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(ge)變壓器(qi)降壓、單二極管半波(bo)整(zheng)流(liu)裝置，充電(dian)(dian)(dian)時間很難(nan)掌握(wo)。由于電(dian)(dian)(dian)池虧電(dian)(dian)(dian)或(huo)過(guo)充電(dian)(dian)(dian)往往會造成電(dian)(dian)(dian)池壽命縮短，本人(ren)設計制(zhi)作了一個(ge)簡易自動充電(dian)(dian)(dian)裝置，可有(you)效延長電(dian)(dian)(dian)池壽命。

        元(yuan)件選用(yong)與制作

　　T1可(ke)使用10VA左右，次(ci)級(ji)有9V和12V輸(shu)(shu)出(chu)的(de)電(dian)(dian)(dian)(dian)源變(bian)壓(ya)器(qi)(qi)(qi)(qi)，若使用原配變(bian)壓(ya)器(qi)(qi)(qi)(qi)(次(ci)級(ji)輸(shu)(shu)出(chu)9V)時(shi)，繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)K1工作電(dian)(dian)(dian)(dian)壓(ya)也應選9V。繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)選用4088、4089、JRX-13F等(deng)12V繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)。VT使用9013、9014、8050等(deng)小(xiao)功率晶體管，要(yao)求穿透電(dian)(dian)(dian)(dian)流要(yao)小(xiao)，開關特性好，β=100～1500光(guang)耦合器(qi)(qi)(qi)(qi)IC可(ke)用4N23、4N25、4N33等(deng)型(xing)號。C1的(de)耐壓(ya)不得小(xiao)于(yu)450V，容量取220nF～470nF，容量越大(da)，LED1越亮。調試時(shi)，先斷開VD2，在X1、X2兩端加7.5V直流電(dian)(dian)(dian)(dian)壓(ya)，從大(da)到小(xiao)調電(dian)(dian)(dian)(dian)位(wei)器(qi)(qi)(qi)(qi)RP，使4N250⑤腳電(dian)(dian)(dian)(dian)位(wei)突然下降(K1釋放)即可(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，充電器仍然工作。圖中，R2是VT的偏(pian)置電(dian)(dian)(dian)(dian)(dian)阻;C1是降壓(ya)電(dian)(dian)(dian)(dian)(dian)容，LED1(紅)為(wei)(wei)市電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)源指(zhi)示管;啟動(dong)完成后，交流9V電(dian)(dian)(dian)(dian)(dian)壓(ya)經VD2整流為(wei)(wei)電(dian)(dian)(dian)(dian)(dian)瓶(ping)GB充(chong)電(dian)(dian)(dian)(dian)(dian)，LED2(綠)為(wei)(wei)充(chong)電(dian)(dian)(dian)(dian)(dian)指(zhi)示管。隨著(zhu)充(chong)電(dian)(dian)(dian)(dian)(dian)過程的進行，電(dian)(dian)(dian)(dian)(dian)瓶(ping)兩端電(dian)(dian)(dian)(dian)(dian)壓(ya)不(bu)斷上升，當升至極(ji)限電(dian)(dian)(dian)(dian)(dian)壓(ya)值(約7.5V)時(shi)，穩壓(ya)管VD3反(fan)向(xiang)擊(ji)穿導(dao)通(tong)，光(guang)耦(ou)合器(qi)4N25①、②腳內發(fa)光(guang)二極(ji)管發(fa)光(guang)，④、⑤腳內光(guang)電(dian)(dian)(dian)(dian)(dian)管受光(guang)后隨之導(dao)通(tong)，VT基(ji)極(ji)被下拉(約0V)而(er)失去正(zheng)偏(pian)壓(ya)，所以(yi)VT截止，K1釋(shi)放使K1-1斷開(kai)，停止充(chong)電(dian)(dian)(dian)(dian)(dian)，充(chong)電(dian)(dian)(dian)(dian)(dian)指(zhi)示管LED2熄滅。