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)流(liu)(liu)(liu)浮(fu)充(chong)充(chong)電(dian)(dian)階(jie)段時(shi)(shi)，充(chong)電(dian)(dian)器紅色二極(ji)管(guan)LED1兩端變(bian)為(wei)零電(dian)(dian)壓熄滅(mie)(充(chong)電(dian)(dian)器綠色二極(ji)管(guan)則發光(guang))，此時(shi)(shi)VT3也因基極(ji)零電(dian)(dian)壓而(er)截止，電(dian)(dian)源(yuan)調整管(guan)VT4正常導通，輸出2.1V直流(liu)(liu)(liu)電(dian)(dian)源(yuan)，石(shi)英(ying)小鬧(nao)鐘(zhong)得電(dian)(dian)開始計時(shi)(shi)，當計時(shi)(shi)到預(yu)先設定(ding)值(zhi)時(shi)(shi)，石(shi)英(ying)小鬧(nao)鐘(zhong)輸出低(di)電(dian)(dian)平(ping)音(yin)頻脈沖訊響信(xin)(xin)號，該低(di)電(dian)(dian)平(ping)音(yin)頻脈沖信(xin)(xin)號通過VT2放大(da)整流(liu)(liu)(liu)經電(dian)(dian)容C5濾(lv)波輸出一直流(liu)(liu)(liu)電(dian)(dian)壓，使VT1飽和(he)導通，開關S1電(dian)(dian)磁脫鉤線圈得電(dian)(dian)產生磁力，使開關按鈕脫鉤跳開，斷開交流(liu)(liu)(liu)電(dian)(dian)源(yuan)，從(cong)而(er)實(shi)現(xian)自動結束(shu)充(chong)電(dian)(dian)。

   智能(neng)定時(shi)插(cha)座(zuo)的(de)電(dian)(dian)(dian)路(lu)(lu)見(jian)圖，共由(you)交(jiao)流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)開(kai)關、電(dian)(dian)(dian)磁脫(tuo)鉤線圈(quan)驅動電(dian)(dian)(dian)路(lu)(lu)、定時(shi)電(dian)(dian)(dian)路(lu)(lu)、直流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)路(lu)(lu)4部分組成(cheng)。將(jiang)(jiang)該(gai)(gai)電(dian)(dian)(dian)路(lu)(lu)插(cha)上電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)插(cha)頭，按(an)下交(jiao)流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)開(kai)關S1按(an)鈕，接通220V交(jiao)流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)即可開(kai)始工作。220V交(jiao)流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)一路(lu)(lu)經(jing)(jing)14V電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)變壓(ya)器(qi)T降壓(ya)、橋(qiao)式整流(liu)電(dian)(dian)(dian)路(lu)(lu)整流(liu)、濾(lv)(lv)波電(dian)(dian)(dian)容C1濾(lv)(lv)波、三(san)端穩壓(ya)集成(cheng)電(dian)(dian)(dian)路(lu)(lu)IC1穩壓(ya)、濾(lv)(lv)波電(dian)(dian)(dian)容C2濾(lv)(lv)波產(chan)生穩定的(de)+12V直流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)，該(gai)(gai)+12V分三(san)路(lu)(lu)輸出：(1)經(jing)(jing)R4加(jia)到(dao)(dao)LED2作+12V直流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)工作指示。(2)經(jing)(jing)R3、VD2、LED3串聯(lian)穩壓(ya)后(hou)(hou)經(jing)(jing)C3濾(lv)(lv)波加(jia)到(dao)(dao)穩壓(ya)調整管VT4基極，使VT4將(jiang)(jiang)+12V穩壓(ya)為(wei)2.1V，由(you)VT4發(fa)射極輸出，該(gai)(gai)2.1V經(jing)(jing)C4濾(lv)(lv)波后(hou)(hou)加(jia)到(dao)(dao)石英小鬧鐘電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)正負(fu)極為(wei)其提供直流(liu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(提示一點：2.1V高了(le)些，石英小鬧鐘走(zou)時(shi)稍快一些，定時(shi)值按(an)4~5小時(shi)即可)。(3)加(jia)到(dao)(dao)開(kai)關S1的(de)電(dian)(dian)(dian)磁脫(tuo)鉤線圈(quan)上。

　　元件選擇
　　元件選(xuan)(xuan)(xuan)擇如電(dian)(dian)路原理圖上的標注：VT1、VT3、VT4選(xuan)(xuan)(xuan)用(yong)(yong)(yong)S8050型三(san)極管(guan)，VT2選(xuan)(xuan)(xuan)用(yong)(yong)(yong)S8550型三(san)極管(guan)，IC1選(xuan)(xuan)(xuan)用(yong)(yong)(yong)LM7812，VD1選(xuan)(xuan)(xuan)用(yong)(yong)(yong)IN4148型二極管(guan)，VD2～D6選(xuan)(xuan)(xuan)用(yong)(yong)(yong)IN4007型二極管(guan)，LED1、LED2選(xuan)(xuan)(xuan)用(yong)(yong)(yong)普(pu)(pu)通(tong)紅色發光二極管(guan)，LED3選(xuan)(xuan)(xuan)用(yong)(yong)(yong)普(pu)(pu)通(tong)綠(lv)色發光二極管(guan)，R1選(xuan)(xuan)(xuan)用(yong)(yong)(yong)2kΩ普(pu)(pu)通(tong)電(dian)(dian)阻，R2選(xuan)(xuan)(xuan)用(yong)(yong)(yong)10kΩ普(pu)(pu)通(tong)電(dian)(dian)阻，R3、R4選(xuan)(xuan)(xuan)用(yong)(yong)(yong)1kΩ普(pu)(pu)通(tong)電(dian)(dian)阻，開關S1選(xuan)(xuan)(xuan)用(yong)(yong)(yong)KDC-A01-06Y型的，P1和J1分(fen)別選(xuan)(xuan)(xuan)用(yong)(yong)(yong)普(pu)(pu)通(tong)單聲道耳機插(cha)頭(tou)、插(cha)孔。變壓器T選(xuan)(xuan)(xuan)用(yong)(yong)(yong)3W/14V電(dian)(dian)源變壓器，C1選(xuan)(xuan)(xuan)用(yong)(yong)(yong)1000μF/25V電(dian)(dian)解(jie)電(dian)(dian)容，C2、C3、C4選(xuan)(xuan)(xuan)470μF/25V電(dian)(dian)解(jie)電(dian)(dian)容，C5選(xuan)(xuan)(xuan)用(yong)(yong)(yong)47μF/25V電(dian)(dian)解(jie)電(dian)(dian)容。