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(zhuan)入涓電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)浮充充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)階段(duan)時(shi)，充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)紅色二極管LED1兩端變為零(ling)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)熄滅(mie)(充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)綠色二極管則發(fa)光)，此時(shi)VT3也因基極零(ling)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)而(er)截止，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)調整管VT4正常(chang)導通，輸(shu)出2.1V直流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，石英小(xiao)鬧鐘(zhong)得電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)開(kai)始計(ji)時(shi)，當計(ji)時(shi)到預(yu)先設定值時(shi)，石英小(xiao)鬧鐘(zhong)輸(shu)出低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平音頻(pin)脈(mo)沖訊響信號，該低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平音頻(pin)脈(mo)沖信號通過(guo)VT2放大(da)整流(liu)經電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容C5濾波輸(shu)出一直流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，使VT1飽和導通，開(kai)關(guan)S1電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁脫鉤(gou)線(xian)圈(quan)得電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)產生磁力，使開(kai)關(guan)按鈕脫鉤(gou)跳開(kai)，斷開(kai)交流(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，從而(er)實(shi)現自動結束充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。

   智能定(ding)時插(cha)座的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)見圖，共由(you)交(jiao)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)開(kai)關、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁脫鉤(gou)線(xian)圈驅動電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)、定(ding)時電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)、直流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)4部分(fen)組成。將該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)插(cha)上電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)插(cha)頭，按(an)下交(jiao)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)開(kai)關S1按(an)鈕，接通220V交(jiao)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)即可開(kai)始工作。220V交(jiao)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)一(yi)路(lu)經(jing)14V電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)變壓(ya)(ya)器(qi)T降(jiang)壓(ya)(ya)、橋式整流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)整流、濾(lv)波電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C1濾(lv)波、三端穩(wen)壓(ya)(ya)集成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)IC1穩(wen)壓(ya)(ya)、濾(lv)波電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C2濾(lv)波產生穩(wen)定(ding)的(de)+12V直流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，該+12V分(fen)三路(lu)輸出：(1)經(jing)R4加(jia)到(dao)LED2作+12V直流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)工作指示。(2)經(jing)R3、VD2、LED3串聯穩(wen)壓(ya)(ya)后(hou)經(jing)C3濾(lv)波加(jia)到(dao)穩(wen)壓(ya)(ya)調整管VT4基(ji)極(ji)，使VT4將+12V穩(wen)壓(ya)(ya)為2.1V，由(you)VT4發射極(ji)輸出，該2.1V經(jing)C4濾(lv)波后(hou)加(jia)到(dao)石(shi)英小鬧(nao)鐘電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)正負(fu)極(ji)為其提供(gong)直流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(提示一(yi)點：2.1V高(gao)了(le)些，石(shi)英小鬧(nao)鐘走時稍快一(yi)些，定(ding)時值按(an)4~5小時即可)。(3)加(jia)到(dao)開(kai)關S1的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁脫鉤(gou)線(xian)圈上。

　　元件選擇
　　元件選(xuan)擇(ze)如電(dian)(dian)路原理圖(tu)上的標注：VT1、VT3、VT4選(xuan)用S8050型(xing)(xing)三極管(guan)，VT2選(xuan)用S8550型(xing)(xing)三極管(guan)，IC1選(xuan)用LM7812，VD1選(xuan)用IN4148型(xing)(xing)二極管(guan)，VD2～D6選(xuan)用IN4007型(xing)(xing)二極管(guan)，LED1、LED2選(xuan)用普(pu)(pu)通(tong)(tong)紅色發光二極管(guan)，LED3選(xuan)用普(pu)(pu)通(tong)(tong)綠(lv)色發光二極管(guan)，R1選(xuan)用2kΩ普(pu)(pu)通(tong)(tong)電(dian)(dian)阻，R2選(xuan)用10kΩ普(pu)(pu)通(tong)(tong)電(dian)(dian)阻，R3、R4選(xuan)用1kΩ普(pu)(pu)通(tong)(tong)電(dian)(dian)阻，開關S1選(xuan)用KDC-A01-06Y型(xing)(xing)的，P1和J1分(fen)別(bie)選(xuan)用普(pu)(pu)通(tong)(tong)單聲(sheng)道(dao)耳機插頭、插孔。變壓器T選(xuan)用3W/14V電(dian)(dian)源變壓器，C1選(xuan)用1000μF/25V電(dian)(dian)解(jie)電(dian)(dian)容(rong)，C2、C3、C4選(xuan)470μF/25V電(dian)(dian)解(jie)電(dian)(dian)容(rong)，C5選(xuan)用47μF/25V電(dian)(dian)解(jie)電(dian)(dian)容(rong)。