用6V免維護電瓶供電的應急手提燈在農村應用非常廣泛，其配用的充電器是(shi)一(yi)個(ge)變壓(ya)器降(jiang)壓(ya)、單二極(ji)管半(ban)波整流裝置，充(chong)電(dian)(dian)時間很難掌握。由于電(dian)(dian)池虧電(dian)(dian)或過充(chong)電(dian)(dian)往(wang)往(wang)會造(zao)成電(dian)(dian)池壽命縮短，本人設計制作了一(yi)個(ge)簡易自動充(chong)電(dian)(dian)裝置，可(ke)有效延長電(dian)(dian)池壽命。

        元件(jian)選用與制(zhi)作

　　T1可(ke)使(shi)用(yong)(yong)10VA左右，次(ci)級(ji)有9V和12V輸(shu)出的(de)電(dian)(dian)源變壓(ya)(ya)器(qi)(qi)(qi)，若(ruo)使(shi)用(yong)(yong)原配變壓(ya)(ya)器(qi)(qi)(qi)(次(ci)級(ji)輸(shu)出9V)時(shi)，繼(ji)(ji)(ji)電(dian)(dian)器(qi)(qi)(qi)K1工作(zuo)電(dian)(dian)壓(ya)(ya)也應選(xuan)9V。繼(ji)(ji)(ji)電(dian)(dian)器(qi)(qi)(qi)選(xuan)用(yong)(yong)4088、4089、JRX-13F等(deng)(deng)12V繼(ji)(ji)(ji)電(dian)(dian)器(qi)(qi)(qi)。VT使(shi)用(yong)(yong)9013、9014、8050等(deng)(deng)小(xiao)功(gong)率晶體管，要(yao)求(qiu)穿透電(dian)(dian)流要(yao)小(xiao)，開(kai)(kai)關(guan)特性好(hao)，β=100～1500光耦合器(qi)(qi)(qi)IC可(ke)用(yong)(yong)4N23、4N25、4N33等(deng)(deng)型號(hao)。C1的(de)耐壓(ya)(ya)不得小(xiao)于450V，容(rong)量(liang)取220nF～470nF，容(rong)量(liang)越(yue)大(da)，LED1越(yue)亮。調(diao)試時(shi)，先斷(duan)開(kai)(kai)VD2，在X1、X2兩端(duan)加7.5V直流電(dian)(dian)壓(ya)(ya)，從大(da)到小(xiao)調(diao)電(dian)(dian)位器(qi)(qi)(qi)RP，使(shi)4N250⑤腳電(dian)(dian)位突然下降(K1釋放)即(ji)可(ke)。

　　工作原理

　　電路如圖1所示。GB為待充電電池，平時只要不再使用，就將充電器插頭X1、X2插入手提燈的充電插孔內。按一下啟動按鈕SB，220V交流市電經保險Fu、SB加在電源變壓器T1初級。其次級輸出兩路交流電壓：交流12V經VD1半波整流、C2平滑濾波，使VT導通。繼電器K1吸合，K1-1閉合。此時松手使SB斷開后，充電器仍(reng)然工作。圖(tu)中(zhong)，R2是VT的偏置(zhi)電(dian)(dian)(dian)阻;C1是降(jiang)壓電(dian)(dian)(dian)容，LED1(紅)為市電(dian)(dian)(dian)電(dian)(dian)(dian)源(yuan)指(zhi)示管(guan)(guan);啟動(dong)完(wan)成(cheng)后(hou)，交流(liu)9V電(dian)(dian)(dian)壓經VD2整流(liu)為電(dian)(dian)(dian)瓶GB充(chong)(chong)電(dian)(dian)(dian)，LED2(綠(lv))為充(chong)(chong)電(dian)(dian)(dian)指(zhi)示管(guan)(guan)。隨(sui)著充(chong)(chong)電(dian)(dian)(dian)過程的進行，電(dian)(dian)(dian)瓶兩端電(dian)(dian)(dian)壓不(bu)斷上(shang)升，當升至(zhi)極(ji)限電(dian)(dian)(dian)壓值(約7.5V)時(shi)，穩壓管(guan)(guan)VD3反向擊穿導通，光耦(ou)合器4N25①、②腳(jiao)內發光二極(ji)管(guan)(guan)發光，④、⑤腳(jiao)內光電(dian)(dian)(dian)管(guan)(guan)受光后(hou)隨(sui)之導通，VT基極(ji)被下拉(約0V)而失去正偏壓，所以VT截止(zhi)(zhi)，K1釋放使K1-1斷開，停止(zhi)(zhi)充(chong)(chong)電(dian)(dian)(dian)，充(chong)(chong)電(dian)(dian)(dian)指(zhi)示管(guan)(guan)LED2熄(xi)滅。