該充電器設計具有電池極性(xing)自動識別電路，免去了以往需要(yao)人(ren)工轉換極性(xing)的(de)操作，使用起來更(geng)加(jia)方便(bian)

一、電路原理

　　電(dian)(dian)(dian)路(lu)如附圖(tu)所示(shi)：Q1及外(wai)圍元(yuan)件(jian)構成(cheng)自(zi)激振蕩器(qi)．經變壓(ya)器(qi)B降壓(ya)、D5整流(liu)(liu)后在(zai)C4上得到9.4v的直流(liu)(liu)電(dian)(dian)(dian)壓(ya)。通(tong)(tong)過R6限流(liu)(liu)．Q10(TL431)穩壓(ya)后．在(zai)Q3發射極(ji)(ji)輸出4.2v電(dian)(dian)(dian)壓(ya)供(gong)鋰電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)。其極(ji)(ji)性自(zi)動識(shi)別電(dian)(dian)(dian)路(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因為有(you)R12提供(gong)正偏(pian)電(dian)(dian)(dian)壓(ya)而(er)導通(tong)(tong)，Q5由(you)R14提供(gong)偏(pian)壓(ya)導通(tong)(tong)。充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)由(you)Q5→A點(dian)→電(dian)(dian)(dian)池(chi)E→B點(dian)→Q8的C極(ji)(ji)形成(cheng)充電(dian)(dian)(dian)回(hui)路(lu)。當A點(dian)接電(dian)(dian)(dian)池(chi)負極(ji)(ji)，而(er)B接電(dian)(dian)(dian)池(chi)正極(ji)(ji)時(shi)充電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)則(ze)由(you)Q7→B點(dian)→電(dian)(dian)(dian)池(chi)E→A點(dian)→Q6的C極(ji)(ji)形成(cheng)充電(dian)(dian)(dian)回(hui)路(lu)．從(cong)而(er)完成(cheng)自(zi)動識(shi)別電(dian)(dian)(dian)池(chi)極(ji)(ji)性的功(gong)能。

　　當有充(chong)電(dian)(dian)電(dian)(dian)流流過R6時，Q4導通(tong)，LED1閃爍(shuo)發光(LED1為(wei)自帶(dai)振蕩器的三色(se)發光二極管，能夠隨(sui)機變幻出多彩的閃光)。充(chong)電(dian)(dian)完成后Q4因(yin)為(wei)沒有足夠的導通(tong)電(dian)(dian)壓(ya)而截止，LED1熄滅。LED2為(wei)電(dian)(dian)源(yuan)指(zhi)示燈。

 電路原理圖

 　二、常(chang)見故障排除(chu)

　　故障一：電源指(zhi)示(shi)燈(deng)不(bu)亮。

　　檢修：測Q1管正常,但(dan)b極無(wu)偏置電(dian)壓；再測R2為開路,更換R2后(hou)故(gu)障排(pai)除(chu)。

　　故障二(er)：電源(yuan)指示燈不亮。檢修：測Q1已經(jing)擊穿,再測R1及R3均已開路。測其他元件(jian)正常，更換(huan)上述(shu)元件(jian)后故障排(pai)除。