該充電器設計具有(you)電(dian)池極性(xing)自動識別電(dian)路，免去了以往需(xu)要人工(gong)轉換極性(xing)的(de)操(cao)作，使用起來(lai)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(jian)構(gou)成(cheng)(cheng)自激振蕩器(qi)．經變壓(ya)(ya)器(qi)B降壓(ya)(ya)、D5整流后在C4上得到9.4v的直流電(dian)(dian)(dian)壓(ya)(ya)。通過R6限流．Q10(TL431)穩(wen)壓(ya)(ya)后．在Q3發(fa)射極(ji)(ji)(ji)輸(shu)出4.2v電(dian)(dian)(dian)壓(ya)(ya)供(gong)鋰(li)電(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)。其極(ji)(ji)(ji)性自動(dong)(dong)識別電(dian)(dian)(dian)路由(you)(you)Q5～Q8、R12～R15組成(cheng)(cheng)。當A點(dian)(dian)接(jie)(jie)電(dian)(dian)(dian)池正極(ji)(ji)(ji)，B點(dian)(dian)接(jie)(jie)負(fu)極(ji)(ji)(ji)時(shi)，Q8因為(wei)有R12提供(gong)正偏電(dian)(dian)(dian)壓(ya)(ya)而(er)導通，Q5由(you)(you)R14提供(gong)偏壓(ya)(ya)導通。充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流由(you)(you)Q5→A點(dian)(dian)→電(dian)(dian)(dian)池E→B點(dian)(dian)→Q8的C極(ji)(ji)(ji)形成(cheng)(cheng)充(chong)(chong)電(dian)(dian)(dian)回路。當A點(dian)(dian)接(jie)(jie)電(dian)(dian)(dian)池負(fu)極(ji)(ji)(ji)，而(er)B接(jie)(jie)電(dian)(dian)(dian)池正極(ji)(ji)(ji)時(shi)充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流則由(you)(you)Q7→B點(dian)(dian)→電(dian)(dian)(dian)池E→A點(dian)(dian)→Q6的C極(ji)(ji)(ji)形成(cheng)(cheng)充(chong)(chong)電(dian)(dian)(dian)回路．從(cong)而(er)完(wan)成(cheng)(cheng)自動(dong)(dong)識別電(dian)(dian)(dian)池極(ji)(ji)(ji)性的功能。

　　當有充(chong)電(dian)電(dian)流流過(guo)R6時，Q4導通，LED1閃爍發光(guang)(LED1為自(zi)帶振(zhen)蕩器的(de)三色發光(guang)二極管，能夠(gou)隨機變幻出多(duo)彩的(de)閃光(guang))。充(chong)電(dian)完成后Q4因為沒有足夠(gou)的(de)導通電(dian)壓而截止，LED1熄滅。LED2為電(dian)源指(zhi)示(shi)燈。

 電路原理圖

 　二、常(chang)見故障排(pai)除

　　故障一：電源指示燈不亮。

　　檢修：測Q1管正常,但b極無(wu)偏置電壓；再測R2為開(kai)路,更(geng)換(huan)R2后故障(zhang)排除。

　　故障二：電源指示燈(deng)不亮。檢修：測Q1已(yi)經擊穿(chuan),再測R1及R3均(jun)已(yi)開路(lu)。測其他元(yuan)件正(zheng)常，更換上述(shu)元(yuan)件后故障排除。