Cov txheej txheem:
- Kauj Ruam 1: Hais Nyob Zoo rau LM1875
- Kauj ruam 2: Pinout
- Kauj Ruam 3: Schematic thiab BOM
- Kauj Ruam 4: Tsim Breadboard
- Kauj Ruam 5: Tsis txhob hnov qab lub Heatsink
- Kauj Ruam 6: Xeem Nws
- Kauj Ruam 7: Tus Dab Tooj
Video: Tales From the Chip: LM1875 Audio Amplifier: 8 Kauj Ruam (nrog Duab)
2024 Tus sau: John Day | [email protected]. Kawg hloov kho: 2024-01-30 09:29
Kuv hlub kuv qee qhov nti amps - pob me me ntawm lub zog ntshiab lub suab. Nrog tsuas yog ob peb yam sab nrauv, lub hwj huam huv thiab qee qhov heatsinking hnyav koj tuaj yeem tau txais lub suab zoo tiag tiag uas sib tw nyuaj, txiav txim siab transistor tsim.
Kuv tau mus rau hauv qhov nthuav dav me ntsis txog qhov txiaj ntsig ntawm nti amps hauv kuv LM386 khoom plig - uas yuav yog qhov chaw zoo pib. Ntawm no, Kuv yuav dhia ncaj qha rau yam uas ua rau LM1875 zoo heev thiab yuav tsim txoj kev yooj yim li cas. Caij, Dobbin!
Kauj Ruam 1: Hais Nyob Zoo rau LM1875
LM1875 ("kaum yim-seventy-tsib") yog dab ntawm chip nyob rau hauv pob unassuming heev, thiab lwm qhov ntau-hlub nti hauv DIY suab zej zog. Cov ntaub ntawv raug cai (PDF) thov kom muaj peev xwm tsav 20W rau 8Ω thauj khoom muab rau +-25V, thiab txog li 30W muab nrog ntxiv +-5V kua txiv… thiab tag nrho tsawg dua 1% THD. Thiab tsis tshua muaj raws li nws yuav yog, Kuv tuaj yeem lees paub qhov khav theeb hauv cov ntawv teev tseg yog qhov chaw - cov duab no tuaj yeem mus txog qhov yooj yim heev hauv qhov tseeb (muab qee qhov txias txias).
Kauj ruam 2: Pinout
Lub pob TO-220, nrog tsuas yog 5 tus pin, yog tuag yooj yim rau xaim:
1 - Cov tswv yim tsis zoo (-IN)
2 - Cov tswv yim zoo (+IN)
Txheem op-amp cov tswv yim, nrog cov tswv yim zoo tau txais lub suab thiab tsis zoo tawm tswv yim khi rau hauv av.
3 - Cov Khoom Tsis Zoo (-Vee)
5 - Cov Khoom Zoo (Vcc)
Ntawm no koj pub lub suab nrov, lub hom phiaj nrog cov khoom siv ob. Nws kuj tseem tuaj yeem tsav los ntawm cov khoom siv ib leeg los ntawm khawm tus pin 3 rau hauv av, txawm li cas los xij qhov ua tau zoo yuav raug kev txom nyem.
4 - Tso Tawm
Nov yog qhov koj noj hmo ntawm qee qhov qab zib, ua kom lub suab nrov nrov.
Kauj Ruam 3: Schematic thiab BOM
Nov yog cov txheej txheem yooj yim rau ib qho channel - rau lub tso suab koj yuav xav tau ob qho no.
R1 thiab R2 yog qhov nce cov khoom tiv thaiv txuas nrog kev hloov pauv ntawm lub suab nrov. Qhov tseem ceeb ntawm 22KΩ thiab 1KΩ ua haujlwm kom tau txais txiaj ntsig ntawm 23:
Tau = 1 + (R1 / R2)
= 1 + (22 / 1) = 23
Txhawm rau hloov qhov nce, yooj yim pauv R1 tawm nrog lwm tus tiv thaiv hauv kohm ntau thiab ntsaws nws rau hauv cov mis.
CIC1 rau CIC4 yog lub tshuab txiav txiav tawm rau LM1875. Lub tshuab hluav taws xob me me (100nF) lim tawm lub suab nrov nrov ntawm txoj kev tsheb nqaj hlau, thaum lub hau loj dua (220uF) muab cov peev txheej los ua kom du tawm hauv cov khoom siv hluav taws xob. Hauv kev tsim hluav taws xob, cov kaus mom no yuav tsum tau muab tso kom ze rau ntawm lub hwj chim nkag ntawm tus pin raws li ua tau. Yog xav paub ntxiv, txheeb xyuas qhov tsab xov xwm no kom nkag siab yooj yim los ntawm Analog Devices ntawm cov txheej txheem txiav kom raug.
Ib yam li C1, C2, R2 thiab R3 nyob ntawd los lim cov suab nrov, thaum R5 ua raws li qhov rub tawm qhov ntsuas, tso txoj hauv kev rau hauv av yog tias tsis muaj teeb liab txuas (txo qis).
R6 thiab C3 tsim ib qho RC Circuit, lub lim dej uas tshem tawm xov tooj cua ntau zaus los ntawm kev pub zaub mov rov qab mus rau hauv Circuit Court thiab tiv thaiv kev sib kis ntawm tus neeg hais lus los ntawm rov qab mus rau lub suab nrov.
_
BOM:
Qauv: LM1875
R1: 22kΩ
R2: 1k ua
R3: 1k ua
R4: 1m2 ua
R5: 22 ib
R6: 1Ω, 1W
C1: 10uF electrolytic (lossis nyiam dua, polyester/polypropylene zaj duab xis)
C2: 47uF electrolytic
C3: 220nF X7R / zaj duab xis
CIC1, CIC3: 220uF electrolytic
CIC2, CIC4: 100nF X7R / zaj duab xis
_
Koj yuav xav tau ib txoj hauv kev pub suab hauv - Kuv tau sau 3.5mm nkaus los ntawm lub cuab yeej qub thiab ua qhov tawg uas ntsaws ncaj rau hauv lub khob cij, lossis koj tuaj yeem txiav lub taub hau tawm ntawm 3.5mm lub suab qub, lo qee lub taub hau qhov kawg thiab txuas nws ncaj qha.
Tsis tas li, koj yuav xav tau cov dhia ib txwm, cov xov hlau, tus hais lus/dummy thauj khoom thiab lub zog siv - qhov tsim nyog hloov pauv lub rooj zaum PSU uas tuaj yeem muab +/- 30V yuav muaj txiaj ntsig.
Thaum kawg - lub rhaub dej kub! Feem ntau chav kawm A/B chipamps xav tau qhov txias txias, yog li tau txais lub rhaub dej loj dua li koj xav tias koj xav tau thiab khaws nws ib puag ncig rau lub hom phiaj ua qauv.
Kauj Ruam 4: Tsim Breadboard
Yog li ntawm no yog kuv daim ntawv qhia zaub mov …
… tab sis DISCLAIMER
Qhov no tsis yog qhov kev teeb tsa pom zoo tshaj plaws - qhov zoo tshaj plaws, cov khoom siv yuav tsum tau nyob ze ua ke, thiab lub kaus mom txiav tshwj xeeb yog nyob deb dhau ntawm IC pins. Txawm li cas los xij, kuv nthuav tawm nws kom nkag siab yooj yim dua hauv cov duab, thiab ua rau kuv qhov txawv txav heatsink haum. Cov txiaj ntsig tau zoo rau lub sijhawm sim luv.
Kuv muab ob txoj hlua kab hluav taws xob tso rau ntawm ib sab ntawm daim ntawv qhia zaub mov, yog li kuv tuaj yeem khaws chaw nyob ib puag ncig IC rau lub rhaub dej kub. Qhov no muaj qhov txiaj ntsig ntxiv ntawm kev ua kom muaj kev mob siab rau, qhov tsis zoo thiab cov kab hauv av nkag tau yooj yim raws hauv qab ntawm pawg thawj coj.
Kauj Ruam 5: Tsis txhob hnov qab lub Heatsink
Txhawm rau npaj lub rhaub dej kub, thawj kab nws ntawm lub rooj tsavxwm thiab cim qhov twg lub qhov yuav tsum mus kom ruaj ntseg rau IC. Tom qab ntawd laum lub qhov, thiab xuab zeb tag nrho qhov chaw tiv tauj nrog daim ntawv zoo heev kom txog thaum qhov chaw du thiab ci.
Tom ntej no, siv qhov ntsuas cua sov rau qhov chaw tiv tauj thiab tso lub insulating mica rau saum nrog qee tus tweezers - sim tsis txhob tuav mica nrog koj cov ntiv tes.
Thaum kawg, siv lub hau sab saum toj (lossis "hav txwv yeem"), txiv ntseej thiab ntsia liaj qhov rooj kom ruaj ntseg nti rau lub rhaub dej kub. Nws yuav tsum tsuas yog nruj txaus tias IC tsis tuaj yeem tig ncig lub ntsia liaj qhov rooj, thiab tsis nruj dua!
Thaum kawg, ob zaug tshuaj xyuas tias lub tab ntawm lub nti raug thaiv los ntawm lub rhaub dej kub los ntawm kev ntsuas ntsuas txuas nrog koj lub ntsuas cua - nrog ib qho kev sojntsuam ntawm lub heatsink tab thiab lwm qhov ntawm lub heatsink nws tus kheej. Tsis muaj beep = txoj haujlwm zoo!
Kauj Ruam 6: Xeem Nws
Txheeb xyuas thiab txheeb xyuas ob zaug tias tag nrho koj cov kev sib txuas tau ruaj khov, thiab xyuas kom koj tau xa + thiab - qhov hluav taws xob mus rau qhov raug. Teem lub hwj chim rau ib puag ncig +-10V, sawv rov qab thiab hloov mus!
Yog tias tsis muaj qhov txaus ntshai ntawm cov pa luam yeeb tshwm sim, koj yuav zaum ua tiav. Ua si qee cov nkauj thiab mloog koj tus neeg hais lus xeem. Yog tias koj lub rooj zaum siv hluav taws xob muaj lub ntsuas hluav taws xob built -in, koj tuaj yeem pom ntau npaum li cas tam sim no koj lub tshuab hluav taws xob tau teeb tsa thaum lub sijhawm twg los xij - sim tig lub ntim kom pom qhov kos tam sim no nce.
Ntawm qhov hluav taws xob qis, koj yuav muaj peev xwm khiav mus rau lwm qhov lossis cuam tshuam qhov cuam tshuam sai dua li sai dua tom qab, thiab ntawm qhov ntau dua koj cov nkauj yuav suab tsis txaus ntseeg. Maj mam tig qhov hluav taws xob - LM1875 tuav +-25V zoo li tus yeej, yog li yog tias koj muaj lub rhaub dej kom tsim nyog yuav tsum tsis muaj dab tsi txhawj txog.
Tso zis Voltage
Kuv tau khiav cov khoom tso rau hauv qhov hnyav dummy load (300W, 8Ω resistor) thiab ntsuas qhov tso tawm. Nrog 1kHz sinewave ntawm 810mV ncov, LM1875 muab rau kuv ib qho kev hwm, huv 20.15V ncov (14.32V RMS) ntawm qhov tso tawm - tsuas yog me ntsis dhau ntawm peb qhov chaw teeb tsa.
Fais fab
Hais txog lub zog huv, Kuv ua qhov ntawd…
Hwj chim RMS = Vrms^2 / R = 14.32^2 /8 = 25.63W
… tsuas yog txaj muag ntawm 26W! Tsis phem kiag li.
Txij ntawm no mus, Kuv xav pom yog tias kuv tuaj yeem nkag mus rau qhov kev ntseeg LM1875 30W cim, tab sis ua ntej kuv xav tau los pauv lub rhaub dej kub nrog qee yam kom ntseeg tau me ntsis …
Kauj Ruam 7: Tus Dab Tooj
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