Amasu Okwenza Umsakazo we-AM Ngezingxenye Ezilula
Umsakazo we-AM (Amplitude Modulation) ungomunye wobuchwepheshe bokuxhumana obujwayelekile nobuthakazelisayo kakhulu ongabufunda. Nakuba abantu abaningi bejwayelene kakhulu nomsakazo we-FM noma ukusakaza kwedijithali, umsakazo we-AM uhlala uyindlela yokufundisa kakhulu ngenxa yesekethe yawo elula futhi elula ukuyiqonda. Ngezingxenye ezimbalwa eziyisisekelo, ungakha isamukeli somsakazo we-AM esilula esikwazi ukwamukela iziteshi zasendaweni—okungenani ezindaweni ezinesignali eqinile. Lesi sihloko sixoxa ngendlela yokwakha umsakazo we-AM usebenzisa izingxenye ezilula, izimiso zawo zokusebenza, kanye nezinyathelo zokuhlanganisa.
1. Isimiso Esifushane Sokusebenza Somsakazo we-AM
Umsakazo we-AM usebenza ngokuthwebula amaza omsakazo amamitha awo "ashintsha" ngokwesimo sesignali yomsindo (umsindo). Isamukeli somsakazo se-AM esilula senza izinto ezintathu eziyinhloko:
1. Bamba amasignali omsakazo nge-antenna kanye nesekethe ye-tuner.
2. Ukuhlukanisa (ukususa) isignali yomsindo kusuka kugagasi lokuthwala le-RF kusetshenziswa i-detector (ngokuvamile i-diode).
3. Guqula amasignali omsindo abe umsindo ngokusebenzisa ama-earphone noma ama-amplifiers omsindo kanye nezipikha.
Umsakazo we-AM olula kakhulu waziwa ngokuthi umsakazo wekristalu, ongasebenza ngaphandle kwamabhethri uma isignali inamandla ngokwanele. Kodwa-ke, ukuze uthole imiphumela engcono, singangeza i-amplifier yomsindo elula.
2. Kudingeka Izingxenye Ezilula
Izingxenye ezilandelayo zivame ukusetshenziswa kwi-receiver elula ye-AM:
– Ucingo lwe-enamel (ucingo lwe-magnet) lokwenza amakhoyili, isibonelo ububanzi obungu-0,2–0,5 mm.
– Induku ye-Ferrite (ongakukhetha kodwa ewusizo kakhulu) njenge-core coil yokwandisa ukuzwela.
– I-capacitor eguquguqukayo (cishe i-10–365 pF) yokulungisa imvamisa. Ungasebenzisa futhi i-varco capacitor evela kumsakazo omdala.
– I-detector diode: I-1N34A (germanium) ifanelekile, kodwa ungasebenzisa futhi i-1N60 noma i-Schottky njenge-BAT41 (ingcono kune-silicon diodes evamile).
– I-capacitor encane (isb. 10 nF–100 nF) yokuhlunga/ukuhlukanisa umsindo (ongakukhetha).
– Ama-earphone ane-high impedance noma ama-earphone e-piezo. Ama-earphone eselula esimanje ngokuvamile ane-low impedance, okwenza angafaneleki kangako ngaphandle kwe-amplifier.
– I-Antenna: Ikhebula eliyimitha engu-5–20 ubude (uma lide kungcono).
– Umhlaba: uxhumano nepayipi lamanzi/umhlaba kagesi (ngokuphephile) noma umhlabathi omanzi ngenduku yensimbi.
– Ibhodi lesinkwa noma ibhodi elinezimbobo (ibhodi le-perforation), insimbi yokunamathisela, kanye nezintambo zokuxhuma.
Uma ufuna ukwandisa induduzo yokulalela:
– I-audio amplifier IC (isb. LM386), isikhulumi esincane esingu-8 ohm, kanye nebhethri engu-9V.
3. Umqondo Wesekethe: I-LC Tuner kanye ne-Diode Detector
Ingxenye ebalulekile yomsakazo we-AM yisekethe yokulungisa i-LC (i-inductor L kanye ne-capacitor C). Le sekethe ikhetha imvamisa eyodwa kusuka kumasignali amaningi atholwa yi-antenna. Imvamisa ye-resonant cishe ilandelayo:
\[
f = \frac{1}{2\pi\sqrt{LC}}
\]
Nge-capacitor eguquguqukayo, inani lika-C lingashintshwa ukuze umsakazo ukwazi “ukushanela” amaza e-AM (cishe angu-530–1600 kHz, kuye ngezindinganiso zesifunda).
Ngemva kokuba isignali ikhethiwe yisekethe ye-LC, i-diode inesibopho sokuthola/ukuthola imvilophu: isigaba segagasi le-RF siyalungiswa ukuze kwakheke isignali yomsindo.
4. Izinyathelo Zokwenza Umsakazo Olula We-AM (Umsakazo We-Crystal)
A. Ukwenza Ikhoyili
Kunezindlela ezimbili ezijwayelekile:
1) Ikhoyili ngenduku ye-ferrite
– Lungisa induku ye-ferrite (isib. 8–12 cm ubude).
– Songa ucingo lwe-enamel cishe amajika angu-60–100, kuye ngokuthi i-varco kanye nebhendi eliqondiwe.
– Yenza “ukuthepha” uma kudingeka (isibonelo ekugoqeni kwe-10 noma kwe-20) ukuze kuxhunywe i-antenna ukuze ukulungiswa kuzinzile.
2) Ikhoyili yomoya (ingqikithi yomoya)
– Sebenzisa ipayipi le-PVC elingu-2–3 cm ububanzi njenge-former.
– Phendula ucingo ngama-80–120.
– Amakhoyili asemoyeni ngokuvamile makhulu kodwa angasebenza kahle, ikakhulukazi uma i-antenna yanele.
Qaphela: Inani lokujika akudingeki libe ngqo. Ungazama: uma unenkinga yokuthola isignali, zama ukwengeza noma ukunciphisa inani lokujika.
B. Ukuhlanganisa i-LC Tuner
– Xhuma ikhoyili L ngokuhambisana ne-capacitor C eguquguqukayo.
– Uhlangothi olulodwa lwe-LC luxhunywe ku-antenna (ngokuvamile ngompompi), kanti olunye luxhunywe phansi.
Amasu okuxhuma i-antenna angathinta ukusebenza. Emiklamo eminingi, i-antenna ayixhunyiwe ngqo ekugcineni kwekhoyili eyinhloko, kodwa ixhunywe ekuphenduleni okuningana ukuze kuncishiswe umthwalo futhi kuthuthukiswe ukukhetha.
C. Ukwengeza ama-Diode e-Detector kanye ne-Audio Loads
– Thatha isignali endaweni yokuphuma kwesekethe ye-LC (ngokuvamile ukuphela “okushisayo” kwekhoyili).
– Faka ku-germanium diode (i-anode ibe yi-LC, i-cathode ibe yi-audio side).
– Ngemva kwe-diode, yixhume ku-earphone ene-impedance ephezulu.
– Faka i-capacitor engu-10 nF–100 nF efanayo ku-earphone (ongakukhetha) ukuze ulungise noma iyiphi i-RF esele ukuze uthole umsindo ohlanzekile.
Uhlelo olulula lomqondo:
1. I-Antenna → (ikhoyili yokuthepha) → ithangi le-LC
2. Ithangi le-LC → i-diode → i-earphone → umhlabathi
D. Ukuxhumanisa i-Antenna kanye ne-Ground
Imisakazo engasebenzi njengale incike kakhulu ku-antenna kanye nomhlabathi:
– Sebenzisa ikhebula le-antenna elide kakhulu ngangokunokwenzeka, elibekwe phezulu futhi kude nemithombo yomsindo.
– Umhlaba uwusizo kakhulu; ukuxhumana nomhlabathi omanzi kungcono kunomhlabathi “ontantayo”.
– Gwema izindawo eziseduze nokushintsha amashaja, izibani ze-LED ezishibhile, ama-router, noma ama-laptop ngoba angabangela umsindo.
E. Ukuhlela
– Jikelezisa i-capacitor eguquguqukayo kancane ukuze useshe iziteshi.
– Ngezinye izikhathi udinga ukushintsha indawo yekhoyili entongeni ye-ferrite ukuze ushintshe ukuxhumanisa bese uthola isignali ephezulu.
5. Amathiphu Okuthuthukisa Ukuzwela Komsindo Nekhwalithi
1. Sebenzisa i-diode efanele
Ama-diode e-Germanium (1N34A/1N60) ane-voltage ephansi phambili, okwenza afanelekele izimpawu ezibuthakathaka. Ama-diode avamile e-silicon njenge-1N4148 angasebenza, kodwa ngokuvamile akhiqiza umphumela ophansi.
2. Sebenzisa ama-earphone e-piezo noma ama-earphone ane-impedance ephezulu
Ama-earphone angenawo umthelela ophansi angalayisha kakhulu isekethe ye-detector, okwenza umsindo ungezwakali kahle. Ngaphandle kwalokho, sebenzisa i-transformer encane yomsindo noma engeza i-amplifier.
3. Engeza i-amplifier ye-LM386 (ongakukhetha)
Uma ufuna ukusebenzisa izipikha, dala isigaba se-amplifier:
– Umphumela ngemva kwe-diode uya kokufakwayo kwe-LM386 (nge-coupling capacitor).
– I-LM386 ifakwe ibhethri elingu-6–9V.
– Ukukhipha izipikha ezingama-8 ohm.
Lokhu kuzokwandisa kakhulu ivolumu.
4. Hlela kabusha ukwakheka
Amakhebula amade kakhulu angabamba umsindo. Emazameni omsakazo, ukwakheka kwawo kubalulekile. Gcina ukuxhumana kwe-LC kufushane ngangokunokwenzeka.
5. Naka ukukhetha
Uma iziteshi zihlangana, zama ukushintsha indlela oxhuma ngayo i-antenna (sebenzisa ukujika okumbalwa kompompi) noma sebenzisa ikhoyili ene-ferrite ukuze uthuthukise ukukhetha.
6. Amanothi Okuphepha Nokusebenza
Imisakazo elula ngokuvamile iphephile ngoba ayibandakanyi ama-voltage aphezulu. Kodwa-ke:
– Uma uxhuma umhlabathi endaweni yokufakwa kwendlu, qiniseka ukuthi uyaqonda ukuphepha kukagesi. Ungaxhumi kunoma iyiphi isekethe eyingozi.
– Ama-antenna angaphandle asengozini yokushaywa umbani. Ngesikhathi sezulu esibi, susa i-antenna kusekethe.
– Uma ufaka i-antenna ende ngaphandle, sebenzisa ama-isolator kanye nendawo yokungena ephephile.
7. Isiphetho
Ukwakha umsakazo we-AM ngezakhi ezilula kuyiphrojekthi ye-elekthronikhi ewusizo kakhulu ekuqondeni imiqondo ye-resonance, ukukhethwa kwemvamisa, kanye nokususwa kwesignali. Nge-coil, i-variable capacitor, i-diode, i-antenna, nama-earphone, ungakha isamukeli se-AM esiyisisekelo esikwazi ukwamukela ukusakazwa kwendawo. Umphumela ungase ungabi namandla njengomsakazo owenziwe efektri, kodwa yilapho inani lokufunda likhona: ungazama ngenani lama-coil, uhlobo lwe-diode, ubude be-antenna, ngisho nokwengezwa kwe-audio amplifier.
Uma ufuna, ngingakwenza futhi:
– Dala isimiso sesekethe esiphelele (umsakazo wekristalu noma inguqulo ye-LM386),
- Bala inani elilinganisiwe lokujika ngokusekelwe ku-varco onayo,
- Nikeza izincomo zezingxenye ezilula ukuzithola ezitolo/ezimakethe zasendaweni.
