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(ya)(ya)器(qi)降壓(ya)(ya)、單二極管半波整流裝置(zhi)，充電(dian)(dian)時間(jian)很難(nan)掌(zhang)握。由于電(dian)(dian)池(chi)虧電(dian)(dian)或(huo)過充電(dian)(dian)往(wang)往(wang)會造成電(dian)(dian)池(chi)壽命縮短，本人設計制(zhi)作了一個簡(jian)易自(zi)動充電(dian)(dian)裝置(zhi)，可有效延長電(dian)(dian)池(chi)壽命。

        元件選用與(yu)制作

　　T1可(ke)使(shi)用(yong)(yong)10VA左右，次(ci)級有9V和12V輸出的電(dian)(dian)(dian)(dian)源(yuan)變壓器，若使(shi)用(yong)(yong)原(yuan)配(pei)變壓器(次(ci)級輸出9V)時，繼電(dian)(dian)(dian)(dian)器K1工作電(dian)(dian)(dian)(dian)壓也(ye)應選9V。繼電(dian)(dian)(dian)(dian)器選用(yong)(yong)4088、4089、JRX-13F等(deng)12V繼電(dian)(dian)(dian)(dian)器。VT使(shi)用(yong)(yong)9013、9014、8050等(deng)小(xiao)(xiao)功(gong)率晶體管，要(yao)求穿(chuan)透(tou)電(dian)(dian)(dian)(dian)流要(yao)小(xiao)(xiao)，開(kai)關特性好，β=100～1500光耦合(he)器IC可(ke)用(yong)(yong)4N23、4N25、4N33等(deng)型號(hao)。C1的耐(nai)壓不(bu)得小(xiao)(xiao)于450V，容(rong)量取(qu)220nF～470nF，容(rong)量越(yue)大(da)，LED1越(yue)亮。調試(shi)時，先(xian)斷開(kai)VD2，在(zai)X1、X2兩端加7.5V直流電(dian)(dian)(dian)(dian)壓，從大(da)到小(xiao)(xiao)調電(dian)(dian)(dian)(dian)位器RP，使(shi)4N250⑤腳電(dian)(dian)(dian)(dian)位突然下降(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(zhi)電(dian)阻;C1是降(jiang)壓(ya)(ya)電(dian)容，LED1(紅(hong))為(wei)市電(dian)電(dian)源(yuan)指(zhi)示(shi)(shi)(shi)管;啟動完成后，交流(liu)9V電(dian)壓(ya)(ya)經VD2整流(liu)為(wei)電(dian)瓶(ping)GB充(chong)(chong)電(dian)，LED2(綠)為(wei)充(chong)(chong)電(dian)指(zhi)示(shi)(shi)(shi)管。隨(sui)(sui)著充(chong)(chong)電(dian)過程的進行，電(dian)瓶(ping)兩(liang)端(duan)電(dian)壓(ya)(ya)不斷(duan)上(shang)升，當升至極限(xian)電(dian)壓(ya)(ya)值(約7.5V)時，穩壓(ya)(ya)管VD3反向(xiang)擊穿導(dao)通，光(guang)(guang)耦合器4N25①、②腳內發光(guang)(guang)二極管發光(guang)(guang)，④、⑤腳內光(guang)(guang)電(dian)管受光(guang)(guang)后隨(sui)(sui)之導(dao)通，VT基極被下(xia)拉(約0V)而失去正偏(pian)壓(ya)(ya)，所以VT截止(zhi)，K1釋放使K1-1斷(duan)開，停止(zhi)充(chong)(chong)電(dian)，充(chong)(chong)電(dian)指(zhi)示(shi)(shi)(shi)管LED2熄(xi)滅(mie)。