220V交流電源另一路經定時插座加到充電器，當充電器還未轉入浮充充電狀態時，充電器的紅燈LED1得電發光，LED1兩端的2V電壓經插頭P1、插孔J1、電阻R2加到VT3基極，VT3飽和導通，將2.1V穩壓調整管VT4基極短路到地，穩壓調整管VT4截止，石英小鬧鐘無直流電源供給而不工作，當充電器轉入涓電(dian)(dian)(dian)流(liu)浮充(chong)充(chong)電(dian)(dian)(dian)階段時(shi)，充(chong)電(dian)(dian)(dian)器(qi)紅色二極(ji)管LED1兩端變為(wei)零電(dian)(dian)(dian)壓(ya)熄滅(充(chong)電(dian)(dian)(dian)器(qi)綠色二極(ji)管則發(fa)光)，此時(shi)VT3也因基極(ji)零電(dian)(dian)(dian)壓(ya)而截止，電(dian)(dian)(dian)源調整管VT4正(zheng)常導通，輸(shu)(shu)出2.1V直流(liu)電(dian)(dian)(dian)源，石英小鬧鐘(zhong)得電(dian)(dian)(dian)開(kai)(kai)始計時(shi)，當計時(shi)到預先設定值(zhi)時(shi)，石英小鬧鐘(zhong)輸(shu)(shu)出低電(dian)(dian)(dian)平(ping)(ping)音(yin)頻脈沖訊響信號，該(gai)低電(dian)(dian)(dian)平(ping)(ping)音(yin)頻脈沖信號通過VT2放大(da)整流(liu)經(jing)電(dian)(dian)(dian)容C5濾波輸(shu)(shu)出一直流(liu)電(dian)(dian)(dian)壓(ya)，使VT1飽和(he)導通，開(kai)(kai)關S1電(dian)(dian)(dian)磁(ci)脫鉤線圈(quan)得電(dian)(dian)(dian)產(chan)生磁(ci)力，使開(kai)(kai)關按鈕(niu)脫鉤跳開(kai)(kai)，斷開(kai)(kai)交流(liu)電(dian)(dian)(dian)源，從而實現(xian)自動結束充(chong)電(dian)(dian)(dian)。

   智能定時插(cha)座的電(dian)(dian)(dian)(dian)路(lu)(lu)見圖，共(gong)由交流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)開(kai)(kai)關(guan)(guan)、電(dian)(dian)(dian)(dian)磁(ci)脫鉤線圈驅動電(dian)(dian)(dian)(dian)路(lu)(lu)、定時電(dian)(dian)(dian)(dian)路(lu)(lu)、直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)路(lu)(lu)4部分組成(cheng)(cheng)。將(jiang)該(gai)電(dian)(dian)(dian)(dian)路(lu)(lu)插(cha)上電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)插(cha)頭，按(an)下交流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)開(kai)(kai)關(guan)(guan)S1按(an)鈕(niu)，接通220V交流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)即(ji)可開(kai)(kai)始(shi)工(gong)作(zuo)。220V交流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)一路(lu)(lu)經14V電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)變壓(ya)(ya)器(qi)T降(jiang)壓(ya)(ya)、橋式整流(liu)電(dian)(dian)(dian)(dian)路(lu)(lu)整流(liu)、濾波電(dian)(dian)(dian)(dian)容C1濾波、三端穩(wen)壓(ya)(ya)集(ji)成(cheng)(cheng)電(dian)(dian)(dian)(dian)路(lu)(lu)IC1穩(wen)壓(ya)(ya)、濾波電(dian)(dian)(dian)(dian)容C2濾波產生穩(wen)定的+12V直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)，該(gai)+12V分三路(lu)(lu)輸(shu)出：(1)經R4加到(dao)LED2作(zuo)+12V直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)工(gong)作(zuo)指示(shi)。(2)經R3、VD2、LED3串聯(lian)穩(wen)壓(ya)(ya)后(hou)經C3濾波加到(dao)穩(wen)壓(ya)(ya)調(diao)整管VT4基極(ji)，使VT4將(jiang)+12V穩(wen)壓(ya)(ya)為2.1V，由VT4發(fa)射(she)極(ji)輸(shu)出，該(gai)2.1V經C4濾波后(hou)加到(dao)石(shi)英小鬧鐘電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)正(zheng)負極(ji)為其(qi)提供直(zhi)(zhi)流(liu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(提示(shi)一點：2.1V高(gao)了些(xie)，石(shi)英小鬧鐘走時稍快一些(xie)，定時值按(an)4~5小時即(ji)可)。(3)加到(dao)開(kai)(kai)關(guan)(guan)S1的電(dian)(dian)(dian)(dian)磁(ci)脫鉤線圈上。

　　元件選擇
　　元件選(xuan)(xuan)(xuan)(xuan)擇(ze)如電(dian)(dian)路原理圖上的標注：VT1、VT3、VT4選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)S8050型三(san)極(ji)(ji)管(guan)，VT2選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)S8550型三(san)極(ji)(ji)管(guan)，IC1選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)LM7812，VD1選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)IN4148型二(er)極(ji)(ji)管(guan)，VD2～D6選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)IN4007型二(er)極(ji)(ji)管(guan)，LED1、LED2選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)普通(tong)紅(hong)色發光二(er)極(ji)(ji)管(guan)，LED3選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)普通(tong)綠(lv)色發光二(er)極(ji)(ji)管(guan)，R1選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)2kΩ普通(tong)電(dian)(dian)阻(zu)，R2選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)10kΩ普通(tong)電(dian)(dian)阻(zu)，R3、R4選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)1kΩ普通(tong)電(dian)(dian)阻(zu)，開(kai)關(guan)S1選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)KDC-A01-06Y型的，P1和J1分別選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)普通(tong)單聲道耳機插頭、插孔。變(bian)壓器(qi)T選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)3W/14V電(dian)(dian)源變(bian)壓器(qi)，C1選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)1000μF/25V電(dian)(dian)解電(dian)(dian)容(rong)，C2、C3、C4選(xuan)(xuan)(xuan)(xuan)470μF/25V電(dian)(dian)解電(dian)(dian)容(rong)，C5選(xuan)(xuan)(xuan)(xuan)用(yong)(yong)(yong)47μF/25V電(dian)(dian)解電(dian)(dian)容(rong)。