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)流浮充充電(dian)(dian)(dian)階段時(shi)，充電(dian)(dian)(dian)器紅色二(er)極管LED1兩端變(bian)為零電(dian)(dian)(dian)壓熄滅(充電(dian)(dian)(dian)器綠色二(er)極管則(ze)發光(guang))，此時(shi)VT3也因基極零電(dian)(dian)(dian)壓而截(jie)止，電(dian)(dian)(dian)源調(diao)整管VT4正(zheng)常導(dao)通，輸出2.1V直流電(dian)(dian)(dian)源，石英小鬧鐘(zhong)得(de)電(dian)(dian)(dian)開(kai)始計時(shi)，當計時(shi)到(dao)預先設定值時(shi)，石英小鬧鐘(zhong)輸出低(di)電(dian)(dian)(dian)平(ping)音(yin)頻脈沖(chong)訊響信(xin)號(hao)，該(gai)低(di)電(dian)(dian)(dian)平(ping)音(yin)頻脈沖(chong)信(xin)號(hao)通過VT2放大整流經電(dian)(dian)(dian)容C5濾(lv)波輸出一直流電(dian)(dian)(dian)壓，使VT1飽和導(dao)通，開(kai)關S1電(dian)(dian)(dian)磁脫鉤線圈(quan)得(de)電(dian)(dian)(dian)產生磁力(li)，使開(kai)關按(an)鈕(niu)脫鉤跳開(kai)，斷開(kai)交流電(dian)(dian)(dian)源，從而實(shi)現自(zi)動結(jie)束充電(dian)(dian)(dian)。

   智能定(ding)時(shi)插(cha)座的電(dian)(dian)路(lu)見(jian)圖，共由交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)開(kai)(kai)關、電(dian)(dian)磁脫(tuo)鉤線圈驅動(dong)電(dian)(dian)路(lu)、定(ding)時(shi)電(dian)(dian)路(lu)、直流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)電(dian)(dian)路(lu)4部分組成(cheng)(cheng)。將(jiang)該(gai)電(dian)(dian)路(lu)插(cha)上電(dian)(dian)源(yuan)(yuan)插(cha)頭，按下交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)開(kai)(kai)關S1按鈕，接通220V交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)即(ji)可開(kai)(kai)始工作。220V交(jiao)流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)一路(lu)經(jing)14V電(dian)(dian)源(yuan)(yuan)變壓(ya)器T降壓(ya)、橋式整流(liu)(liu)(liu)(liu)電(dian)(dian)路(lu)整流(liu)(liu)(liu)(liu)、濾(lv)波電(dian)(dian)容(rong)C1濾(lv)波、三端穩(wen)壓(ya)集成(cheng)(cheng)電(dian)(dian)路(lu)IC1穩(wen)壓(ya)、濾(lv)波電(dian)(dian)容(rong)C2濾(lv)波產生(sheng)穩(wen)定(ding)的+12V直流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)，該(gai)+12V分三路(lu)輸(shu)出：(1)經(jing)R4加到LED2作+12V直流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)工作指示。(2)經(jing)R3、VD2、LED3串聯穩(wen)壓(ya)后(hou)經(jing)C3濾(lv)波加到穩(wen)壓(ya)調(diao)整管(guan)VT4基(ji)極，使VT4將(jiang)+12V穩(wen)壓(ya)為2.1V，由VT4發(fa)射(she)極輸(shu)出，該(gai)2.1V經(jing)C4濾(lv)波后(hou)加到石英(ying)小鬧鐘(zhong)電(dian)(dian)源(yuan)(yuan)正負(fu)極為其提(ti)供直流(liu)(liu)(liu)(liu)電(dian)(dian)源(yuan)(yuan)(提(ti)示一點：2.1V高了些，石英(ying)小鬧鐘(zhong)走時(shi)稍快(kuai)一些，定(ding)時(shi)值按4~5小時(shi)即(ji)可)。(3)加到開(kai)(kai)關S1的電(dian)(dian)磁脫(tuo)鉤線圈上。

　　元件選擇
　　元件選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)擇(ze)如電(dian)(dian)路原理(li)圖上(shang)的(de)標(biao)注：VT1、VT3、VT4選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用S8050型(xing)(xing)(xing)三極(ji)(ji)管(guan)，VT2選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用S8550型(xing)(xing)(xing)三極(ji)(ji)管(guan)，IC1選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用LM7812，VD1選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用IN4148型(xing)(xing)(xing)二(er)(er)極(ji)(ji)管(guan)，VD2～D6選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用IN4007型(xing)(xing)(xing)二(er)(er)極(ji)(ji)管(guan)，LED1、LED2選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用普(pu)通(tong)(tong)(tong)(tong)紅色發(fa)光(guang)二(er)(er)極(ji)(ji)管(guan)，LED3選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用普(pu)通(tong)(tong)(tong)(tong)綠色發(fa)光(guang)二(er)(er)極(ji)(ji)管(guan)，R1選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用2kΩ普(pu)通(tong)(tong)(tong)(tong)電(dian)(dian)阻(zu)，R2選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用10kΩ普(pu)通(tong)(tong)(tong)(tong)電(dian)(dian)阻(zu)，R3、R4選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用1kΩ普(pu)通(tong)(tong)(tong)(tong)電(dian)(dian)阻(zu)，開關S1選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用KDC-A01-06Y型(xing)(xing)(xing)的(de)，P1和J1分別選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用普(pu)通(tong)(tong)(tong)(tong)單聲道耳(er)機(ji)插頭、插孔(kong)。變壓器T選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用3W/14V電(dian)(dian)源變壓器，C1選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用1000μF/25V電(dian)(dian)解電(dian)(dian)容(rong)(rong)，C2、C3、C4選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)470μF/25V電(dian)(dian)解電(dian)(dian)容(rong)(rong)，C5選(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)(xuan)用47μF/25V電(dian)(dian)解電(dian)(dian)容(rong)(rong)。