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(yi)個(ge)變壓器降壓、單二極管半波整流裝置，充(chong)電(dian)(dian)(dian)時間(jian)很(hen)難掌握(wo)。由于電(dian)(dian)(dian)池(chi)虧電(dian)(dian)(dian)或過充(chong)電(dian)(dian)(dian)往往會造成電(dian)(dian)(dian)池(chi)壽命縮短，本人設(she)計(ji)制作了一(yi)個(ge)簡易(yi)自動充(chong)電(dian)(dian)(dian)裝置，可有(you)效延長(chang)電(dian)(dian)(dian)池(chi)壽命。

        元件選(xuan)用與制(zhi)作

　　T1可使(shi)(shi)用(yong)10VA左右(you)，次級有9V和12V輸出的電(dian)(dian)(dian)(dian)源(yuan)變壓(ya)器(qi)，若使(shi)(shi)用(yong)原配(pei)變壓(ya)器(qi)(次級輸出9V)時，繼電(dian)(dian)(dian)(dian)器(qi)K1工作電(dian)(dian)(dian)(dian)壓(ya)也應選(xuan)9V。繼電(dian)(dian)(dian)(dian)器(qi)選(xuan)用(yong)4088、4089、JRX-13F等(deng)(deng)12V繼電(dian)(dian)(dian)(dian)器(qi)。VT使(shi)(shi)用(yong)9013、9014、8050等(deng)(deng)小功率(lv)晶(jing)體管，要求穿透(tou)電(dian)(dian)(dian)(dian)流要小，開關特性好，β=100～1500光(guang)耦合器(qi)IC可用(yong)4N23、4N25、4N33等(deng)(deng)型號(hao)。C1的耐壓(ya)不得小于450V，容量(liang)取220nF～470nF，容量(liang)越(yue)大，LED1越(yue)亮。調試(shi)時，先斷開VD2，在X1、X2兩端加(jia)7.5V直流電(dian)(dian)(dian)(dian)壓(ya)，從大到小調電(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)RP，使(shi)(shi)4N250⑤腳電(dian)(dian)(dian)(dian)位(wei)(wei)突然下(xia)降(K1釋放(fang))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(ran)工(gong)作。圖中，R2是VT的(de)偏置電(dian)阻;C1是降(jiang)壓(ya)電(dian)容(rong)，LED1(紅)為(wei)市電(dian)電(dian)源(yuan)指示(shi)管(guan);啟動完成后(hou)(hou)，交流9V電(dian)壓(ya)經VD2整(zheng)流為(wei)電(dian)瓶(ping)GB充(chong)電(dian)，LED2(綠)為(wei)充(chong)電(dian)指示(shi)管(guan)。隨(sui)著充(chong)電(dian)過程的(de)進行，電(dian)瓶(ping)兩端(duan)電(dian)壓(ya)不斷上(shang)升(sheng)，當升(sheng)至極(ji)限電(dian)壓(ya)值(約7.5V)時，穩壓(ya)管(guan)VD3反向擊穿導(dao)通(tong)，光(guang)耦合器4N25①、②腳內(nei)發(fa)光(guang)二極(ji)管(guan)發(fa)光(guang)，④、⑤腳內(nei)光(guang)電(dian)管(guan)受光(guang)后(hou)(hou)隨(sui)之導(dao)通(tong)，VT基極(ji)被下(xia)拉(約0V)而失去正偏壓(ya)，所以(yi)VT截止，K1釋放使K1-1斷開，停止充(chong)電(dian)，充(chong)電(dian)指示(shi)管(guan)LED2熄滅。