Kev Taw Qhia Txog Cov Qauv Cai Hauv Kev Tsim Hluav Taws Xob
Hauv ntiaj teb ntawm hluav taws xob thiab khoom siv hluav taws xob, "cov lej txheem" yog ib hom lus sib koom uas tso cai rau cov kws kho tshuab, cov engineers, cov tub ntxhais kawm, thiab cov kws tshaj lij hauv kev lag luam nyeem, tsim, sib sau ua ke, thiab kho cov circuits sai dua thiab muaj kev nyab xeeb. Cov lej txheem no suav nrog cov cim ntawm cov khoom (piv txwv li, resistors, capacitors, diodes), lub npe ntawm lub davhlau ya nyob twg thiab txoj kev, cov cim schematic, thiab cov qauv kev txuas hluav taws xob thiab kev nyab xeeb. Yog tsis muaj cov lej txheem, txhua yam khoom lossis circuit tuaj yeem siv txoj kev sau ntawv sib txawv, ua rau muaj kev nkag siab yuam kev, kev teeb tsa yuam kev, thiab txawm tias muaj kev pheej hmoo ntawm hluav taws lossis hluav taws xob poob siab. Tsab xov xwm no muab kev qhia txog cov lej txheem feem ntau hauv thaj chaw hluav taws xob, tshwj xeeb tshaj yog cov uas cuam tshuam nrog cov khoom thiab cov ntaub ntawv circuit.
1. Vim li cas tus lej txheem thiaj tseem ceeb?
Tus lej txheem ua haujlwm rau:
1. Tsis txhob txhais yuam kev: Piv txwv li, ib lub cim tshwj xeeb ntawm daim duab qhia yuav tsum txhais tib yam hauv cov phau ntawv, cov chaw tsim khoom, lossis lub tebchaws sib txawv.
2. Ua kom cov teeb meem sai dua: Cov kws kho tshuab tuaj yeem taug qab lub voj voog los ntawm kev nkag siab cov ntawv lo, cov nqi, thiab kev taw qhia ntawm cov khoom.
3. Xyuas kom meej tias muaj kev sib haum xeeb thiab zoo: Muaj ntau tus qauv tshwm sim los ntawm qhov kev xav tau ntawm kev lag luam rau cov khoom kom raug kuaj, ntawv pov thawj, thiab tsim tawm ntau.
4. Ua kom muaj kev nyab xeeb ntxiv: Cov lej xim ntawm cov xov hlau, cov cim av, thiab cov ntawv lo rau hluav taws xob yog qhov tseem ceeb heev los tiv thaiv cov neeg siv kom tsis txhob ua qhov kev sib txuas tsis raug.
2. Cov Cim Txheem ntawm Cov Duab Qhia (Cov Cim Qhia)
Ib qho ntawm cov qauv yooj yim tshaj plaws ntawm cov lej txheem yog cov cim ntawm cov duab qhia txog lub voj voog. Ob qho kev siv thoob ntiaj teb yog IEC (International Electrotechnical Commission) thiab ANSI/IEEE. Txawm hais tias muaj qhov sib txawv ntawm cov qauv kos duab (piv txwv li, lub cim ANSI zigzag resistor piv rau IEC rectangular), lub ntsiab lus tseem zoo ib yam.
Qee cov piv txwv ntawm cov cim uas siv ntau:
– Resistor: ib qho khoom txwv tam sim no; feem ntau muaj daim ntawv lo "R1, R2, ...".
– Capacitor: chaw cia khoom them; muaj daim ntawv lo "C1, C2, ...".
– Inductor: lub zog khaws cia hlau nplaum; “L1, L2, ...".
– Diode: ib txoj kev tivthaiv; “D1, D2, ...".
– Transistor: lub amplifier lossis lub switch; “Q1, Q2, ...".
– Av: qhov siv xoom volt; tuaj yeem yog "GND", "Lub Ntiaj Teb", lossis ib lub cim tshwj xeeb.
Kev nkag siab txog cov cim yog thawj kauj ruam los ua kom nyeem tau daim duab qhia zoo li nyeem daim ntawv qhia: paub qhov kev taw qhia ntawm qhov tam sim no, cov ntsiab lus siv, thiab kev ua haujlwm ntawm txhua lub voj voog.
3. Tus lej siv rau kev siv Cheebtsam (Tus lej siv rau kev siv)
Hauv cov duab kos lossis PCBs, cov khoom sib xyaw tau muab cov cim qhia kom yooj yim nrhiav. Cov qauv feem ntau suav nrog:
- R: tiv taus (R1, R2)
- C: lub zog hluav taws xob (C1, C2)
L: inductor / inductor (L1, L2)
– D: diode (D1, D2)
- Q: transistor (Q1, Q2)
– U/IC: kev sib xyaw ua ke (U1, U2 lossis IC1, IC2)
- T: transformer / transformer (T1)
– F: lub fuse (F1)
– SW/S: hloov/hloov (SW1)
– J/P: lub qhov (jack/connector) thiab lub qhov ntsaws (plug/header) (J1, P1)
– K: relay (K1)
Cov lej no yuav zoo li yooj yim, tab sis nws pab tau zoo heev thaum sib dhos, tshuaj xyuas, lossis kho. Piv txwv li, yog tias phau ntawv qhia hais tias "tshawb xyuas R15," tus kws kho tshuab paub tam sim ntawd tias nws tus lej resistor yog 15 ntawm lub rooj tsavxwm.
4. Tus lej ntawm tus nqi resistor: Xim Code thiab SMD Writing
Cov resistors yog cov khoom uas feem ntau siv cov lej nqi.
a) Cov xim code ntawm resistor (los ntawm qhov)
Feem ntau cov axial resistors muaj cov kab xim. Cov kab no qhia txog tus lej, tus lej sib npaug, thiab kev kam rau siab. Ib qho piv txwv zoo li no:
– Xim av, Dub, Liab, Kub
= 1, 0, ×100, kev kam rau siab ±5%
= 1000 Ω (1 kΩ) ±5%
Kev kam rau xim kuj tseem ceeb: kub ± 5%, nyiaj ± 10%, thaum tsis muaj lub kauj tes feem ntau txhais tau tias ± 20% (nyob ntawm tus neeg tsim khoom).
b) SMD resistor code (resistor chip)
Cov resistors SMD feem ntau siv cov lej lej:
– 3 tus lej: ob tus lej thawj zaug yog cov nqi tseem ceeb, tus lej thib peb yog tus lej sib npaug.
Piv txwv li “472” = 47 × 10² = 4700 Ω (4,7 kΩ).
– 4 tus lej (paub meej dua): peb tus lej tseem ceeb + tus lej sib npaug.
Piv txwv "1001" = 100 × 10¹ = 1000 Ω.
– Tus lej EIA-96: rau 1% precision resistors, kev sib xyaw ua ke ntawm cov lej thiab cov ntawv (piv txwv li, "49C"). Qhov no xav tau lub rooj siv los ua piv txwv.
5. Tus lej Capacitor: Cov lej, Cov ntawv, thiab cov chav nyob
Cov capacitors feem ntau tsis meej pem vim tias lawv cov nqi tuaj yeem sib txawv ntawm me me (pF) mus rau loj (µF), thiab cov cim sib txawv.
a) Peb tus lej
Feem ntau siv rau hauv cov capacitors ceramic:
- 104 = 10 × 10⁴ pF = 100.000 pF = 100 nF (0,1 µF)
– "103" = 10 × 10³ pF = 10 nF
b) Kev kam rau siab thiab kev ntxhov siab ua haujlwm
Cov capacitors feem ntau muaj xws li:
– Cov ntawv qhia txog kev kam rau siab (piv txwv li J = ±5%, K = ±10%, M = ±20%)
- Ua haujlwm voltage (piv txwv li 50V, 16V, 400V)
c) Polarity ntawm electrolytes
Cov electrolytic capacitors muaj polarity (+ thiab –). Feem ntau, sab tsis zoo yog cim nrog ib daim kab, lossis ceg luv dua yog cim tias tsis zoo. Kev teeb tsa tsis raug tuaj yeem ua rau kub dhau, xau, thiab txawm tias tawg.
6. Cov lej ntawm Diode thiab LED: Cov lus qhia thiab cov cim
Ib lub diode muaj ob lub qhov kawg: lub anode thiab lub cathode. Ntawm lub diode lub cev, lub cathode feem ntau yog cim nrog lub nplhaib/kab. Ntawm daim duab qhia, qhov kev taw qhia ntawm lub diode qhia txog qhov kev taw qhia tam sim no.
LEDs kuj muaj polarity:
- Ceg ntev feem ntau yog qhov anode (+)
– Feem ntau, qhov chaw tiaj tiaj ntawm lub cev yog sab cathode (–)
– Ntawm PCB, feem ntau muaj lub cim "+" lossis ib lub duab ntawm lub ncoo.
Kev lees paub cov lej qhia kev taw qhia no yog qhov tseem ceeb rau lub voj voog kom ua haujlwm raws li tsim, tshwj xeeb tshaj yog rau cov rectifiers, kev tiv thaiv polarity, thiab cov cim qhia.
7. Cov lej Transistor thiab IC : Hom, Pinouts, thiab Datasheets
Cov transistors thiab ICs siv cov lej hom (piv txwv li, BC547, 2N2222, IRFZ44N, LM358, NE555). Cov lej no tsis yog tsuas yog cov npe xwb; lawv yog cov cim qhia txog cov khoom uas yuav tsum tau kuaj xyuas hauv daim ntawv qhia txog cov khoom kom paub meej tias:
- Pinout (kev teeb tsa ceg)
- Cov kev txwv voltage / tam sim no
- Cov yam ntxwv hluav taws xob
– Ntim (TO-92, SOT-23, DIP, SOIC, QFN, thiab lwm yam)
Feem ntau yuam kev tshwm sim vim tias ob lub transistors sib txawv tuaj yeem muaj cov duab zoo sib xws tab sis cov pinouts sib txawv. Yog li ntawd, tus qauv "nyeem cov lej ntawm cov khoom thiab tom qab ntawd xa mus rau daim ntawv qhia" yog kev xyaum ua haujlwm uas yuav tsum tau ua.
8. Cov lej Cable thiab Terminal: Xim, Cov ntawv lo, thiab Av
Hauv kev teeb tsa hluav taws xob thiab cov vaj huam sib luag tswj, kev sau xim ntawm cov cables pab nrog kev nyab xeeb thiab kev saib xyuas. Cov kev coj ua yuav txawv ntawm tus qauv / lub tebchaws, tab sis lub hauv paus ntsiab lus yog:
- Muaj kev sib cais meej ntawm theem / nyob, nruab nrab, thiab av / av.
- Cov xov hlau hauv av feem ntau muab cov xim ntsuab-daj ua ke hauv ntau tus qauv thoob ntiaj teb.
- Ntawm cov vaj huam sib luag, cov davhlau ya nyob twg feem ntau muaj tus lej (piv txwv li X1: 1, X1: 2) rau kev taug qab yooj yim.
Dhau li ntawm xim, daim ntawv lo "L, N, PE (Protective Earth)" feem ntau yog siv los txhais cov haujlwm ntawm lub cable.
9. Cov Qauv Kev Nyab Xeeb thiab Daim Ntawv Pov Thawj
Cov lej txheem hauv cov khoom siv hluav taws xob kuj tseem muaj feem cuam tshuam nrog kev nyab xeeb, piv txwv li:
- IEC rau ntau yam qauv thoob ntiaj teb
- UL (Underwriters Laboratories) rau daim ntawv pov thawj kev nyab xeeb khoom (ntau hauv Asmeskas)
– SNI (Indonesian National Standard) rau kev ua raws li txoj cai hauv Indonesia
Ntawm cov khoom siv hluav taws xob , cov ntawv lo xws li qhov hluav taws xob nkag, qhov ntsuas hluav taws xob, chav kawm rwb thaiv tsev, thiab cov cim ceeb toom yog ib feem ntawm "code" uas yuav tsum tsis txhob tsis quav ntsej. Kev nyeem cov ntawv lo no pab ua kom ntseeg tau tias cov khoom siv tau raws li cov lus qhia thiab muaj kev nyab xeeb.
10. Cov Lus Qhia Siv Tau Rau Kev Kawm Cov lej hluav taws xob txheem
Yuav kom ua tau zoo sai sai, ua cov kauj ruam nram qab no:
1. Kawm nyeem cov duab qhia: pib ntawm cov voj voog yooj yim (LED + resistor), txav mus rau cov regulators, chargers, thiab amplifiers.
2. Nco ntsoov cov lej yooj yim: tus qauv siv rau kev siv thiab qee cov lej muaj nqis (104, 103, 472, thiab lwm yam).
3. Ib txwm siv daim ntawv qhia txog cov ntaub ntawv: tshwj xeeb tshaj yog rau cov transistors, ICs, regulators, MOSFETs, thiab cov khoom siv fais fab.
4. Siv lub multimeter: xyuas seb tus nqi resistor, polarity, voltage, thiab continuity ntawm txoj kab puas sib txuas.
5. Nco ntsoov cov qauv uas siv: yog tias ua haujlwm hauv kev lag luam, xyuas kom koj ua raws li cov qauv sab hauv ntawm lub tuam txhab thiab cov qauv hauv tebchaws/thoob ntiaj teb.
Xaus
Cov lej txheem hauv kev tsim hluav taws xob yog cov kab ke ntawm kev cim thiab cov cim uas ua rau kev tsim, sib dhos, thiab kho cov voj voog sib xws, muaj kev nyab xeeb, thiab ua haujlwm tau zoo. Txij li cov cim schematic thiab cov cim qhia siv, cov lej xim resistor thiab cov lej capacitor, mus rau cov ntawv lo rau xov hlau thiab cov ntawv pov thawj kev nyab xeeb, txhua yam pab txo qhov yuam kev thiab txhim kho qhov zoo ntawm kev ua haujlwm. Los ntawm kev nkag siab txog cov hauv paus ntawm cov lej txheem no thiab tau siv rau kev nyeem cov ntaub ntawv thiab cov duab qhia, txhua tus neeg kawm txog kev tsim hluav taws xob yuav muaj lub hauv paus ruaj khov rau kev nce qib mus rau qib kev tshaj lij ntxiv.
Yog tias koj xav tau, kuv tuaj yeem kho tsab xov xwm no kom meej dua: piv txwv li tsuas yog hais txog cov lej xim resistor, tsuas yog hais txog cov lej capacitor, lossis tsuas yog hais txog cov qauv kev teeb tsa hluav taws xob (cables, MCB, grounding).
