用6V免維護電瓶供電的應急手提燈在農村應用非常廣泛，其配用的充電器是一個變壓器降壓、單二極管半波(bo)整流裝置(zhi)，充(chong)電(dian)(dian)(dian)時間(jian)很(hen)難(nan)掌握。由于電(dian)(dian)(dian)池(chi)虧電(dian)(dian)(dian)或過(guo)充(chong)電(dian)(dian)(dian)往往會造(zao)成電(dian)(dian)(dian)池(chi)壽命(ming)縮短，本人設計制作了一個簡(jian)易(yi)自動充(chong)電(dian)(dian)(dian)裝置(zhi)，可有效延(yan)長電(dian)(dian)(dian)池(chi)壽命(ming)。

        元件(jian)選用(yong)與制(zhi)作

　　T1可使用10VA左右，次(ci)級有9V和12V輸出的電(dian)(dian)源變(bian)(bian)壓(ya)器(qi)，若使用原配變(bian)(bian)壓(ya)器(qi)(次(ci)級輸出9V)時(shi)，繼(ji)電(dian)(dian)器(qi)K1工作電(dian)(dian)壓(ya)也應選9V。繼(ji)電(dian)(dian)器(qi)選用4088、4089、JRX-13F等12V繼(ji)電(dian)(dian)器(qi)。VT使用9013、9014、8050等小(xiao)(xiao)功率晶體管，要求穿透(tou)電(dian)(dian)流要小(xiao)(xiao)，開(kai)關特性好，β=100～1500光耦合器(qi)IC可用4N23、4N25、4N33等型(xing)號。C1的耐壓(ya)不得(de)小(xiao)(xiao)于(yu)450V，容量(liang)取(qu)220nF～470nF，容量(liang)越大(da)，LED1越亮。調(diao)試時(shi)，先斷開(kai)VD2，在(zai)X1、X2兩(liang)端(duan)加7.5V直流電(dian)(dian)壓(ya)，從大(da)到(dao)小(xiao)(xiao)調(diao)電(dian)(dian)位器(qi)RP，使4N250⑤腳(jiao)電(dian)(dian)位突然下降(K1釋(shi)放)即可。

　　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，充電器仍然工作。圖中，R2是VT的偏(pian)(pian)置電(dian)(dian)(dian)(dian)阻;C1是降壓電(dian)(dian)(dian)(dian)容，LED1(紅)為市電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)源指示管(guan)(guan);啟動完成后，交流(liu)9V電(dian)(dian)(dian)(dian)壓經VD2整(zheng)流(liu)為電(dian)(dian)(dian)(dian)瓶GB充電(dian)(dian)(dian)(dian)，LED2(綠(lv))為充電(dian)(dian)(dian)(dian)指示管(guan)(guan)。隨(sui)著充電(dian)(dian)(dian)(dian)過程的進行，電(dian)(dian)(dian)(dian)瓶兩端電(dian)(dian)(dian)(dian)壓不斷(duan)上升，當升至極(ji)限電(dian)(dian)(dian)(dian)壓值(約7.5V)時，穩壓管(guan)(guan)VD3反向(xiang)擊穿(chuan)導通，光(guang)(guang)耦合器4N25①、②腳內(nei)發光(guang)(guang)二極(ji)管(guan)(guan)發光(guang)(guang)，④、⑤腳內(nei)光(guang)(guang)電(dian)(dian)(dian)(dian)管(guan)(guan)受光(guang)(guang)后隨(sui)之導通，VT基極(ji)被下(xia)拉(約0V)而失去正偏(pian)(pian)壓，所(suo)以VT截止，K1釋放使K1-1斷(duan)開(kai)，停止充電(dian)(dian)(dian)(dian)，充電(dian)(dian)(dian)(dian)指示管(guan)(guan)LED2熄滅(mie)。