在大(da)多(duo)數(shu)情況(kuang)(kuang)下，對電容(rong)器的容(rong)量要求(qiu)并不嚴格(ge)，如在去(qu)耦(ou)、低頻(pin)耦(ou)合(he)電路(lu)中(zhong)。在大(da)多(duo)數(shu)情況(kuang)(kuang)下，對電容(rong)器的容(rong)量要求(qiu)并不嚴格(ge)，如在去(qu)耦(ou)、低頻(pin)耦(ou)合(he)電路(lu)中(zhong)。

1．電容器的選用方(fang)法

（1）型號合適。一(yi)般用(yong)于低頻(pin)、旁路(lu)等場(chang)合，電(dian)(dian)(dian)氣特(te)性(xing)要求低時，可采用(yong)紙介(jie)、有機薄膜電(dian)(dian)(dian)容器(qi)；在高(gao)頻(pin)電(dian)(dian)(dian)路(lu)和高(gao)壓電(dian)(dian)(dian)路(lu)中，應選用(yong)云母(mu)或瓷介(jie)電(dian)(dian)(dian)容器(qi)；在電(dian)(dian)(dian)源濾波、去耦、延時等電(dian)(dian)(dian)路(lu)中，采用(yong)電(dian)(dian)(dian)解電(dian)(dian)(dian)容器(qi)。

（2）精(jing)度(du)合理。在(zai)大多數情(qing)況下，對電(dian)容(rong)器的(de)容(rong)量(liang)要(yao)求(qiu)并不嚴格，如在(zai)去耦(ou)、低頻(pin)耦(ou)合電(dian)路中(zhong)。但在(zai)振蕩回路、延時電(dian)路、音(yin)調控制等電(dian)路中(zhong)，電(dian)容(rong)器的(de)容(rong)量(liang)應(ying)盡可能和計(ji)算(suan)值一致。在(zai)各種濾(lv)波(bo)器和各種網(wang)絡中(zhong)，要(yao)求(qiu)精(jing)度(du)值應(ying)小于(yu)±（0.3～0.5）%。

（3）額(e)定工(gong)作(zuo)電(dian)壓應有余量。因為電(dian)容器(qi)額(e)定工(gong)作(zuo)電(dian)壓低于電(dian)路工(gong)作(zuo)電(dian)壓時，電(dian)容器(qi)就可能爆(bao)炸。一般(ban)來說(shuo)，宜(yi)選用額(e)定工(gong)作(zuo)電(dian)壓高于電(dian)路工(gong)作(zuo)電(dian)壓的20%以上。

（4）通過電(dian)容器的交(jiao)流電(dian)壓和電(dian)流值不能(neng)超過額定值。有性(xing)的電(dian)解電(dian)容器不宜在交(jiao)流電(dian)路中使(shi)用，但可(ke)以在脈(mo)動電(dian)路中使(shi)用。

（5）因(yin)地(di)制宜選用(yong)(yong)。氣候炎熱(re)、工作(zuo)溫度(du)較高的(de)環(huan)境，設計時宜將電(dian)容(rong)器(qi)遠離(li)熱(re)源或(huo)采(cai)取通(tong)風降溫措施；寒(han)冷地(di)區使(shi)用(yong)(yong)普(pu)通(tong)電(dian)解電(dian)容(rong)器(qi)時，其電(dian)解液易(yi)于結(jie)冰而(er)失效，使(shi)電(dian)子裝(zhuang)置無法工作(zuo)，因(yin)而(er)選擇鉭電(dian)解電(dian)容(rong)器(qi)合適(shi)。在(zai)濕度(du)大的(de)環(huan)境中，應選用(yong)(yong)密封型電(dian)容(rong)器(qi)。

2．選用電容器時(shi)的注(zhu)意事項(xiang)

（1）電(dian)(dian)(dian)容器(qi)裝接前應(ying)注意進行測量(liang)，看(kan)其是否短(duan)路、斷(duan)路或漏電(dian)(dian)(dian)嚴(yan)重，并在裝入(ru)電(dian)(dian)(dian)路時，應(ying)使電(dian)(dian)(dian)容器(qi)的標(biao)志易于(yu)觀察(cha)，且標(biao)志順序一致。

（2）電路中，電容器(qi)兩端的電壓(ya)不(bu)能超過電容器(qi)本身(shen)的工(gong)作(zuo)電壓(ya)。裝(zhuang)接時注意正、負性不(bu)能接反。

（3）當(dang)現(xian)有電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)與電(dian)(dian)(dian)(dian)路要求的(de)(de)容(rong)(rong)(rong)量(liang)(liang)或(huo)耐(nai)壓(ya)(ya)(ya)不(bu)合適時(shi)，可以(yi)采用串聯(lian)或(huo)并聯(lian)的(de)(de)方法予以(yi)調(diao)整。當(dang)兩(liang)個(ge)工作電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)同(tong)(tong)的(de)(de)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)并聯(lian)時(shi)，耐(nai)壓(ya)(ya)(ya)值取決于低的(de)(de)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)；當(dang)兩(liang)個(ge)容(rong)(rong)(rong)量(liang)(liang)不(bu)同(tong)(tong)的(de)(de)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)串聯(lian)時(shi)，容(rong)(rong)(rong)量(liang)(liang)小(xiao)的(de)(de)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)所承受的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)高于容(rong)(rong)(rong)量(liang)(liang)大的(de)(de)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)。

（4）技術要(yao)求不同(tong)的(de)(de)電(dian)(dian)(dian)(dian)路，應選(xuan)(xuan)用(yong)不同(tong)類型的(de)(de)電(dian)(dian)(dian)(dian)容(rong)器(qi)。例如，諧振回路中(zhong)需要(yao)介(jie)質損耗(hao)小的(de)(de)電(dian)(dian)(dian)(dian)容(rong)器(qi)，應選(xuan)(xuan)用(yong)高(gao)頻陶瓷電(dian)(dian)(dian)(dian)容(rong)器(qi)（CC型）；隔(ge)直、耦合電(dian)(dian)(dian)(dian)容(rong)可選(xuan)(xuan)紙(zhi)介(jie)、滌(di)綸、電(dian)(dian)(dian)(dian)解等電(dian)(dian)(dian)(dian)容(rong)器(qi)；低頻濾波電(dian)(dian)(dian)(dian)路一般應選(xuan)(xuan)用(yong)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)器(qi)；旁路電(dian)(dian)(dian)(dian)容(rong)可選(xuan)(xuan)滌(di)綸、紙(zhi)介(jie)、陶瓷和電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)器(qi)。

（5）選用(yong)電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)時應(ying)根據電(dian)(dian)路(lu)中(zhong)信號(hao)頻率(lv)的(de)(de)高(gao)低來選擇。一個電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)可(ke)等(deng)效(xiao)成一個R、L、C二端線性網絡，不同(tong)類型的(de)(de)電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)其等(deng)效(xiao)參數R、L、C的(de)(de)差異很大。等(deng)效(xiao)電(dian)(dian)感大酌電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)（如電(dian)(dian)解(jie)電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)）不適合用(yong)于耦合、旁路(lu)高(gao)頻信號(hao)；等(deng)效(xiao)電(dian)(dian)阻大的(de)(de)電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)不適合用(yong)于Q值要求(qiu)高(gao)的(de)(de)振(zhen)蕩回路(lu)中(zhong)。為滿足從低頻到高(gao)頻濾波旁路(lu)的(de)(de)要求(qiu)，在實際電(dian)(dian)路(lu)中(zhong)，常將(jiang)一個大容(rong)(rong)(rong)(rong)量(liang)的(de)(de)電(dian)(dian)解(jie)電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)與一個小容(rong)(rong)(rong)(rong)量(liang)的(de)(de)適合于高(gao)頻的(de)(de)電(dian)(dian)容(rong)(rong)(rong)(rong)器(qi)并聯(lian)使用(yong)。