穩(wen)壓(ya)(ya)器是一種能自動調整輸(shu)出電(dian)(dian)(dian)(dian)壓(ya)(ya)的供(gong)(gong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)路或供(gong)(gong)電(dian)(dian)(dian)(dian)設(she)備，其(qi)作用是將波動較大和(he)達不到電(dian)(dian)(dian)(dian)器設(she)備要求的電(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)壓(ya)(ya)穩(wen)定在它的設(she)定值(zhi)范圍內，使各種電(dian)(dian)(dian)(dian)路或電(dian)(dian)(dian)(dian)器設(she)備能在額定工(gong)作電(dian)(dian)(dian)(dian)壓(ya)(ya)下正(zheng)常工(gong)作。

最初的(de)電(dian)(dian)力穩壓器(qi)(qi)是(shi)靠繼電(dian)(dian)器(qi)(qi)的(de)跳動(dong)穩定電(dian)(dian)壓的(de)。當(dang)電(dian)(dian)網(wang)電(dian)(dian)壓出(chu)現(xian)波動(dong)時，電(dian)(dian)力穩壓器(qi)(qi)的(de)自動(dong)糾正電(dian)(dian)路(lu)(lu)啟動(dong)，使內部繼電(dian)(dian)器(qi)(qi)動(dong)作(zuo)。迫使輸出(chu)電(dian)(dian)壓保持在設定值附(fu)近(jin)，這種(zhong)電(dian)(dian)路(lu)(lu)優點是(shi)電(dian)(dian)路(lu)(lu)簡單，缺點是(shi)穩壓精度(du)不高(gao)并(bing)且每一次繼電(dian)(dian)器(qi)(qi)跳動(dong)換擋，都會使供電(dian)(dian)電(dian)(dian)源發生(sheng)(sheng)一次瞬時的(de)中斷并(bing)產(chan)生(sheng)(sheng)火花干(gan)擾(rao)。

這對電(dian)(dian)腦設備的讀(du)寫工作(zuo)干擾很大(da)，容(rong)易造成(cheng)電(dian)(dian)腦出現錯誤信號，嚴重時還會使硬(ying)盤損壞。

高(gao)質量的(de)小型穩(wen)壓器(qi)，大多采(cai)用電機拖動碳刷的(de)方法穩(wen)定電壓，這種穩(wen)壓器(qi)對電器(qi)設備產生的(de)干擾(rao)很小穩(wen)壓精度相對較高(gao)。