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常见电子元器件及仪器的介绍

www.bysj580.com / 2017-02-21
常见电子元器件及仪器的介绍
21世纪是电子技术的世纪。
电子技术是当代迅速发展的科学。它在自动控制、通信,计算机、家用电器等各个领域的应用日益广泛。那么,什么是电子技术呢?简单地说电子技术就是应用电子元器件或电子设备来达到某种特定目的或完成某项特定任务的技术。电子技术研究的对象是电子器件和由器件构成的各种基本功能电路,以及由某些基本功能电路所组成的有各种用途的装置或系统。如果在模拟电子电路的输入端接入其他如气敏的,光敏的,磁敏的,热敏的等敏感元件,人们就可以做出煤气报警器,自动路灯控制器,温度控制器,等设备。
由于电子技术已经深入各部门生产、科研、经济管理等方面,深入人民群众的生活之中,因此,学习好电子技术就显得尤为重要了。它可以在以后的学习、生活、工作等很多方面给你带来很大的帮助。高等职业技术学院电类专业都必修模拟电子,数字电子这两门课,他们是属于电子技术入门的基础课程。在以后还将转向专业课的学习,如单片机、DSP、嵌入式等课程。
学习电子技术,要从基础开始。首先要了解一下有关电子方面常见的一些元器件和实验仪器。常见的元器件有:电阻器、电容器、电感器、变压器、二极管、三极管等。而实验仪器常用的有:示波器、信号发生器、万用表等。
下面就简单为大家介绍一下这些器件和仪器:
一、电阻器:
顾名思义,就是阻碍电流运动的一种器件,在电阻器中流过的电流与加在电阻两端的电压成正比,与电阻的阻值成反比。这也就是伟大的欧姆定律。电阻器常用做限流器用以保护元件。也可用作分压器,以减小其他电路的电压,如晶体管偏置电路。电阻器还可以用做电路的负载。小功率电阻器通常为封装在塑料外壳中的碳膜构成,而大功率的电阻器通常为绕线电阻器,通过将大电阻率的金属丝绕在瓷心上而制成。如果一个电阻器的电阻值接近零欧姆(例如,两个点之间的大截面导线),则该电阻器对电流没有阻碍作用,串接这种电阻器的回路被短路,电流无限大。如果一个电阻器具有无限大的或很大的电阻,则串接该电阻器的回路可看作开路,电流为零。工业中常用的电阻器介于两种极端情况之间,它具有一定的电阻,可通过一定的电流,但电流不像短路时那样大。电阻器的限流作用类似于接在两根大直径管子之间的小直径管子限制水流量的作用。电阻,英文名resistance,通常缩写为R,它是导体的一种基本性质,与导体的尺寸、材料、温度有关。事实上,“电阻”说的是一种性质,而通常在电子产品中所指的电阻,是指电阻器这样一种元件。师傅对徒弟说:“找一个100欧的电阻来!”,指的就是一个“电阻值”为100欧姆的电阻器,欧姆常简称为欧。表示电阻阻值的常用单位还有千欧(kΩ),兆欧(MΩ)。
二、电容器:
电容器(capacitor)简称电容,也是组成电子电路的主要元件。它可以储存电能,具有充电、放电及通交流、隔直流的特性。从某种意义上说,电容器有点像电池。尽管两者的工作方式截然不同,但它们都能存储电能。电池有两个电极,在电池内部,化学反应使一个电极产生电子,另一个电极吸收电子。而电容器则要简单得多,它不能产生电子——它只是存储电子。它是各类电子设备大量使用的不可缺少的基本元件之一。各种电容器在电路中能起不同的作用,如耦合和隔直流、旁路、整流滤波、高频滤波、调谐、储能和分频等。电容器应根据电路中电压、频率、信号波形、交直流成分和温湿度条件来加以选用。电容是指容纳电场的能力。任何静电场都是由许多个电容组成,有静电场就有电容,电容是用静电场描述的。一般认为:孤立导体与无穷远处构成电容,导体接地等效于接到无穷远处,并与大地连接成整体。电子制作中需要用到各种各样的电容器,它们在电路中分别起着不同的作用。与电阻器相似,通常简称其为电容,用字母C表示。顾名思义,电容器就是“储存电荷的容器”。尽管电容器品种繁多,但它们的基本结构和原理是相同的。两片相距很近的金属中间被某物质(固体、气体或液体)所隔开,就构成了电容器。两片金属称为极板,中间的物质叫做介质。电容器也分为容量固定的与容量可变的。但常见的是固定容量的电容,最多见的是电解电容和瓷片电容。   不同的电容器储存电荷的能力也不相同。规定把电容器外加1伏特直流电压时所储存的电荷量称为该电容器的电容量。电容的基本单位为法拉(F)。但实际上,法拉是一个很不常用的单位,因为电容器的容量往往比1法拉小得多,常用微法(μF)、纳法(nF)、皮法(pF)(皮法又称微微法)等,它们的关系是:1法拉(F)= 1000000微法(μF) 1微法(μF)= 1000纳法(nF)= 1000000皮法(pF)
三、电感器:
电感器是能够把电能转化为磁能而存储起来的元件。电感器的结构类似于变压器,但只有一个绕组。电感器具有一定的电感,它只阻止电流的变化。如果电感器中没有电流通过,则它阻止电流流过它;如果有电流流过它,则电路断开时它将试图维持电流不变。电感器又称扼流器、电抗器、动态电抗器。电感器总是反电流的变化,对直流电而言,电感器是没有阻碍作用的,但对交流电来说,电感器有一个交流阻抗,称为感抗。这个感抗量和交流电的频率有关。我们晓得,电生磁、磁生电,两者相反相成,总是随同显示。当一根导线中拥有恒定电流流过时,总会在导线四周激起恒定的磁场。当我们把这根导线都弯曲成为螺旋线圈时,应用中学学过的电磁感应定律,我们就能断定,螺旋线圈中发生了磁场。接上去,我们将这个螺旋线圈放在某个电流回路中,当这个回路中的直流电变化时(如从小到大或许相反),电感中的磁场也应该会发生变化,变化的磁场会带来变化的“新电流”,由电磁感应定律,这个“新电流”一定和原来的直流电方向相反,从而在短时刻内关于直流电的变化构成一定的抵抗力。只是,一旦变化完成,电流稳固上去,磁场也不再变化,便不再有任何障碍发生。
四、变压器:
变压器与电感器的特性有关。在一个线圈上加上交流电,产生磁场变化,在另一个线圈上产生交流电压。基本原理就是这样。变压器通常用于电源的升压、降压,电气隔离,阻抗匹配和电路之间的信号耦合。一般来说,直流电是不能输入变压器的,它会使线圈饱和,所以一个变压器通常认为是一个交流器件。变压器组成部件包括器身(铁芯、绕组、绝缘、引线)、变压器油、油箱和冷却装置、调压装置、保护装置(吸湿器、安全气道、气体继电器、储油柜及测温装置等)和出线套管。1.铁芯:铁芯是变压器中主要的磁路部分。通常由含硅量较高,厚度分别为0.35 mm\0.3mm\0.27 mm,表面涂有绝缘漆的热轧或冷轧硅钢片叠装而成 ,铁芯分为铁芯柱和横片两部分,铁芯柱套有绕组;横片是闭合磁路之用。 铁芯结构的基本形式有心式和壳式两种 2.绕组:绕组是变压器的电路部分,它是用双丝包绝缘扁线或漆包圆线绕成。变压器的基本原理是电磁感应原理。
五、二极管:
二极管是半导体二极管的简称,它是由半导体材料制成的PN结。PN结具有单向导电性。P型材料称正极,N型材料称负极。当二极管正极电位高于负极电位,且其差值大于开启电压时称二极管是正向偏置。这时二极管内部电阻是很小的,有较大的电流流过二极管,流过电流的大小取决于外部电路的电阻值。反之,当正极电位低于负极电位,二极管反向偏置,这时二极管内部的电阻非常高。当不存在外加电压时,由于PN 结两边载流子浓度差引起的扩散电流和自建电场引起的漂移电流相等而处于电平衡状态。二极管主要有以下特性:
(1)正向性:外加正向电压时,在正向特性的起始部分,正向电压很小,不足以克服PN结内电场的阻挡作用,正向电流几乎为零,这一段称为死区。这个不能使二极管导通的正向电压称为死区电压。当正向电压大于死区电压以后,PN结内电场被克服,二极管导通,电流随电压增大而迅速上升。在正常使用的电流范围内,导通时二极管的端电压几乎维持不变,这个电压称为二极管的正向电压。
(2)反向性:外加反向电压不超过一定范围时,通过二极管的电流是少数载流子漂移运动所形成反向电流,由于反向电流很小,二极管处于截止状态。这个反向电流又称为反向饱和电流或漏电流,二极管的反向饱和电流受温度影响很大。击穿:外加反向电压超过某一数值时,反向电流会突然增大,这种现象称为电击穿。引起电击穿的临界电压称为二极管反向击穿电压。电击穿时二极管失去单向导电性。如果二极管没有因电击穿而引起过热,则单向导电性不一定会被永久破坏,在撤除外加电压后,其性能仍可恢复,否则二极管就损坏了。因而使用时应避免二极管外加的反向电压过高。二极管是一种具有单向导电的二端器件,有电子二极管和晶体二极管之分,电子二极管现已很少见到,比较常见和常用的多是晶体二极管。二极管的单向导电特性,几乎在所有的电子电路中,都要用到半导体二极管,它在许多的电路中起着重要的作用,它是诞生最早的半导体器件之一,其应用也非常广泛。二极管的管压降:硅二极管(不发光类型)正向管压降0.7V,锗管正向管压降为0.3V,发光二级管正向管压降为随不同发光颜色而不同。主要有三种颜色,具体压降参考值如下:红色发光二极管的压降为2.0--2.2V,黄色发光二极管的压降为1.8—2.0V,绿色发光二极管的压降为3.0—3.2V,正常发光时的额定电流约为20mA。二极管的电压与电流不是线性关系,所以在将不同的二极管并联的时候要接相适应的电阻。
六、三极管:
晶体三极管也称三极管,是半导体基本元器件之一,具有电流放大作用,是电子电路的核心元件。三极管是在一块半导体基片上制作两个相距很近的PN结,两个PN结把整块半导体分成三部分,中间部分是基区,两侧部分是发射区和集电区,排列方式有PNP和NPN两种。常用的是NPN型,因为这种类型的硅管比搜缴容易制作。一个晶体管可用于构成一个放大器,而要使一个NPN型晶体管导通,基极必须加略大于发射极的正向电压,当晶体管逐渐趋近于饱和时,这个电压大约是+0.7V,这时C级与E级之间的电阻很小,甚至几乎可以看成是短路。对于NPN管,它是由2块N型半导体中间夹着一块P型半导体所组成,发射区与基区之间形成的PN结称为发射结,而集电区与基区形成的PN结称为集电结,三条引线分别称为发射极e、基极b和集电极c。当b点电位高于e点电位零点几伏时,发射结处于正偏状态,而C点电位高于b点电位几伏时,集电结处于反偏状态,集电极电源Ec要高于基极电源Ebo。在制造三极管时,有意识地使发射区的多数载流子浓度大于基区的,同时基区做得很薄,而且,要严格控制杂质含量,这样,一旦接通电源后,由于发射结正偏,发射区的多数载流子(电子)及基区的多数载流子(空穴)很容易地越过发射结互相向对方扩散,但因前者的浓度基大于后者,所以通过发射结的电流基本上是电子流,这股电子流称为发射极电流了。由于基区很薄,加上集电结的反偏,注入基区的电子大部分越过集电结进入集电区而形成集电集电流Ic,只剩下很少(1-10%)的电子在基区的空穴进行复合,被复合掉的基区空穴由基极电源Eb重新补给,从而形成了基极电流Ibo.根据电流连续性原理得:Ie=Ib+Ic,这就是说,在基极补充一个很小的Ib,就可以在集电极上得到一个较大的Ic,这就是所谓电流放大作用,Ic与Ib是维持一定的比例关系,即:β1=Ic/Ib 式中:β1--称为直流放大倍数,集电极电流的变化量△Ic与基极电流的变化量△Ib之比为:β= △Ic/△Ib。式中β--称为交流电流放大倍数,由于低频时β1和β的数值相差不大,所以有时为了方便起见,对两者不作严格区分,β值约为几十至一百多。三极管是一种电流放大器件,但在实际使用中常常利用三极管的电流放大作用,通过电阻转变为电压放大作用。三极管放大时管子内部的工作原理:1、发射区向基区发射电子,电源Ub经过电阻Rb加在发射结上,发射结正偏,发射区的多数载流子(自由电子)不断地越过发射结进入基区,形成发射极电流Ie。同时基区多数载流子也向发射区扩散,但由于多数载流子浓度远低于发射区载流子浓度,可以不考虑这个电流,因此可以认为发射结主要是电子流。2、基区中电子的扩散与复合,电子进入基区后,先在靠近发射结的附近密集,渐渐形成电子浓度差,在浓度差的作用下,促使电子流在基区中向集电结扩散,被集电结电场拉入集电区形成集电极电流Ic。也有很小一部分电子(因为基区很薄)与基区的空穴复合,扩散的电子流与复合电子流之比例决定了三极管的放大能力。3、集电区收集电子,由于集电结外加反向电压很大,这个反向电压产生的电场力将阻止集电区电子向基区扩散,同时将扩散到集电结附近的电子拉入集电区从而形成集电极主电流Icn。另外集电区的少数载流子(空穴)也会产生漂移运动,流向基区形成反向饱和电流,用Icbo来表示,其数值很小,但对温度却异常敏感。三极管的特性还有很多很多,这里由于篇幅原因就不一一介绍,有兴趣者可另行参考。
    主要元器件介绍完了、下面我们再来说说一些常用仪器:
一、示波器:
简单来说示波器就是用力现实波形的仪器,是一个图像显示设备。它是一种用途十分广泛的电子测量仪器。它能把肉眼看不见的电信号变换成看得见的图象,便于人们研究各种电现象的变化过程。示波器利用狭窄的、由高速电子组成的电子束,打在涂有荧光物质的屏面上,就可产生细小的光点。在被测信号的作用下,电子束就好像一支笔的笔尖,可以在屏面上描绘出被测信号的瞬时值的变化曲线。利用示波器能观察各种不同信号幅度随时间变化的波形曲线,还可以用它测试各种不同的电量,如电压、电流、频率、相位差、调幅度等等以图像形式在阴极射线管荧光屏上显示两个或两个以上参数间的函数关系的电子测量仪器。示波器根据对不同时域测量的要求有通用示波器、存储示波器和取样示波器三类。示波器还可分为模拟示波器和数字示波器,对于大多数的电子应用,无论模拟示波器和数字示波器都是可以胜任的,只是对于一些特定的应用,由于模拟示波器和数字示波器所具备的不同特性,才会出现适合和不适合的地方。模拟示波器:模拟示波器的工作方式是直接测量信号电压,并且通过从左到右穿过示波器屏幕的电子束在垂直方向描绘电压。数字示波器:数字示波器的工作方式是通过模拟转换器(ADC)把被测电压转换为数字信息。数字示波器捕获的是波形的一系列样值,并对样值进行存储,存储限度是判断累计的样值是否能描绘出波形为止,随后,数字示波器重构波形。数字示波器可以分为数字存储示波器(DSO),数字荧光示波器(DPO)和采样示波器。波形显示的基本原理:由示波管的原理可知,一个直流电压加到一对偏转板上时,将使光点在荧光屏上产生一个固定位移,该位移的大小与所加直流电压成正比。如果分别将两个直流电压同时加到垂直和水平两对偏转板上,则荧光屏上的光点位置就由两个方向的位移所共同决定。
二、信号发生器:
信号发生器是指产生所需参数的电测试信号的仪器。按信号波形可分为正弦信号、函数(波形)信号、脉冲信号和随机信号发生器等四大类。信号发生器用来产生频率为20Hz~200kHz的正弦信号(低频)。除具有电压输出外,有的还有功率输出。所以用途十分广泛,可用于测试或检修各种电子仪器设备中的低频放大器的频率特性、增益、通频带,也可用作高频信号发生器的外调制信号源。另外,在校准电子电压表时,它可提供交流信号电压。低频信号发生器的原理:系统包括主振级、主振输出调节电位器、电压放大器、输出衰减器、功率放大器、阻抗变换器(输出变压器)和指示电压表。 主振级产生低频正弦振荡信号,经电压放大器放大,达到电压输出幅度的要求,经输出衰减器可直接输出电压,用主振输出调节电位器调节输出电压的大小。信号发生器又称信号源或振荡器,在生产实践和科技领域中有着广泛的应用。各种波形曲线均可以用三角函数方程式来表示。能够产生多种波形,如三角波、锯齿波、矩形波(含方波)、正弦波的电路被称为函数信号发生器。
三、万用表:
万用表是电子测试领域最基本的工具,也是一种使用广泛的测试仪器。万用表又叫多用表、三用表(A,V,Ω也即电流,电压,电阻三用)、复用表、万能表,万用表分为指针式万用表和数字万用表。一般万用表可测量直流电流、直流电压、交流电压、电阻和音频电平等,有的还可以测交流电流、电容量、电感量及半导体的一些参数。万用表由表头、测量电路及转换开关等三个主要部分组成。数字式万用表已成为主流,已经取代模拟式仪表。与模拟式仪表相比,数字式仪表灵敏度高,精确度高,显示清晰,过载能力强,便于携带,使用更简单。但总的来说,指针式万用表和数字万用表各有优缺点。指针万用表是一种平均值式仪表,它具有直观、形象的读数指示。(一般读数值与指针摆动角度密切相关,所以很直观)。数字万用表是瞬时取样式仪表。它采用0.3秒取一次样来显示测量结果,有时每次取样结果只是十分相近,并不完全相同,这对于读取结果就不如指针式方便。 指针式万用表一般内部没有放大器,所以内阻较小,比如MF-10型,直流电压灵敏度为100千欧/伏。MF-500型的直流电压灵敏度为20千欧/伏。数字式万用表由于内部采用了运放电路,内阻可以做得很大,往往在1M欧或更大。(即可以得到更高的灵敏度)。这使得对被测电路的影响可以更小,测量精度较高。指针式万用表由于内阻较小,且多采用分立元件构成分流分压电路。所以频率特性是不均匀的(相对数字式来说),而数字式万用表的频率特性相对好一点。指针式万用表内部结构简单,所以成本较低,功能较少,维护简单,过流过压能力较强。数字式万用表内部采用了多种振荡,放大、分频保护等电路,所以功能较多。比如可以测量温度、频率(在一个较低的范围)、电容、电感,做信号发生器等等。对于初学者应当使用指针式万用表,对于非初学者应当使用两种仪表。
当然,有关电子方面的基础部分内容是很多很多的,由于篇幅原因,这里就不一一叙说了。最后说一句,要想学好电子技术,关键还是在于自身。要把应用的原理与动手实践相结合,不能好高骛远,要从基础开始,一步一个脚印。只有这样,你的能力才会逐步提高。
-----书山有路勤为径,学海无涯苦作舟!努力吧!

Common electronic components and equipment introduced
21 century is the century of electronic technology.
Electronic technology is a contemporary of the rapid development of the science. It in automatic control, communications, computers, home appliances, and other fields are applied widely. So, what is electronic technology? Say simply electronic technology is the application of electronic components or electronic equipment to achieve a particular purpose or complete a specific task of technology. Electronic technology research objects of electronic devices and is the basic function of the components of the circuit, and by some basic functions of circuit of have a variety of USES the device or system. If the electronic circuit simulation of input access other such as gas sensor, photosensitive, magnetic susceptibility, thermal and other sensitive components of, people can make a gas alarm, automatic street light controller, temperature controller, equipment an so on.
Because electronic technology has been deeply departments production, scientific research, economic management, the thorough people's life, therefore, the study the electronic technology is particularly important. It can be in the later study, life and work many respects brought you a lot of help. Higher vocational technology college electricity class specialized are required analog electronic and digital electronic these two subjects, they belong to the electronic technology introduction of foundation course. In the future will also turn to major area of study, such as single chip microcomputer, DSP, embedded, etc.
Learning electronic technology, to start from the base. The first step to know about electronic aspects to some common components and experimental instrument.Common components are: resistor, capacitor, inductor, transformer, diodes and transistors.And the experiment instrument commonly used are: the oscilloscope, the signal generator, a multimeter, etc.
Here is simple to introduce some of these devices and instruments:
Ⅰ.Resistors
Just as its name implies, is that the current motion a device,The current flows in resistor and add in the resistance on both ends of the voltage is proportional to the resistance of the resistance is inversely proportional to the.This is the great ohm's law.A resistor is used to do the current limit to protect components. Also can be used as bleeder, to minimize other circuit voltage, such as transistors offset circuit. A resistor can also used as the load of the circuit.Small power resistor is usually enclosed in plastic shell of carbon membrane structure, and high power resistor is usually coiling resistors, through the will of the big resistivity metal wire around the porcelain heart and manufactured. If a resistor resistance close to zero ohms (for example, two points of between large cross-section wire), the resistor to current no side effect, combination of the resistor is short circuit loop, current is infinite. If a resistor has infinite or a lot of resistance, the combination of the resistor can be as open loop, current is zero. The industrial used in between two kind of extreme resistor between, it has a certain resistance, but through some current, but current is not like a short circuit as big. The current limit of the resistor function similar to meet in two large diameter of pipe diameter tube between small limit the role of the flow of water. Resistance, English name resistance, usually abbreviation for R, it is a kind of basic properties of the conductor, and the size of the conductor, the material, the temperature. things.
Ⅱ.Capacitor
Capacitor abbreviation capacitance, also is the main components of electronic circuits. It can store electrical energy, has charged, and discharge and the exchange, the dc properties. In a sense, a bit like the battery capacitor. Although the way work are entirely different, but they can store electrical energy. The battery has two electrodes, in the internal battery, chemical reaction makes a electrode produce electronic, another electrode absorption electronic. And capacitor is much more simple, it cannot produce electronic-it just storage electronic. It is all kinds of electronic equipment the use of the indispensable one of the basic components. All kinds of capacitor in circuit can a different role, such as the coupling and the dc, bypass, rectifier filter, the high frequency filtering, tuning, energy storage and energy points frequency etc. Capacitors should be based on the circuit voltage, frequency, signal waveform, ac/dc component and the temperature and humidity conditions to be choose.Capacitor is to point to accommodate the ability of the electric field. Any electrostatic field is composed by many a capacitor, electrostatic field have capacitance, capacitance is described with electrostatic field. Generally think: isolated conductor and infinity constitute a capacitor, conductor grounding equivalent to received infinity, and the earth and connected to the whole. Electronic production need to use all kinds of capacitor, they were in a circuit plays a different role. And resistor similar, usually calls for the capacitance, with the letter "C" said. Just as its name implies, capacitors is "stored charge of containers". Although capacitor variety, but their basic structure and principles are the same. Two pieces of are located very close in the middle of a metal material (solid, gas or liquid) separated by, they form a capacitor. Two pieces of metal called plate, the intermediate material called medium. Capacitors are divided into fixed and capacity and capacity of the variable. But common is fixed capacity of the capacitance, most seen is electrolytic capacitors and ceramics capacitor. Different electricity
Ⅲ.Inductor
Inductor is able to put the electric energy into the energy and the components are stored. The structure of the inductor is similar to the transformer, but only a winding. Inductance instruments have certain inductance, it only stop current changes. If no current through inductors, it stop current through it; If there is a current through it, then it will disconnect circuit trying to maintain current unchanged. Inductor say again dominates the flow, reactor, dynamic reactor.。Inductor is always the current changes in for dc, inductor is no side effect, but for alternating current speaking, inductors have a exchange impedance, called inductance. The inductance quantity and the frequency of the alternating current relevant.We know that, magnetic, electric magnetic born born electric, both supplement each other, always along with the show. When a wire with the constant current through, there is always in wire up the magnetic field around the constant. When we connect this wire bending become all spirals, application of middle school studied electromagnetic induction's law, we can conclude that spirals happened in the magnetic field. Pick up, we will be the spirals in some current loop, when the circuits of direct current changes (such as from small perhaps instead), inductance of the magnetic field should also can change, change will bring change of the magnetic field of the "new current", by the law on electromagnetic induction, this "new current" certain and original dc in opposite directions, and in a short time about the change of dc motor in a certain resistance. But, once change completed, current firm up, magnetic field also no longer changes, they no longer have any obstacles happening.
Ⅳ.Transformers: 
The characteristics of transformer and inductor relevant. In a coil with alternating current, produce a magnetic field changes, in another coil produce ac voltage. The basic principle is such. Usually used in power transformer the booster, step-down, electrical isolation, impedance matching and circuit of the coupling between signal. Generally speaking, a direct current is can't enter the transformer, it will make the coil saturated, so a transformer usually think is a communication devices. Transformer components including implement body (iron core, winding, insulation, lead), transformer oil, fuel tanks and cooling device, pressure regulating devices, protection device (moisture absorption device, security, gas relay, airway ark and temperature measuring device storage, etc) and qualify the casing. 1. The iron core: iron core is the main part of the magnetic circuit in the transformer. Usually the content of silicon is higher, thickness of 0.35 mm respectively, 0.3 mm and 0.27 mm, is coated with insulation varnish hot rolling steel or cold-rolled steel pack and fold into, the iron core is divided into the core of column and two parts, the iron core is set around the column.
Ⅴ.Diodes:
Diode is the abbreviation of semiconductor diodes, it is by the semiconductor material made of PN junction. PN junction with one-way electrical conductivity. P type materials says the positive, N type materials called negative. When diode positive potential than negative potential, and the poor a value greater than open voltage bias as diode is positive. Then diode internal resistance is very small, with a larger current through the diode, through the size of the current depends on external circuit resistance. Conversely, when the positive potential below negative potential, diode reverse bias, at this moment the resistance of the internal diode is very high. When there is no to an external voltage, as the PN junction caused by poor concentration on both sides carriers diffusion current and self-built electric field of current caused equal in electricity and drift balance.Diode basically has the following characteristics: (1)Positive sex: plus the forward voltage, the positive characteristics of the initial part, the forward voltage is small enough to overcome PN junction of the electric field in blocking effect, positive current is almost zero, this is called a dead zone. This can't make diode conduction positive voltage called dead zone voltage. When positive voltage is greater than the dead zone after voltage, electric field in the PN junction is overcome, diode conduction, current and voltage increase with the rising rapidly. In normal use of the current range, the turn-on voltage of the diode almost unchanged, the voltage is called the forward voltage diode. (2)FanXiangXing: plus reverse voltage does not exceed a certain range, through the diode current minority carriers drift is formed by the movement reverse current, because the reverse current is small, diode is by state. The reverse current also called reverse saturated current or leakage current, diode current reverse saturated by temperature influence. Breakdown: plus more than a reverse voltage value,
Ⅵ.Transistor:
Transistor also called transistor, is one of the basic components of semiconductor, with current amplification effect, is the core of the electronic circuit components. Transistor is on a semiconductor substrate making two are located very close of PN junction, two PN junction the whole piece of semiconductor into three parts, and the middle part is the base area, two side part is the launch region and set the area, arrangement and two have PNP NPN. Commonly used is NPN type, because this type of silicon tube than SouJiao easy to make. A transistor can be used to form an amplifier, and should make an NPN transistor type conduction, base must be slightly higher than the forward voltage of the emitter, when the transistor is approaching to gradually saturated, the voltage is about + 0.7 V, then grade C and E level of between very little resistance, and almost even can be seen as a short circuit.For the NPN transistors, it is made of 2 N type semiconductor between them with a P type of semiconductor, launch area and the area formed between the PN junction called launch ", and set the area and the area of the formation of the PN junction called set electricity ", three lead respectively called emitter e, base and the collector b c. When b e points higher than the potential potential zero a few volts, launch "in a state is partial, and C points higher than the potential b potential a few volts, set in the electric and partial state, the collector power more than the base power Ebo Ec. In manufacturing transistor, consciously to make the majority carrier launch concentrations greater than the yankees, and the area to do very thin, and, it must be strictly control the content of impurities, that way, if you switch on the power, due to launch "are partial, launch region majority carrier (electronic) and the yankees majority carrier (hole) easily launch" to each other across each other spread, but by the former concentration and greater than the latter, so by sending "is basically the current electron stream, the electron stream says The characteristics of the transistor many, not reason owing to space here a introduction, are interested in can be reference.
The main components, below we had introduced some commonly used again for said instrument:
Ⅰ.Oscilloscope:
Simple for an oscilloscope is hard reality waveform instrument, is an image display device. It is a very versatile electronic measuring instrument. It can put the invisible to the naked eye electrical signal transform into visible images, for people to study various electric phenomenon change process. Using an oscilloscope narrow, by the electronic component of the electron beam, play with fluorescent material in the screen, can produce tiny points of light. In the measured signal under the action of electron beam is like a pen of the tip, on the screen can describe the measured signal of the instantaneous changing curves. Using an oscilloscope to view all kinds of different signal amplitude change over time of the wave curve, can also use it test various different power, such as voltage, current and frequency, phase difference, the amplitude and so on by image form in the cathode ray tube screen shows two or more than two parameters of the relationship between function of electronic measuring instrument. Oscilloscope according to the different time domain measurement requirements have general oscilloscope, storage oscilloscope and sampling oscilloscope three categories.Oscilloscope also may be classified as analog and digital oscilloscopes oscilloscope, for most of the electronic application, whether analogue oscilloscope and digital oscilloscopes can handle the job, just for some specific application, because the analogue oscilloscope and digital oscilloscopes have different characteristics, just can appear for and not suitable for place. Analogue oscilloscope: analogue oscilloscope way of working is a direct measurement signal voltage, and through the from left to right across the oscilloscope screen in vertical direction describe voltage electron beam. Digital oscilloscopes: digital oscilloscopes way of working is through the simulation converter (ADC) put the voltage to be measured into digital information. Digital oscilloscopes capture is a series of sample value wave, and the sample values in storage, storage limit the total sample value judgment is whether to depict the waveform so far, then, digital oscilloscopes reconstruction waveform. Digital oscilloscopes can be divided into digital storage oscilloscope (DSO), digital fluorescence oscilloscope (DPO) and a sampling oscilloscope. Waveform display base.
Ⅱ.Signal generator:
Signal generator is required to produce the parameters of the apparatus electrical testing signals. According to the signal waveform can be divided into sine signals, function (wave) signal, the pulse signal and random signal generator on four major.Used to generate frequency signal generator for 20 Hz ~ 200 kHz sine signals (low frequency). Besides having voltage output outside, some still have power output. So very versatile, can be used for testing or maintenance of various electronic instrument equipment of low frequency amplifier frequency characteristics of the, gain, passband, also used for the high frequency signal generator outside modulation signal generator. In addition, the calibration electronic voltmeter, it can provide the ac signal voltage. Low frequency signal generator principle: system includes main vibration level, main vibration output voltage amplifier, adjust potentiometer, attenuators, output power amplifier, impedance transformer (output transformer) and instructions voltmeter. Main vibration level produce low-frequency sine oscillation signal, the voltage amplifier amplification, achieve the requirement of voltage output amplitude, the output decay can be directly output voltage, with the main vibration adjust potentiometer output regulation of the size of the output voltage. Signal generator and says the signal source or oscillator, on the production practice and in the field of science and technology in a wide range of applications. Various waveform curve can be by trigonometric function equation. Have the ability to produce various waveform, such as triangle wave, the sawtooth wave, rectangle wave (including square wave), the circuit is called sine wave function signal generator.
 
Ⅲ.Multimeter:
A multimeter electronic test field is the most basic tools, is also a kind of use extensive testing instruments. A multimeter also called multimeters, three in table (A, V, Ω that current, voltage, resistance with three), reuse table, the multimeter, multimeter divided into an analogue meter and digital multimeter. General multimeter can measure dc current, dc volts, ac voltage, resistance and audio electricity equal, some still can examine ac current, electricity capacity, the quantity and the inductance of the semiconductor some parameters. A multimeter, measurement circuit and header by transfer switch and so on three main parts. Digital multimeters have become mainstream, has replaced the analog instrument. Compared with analog meter, digital meter high sensitivity, the accuracy is high, show clear, overload ability strong, easy to carry, using more simple.But on the whole, an analogue meter and digital multimeter has its advantages and disadvantages. Pointer multimeter is a kind of average type instrument, it is intuitionistic and image of the reading instruction. (generally read numerical and pointer is closely related to swing Angle so very intuitive). Digital multimeter is instantaneous take style instrument. It USES 0.3 seconds take a sample to display the measurement result, sometimes sample results only every time very similar, not exactly the same, this to read the results were not pointer type is convenient. An analogue meter general internal no amplifier, so less resistance, such as MF-10 type, dc voltage sensitivity for 100000 Europe/v. MF-500 type of dc voltage sensitivity for 20000 Europe/v. Digital multimeter due to internal used the amplifier, resistance can do much, often in 1 M Europe or greater. (namely can get higher sensitivity). This led to the influence of the circuit under test can be more small, has high accuracy. An analogue meter resistance due to the smaller, and use more division shunt components.
Of course, the basic parts of electronic content is many, many, because length reason, there is a different narrates. The last one said, if you want to learn electronic technology, the key lies in itself.The application of principle and practice, and the combination of can't chew, to start from the foundation, one step at a time. Only in this way, you will gradually improve the ability.
-----There is no royal road diameter is short work boat! Work hard ! 
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