1、安規電容器基本特性知識

安規電容器是一種可儲存電能的元件(儲存電荷)。它的結構非常簡單，主要是由兩個互相靠近的導體，中間夾一層不導電的絕緣介質構成的。兩塊金屬板相對平行放置，不相接觸，就可構成一個簡單的電容器。電容器具有隔直流、通交流的特點。因為構成電容器的兩塊不相接觸的平行金屬板是絕緣的，直流電流不能通過電容器，而交流電流可以通過電容器。下圖為電容器的充、放電原理及基本工作特性示意圖。

充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程(cheng):把電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器的兩端分別接到電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的正、負磁，電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)流就會(hui)對電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器有電(dian)(dian)(dian)(dian)(dian)(dian)荷后就產生(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)壓，當電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)所充(chong)的電(dian)(dian)(dian)(dian)(dian)(dian)壓與電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)壓相等時，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)停止。電(dian)(dian)(dian)(dian)(dian)(dian)路中不再有電(dian)(dian)(dian)(dian)(dian)(dian)流流動，相當于開路。

放電(dian)(dian)(dian)過程:將電(dian)(dian)(dian)路中的(de)(de)(de)開關斷開，在電(dian)(dian)(dian)源斷開的(de)(de)(de)一-瞬間，電(dian)(dian)(dian)容器上(shang)的(de)(de)(de)電(dian)(dian)(dian)荷會通過電(dian)(dian)(dian)阻流動(dong)，電(dian)(dian)(dian)流的(de)(de)(de)方向與原充電(dian)(dian)(dian)時的(de)(de)(de)電(dian)(dian)(dian)流方向相(xiang)反。隨(sui)著(zhu)電(dian)(dian)(dian)流的(de)(de)(de)流動(dong)，兩(liang)車(che)之間的(de)(de)(de)電(dian)(dian)(dian)壓也逐漸降(jiang)低(di)，直到兩(liang)磁上(shang)的(de)(de)(de)正、負電(dian)(dian)(dian)荷完全(quan)消失，這種現象叫做“放電(dian)(dian)(dian)”。

提示電(dian)容(rong)器的兩個重(zhong)要特性(xing)：

①阻(zu)止直流電(dian)流通(tong)過，允許(xu)交流電(dian)流通(tong)過;

②電容(rong)器的(de)阻(zu)(zu)抗與傳輸(shu)的(de)信(xin)(xin)號(hao)頻率有關，信(xin)(xin)號(hao)的(de)頻率越(yue)高，電容(rong)器的(de)阻(zu)(zu)抗越(yue)小(xiao)。

2、安(an)規電容(rong)器的濾(lv)波作用

電(dian)(dian)(dian)容器(qi)的充電(dian)(dian)(dian)和(he)放電(dian)(dian)(dian)需要一(yi)個過程(cheng)，電(dian)(dian)(dian)壓不能(neng)突(tu)(tu)變(bian)。根據這個特性(xing)，電(dian)(dian)(dian)容器(qi)在電(dian)(dian)(dian)路中可以起到濾波(bo)或(huo)信號傳輸的作用。電(dian)(dian)(dian)容器(qi)的濾波(bo)功能(neng)是(shi)指能(neng)夠消除脈沖和(he)噪(zao)波(bo)功能(neng)，是(shi)電(dian)(dian)(dian)容器(qi)很基本、且突(tu)(tu)出的功能(neng)。

3.安規(gui)電(dian)容器的耦合功(gong)能

電容器(qi)對(dui)交(jiao)(jiao)流(liu)(liu)(liu)信號的(de)阻抗(kang)(kang)較小，易于通過，而對(dui)直流(liu)(liu)(liu)信號的(de)阻抗(kang)(kang)很大，可視為斷路。在放大器(qi)中，無磁(ci)性電容器(qi)常作為交(jiao)(jiao)流(liu)(liu)(liu)信號輸(shu)入(ru)和輸(shu)出傳(chuan)輸(shu)的(de)耦合器(qi)件(jian)，即將前級(ji)電路的(de)交(jiao)(jiao)流(liu)(liu)(liu)信號耦合至后(hou)級(ji)電路。

4.可變(bian)電容器的功(gong)能應用(yong)

由(you)于可(ke)變電(dian)容(rong)(rong)器電(dian)容(rong)(rong)量(liang)可(ke)調(diao)的特(te)性，其主要應(ying)用于需要調(diao)整電(dian)容(rong)(rong)量(liang)電(dian)路中，如收音機(ji)調(diao)諧(xie)電(dian)路、選頻電(dian)路等(deng)。