該充電器設計具有電(dian)池極(ji)(ji)性自(zi)動(dong)識別電(dian)路，免去(qu)了以(yi)往需要人工轉換(huan)極(ji)(ji)性的操(cao)作，使用起來更加方便

一、電路原理

　　電(dian)(dian)(dian)路(lu)(lu)如(ru)附圖所(suo)示：Q1及外圍元件構成(cheng)自(zi)激(ji)振蕩器(qi)．經變壓(ya)器(qi)B降壓(ya)、D5整流后在(zai)C4上得到(dao)9.4v的(de)直流電(dian)(dian)(dian)壓(ya)。通過R6限流．Q10(TL431)穩壓(ya)后．在(zai)Q3發射極(ji)(ji)輸(shu)出(chu)4.2v電(dian)(dian)(dian)壓(ya)供(gong)(gong)鋰電(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)。其極(ji)(ji)性自(zi)動(dong)識別電(dian)(dian)(dian)路(lu)(lu)由(you)Q5～Q8、R12～R15組成(cheng)。當A點(dian)接電(dian)(dian)(dian)池(chi)正極(ji)(ji)，B點(dian)接負極(ji)(ji)時(shi)，Q8因為(wei)有(you)R12提供(gong)(gong)正偏電(dian)(dian)(dian)壓(ya)而導(dao)通，Q5由(you)R14提供(gong)(gong)偏壓(ya)導(dao)通。充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流由(you)Q5→A點(dian)→電(dian)(dian)(dian)池(chi)E→B點(dian)→Q8的(de)C極(ji)(ji)形成(cheng)充(chong)(chong)(chong)電(dian)(dian)(dian)回(hui)路(lu)(lu)。當A點(dian)接電(dian)(dian)(dian)池(chi)負極(ji)(ji)，而B接電(dian)(dian)(dian)池(chi)正極(ji)(ji)時(shi)充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流則由(you)Q7→B點(dian)→電(dian)(dian)(dian)池(chi)E→A點(dian)→Q6的(de)C極(ji)(ji)形成(cheng)充(chong)(chong)(chong)電(dian)(dian)(dian)回(hui)路(lu)(lu)．從而完成(cheng)自(zi)動(dong)識別電(dian)(dian)(dian)池(chi)極(ji)(ji)性的(de)功(gong)能。

　　當有充電電流流過R6時(shi)，Q4導通，LED1閃爍發光(LED1為(wei)自帶振蕩器的三(san)色發光二極管，能(neng)夠(gou)隨(sui)機變(bian)幻出多(duo)彩的閃光)。充電完成后Q4因為(wei)沒有足夠(gou)的導通電壓而截止，LED1熄滅。LED2為(wei)電源指示(shi)燈。

 電路原理圖

 　二(er)、常見(jian)故(gu)障(zhang)排除(chu)

　　故障一：電源(yuan)指示燈(deng)不(bu)亮。

　　檢修：測Q1管正常,但b極無偏置電壓；再測R2為開(kai)路,更(geng)換R2后故(gu)障排除(chu)。

　　故障二(er)：電源指示燈不(bu)亮(liang)。檢(jian)修：測Q1已經擊穿,再測R1及R3均(jun)已開路。測其他元件(jian)正常，更換上(shang)述元件(jian)后(hou)故障排除。