Njira Zopangira Ma Radio a AM ndi Zigawo Zosavuta
Wailesi ya AM (Amplitude Modulation) ndi imodzi mwa njira zamakono zolankhulirana zomwe anthu ambiri amaphunzira. Ngakhale anthu ambiri amadziwa bwino wailesi ya FM kapena kuwulutsa kwa digito, wailesi ya AM ikadali njira yophunzitsira kwambiri chifukwa cha ma circuitry ake osavuta komanso osavuta kumva. Ndi zigawo zochepa zoyambira, mutha kupanga cholandirira wailesi cha AM chosavuta kulandira masiteshoni am'deralo—osachepera m'malo omwe ali ndi chizindikiro champhamvu. Nkhaniyi ikufotokoza momwe mungapangire wailesi ya AM pogwiritsa ntchito zigawo zosavuta, mfundo zake zogwirira ntchito, ndi njira zosonkhanitsira.
1. Mfundo Yachidule Yogwirira Ntchito ya AM Radio
Wailesi ya AM imagwira ntchito pojambula mafunde a wailesi omwe "amasintha" malinga ndi mawonekedwe a chizindikiro cha mawu (mawu). Wolandila wailesi ya AM wosavuta kwenikweni amachita zinthu zitatu zazikulu:
1. Jambulani zizindikiro za wailesi kudzera mu antenna ndi tuner circuit.
2. Kulekanitsa (kuchotsa) chizindikiro cha mawu kuchokera ku mafunde a RF carrier pogwiritsa ntchito chowunikira (nthawi zambiri diode).
3. Sinthani ma siginolo a mawu kukhala mawu kudzera m'makutu kapena ma amplifiers a mawu ndi ma speaker.
Wailesi ya AM yosavuta kwambiri imadziwika kuti wailesi ya kristalo, yomwe imatha kugwira ntchito popanda mabatire ngati chizindikirocho chili champhamvu mokwanira. Komabe, kuti tipeze zotsatira zabwino, titha kuwonjezera chowonjezera mawu chosavuta.
2. Zigawo Zosavuta Zofunikira
Zinthu zotsatirazi zimagwiritsidwa ntchito kwambiri pa cholandirira wailesi cha AM chosavuta:
– Waya wa enamel (waya wa maginito) wopangira ma coil, mwachitsanzo m'mimba mwake wa 0,2–0,5 mm.
– Ndodo ya Ferrite (ngati mukufuna koma yothandiza kwambiri) ngati maziko a coil kuti muwonjezere mphamvu ya kumva.
- Chosinthira mphamvu (pafupifupi 10–365 pF) pokonza ma frequency. Muthanso kugwiritsa ntchito chosinthira mphamvu cha varco kuchokera ku wailesi yakale.
– Detector diode: 1N34A (germanium) ndi yabwino, koma mungagwiritsenso ntchito 1N60 kapena Schottky monga BAT41 (bwino kuposa ma silicon diode wamba).
- Kachipangizo kakang'ono (monga 10 nF–100 nF) kosefera/kudula mawu (ngati mukufuna).
- Mahedifoni okhala ndi mphamvu yotsika kwambiri kapena ma piezo earphone. Mahedifoni amakono nthawi zambiri amakhala ndi mphamvu yotsika kwambiri, zomwe zimapangitsa kuti asamagwiritsidwe ntchito bwino popanda amplifier.
– Antena: Chingwe chautali wa mamita 5–20 (chitali chimakhala chabwino).
– Pansi: kulumikiza ku chitoliro cha madzi/pansi pa magetsi (motetezeka) kapena pansi ponyowa pogwiritsa ntchito ndodo yachitsulo.
– Bolodi la mkate kapena bolodi loboola (bolodi la perf), chitsulo chosungunula, ndi zingwe zolumikizira.
Ngati mukufuna kuwonjezera chitonthozo pakumvetsera:
- Chojambulira mawu cha IC (monga LM386), cholankhulira chaching'ono cha 8 ohm, ndi batire ya 9V.
3. Dongosolo la Circuit: LC Tuner ndi Diode Detector
Gawo lofunika kwambiri la wailesi ya AM ndi dera losinthira la LC (inductor L ndi capacitor C). Dera ili limasankha frequency imodzi kuchokera ku ma signali ambiri omwe alandiridwa ndi antenna. Ma frequency a resonant ndi pafupifupi:
\[
f = \frac{1}{2\pi\sqrt{LC}}
\]
Ndi capacitor yosinthika, mtengo wa C ukhoza kusinthidwa kuti wailesi "ithe kusesa" ma frequency a AM (pafupifupi 530–1600 kHz, kutengera miyezo ya madera).
Pambuyo poti chizindikiro chasankhidwa ndi dera la LC, diode imakhala ndi udindo wozindikira/kuzindikira envelopu: gawo la mafunde a RF limakonzedwa kuti chizindikiro cha mawu chipangidwe.
4. Njira Zopangira Wailesi Yosavuta ya AM (Wailesi ya Crystal)
A. Kupanga Koyilo
Pali njira ziwiri zazikulu:
1) Chophimba ndi ndodo ya ferrite
– Konzani ndodo ya ferrite (monga kutalika kwa 8–12 cm).
- Pukutani waya wa enamel pafupifupi maulendo 60-100, kutengera varco ndi gulu la chandamale.
- Pangani "kugogoda" ngati kuli kofunikira (monga pa 10th kapena 20th winding) kuti mulumikizane ndi antenna kuti kusintha kukhale kokhazikika.
2) Choyimbira mpweya (pakati pa mpweya)
- Gwiritsani ntchito chitoliro cha PVC cha mainchesi 2–3 ngati chogwirira.
– Mphepo ya waya imazungulira 80–120.
– Ma coil amlengalenga nthawi zambiri amakhala akuluakulu koma amatha kugwira ntchito bwino, makamaka ngati antenna ndi yokwanira.
Dziwani: Chiwerengero cha ma turn sikuyenera kukhala cholondola. Mutha kuyesa: ngati mukuvutika kupeza chizindikiro, yesani kuwonjezera kapena kuchepetsa chiwerengero cha ma turn.
B. Kusonkhanitsa LC Tuner
- Lumikizani coil L pamodzi ndi variable capacitor C.
- Mbali imodzi ya LC imalumikizidwa ku antenna (nthawi zambiri kudzera pa pompo), ndipo inayo imalumikizidwa pansi.
Njira zolumikizira ma antenna zimatha kukhudza magwiridwe antchito. Mu mapangidwe ambiri, antenna simalumikizidwa mwachindunji kumapeto kwa coil yayikulu, koma m'malo mwake imalumikizidwa ndi kugwedezeka kangapo kuti ichepetse katundu ndikuwonjezera kusankha.
C. Kuonjezera ma Diode a Detector ndi Audio Loads
– Tengani chizindikiro kuchokera pamalo otulutsira magetsi a LC circuit (nthawi zambiri kumapeto kwa "kotentha" kwa coil).
- Ikani mu germanium diode (anode ku LC, cathode ku mbali ya audio).
- Mukamaliza kugwiritsa ntchito diode, ilumikizeni ku earphone yokhala ndi impedance yapamwamba.
- Onjezani capacitor ya 10 nF–100 nF yofanana ku earphone (ngati mukufuna) kuti muwongolere RF yotsala kuti mawu akhale oyera.
Ndondomeko yosavuta ya malingaliro:
1. Antena → (cholumikizira chopopera) → thanki ya LC
2. Thanki ya LC → diode → earphone → pansi
D. Kulumikiza Antena ndi Pansi
Ma wailesi osagwira ntchito ngati awa amadalira kwambiri antenna ndi nthaka:
- Gwiritsani ntchito chingwe cha antenna chachitali kwambiri, choyikidwa pamwamba komanso kutali ndi malo osowetsa phokoso.
- Nthaka ndi yothandiza kwambiri; kulumikizana ndi nthaka yonyowa ndikwabwino kuposa nthaka "yoyandama".
- Pewani malo omwe ali pafupi ndi ma charger osinthira, magetsi otsika mtengo a LED, ma router, kapena ma laptop chifukwa angayambitse phokoso/phokoso.
E. Kukonza
- Tembenuzani pang'onopang'ono chosinthira cha capacitor kuti mufufuze malo oimikapo magalimoto.
- Nthawi zina mumafunika kusintha malo a coil pa ndodo ya ferrite kuti musinthe cholumikizira ndikupeza chizindikiro chapamwamba kwambiri.
5. Malangizo Othandizira Kumvetsetsa ndi Kukonza Mamvekedwe a Mawu
1. Gwiritsani ntchito diode yoyenera
Ma diode a germanium (1N34A/1N60) ali ndi mphamvu yotsika kutsogolo, zomwe zimapangitsa kuti azigwiritsidwa ntchito popereka ma signali ofooka. Ma diode wamba a silicon monga 1N4148 amatha kugwira ntchito, koma nthawi zambiri amapereka mphamvu zochepa.
2. Gwiritsani ntchito mahedifoni a piezo kapena ma earphone okhala ndi impedance yayikulu
Mahedifoni okhala ndi mphamvu zochepa amatha kudzaza dera lozindikira mawu, zomwe zimapangitsa kuti mawuwo asamveke bwino. Kapena, gwiritsani ntchito chosinthira mawu chaching'ono kapena onjezani amplifier.
3. Onjezani amplifier ya LM386 (ngati mukufuna)
Ngati mukufuna kugwiritsa ntchito ma speaker, pangani siteji ya amplifier:
– Chotuluka pambuyo pa diode chimapita ku cholowera cha LM386 (kudzera pa cholumikizira cha coupling).
– LM386 ili ndi batire ya 6–9V.
- Kutulutsa mawu ku ma speaker a 8 ohm.
Izi zidzawonjezera voliyumu kwambiri.
4. Konzani bwino kapangidwe kake
Mawaya ataliatali kwambiri amatha kumva phokoso. Pa mafunde a wailesi, kapangidwe kake n'kofunika kwambiri. Sungani maulumikizidwe a LC afupiafupi momwe mungathere.
5. Samalani kusankha bwino
Ngati malo olumikizirana akugwirizana, yesani kusintha momwe mumalumikizira antenna (gwiritsani ntchito kutembenuza pang'ono kwa kupopera) kapena gwiritsani ntchito coil yokhala ndi ferrite kuti muwongolere kusankha.
6. Malangizo Okhudza Chitetezo ndi Zothandiza
Ma wailesi osavuta nthawi zambiri amakhala otetezeka chifukwa sagwiritsa ntchito ma voltage ambiri. Komabe:
- Ngati mulumikiza pansi ndi malo okhazikitsa nyumba, onetsetsani kuti mwamvetsa chitetezo chamagetsi. Musalumikize ku dera lililonse loopsa.
– Ma antenna akunja ali pachiwopsezo chogundidwa ndi mphezi. Nthawi yamvula, chotsani antennayo pamagetsi.
- Ngati mukuyika antenna yayitali panja, gwiritsani ntchito zolekanitsa ndi malo otetezeka olowera.
7. Mapeto
Kupanga wailesi ya AM yokhala ndi zigawo zosavuta ndi pulojekiti yothandiza kwambiri yamagetsi pomvetsetsa malingaliro a resonance, kusankha ma frequency, ndi demodulation ya ma signal. Ndi coil, variable capacitor, diode, antenna, ndi mahedifoni, mutha kupanga cholandirira cha AM choyambira chomwe chingathe kulandira mawayilesi am'deralo. Zotsatira zake sizingakhale zamphamvu ngati wailesi yopangidwa ku fakitale, koma pamenepo ndi pomwe phindu lophunzirira lili: mutha kuyesa kuchuluka kwa ma coil, mtundu wa diode, kutalika kwa antenna, komanso kuwonjezera chowonjezera mawu.
Ngati mukufuna, ndithanso:
- Pangani dongosolo lonse la ma circuit (crystal radio kapena LM386 version),
- Werengani chiwerengero cha maulendo oyerekeza kutengera varco yomwe muli nayo,
- Perekani malangizo a zinthu zomwe zimapezeka mosavuta m'masitolo/misika yapafupi.
