交流電(dian)(dian)網電(dian)(dian)壓(ya)的波動和(he)(he)負載電(dian)(dian)流的變(bian)化都會使(shi)整流電(dian)(dian)源的輸(shu)出(chu)電(dian)(dian)壓(ya)和(he)(he)電(dian)(dian)流隨(sui)之變(bian)動，因(yin)此要求較(jiao)高的電(dian)(dian)子電(dian)(dian)路必須使(shi)用穩(wen)壓(ya)電(dian)(dian)源。
(1 ）穩壓管并聯(lian)穩壓電路(lu)
用一個穩(wen)(wen)壓(ya)管和負載并聯(lian)的(de)電(dian)(dian)(dian)路是(shi)最簡單的(de)穩(wen)(wen)壓(ya)電(dian)(dian)(dian)路，見圖(tu) 4 （ a ）。圖(tu)中(zhong) R 是(shi)限流電(dian)(dian)(dian)阻(zu)。這(zhe)個電(dian)(dian)(dian)路的(de)輸出電(dian)(dian)(dian)流很小，它的(de)輸出電(dian)(dian)(dian)壓(ya)等(deng)于穩(wen)(wen)壓(ya)管的(de)穩(wen)(wen)定電(dian)(dian)(dian)壓(ya)值(zhi) V Z 。
(2 ）串聯型(xing)穩壓電(dian)路
有(you)放大(da)和負反饋作(zuo)用(yong)的(de)串聯(lian)型(xing)穩(wen)壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)路(lu)(lu)是(shi)最(zui)常用(yong)的(de)穩(wen)壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)路(lu)(lu)。它(ta)的(de)電(dian)(dian)(dian)(dian)路(lu)(lu)和框圖見圖 4 （ b ）、（ c ）。它(ta)是(shi)從取樣電(dian)(dian)(dian)(dian)路(lu)(lu)（ R3 、 R4 ）中(zhong)檢測出(chu)(chu)輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)的(de)變(bian)動，與基準電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)（ V Z ）比(bi)較(jiao)并經放大(da)器（ VT2 ）放大(da)后加到調整(zheng)(zheng)管(guan)(guan)(guan)(guan)（ VT1 ）上，使(shi)調整(zheng)(zheng)管(guan)(guan)(guan)(guan)兩(liang)端(duan)的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)隨著(zhu)變(bian)化。如果輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)下降(jiang)(jiang)，就(jiu)使(shi)調整(zheng)(zheng)管(guan)(guan)(guan)(guan)管(guan)(guan)(guan)(guan)壓(ya)(ya)(ya)(ya)降(jiang)(jiang)也降(jiang)(jiang)低，于(yu)是(shi)輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)被提升(sheng)；如果輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)上升(sheng)，就(jiu)使(shi)調整(zheng)(zheng)管(guan)(guan)(guan)(guan)管(guan)(guan)(guan)(guan)壓(ya)(ya)(ya)(ya)降(jiang)(jiang)也上升(sheng)，于(yu)是(shi)輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)被壓(ya)(ya)(ya)(ya)低，結果就(jiu)使(shi)輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)基本不變(bian)。在(zai)這個電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)基礎上發展成很多(duo)變(bian)型(xing)電(dian)(dian)(dian)(dian)路(lu)(lu)或增(zeng)加一些輔(fu)助(zhu)電(dian)(dian)(dian)(dian)路(lu)(lu)，如用(yong)復合管(guan)(guan)(guan)(guan)作(zuo)調整(zheng)(zheng)管(guan)(guan)(guan)(guan)，輸(shu)(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)可調的(de)電(dian)(dian)(dian)(dian)路(lu)(lu)，用(yong)運算放 大(da)器作(zuo)比(bi)較(jiao)放大(da)的(de)電(dian)(dian)(dian)(dian)路(lu)(lu)，以(yi)及增(zeng)加輔(fu)助(zhu)電(dian)(dian)(dian)(dian)源和過流保護電(dian)(dian)(dian)(dian)路(lu)(lu)等。
（ 3 ）開(kai)關型穩壓電路
近(jin)年來廣泛(fan)應用的新型穩壓電源是(shi)開關型穩壓電源。它的調整(zheng)管工作在開關狀(zhuang)態，本身功耗很(hen)小，所以(yi)有效率高、體(ti)積小等優點，但電路比較(jiao)復雜。
開關(guan)穩(wen)壓電(dian)(dian)源從原(yuan)(yuan)理(li)上分有很多(duo)種。它的基本(ben)原(yuan)(yuan)理(li)框圖(tu)見(jian)圖(tu) 4 （ d ）。圖(tu)中電(dian)(dian)感 L 和電(dian)(dian)容 C 是(shi)儲(chu)能和濾波(bo)元件，二(er)極管 VD 是(shi)調整管在關(guan)斷(duan)狀態時(shi)為(wei) L 、 C 濾波(bo)器(qi)提供電(dian)(dian)流通路(lu)的續(xu)流二(er)極管。開關(guan)穩(wen)壓電(dian)(dian)源的開關(guan)頻率都很高(gao)(gao)，一般為(wei)幾(ji)～幾(ji)十(shi)千赫，所以電(dian)(dian)感器(qi)的體積不(bu)很大，輸出電(dian)(dian)壓中的高(gao)(gao)次諧波(bo)也(ye)不(bu)多(duo)。
它的(de)基(ji)本工作原理是 : 從取樣電路（ R3 、 R4 ）中檢測出取樣電壓經(jing)比較(jiao)放大后去控制一個(ge)矩(ju)形(xing)波(bo)(bo)發生器(qi)。矩(ju)形(xing)波(bo)(bo)發生器(qi)的(de)輸(shu)出脈沖(chong)是控制調整管（ VT ）的(de)導通(tong)和(he)截(jie)止時間(jian)的(de)。如果輸(shu)出電壓 U 0 因(yin)為電網電壓或負載電流的(de)變動而降低，就會使(shi)矩(ju)形(xing)波(bo)(bo)發生器(qi)的(de)輸(shu)出脈沖(chong)變寬，于是調整管導通(tong)時間(jian)增大，使(shi) L 、 C 儲能電路得到(dao)更多的(de)能量(liang)，結果是使(shi)輸(shu)出電壓 U 0 被(bei)提升，達到(dao)了(le)穩(wen)定輸(shu)出電壓的(de)目(mu)的(de)。
（ 4 ）集成(cheng)化穩(wen)壓(ya)電路
近年來已(yi)有(you)(you)大量集成穩(wen)壓(ya)(ya)器產(chan)品(pin)(pin)問(wen)世，品(pin)(pin)種很多(duo)，結構(gou)也各(ge)不相同(tong)。目前用得較多(duo)的(de)(de)有(you)(you)三端集成穩(wen)壓(ya)(ya)器，有(you)(you)輸出正電(dian)(dian)(dian)壓(ya)(ya)的(de)(de) CW7800 系(xi)列和輸出負電(dian)(dian)(dian)壓(ya)(ya)的(de)(de) CW7900 系(xi)列等產(chan)品(pin)(pin)。輸出電(dian)(dian)(dian)流從 0.1A ～ 3A ，輸出電(dian)(dian)(dian)壓(ya)(ya)有(you)(you) 5V、 6V 、 9V 、 12V 、 15V 、 18V 、 24V 等多(duo)種。
這種集成穩(wen)壓器只有三個端子，穩(wen)壓電(dian)路(lu)(lu)的所有部分包(bao)括大功率調整管以及保護電(dian)路(lu)(lu)等都已集成在芯(xin)片內。使(shi)用時只要加上散熱片后接到整流濾波電(dian)路(lu)(lu)后面就行了。外圍元件少，穩(wen)壓精度(du)高，工作可(ke)靠，一(yi)般不需調試。
（ e ）是一個三端穩壓器電(dian)(dian)路。圖中 C 是主濾(lv)波電(dian)(dian)容(rong)(rong)， C1 、 C2 是消除寄生振蕩的電(dian)(dian)容(rong)(rong) ,VD 是為防(fang)止輸入短路燒壞集(ji)成塊而使用(yong)的保護二極管。
