交流(liu)電網電壓(ya)(ya)的(de)(de)波動和負載電流(liu)的(de)(de)變化(hua)都會使(shi)整流(liu)電源的(de)(de)輸出(chu)電壓(ya)(ya)和電流(liu)隨之變動，因此要求較高的(de)(de)電子電路必須使(shi)用穩壓(ya)(ya)電源。
(1 ）穩壓(ya)管(guan)并聯穩壓(ya)電(dian)路(lu)
用一個穩壓管(guan)和負(fu)載并聯的電(dian)路是(shi)最(zui)簡單的穩壓電(dian)路，見(jian)圖 4 （ a ）。圖中 R 是(shi)限流(liu)(liu)電(dian)阻(zu)。這個電(dian)路的輸出電(dian)流(liu)(liu)很(hen)小(xiao)，它的輸出電(dian)壓等于(yu)穩壓管(guan)的穩定電(dian)壓值 V Z 。
(2 ）串聯(lian)型穩(wen)壓電路
有放大(da)和負反饋作用(yong)(yong)的串聯型穩壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)是(shi)(shi)最常用(yong)(yong)的穩壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)。它的電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)和框(kuang)圖(tu)見圖(tu) 4 （ b ）、（ c ）。它是(shi)(shi)從取樣電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)（ R3 、 R4 ）中檢(jian)測出(chu)(chu)輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)的變(bian)(bian)動，與基準電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)（ V Z ）比較(jiao)(jiao)并經放大(da)器（ VT2 ）放大(da)后加到(dao)調整(zheng)管(guan)（ VT1 ）上(shang)，使調整(zheng)管(guan)兩端(duan)的電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)隨著變(bian)(bian)化。如果(guo)輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)下降(jiang)(jiang)，就使調整(zheng)管(guan)管(guan)壓(ya)(ya)(ya)(ya)降(jiang)(jiang)也(ye)降(jiang)(jiang)低，于(yu)是(shi)(shi)輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)被(bei)提升(sheng)(sheng)；如果(guo)輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)上(shang)升(sheng)(sheng)，就使調整(zheng)管(guan)管(guan)壓(ya)(ya)(ya)(ya)降(jiang)(jiang)也(ye)上(shang)升(sheng)(sheng)，于(yu)是(shi)(shi)輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)被(bei)壓(ya)(ya)(ya)(ya)低，結(jie)果(guo)就使輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)基本不變(bian)(bian)。在這個(ge)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的基礎(chu)上(shang)發(fa)展(zhan)成很多變(bian)(bian)型電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)或增(zeng)加一些輔助(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，如用(yong)(yong)復(fu)合管(guan)作調整(zheng)管(guan)，輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)可調的電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，用(yong)(yong)運(yun)算放 大(da)器作比較(jiao)(jiao)放大(da)的電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，以及增(zeng)加輔助(zhu)電(dian)(dian)(dian)(dian)(dian)(dian)源和過(guo)流保(bao)護(hu)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)等(deng)。
（ 3 ）開關型穩壓電(dian)路
近年(nian)來廣泛(fan)應用的(de)新型穩壓電(dian)源(yuan)是開(kai)關型穩壓電(dian)源(yuan)。它(ta)的(de)調(diao)整管工作在(zai)開(kai)關狀態，本身功(gong)耗很小(xiao)(xiao)，所(suo)以有效率高、體積小(xiao)(xiao)等優點，但(dan)電(dian)路(lu)比較復雜(za)。
開(kai)關(guan)穩壓(ya)(ya)電源從原理上(shang)分有很多(duo)種。它的(de)基本原理框圖(tu)見(jian)圖(tu) 4 （ d ）。圖(tu)中電感 L 和電容 C 是儲(chu)能(neng)和濾波(bo)元(yuan)件(jian)，二極(ji)管(guan) VD 是調整管(guan)在(zai)關(guan)斷狀態(tai)時為(wei) L 、 C 濾波(bo)器提供(gong)電流通路的(de)續流二極(ji)管(guan)。開(kai)關(guan)穩壓(ya)(ya)電源的(de)開(kai)關(guan)頻(pin)率都很高，一(yi)般為(wei)幾(ji)～幾(ji)十(shi)千赫(he)，所以電感器的(de)體積(ji)不(bu)很大，輸出電壓(ya)(ya)中的(de)高次諧波(bo)也不(bu)多(duo)。
它(ta)的(de)(de)基(ji)本工作原理(li)是 : 從取樣電路（ R3 、 R4 ）中檢測出(chu)取樣電壓(ya)經比(bi)較放大(da)后去控制(zhi)一個矩形(xing)波(bo)發生器(qi)。矩形(xing)波(bo)發生器(qi)的(de)(de)輸(shu)出(chu)脈沖是控制(zhi)調(diao)整(zheng)管（ VT ）的(de)(de)導(dao)通(tong)(tong)和(he)截止時間的(de)(de)。如果輸(shu)出(chu)電壓(ya) U 0 因(yin)為電網(wang)電壓(ya)或(huo)負載電流的(de)(de)變(bian)動而降(jiang)低(di)，就會(hui)使矩形(xing)波(bo)發生器(qi)的(de)(de)輸(shu)出(chu)脈沖變(bian)寬，于是調(diao)整(zheng)管導(dao)通(tong)(tong)時間增大(da)，使 L 、 C 儲能電路得到更多的(de)(de)能量，結果是使輸(shu)出(chu)電壓(ya) U 0 被提(ti)升(sheng)，達到了穩定輸(shu)出(chu)電壓(ya)的(de)(de)目(mu)的(de)(de)。
（ 4 ）集成化(hua)穩壓(ya)電路
近年(nian)來已有(you)(you)(you)大量集(ji)(ji)成(cheng)穩壓(ya)(ya)器產品(pin)問(wen)世，品(pin)種(zhong)很多，結(jie)構也各不相(xiang)同。目前(qian)用得(de)較多的(de)(de)有(you)(you)(you)三端(duan)集(ji)(ji)成(cheng)穩壓(ya)(ya)器，有(you)(you)(you)輸(shu)出正電壓(ya)(ya)的(de)(de) CW7800 系列和(he)輸(shu)出負電壓(ya)(ya)的(de)(de) CW7900 系列等(deng)產品(pin)。輸(shu)出電流從 0.1A ～ 3A ，輸(shu)出電壓(ya)(ya)有(you)(you)(you) 5V、 6V 、 9V 、 12V 、 15V 、 18V 、 24V 等(deng)多種(zhong)。
這種集成穩壓(ya)器只有(you)三個端(duan)子，穩壓(ya)電路(lu)的所(suo)有(you)部(bu)分(fen)包括大功率調整管(guan)以及保護電路(lu)等都已集成在(zai)芯(xin)片內。使用(yong)時(shi)只要加上散熱(re)片后(hou)接(jie)到整流濾(lv)波電路(lu)后(hou)面就行了。外圍元件少，穩壓(ya)精度高，工作可靠，一般不需(xu)調試。
（ e ）是一個三端穩壓器電路(lu)。圖中 C 是主濾波電容(rong)， C1 、 C2 是消(xiao)除(chu)寄生振蕩的(de)電容(rong) ,VD 是為防止輸(shu)入(ru)短路(lu)燒壞集成塊(kuai)而使(shi)用的(de)保護二極(ji)管(guan)。
