nhit km, do ngi ta dng cc in tr R9 v R10 gia tng h s n nh nhit cho Q5, Q6. R11 v R12 l cc in tr nh c cng dng cn bng dng ko y qua loa. C7 l t ra loa, C7 phi ly tr ln v loa vn c tr khng nh. Ngang loa mc mch lc zobel n nh tr khng ca loa trong dy tn tn hiu m thanh.

Cch ly phn cc DC:Vn cp cc mc volt phn cc.Dng PSspice xc nh trng thi phn cc DC ca mch. Vi cc kt qu nh hnh trn, chng ta thy iu kin phn cc ca mch chun xc.Ch : Vi mch khuch i ko y ny, mc p ng ra trung im phi ly bng na mc p ngun. Chng ta bit mc p trung im ph thuc vo mc p trn chn C ca Q2, vy khi iu chnh tr ca in tr R13 cng s lm thay i mc p trung im. Trong mch vi ngui nui l 30V, mc p trung im phi l 15V.

Cch ly phn cc DC: Vn cp cc mc dng phn cc.

Kt qu phn tch cho thy:* Dng lm vic ca Q1 ly khong 1mA.* Dng lm vic ca tng thc ly khong 10mA. trng thi tnh cc transistor tng cng sut ko y c cho phn cc gn nh ngng dn, v tng cng sut cho lm vic hng B mch cho hiu sut cao, khong 78%. Dng ton phn khong 12mA l tt

Kiu 2:Khuch i cng sut m thanh, tng tin khuch i lin lc thng (Mch lm vic vi bin tn hiu ln)Trong mch:* Q1 l tng tin khuch i dng lm tng khuch i ng vo. R1 R2 dng cp dng phn cc cho Q1. R5 l in tr nh dng trn chnE. R4l in tr lm tng n nh nhit cho Q2. tng ny c cp ngun DC vi in tr gim p R3 v t lc ngun C2.* Q2 l tng thc (tng thc cho lm vic theo kiu khuch i cng sut nh hng A), chn B cho ni thng vo chn C ca Q1. Trn chn C c R6 R7 l in tr va nh p chn C v va nh dng IC. D1, D2, D3 dng ly p DC phn cc cho cc transistor tng ko y nhm gim mo gy ra do ro p ( ng vo ca cc transistor, trn chn BE u c ro p khong 0.5V). C4 l t c tr nh dng to hi tip nghch vng tn s cao gi cho mch khng pht sinh dao ng t kch. C3 l t hi tip t c dng lm cn bng bin tn hiu ng ra (gi cho bin tn hiu ln bng vi bin ca tn hiu xung. D nhin Bn c th dng PSpice thy r hn vai tr ca t t c ).* Q3, Q5 v Q4, Q6 l cc transistor ghp phc hp (cn gi l transistor darlington) dng lm tng khuch i cng sut dng ko y. R8 v R9 dng lm tng h s n nh nhit cho cc transistor phc hp. R10, R11 l cc in tr nh dng lm cn bng dng in qua cc transistor cng sut. C5 l t ha c tr ln, dng cp dng in ko y cho loa. Ngang loa dng mch lc zobel n nh tr khng ca loa trong dy tn tn hiu m thanh ( vng tn s cao, tr khng ca loa tng, lc mch lc zobel s lm gim tr khng ca loa, vng tn s thp, tr khng ca loa nh, mch lc zobel s khng c tc dng).Mch lm vic nh sau: Khi tn hiu dng sin qua t lin lc C1 vo chn B ca Q1, tn hiu ny s c khuch i v cho ra trn chn C, n tc dng thng vo chn B ca Q2, tn hiu ra trn chn C ca Q2 s vo thng tng cng sut ko y. Khi bin tn hiu tng n s lm cho Q3, Q5 dn in v lc ny Q4, Q6 trng thi ngng dn, v ngc li, khi bin tn hiu trn chn C ca Q2 gim xung, n s lm cho Q4, Q6 dn in v lc ny th Q3, Q5 trng thi ngng dn. S ln xung ca mc p trung im s qua t C5 to dng xoay chiu lm rung mn loa.Ch : li ca mch ph thuc vo h s hi tip nghch to bi R5 v R13. Tng tr R13, mc hi tip nghch s tng cao v li ca mch s gim v ngc li, nu cho gim tr ca R13, mc hi tip nghch s gim v li ca mch s tng ln. Bn c th kim tra iu ny mt cch d dng khi dng PSpice phn tch mch.

Mch cp mc volt phn cc DC.

Mch cp mc dng phn cc DC.

Kiu 3: Khuch i cng sut vi ng vo dng vi sai, cc tng lin lc thng.

Trong mch:* Q1, Q2 rp thnh mch khuch i vi sai. R1, R5 l in tr cp dng phn cc cho chn B. Chn E chung ca Q1, Q2 c cp dng hng (dng khng i). Tn hiu cho qua t lin lc C1 vo chn B ca Q1 v ly ra trn chn C vo thng chn B ca tng Q4 (Q4 l tng thc).* Q3 rp thnh mch cp dng hng. Chn B cho ghim p vi diode zener D1 v D1 c nh dng vi in tr R4. Cng dng in cp cho Q1, Q2 ly theo tr ca in tr R3.* Q4 l tng thc, n l tng khuch i cng sut nh hng A. Transistor ny c cp dng lm vic bi Q5. Q5 l ngun bm dng hng, chn B cho ghim p vi D1 v chn E nh dng vi R6. Cc diode D2, D3, D4 dng ly p DC (mi diode ly 0.6V) cp cho cc transistor tng khuch i ko y sa mo gy ra do ro p trn cc mi ni BE. T nh C3 dng to tc dng hi tip nghch vng tn s cao gi cho mch khng pht sinh dao ng t kch.* Q6, Q8 v Q7, Q9 l tng cng sut rp theo kiu ko y. Cc transistor ghp theo kiu phc hp cn gi l cc transistor darlington. R7, R8 (phi ly tr bng nhau) l cc in tr lm tng n nh nhit ca cc transistor darlington. D5 l diode lm cn bng tr khng ng vo ca Q7 vi ng vo trn Q6, Q8. in tr R9, R10 dng lm cn bng dng in qua transistor cng sut Q8, Q10. T C4 v R13 lm mch lc zobel gi cho tr khng ca loa khng thay i trong dy tn ca tn hiu m thanh.t im ca kiu mch tng m ny l ng vo dng khuch i vi sai nn c tnh khng nhiu cng sai rt tt, ng ra khng dng t ra loa nn c p ng vng tn s thp rt tt.Ch : li ca mch ty thuc vo t s hi tip nghch to bi R5 v R11. Nu tng tr ca R11, tc dng hi tip nghch s ln, li ca mch s gim v nu gim tr ca R11, tc dng hi tip nghch s nh v li ca mch khuch i s tng.Nhn xt chung, y l kiu mch hin rt thng dng, n c dng v pht trin rp nhiu mch tng m cng sut ln khc. Trong cc phn sau chng ta s cn phn tch k loi mch ny.Cch cp in p phn cc DC cho mch tng m kiu 3.

Dng kt qu phn tch ca PSpice, chng ta thy c cc mc p phn cc trn cc chn ca cc transistor. Khi ly phn cc cho mch ny, iu cn thit nht l mc p ng ra phi bng 0V hay gn bng 0V. Qua cc mc volt cp cho cc chn E, B, C chng ta thy cc transistor tng cng sut c phn cc trng thi gn ngng dn, ngha l tng ko y cho lm vic theo hng B, nh vy hiu sut ca mch mi c nng cao, khong 78%Cch cp dng in phn cc DC cho mch tng m kiu 3.

PSpice cng cho thy dng phn cc ca cc transistor. Vi ngun cp dng hng rp vi Q1, do dng in tr nh dng R3 = 1K, nn mc dng hng s l 1.5mA, dng ny cp cho Q1, Q2.Q4 lm vic vi mc dng l 19.92mA, y l dng hng c cp bi Q5 vi in tr nh dng l R6 (120). Dng ton phn ca mch l 30.79mA. (1)Kho st cc mch lc tn hiu kinh in.Trc ht hy nhc li cc h thc cn nh v 3 linh kin th ng c bn, l: in tr R, cun cm L v t in C.

Trong bng cho thy:* T in c dung khng tnh theo ohm, c sc cn dng t l nghch vi tn s f.* Cun cm c cm khng tnh theo ohm, c sc cn dng t l thun vi tn s f.* in t R c sc cn dng khng ph thuc vo tn s f.Vi cc h thc tnh dung khng ca t C, cm khng ca cun cm L, chng ta c th ni:* Dng in c tn s cng cao cng d qua t in v cng kh qua ng dy.* Dng in c tn s cng thp cng kh qua t in v cng d qua ng dy.Do vy, nu ni cc oan hn m khng sai th:* Vi ngun DC c tn s f=0 th t tc dng nh lm h mch v cun dy tc dng nh ngn mch.* Vi ngun AC c tn s f cao th t in xem nh ngn mch v cun dy xem nh h mch.T cc c tnh ny ca C v L, m ngi ta dng cc t in v cc cun dy trong cc mch lc ly lc b cc tn hiu theo tn s.Tm tt ni dung v transistor1. Gii thiu v BJT2. Mt vi cch phn chia BJT3. S dng BJT vo mc ch khuch i4. Ghp cc transistor li t hiu qu hn5. Mt vi cch dng transistorGii thiu v BJTTransistor co nhiu loai, y chung ta noi n loai transistor 2 mi ni, quen goi la Bi-Junction Transistor, hay BJT. Trong transistor nay co 2 mi ni NP+PN hay PN+NP, hay NPN va PNP. Transistor co 3 chn:* Chn E (Emitter) la chn dung phun ra cac hat mang in. Vi transistor NPN, chn E phun ra dong in t va vi transistor PNP chn E phun ra dong l (dong l la chuyn ng biu kin cua cac hat in t chuyn di trn cac ni trng).* Chn C (Collector) la chn dung thu gm cac hat in phun ra t chn E. Vi transistor NPN, no thu gm cac hat in t va vi transistor PNP no thu gm cac hat l.* Chn B (Base) la chn dung iu khin dong in chay trong transistor, chay t chn E vao chn C.Khi dung transistor lam linh kin khuch ai tin hiu, chung ta cho phn cc thun mi ni B-E va phn cc nghich mi ni B-C. Luc nay tin hiu a vao la mc ap tng giam trn chn B, no se tac ng vao dong chay trong transistor, tin hiu ly ra co th trn chn E hay trn chn C. Hinh ve di y cho thy ky hiu cua transistor, vi loai transistor NPN, mui tn trn chn E chi ra va vi loai PNP mui tn trn chn B chi vao.TransistorMt vi cch phn chia BJTTransistor BJT cung co nhiu chung loai, co nhiu kiu chn. Khi cm mt transistor, chung ta phai bit:* No la transistor cao tn hay m tn.* Transistor khuch ai analog hay transistor ong m digital hay transistor khoa switching* Transistor cng sut nho hay cng sut trung binh hay transistor cng sut ln.* Transistor co li dong ln hay nho.* Transistor co mc ap bao hoa nho hay binh thng...Co th xem mt transistor nh 2 diode (nhng khng th dung 2 diode ghep lai tao ra mt transistor). Do vy khi kim tra mt transistor, chung ta thng dung Ohm k o tinh thut nghich cua 2 diode nay. Chung ta con bit: Diode mi ni BE co tinh chiu ap nghich thp thng khoang di 10V, diode mi ni CB thng co tinh chiu ap nghich cao, thng trn 60V n vai ngan volt.

S dng BJT vo mc ch khuch i:TransistorHinh ve cho thy: Dong in bn chn B rt nho, no co th iu khin dong in rt ln bn chn C, o chinh la tinh khuch ai cua cac transistor. Chung ta a mt tin hiu co cng sut nho vao chn B, chung ta co th nhn c mt tin hiu ln hn, manh hn trn chn C. Do o, chn B goi la nga vao va chn C goi la nga ra. Khi dung mt transistor lam tng khuch ai, chung ta thng thit k theo trinh t sau:Th nht: Phai ly ung phn cc DC. Vi transistor NPN, mc volt trn chn B cao hn E khoang mt diode, mc volt chn C phai cao hn chn B.Th hai: Tim cach a tin hiu vao mach khuch ai va tim cach thu lai tin hiu nga ra. Co cac kiu vao ra nh sau:* Cho tin hiu vao chn B va ly tin hiu ra trn chn C* Cho tin hiu vao chn B va ly tin hiu ra trn chn E* Cho tin hiu vao chn E va ly tin hiu ra trn chn C.Vy chn B lun la nga vao va chn C lun la nga ra, chi co chn E co th luc lam nga vao va luc lam nga ra.Th ba: Dung ky thut hi tip hoan thin mach khuch aiGhp cc transistor li t hiu qu hnChung ta bit, trong ch tao, mt transistor cho li dong ln thi cng sut khng ln, mt transistor cng sut ln thi h s khuch ai dong nho. Vy co cac transistor va co cng sut ln, va co li dong ln, ngi ta dung cach ghep phc hp con goi la cach ghep Darlington.TransistorTransistor phc hp se cho h s khuch ai dong rt ln va co cng sut ln.Mt vi cch dng transistorTransistorHinh ve sau cho thy transistor BJT co th c dung nh mt mt bin tr chinh theo mc ap. Luc nay chn C khng phn cc, chn CE xem nh mt bin tr, tin hiu co th qua lai theo hai chiu, ni tr CE se thay i theo mc ap cao thp trn chn B. Ngi ta thng dung transistor theo kiu nay mach ALC (Automatic Level Control), no co tac dung n inh bin tin hiu luc may mode ghi bng.

Ngi ta thng dung transistor theo kiu, tin hiu tac ng trn chn B va tai t trn chn C.TransistorBn no cn cha r v r le (relay) c th xem li bi vittm hiu v r leMach trn cho thy, ngi ta dung in ap iu khin a vao chn B va ong m dong chay ra trn chn C, dung dong nay kich thich mt relay t trn chn C.* Khi chn B co mc ap cao hn 0.6V, khoang 1V, thi transistor se vao trang thai bao hoa, dong chay ra trn chn C se cp cho cun dy trong relay, relay hut la kim xung va thay i vi tri cua cac tip im la kim.* Khi chn B mt ap, hay 0V thi transistor se vao trang thai ngng dn, luc nay se khng co dong chay ra trn chn C, cun dy trong relay mt dong, tip im la kim bi nha ra, no lai thay i vi tri cua tip im la kim.Do cun dy vn la mt kho cha in nng theo dang dong, nn khi co dong in chay qua cun dy se c nap in nng, va khi cun dy bi ct dong, lng in nng cha trong cun dy se hoan tra lai cho mach, no hoan tra in nng di dang phat ra in ap ng co bin rt cao, mc ap nay co th lam h cac linh kin ban dn trong mach, do o ngang relay, ngi ta phai gn mt diode bao v.TransistorCo th dung quang tr gn trn chn B ong m Led t trn chn C.* Trong hinh bn trai, khi quang tr bi chiu sang, no cho ni tr nho, lam giam mc ap trn chn B, nn transistor vao trang thai tt va khng co dong chay ra trn chn C, nn Led tt. Va khi quang tr bi che sang Led se sang.* Trong hinh bn phai thi ngc lai. Khi quang tr c chiu sang, no se giam ni tr lam tng mc ap trn chn B, transistor dn in, Led sang va khi bi che sang thi Led tt.Trong mach, chit ap 10K dung chinh nhy cua machLm kha in t vi transistor v r le (relay)Bottom of FormTm tt ni dung:Mch lm kha in t vi transistor v r le (relay). Bi vit ny s khng c g kh vi cc bn hiu r v transistor v relay nhng s gip bn hiu hn v 2 linh lin kh ph bin ny v cch kt hp chng vi nhau to nn mt mch rt thc t v ng dng cao.

Mch kha in t transistor v relayNguyn l hot ng:Nu khng c tn hiu vo R1 (chn B ca transistor) th transistor tt, s khng c dng chy qua r le, r le trng thi tt. V cc bn thy trong mch th dng in chnh cn iu khin s khng chy qua c r le.Nu c tn hiu vo R1, transistor dn. Lc ny s c dng chy qua r le , r le hot ng, lm ng tip im thng m ca r le, dng in cn iu khin s chy qua c r le.Diode D1 bo v transistor.V sao phi s dng transistor. Xem li bi vit v r le bn s hiu dng cn cung cp cho r le thng ln hn nhiu tn hiu vo chn B ca transistor. V th ta dng transistor khuch i dng tn hiu nh cung cp cho r le.Mch ny c th s dng ko dng cho nhiu con led (led qung co, LED 7 thanh, LED Matrix...) m bo sng r nt, ng-ct ng tn hiu...*Ch :l s mch trn th transistor s hot ng ch bo ha. iu ny l khng bt buc v bn c th s dng in tr chn C hoc E ca transistor v khng cn transistor phi hot ng ch bo ha ch cn m bo dng ICE cho r le hot ng l c.