該充電器設計具有電池(chi)極性自動識別電路，免去了以往需(xu)要人工轉(zhuan)換極性的操作，使用起來更加方便

一、電路原理

　　電(dian)(dian)(dian)路(lu)(lu)如附圖所示：Q1及外圍元件構成自激振(zhen)蕩(dang)器．經(jing)變壓(ya)(ya)器B降壓(ya)(ya)、D5整流(liu)(liu)后在C4上得(de)到9.4v的(de)直流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)。通過R6限(xian)流(liu)(liu)．Q10(TL431)穩壓(ya)(ya)后．在Q3發射極(ji)(ji)(ji)(ji)輸(shu)出(chu)4.2v電(dian)(dian)(dian)壓(ya)(ya)供鋰電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)。其極(ji)(ji)(ji)(ji)性(xing)自動識(shi)別(bie)電(dian)(dian)(dian)路(lu)(lu)由(you)(you)(you)Q5～Q8、R12～R15組成。當(dang)A點接電(dian)(dian)(dian)池正(zheng)極(ji)(ji)(ji)(ji)，B點接負(fu)極(ji)(ji)(ji)(ji)時，Q8因為有R12提供正(zheng)偏(pian)電(dian)(dian)(dian)壓(ya)(ya)而導通，Q5由(you)(you)(you)R14提供偏(pian)壓(ya)(ya)導通。充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)由(you)(you)(you)Q5→A點→電(dian)(dian)(dian)池E→B點→Q8的(de)C極(ji)(ji)(ji)(ji)形成充(chong)電(dian)(dian)(dian)回路(lu)(lu)。當(dang)A點接電(dian)(dian)(dian)池負(fu)極(ji)(ji)(ji)(ji)，而B接電(dian)(dian)(dian)池正(zheng)極(ji)(ji)(ji)(ji)時充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)則(ze)由(you)(you)(you)Q7→B點→電(dian)(dian)(dian)池E→A點→Q6的(de)C極(ji)(ji)(ji)(ji)形成充(chong)電(dian)(dian)(dian)回路(lu)(lu)．從而完成自動識(shi)別(bie)電(dian)(dian)(dian)池極(ji)(ji)(ji)(ji)性(xing)的(de)功能。

　　當有(you)充(chong)(chong)電(dian)電(dian)流流過R6時，Q4導(dao)通，LED1閃(shan)爍發光(LED1為(wei)自帶(dai)振蕩器(qi)的(de)(de)三(san)色發光二極管，能夠隨機變幻出多彩的(de)(de)閃(shan)光)。充(chong)(chong)電(dian)完成后Q4因為(wei)沒有(you)足(zu)夠的(de)(de)導(dao)通電(dian)壓而截止，LED1熄滅。LED2為(wei)電(dian)源指示燈。

 電路原理圖

 　二(er)、常見故障排除

　　故障一：電(dian)源(yuan)指示燈(deng)不亮(liang)。

　　檢(jian)修：測Q1管正常,但b極無偏置(zhi)電壓；再測R2為開路,更換(huan)R2后故障(zhang)排除。

　　故障二(er)：電源指示燈不亮。檢修(xiu)：測Q1已(yi)經擊(ji)穿(chuan),再測R1及R3均(jun)已(yi)開路。測其他元(yuan)件正(zheng)常(chang)，更換上述元(yuan)件后故障排除。