該充電器設計具有電(dian)池極性(xing)(xing)自動識別電(dian)路，免去了以(yi)往需要人工轉換極性(xing)(xing)的操作，使(shi)用起來更加方便

一、電路原理

　　電(dian)(dian)(dian)路如附圖所示：Q1及外(wai)圍元件構成(cheng)(cheng)自激振蕩器．經變壓(ya)(ya)器B降(jiang)壓(ya)(ya)、D5整流后在(zai)C4上得(de)到(dao)9.4v的(de)(de)(de)直(zhi)流電(dian)(dian)(dian)壓(ya)(ya)。通(tong)過(guo)R6限流．Q10(TL431)穩壓(ya)(ya)后．在(zai)Q3發(fa)射極(ji)(ji)輸出(chu)4.2v電(dian)(dian)(dian)壓(ya)(ya)供(gong)鋰電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)。其極(ji)(ji)性自動識別電(dian)(dian)(dian)路由Q5～Q8、R12～R15組(zu)成(cheng)(cheng)。當A點接(jie)(jie)電(dian)(dian)(dian)池(chi)正(zheng)極(ji)(ji)，B點接(jie)(jie)負極(ji)(ji)時，Q8因為(wei)有(you)R12提(ti)供(gong)正(zheng)偏(pian)電(dian)(dian)(dian)壓(ya)(ya)而導通(tong)，Q5由R14提(ti)供(gong)偏(pian)壓(ya)(ya)導通(tong)。充電(dian)(dian)(dian)電(dian)(dian)(dian)流由Q5→A點→電(dian)(dian)(dian)池(chi)E→B點→Q8的(de)(de)(de)C極(ji)(ji)形(xing)(xing)成(cheng)(cheng)充電(dian)(dian)(dian)回路。當A點接(jie)(jie)電(dian)(dian)(dian)池(chi)負極(ji)(ji)，而B接(jie)(jie)電(dian)(dian)(dian)池(chi)正(zheng)極(ji)(ji)時充電(dian)(dian)(dian)電(dian)(dian)(dian)流則由Q7→B點→電(dian)(dian)(dian)池(chi)E→A點→Q6的(de)(de)(de)C極(ji)(ji)形(xing)(xing)成(cheng)(cheng)充電(dian)(dian)(dian)回路．從而完成(cheng)(cheng)自動識別電(dian)(dian)(dian)池(chi)極(ji)(ji)性的(de)(de)(de)功能。

　　當有充(chong)電電流流過R6時，Q4導(dao)通(tong)，LED1閃爍發光(LED1為(wei)自帶振蕩(dang)器的三色發光二(er)極管(guan)，能夠隨機變幻出多彩(cai)的閃光)。充(chong)電完(wan)成(cheng)后Q4因為(wei)沒有足夠的導(dao)通(tong)電壓而截止(zhi)，LED1熄(xi)滅。LED2為(wei)電源(yuan)指(zhi)示(shi)燈。

 電路原理圖

 　二、常見故障排(pai)除

　　故障一(yi)：電(dian)源指(zhi)示燈不亮(liang)。

　　檢修：測Q1管(guan)正常,但b極(ji)無偏置電壓；再(zai)測R2為開路,更換(huan)R2后(hou)故障排除。

　　故障二：電(dian)源指示(shi)燈不亮。檢修：測(ce)(ce)Q1已(yi)經擊穿,再測(ce)(ce)R1及R3均已(yi)開(kai)路(lu)。測(ce)(ce)其他元(yuan)件(jian)(jian)正常(chang)，更換(huan)上述(shu)元(yuan)件(jian)(jian)后故障排除(chu)。