Ka'idar Aiki ta Oscillators a cikin Lantarki
Oscillator yana ɗaya daga cikin mahimman da'irorin lantarki a cikin na'urorin lantarki domin yana samar da sigina na lokaci-lokaci ba tare da buƙatar shigarwar wutar lantarki ta waje (AC) ba. Kusan dukkan na'urori na zamani suna amfani da oscillators, daga agogon dijital da rediyo zuwa wayoyin hannu da kwamfutoci zuwa tsarin sadarwa na tauraron dan adam. A takaice dai, ana iya ɗaukar oscillator a matsayin "zuciyar" da'ira, yana samar da bugun sigina mai maimaitawa don daidaita lokaci (agogo), ɗaukar bayanai, ko samar da raƙuman ruwa masu ɗaukar kaya. Wannan labarin ya tattauna ƙa'idodin aiki na oscillators, abubuwan da ke cikinsu, da nau'ikan oscillators da ake amfani da su akai-akai.
Fahimtar Oscillators
A taƙaice dai, mai juyawar lantarki (oscillator) wata na'urar lantarki ce da ke samar da siffa ta igiyar lantarki ta lokaci-lokaci, kamar sine, murabba'i, alwatika, ko kuma sawtooth wave. Babban siffa ta mai juyawar lantarki ita ce ikonsa na samar da sigina mai maimaitawa akai-akai a wani takamaiman mita. Wannan mitar na iya zama ƙasa sosai (misali, 'yan Hertz) zuwa mai girma sosai (GHz), ya danganta da buƙatun aikace-aikacen.
Oscillators sun bambanta da amplifiers na gargajiya. Amplifiers suna buƙatar siginar shigarwa don ƙara girma, yayin da oscillators ke "ƙirƙirar" siginar tasu ta hanyar hanyoyin amsawa da wasu yanayi waɗanda ke haifar da juyawa.
Asali: Ra'ayi Mai Kyau
Babban ƙa'ida a cikin oscillators shine amsawa mai kyau. A cikin da'irar amplifier, ana ɗaukar wani ɓangare na siginar fitarwa kuma a mayar da ita zuwa ga shigarwar. Idan siginar da aka dawo tana cikin mataki tare da shigarwar, ana kiran martanin da positive. Ra'ayin da aka samu mai kyau yana ƙara siginar, kuma idan an cika sharuɗɗan, siginar za ta girma zuwa tsayayyen juyawa.
A aikace, oscillators kusan koyaushe suna amfani da wani abu mai ƙara ƙarfi (transistor, op-amp, ko bututun vacuum a cikin tsoffin fasahohi) tare da hanyar sadarwa ta zaɓin amsawa wanda ke ƙayyade mitar.
Sharuɗɗan da Za Su Faru Don Sauyawa (Sharhin Barkhausen)
Domin mai juyawa ya yi juyawa, ana amfani da ka'idojin Barkhausen gabaɗaya, wato manyan sharuɗɗa guda biyu:
1. Yanayin girma (ƙarin madauki):
Ribar madauki ya kamata ta yi daidai da 1 ko kuma ta ɗan fi 1 girma a lokacin farawa. A lissafi:
\|Aβ\| ≥ 1
A nan A shine ribar amplifier, yayin da β shine ma'aunin amsawa.
2. Bukatun mataki:
Jimlar canjin mataki a kan hanyar madauki dole ne ya zama 0° ko kuma ninki na 360°. Wannan yana nufin cewa siginar da ke dawowa zuwa shigarwar dole ne ta kasance a mataki tare da siginar shigarwa.
Idan aka cika waɗannan sharuɗɗa guda biyu, ƙaramin sigina (yawanci yana fitowa daga hayaniyar zafi na ɓangaren) zai ci gaba da ƙaruwa har sai ya kai matsayin da ya dace.
Matakan Aiki na Oscillator
1. Farawa (Fara zuwa juyawa)
Idan aka fara amfani da da'irar, babu siginar shigarwa. Duk da haka, akwai wani hayaniya a cikin abubuwan da ke cikin. Wannan hayaniya tana shiga cikin amplifier kuma ana ƙara ta. Idan a wani mita cibiyar sadarwar amsawa ta cika buƙatun mataki da girma, wannan ɓangaren mita zai zama mai rinjaye kuma ya ci gaba da girma.
2. Ƙara yawan mita da zaɓi
Cibiyoyin sadarwa na mayar da martani yawanci suna zaɓe ne kawai, ma'ana suna ba da damar wasu mitoci kawai su sami ra'ayin da ya dace. Sakamakon haka, mai juyawa zai yi aiki a waɗannan mitoci, yayin da sauran mitoci za su ragu.
3. Daidaita girman (yanayin da ya dace)
Idan ribar madauki ta ci gaba da zama sama da 1, girman zai ci gaba da ƙaruwa har sai da'irar ta cika kuma ta fuskanci karkacewar da ta yi tsanani. Don samar da fitarwa mai ƙarfi, mai juyawa yana buƙatar tsarin iyakance girman ko tsarin sarrafawa, misali:
- Rashin daidaituwa na halitta na transistor/op-amps,
- Amfani da diodes masu iyakancewa,
– Ƙaramin fitilar incandescent (a kan oscillator na Wien Bridge na gargajiya),
- AGC (Sarrafa Samun Gani ta atomatik) akan wasu oscillators.
A wurin da aka tsaya, ingantaccen ribar madauki ya zama kusan 1 don haka girman ba zai ƙara ko raguwa ba.
Abubuwan da ke ƙayyade yawan lokaci
Yawanci ana ƙayyade mitar juyawa ta hanyar hanyar sadarwa mai ƙayyade mita, misali:
1. RC (Resistor-Capacitor)
Ya dace da ƙananan mitoci zuwa matsakaici (sauti har zuwa ɗaruruwan kHz).
2. LC (Inductor-Capacitor)
Wanda aka saba da shi ga mitoci na rediyo (ɗaruruwan kHz zuwa goma na MHz).
3. Crystal (ruwan ma'adini)
Yana samar da kwanciyar hankali mai yawa, wanda aka saba amfani da shi ga agogon microcontroller, kwamfutoci, da sadarwa.
Yayin da sinadarin tantance mita ya fi karko, yawan fitowar oscillator zai fi karko idan aka kwatanta da canje-canje a yanayin zafi, ƙarfin lantarki da kuma matsalolin kaya.
Nau'ikan Oscillators da Aka Fi Sani
1. Mai Juyawa RC
Masu juyawar RC suna amfani da haɗin resistors da capacitors don samar da takamaiman canjin lokaci.
a. Mai Sauyawa na Canjin Mataki na RC
Ta amfani da matakai da yawa na RC tare da jimlar canjin mataki na 180°, an ƙara amplifier mai juyawa don samar da wani 180° don jimlar 360°. Ya dace da samar da raƙuman sine a mitoci na sauti.
b. Wien Bridge Oscillator
Ɗaya daga cikin shahararrun na'urorin juyawar sine. Yana amfani da gadar Wien (haɗin da'irori na series da parallel RC) don tantance mitar. Amfaninsa shine ƙarancin karkacewa idan girman yana da kyau, misali, ta amfani da fitilar incandescent a matsayin abin da ke sarrafa riba.
2. LC Oscillator
Oscillator na LC yana samar da juyawa bisa ga amsawar da'irar inductor (L) da capacitor (C). Mitar amsawa mafi kyau ita ce:
\[
f = \frac{1}{2\pi\sqrt{LC}}
\]
Nau'ikan da suka shahara:
– Hartley Oscillator: yana amfani da famfo a kan inductor ko inductor guda biyu a jere.
– Colpitts Oscillator: yana amfani da mai raba capacitor (capacitors guda biyu a jere).
– Clapp Oscillator: wani nau'in Colpitts ne mai ƙarin capacitor don kwanciyar hankali.
Ana amfani da na'urorin LC sosai a cikin na'urorin watsa rediyo, masu karɓa, VCOs (Masu Sauke Wutar Lantarki Mai Sarrafa), da sauran da'irori na RF.
3. Osilator Kristal
Masu juyawar kristal suna amfani da sautin injina na kristal mai kaifi (high-Q). Saboda haka, mitarsu daidai take kuma tana da karko. Ana samun lu'ulu'u na yau da kullun a cikin 32.768 kHz (agogo), 8 MHz, 16 MHz, 25 MHz, da sauran ƙima da yawa.
Kelebihan:
- Kwanciyar hankali mai yawa,
- Ƙaramin hayaniyar lokaci idan aka kwatanta da RC/LC na yau da kullun.
Kekurangan:
– Sauyin yanayi ba abu ne mai sauƙi ba,
– Ana buƙatar da'irar direba mai dacewa don kada lu'ulu'u ya wuce gona da iri.
4. Na'urar Sauyawa ta Shakatawa
Ba kamar sine wave oscillator ba, relaxation oscillator yana samar da non-sine waves (murabba'i, triangle, sawtooth) ta hanyar caji da kuma fitar da capacitor akai-akai. Misali:
- Mai amfani da wutar lantarki mai ƙarfi (transistor ko IC 555)
- Oscillator mai tushen Schmitt.
Wannan na'urar juyawa ta shahara ga masu samar da bugun jini, masu ƙidayar lokaci, PWM, da kuma da'irori na dijital.
Muhimman Abubuwa a Tsarin Oscillator
1. Daidaiton mita
Ya shafi juriyar sassan, zafin jiki, tsufa, da bambancin ƙarfin lantarki. Don tsarin daidaito, galibi ana zaɓar lu'ulu'u ko TCXO/OCXO.
2. Hayaniya da kuma rawar jiki a lokaci
Yana da matuƙar muhimmanci a cikin sadarwa ta dijital da tsarin agogo. Hayaniyar mataki mai girma na iya lalata ingancin daidaitawa, ƙara BER (Rate Error Error), da kuma ɓata bakan.
3. Karkatar da raƙuman ruwa
Oscillator na sine ya fi dacewa yana da ƙarancin karkacewa. Karkatarwa tana faruwa idan ikon sarrafa girman bai yi kyau ba ko kuma amplifier ɗin yana aiki a yankin da ba na layi ba.
4. Tasirin kaya (lodawa)
Idan aka ɗora kayan fitarwa kai tsaye, hanyar sadarwa ta resonance na iya canzawa, wanda ke haifar da canjin mitar. Saboda haka, ana amfani da buffers (masu bin emitter, masu buffers na op-amp) sau da yawa don "keɓe" da'irar tantance mitar.
Kammalawa
Ka'idar aiki ta oscillator a cikin kayan lantarki ta dogara ne akan ra'ayoyi masu kyau da kuma cika ka'idar Barkhausen: isasshen madauki da kuma jimlar canjin lokaci na 0°/360°. Oscillator yana fara oscillations daga hayaniyar ciki, sannan hanyar sadarwa mai ƙayyade mita (RC, LC, ko crystal) tana zaɓar takamaiman mita, kuma a ƙarshe girman yana daidaita ta hanyar tsarin iyakance riba. Ana zaɓar nau'ikan oscillators daban-daban - RC, LC, crystal, da shakatawa - bisa ga mita, kwanciyar hankali, yanayin raƙuman ruwa, da buƙatun aikace-aikace. Fahimtar waɗannan ƙa'idodi yana taimaka wa injiniyoyi da ɗaliban lantarki su tsara tsarin agogo masu inganci, janareto sigina, da da'irori na sadarwa.
Idan kana so, zan iya ƙara misali na lissafin mita don ɗaya daga cikin nau'ikan oscillator (misali Wien Bridge ko Colpitts) tare da tsarin da'ira na asali.
