門鈴(ling)安裝難？專家推薦各(ge)種實用門鈴(ling)電路圖

叮咚門鈴電路圖

下圖是一種能發出“叮、咚”聲的門鈴的電原理圖。它是利用一塊時基電路集成塊和外圍元件組成的。它的音質優美逼真，裝調簡單容易、成本較低，一節6V迭層電池可用三個月以(yi)上，耗電量較低。

圖中的(de)(de)(de)IC便是時(shi)基電(dian)(dian)路集成(cheng)塊555，它構成(cheng)無穩態多諧振(zhen)(zhen)(zhen)蕩(dang)器。按(an)下按(an)鈕AN（裝在門上(shang)），振(zhen)(zhen)(zhen)蕩(dang)器振(zhen)(zhen)(zhen)蕩(dang)，振(zhen)(zhen)(zhen)蕩(dang)頻(pin)率(lv)約700Hz，揚聲器發(fa)(fa)出(chu)“叮(ding)”的(de)(de)(de)聲音(yin)。與此同時(shi)，電(dian)(dian)源通(tong)(tong)過(guo)二極管D1給C1充電(dian)(dian)。放(fang)開按(an)鈕時(shi)，C1便通(tong)(tong)過(guo)電(dian)(dian)阻(zu)R1放(fang)電(dian)(dian)，維持振(zhen)(zhen)(zhen)蕩(dang)。但由于AN的(de)(de)(de)斷開，電(dian)(dian)阻(zu)R2被(bei)串(chuan)入電(dian)(dian)路，使振(zhen)(zhen)(zhen)蕩(dang)頻(pin)率(lv)有所改變，大約為500Hz左右，揚聲器發(fa)(fa)出(chu)“咚”的(de)(de)(de)聲音(yin)。直到(dao)C1上(shang)電(dian)(dian)壓放(fang)到(dao)不能維持555振(zhen)(zhen)(zhen)蕩(dang)為止。“咚”聲的(de)(de)(de)余音(yin)的(de)(de)(de)長短(duan)可通(tong)(tong)過(guo)改變C1的(de)(de)(de)數值來(lai)改變。

不用電池的雙音門鈴電路圖

隨著電話機的(de)(de)普(pu)及率越來越高，擁有住(zhu)宅電(dian)(dian)(dian)(dian)話(hua)的(de)(de)家(jia)庭也越來越多，但大(da)多數住(zhu)宅電(dian)(dian)(dian)(dian)話(hua)使用(yong)率很低，利用(yong)電(dian)(dian)(dian)(dian)話(hua)入(ru)戶饋(kui)線提(ti)供的(de)(de)48V（60V）直流饋(kui)電(dian)(dian)(dian)(dian)作電(dian)(dian)(dian)(dian)子門(men)(men)鈴(ling)的(de)(de)工作能源是(shi)(shi)經(jing)濟實用(yong)的(de)(de)。現介紹一款不用(yong)電(dian)(dian)(dian)(dian)池(chi)的(de)(de)雙音門(men)(men)鈴(ling)電(dian)(dian)(dian)(dian)路(lu)(lu)。電(dian)(dian)(dian)(dian)路(lu)(lu)原理(li)如圖(tu)所示，不難看(kan)出，圖(tu)中電(dian)(dian)(dian)(dian)路(lu)(lu)是(shi)(shi)常(chang)規的(de)(de)電(dian)(dian)(dian)(dian)話(hua)機(ji)(ji)(ji)(ji)振鈴(ling)電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)變型。a、b分別是(shi)(shi)電(dian)(dian)(dian)(dian)話(hua)機(ji)(ji)(ji)(ji)入(ru)戶線的(de)(de)正(zheng)(zheng)、負兩端。AN為(wei)常(chang)開型門(men)(men)鈴(ling)按(an)(an)鈕(niu)，在電(dian)(dian)(dian)(dian)話(hua)機(ji)(ji)(ji)(ji)候機(ji)(ji)(ji)(ji)時，按(an)(an)下AN，程(cheng)控(kong)(kong)交(jiao)換機(ji)(ji)(ji)(ji)提(ti)供的(de)(de)48V（或60V）電(dian)(dian)(dian)(dian)壓(ya)(ya)，直流饋(kui)電(dian)(dian)(dian)(dian)經(jing)VD1、R1對(dui)(dui)電(dian)(dian)(dian)(dian)容C1充電(dian)(dian)(dian)(dian)，當C1端電(dian)(dian)(dian)(dian)壓(ya)(ya)Vc達(da)到(dao)IC1的(de)(de)起(qi)控(kong)(kong)電(dian)(dian)(dian)(dian)壓(ya)(ya)時，IC1起(qi)振送(song)出雙音電(dian)(dian)(dian)(dian)子鈴(ling)流使蜂鳴器B發聲(sheng)，告知主人有客來訪。而當電(dian)(dian)(dian)(dian)話(hua)機(ji)(ji)(ji)(ji)正(zheng)(zheng)在使用(yong)時，則(ze)圖(tu)中a、b之間的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)較低達(da)不到(dao)IC1的(de)(de)起(qi)控(kong)(kong)電(dian)(dian)(dian)(dian)壓(ya)(ya)，此時，即(ji)使按(an)(an)下AN門(men)(men)鈴(ling)按(an)(an)鈕(niu)也不工作，這是(shi)(shi)因為(wei)由于(yu)R1取值較大(da)，遠大(da)于(yu)電(dian)(dian)(dian)(dian)話(hua)機(ji)(ji)(ji)(ji)的(de)(de)阻抗。故AN按(an)(an)下時對(dui)(dui)電(dian)(dian)(dian)(dian)話(hua)機(ji)(ji)(ji)(ji)的(de)(de)正(zheng)(zheng)常(chang)通(tong)話(hua)無影(ying)響。也對(dui)(dui)程(cheng)控(kong)(kong)交(jiao)換機(ji)(ji)(ji)(ji)無不良影(ying)響，僅在使用(yong)門(men)(men)鈴(ling)時對(dui)(dui)其(qi)間打入(ru)的(de)(de)電(dian)(dian)(dian)(dian)話(hua)遇(yu)忙。

一種對講門鈴電路圖的剖析及改進

有一種對講(jiang)(jiang)門鈴的(de)(de)電(dian)(dian)路如圖(tu)，其工作原理如下：平時(shi)(shi)(shi)掛機(ji)(ji)時(shi)(shi)(shi)叉(cha)簧(huang)開(kai)關(guan)HS的(de)(de)1、2觸點接通(tong)，用AC220V供(gong)電(dian)(dian)，V1有直流輸出，此電(dian)(dian)壓既對電(dian)(dian)池充電(dian)(dian)，也加到音(yin)樂IC的(de)(de)③腳。如按一下S，則音(yin)樂IC的(de)(de)②腳受觸發，④腳有音(yin)樂信號輸出，經V2放大后推動(dong)揚(yang)聲器發聲，同時(shi)(shi)(shi)經R5推動(dong)Y2、Y3。摘機(ji)(ji)后，叉(cha)簧(huang)開(kai)關(guan)HS的(de)(de)1、3接點接通(tong)，通(tong)話電(dian)(dian)路接通(tong)電(dian)(dian)源，這時(shi)(shi)(shi)可進行對講(jiang)(jiang)。

本對講門鈴由于音頻放大(da)器IC2（LM386）的(de)增(zeng)益很高(gao)，容易使Y2、Y3產生嘯叫聲(sheng)(sheng)。經筆者實際(ji)驗證，只要在Y2、Y3兩(liang)端并聯一只幾pF的(de)小(xiao)電(dian)容，嘯叫聲(sheng)(sheng)即可消除。

不用按鈕的音樂門鈴電路圖

本文介紹一(yi)種不用按鈕的(de)音樂門鈴(ling)，來人只要(yao)站在門鈴(ling)前(qian)，便可自動發(fa)出門鈴(ling)聲。

該(gai)音樂門(men)鈴(ling)電(dian)(dian)路原理如(ru)附圖(tu)(tu)所示。IC1等元件(jian)組成紅(hong)外(wai)發(fa)射電(dian)(dian)路，由(you)IC1、RP、R1、C1構成多諧(xie)振(zhen)蕩(dang)頻率(lv)，按圖(tu)(tu)示元件(jian)數(shu)據，振(zhen)蕩(dang)頻率(lv)約(yue)40kHz，輸(shu)出(chu)(chu)電(dian)(dian)流(liu)為(wei)100--200mA，可驅動紅(hong)外(wai)發(fa)光二極管D1發(fa)射出(chu)(chu)40kHz調(diao)制紅(hong)外(wai)脈沖。IC2是紅(hong)外(wai)接收(shou)芯片，靈敏(min)度(du)高、增益高、輸(shu)出(chu)(chu)波形好，并(bing)具(ju)有(you)鑒頻功能。紅(hong)外(wai)接收(shou)管D2接收(shou)到40kHz頻率(lv)的(de)紅(hong)外(wai)脈沖后，轉(zhuan)換為(wei)電(dian)(dian)信號(hao)，送入IC2第(di)⑦腳，經放大和C5、L調(diao)諧(xie)以及IC2內部電(dian)(dian)路檢波、整(zheng)形后，由(you)第(di)①腳輸(shu)出(chu)(chu)脈沖信號(hao)。

平時(shi)，IC2第①腳輸(shu)出(chu)低電(dian)(dian)(dian)瓶，D3截止，音(yin)樂(le)(le)集成電(dian)(dian)(dian)路IC3無觸發(fa)脈沖，不(bu)(bu)產生音(yin)樂(le)(le)信(xin)號輸(shu)出(chu)，揚(yang)聲器(qi)B不(bu)(bu)發(fa)聲。當有(you)人站在門前遮擋(dang)D1發(fa)射的紅(hong)外信(xin)號時(shi)，IC2第①腳電(dian)(dian)(dian)位瞬間(jian)由(you)低電(dian)(dian)(dian)平變為高電(dian)(dian)(dian)平，經(jing)D3觸發(fa)IC3輸(shu)出(chu)音(yin)樂(le)(le)信(xin)號，由(you)V放大推動揚(yang)聲器(qi)發(fa)聲。

IC1選用(yong)NE555，IC2為(wei)μPC1373，IC3選用(yong)9300系列音樂集成(cheng)電路。D1可用(yong)SE303A或LM66R型(xing)5mm圓形紅(hong)外發光二極(ji)管，D2可用(yong)PH302方形紅(hong)外接(jie)收(shou)二極(ji)管。V為(wei)9013NPN管，β≥100。B選用(yong)YD58--1型(xing)、8Ω/0.25W小(xiao)口徑揚聲器(qi)。L用(yong)?0.08mm高(gao)強度(du)漆(qi)包(bao)線，在小(xiao)型(xing)晶體管收(shou)音機(ji)的中頻變壓(ya)器(qi)骨架上密繞30匝即可。

兩種無按鈕音樂門鈴電路圖

門(men)鈴(ling)均需安(an)裝按裝，因而存(cun)在著安(an)裝麻煩(fan)和易于丟失(shi)損壞等(deng)問題。用復合(he)開關管代(dai)替機械觸發開關制作的音樂(le)門(men)鈴(ling)，即可克服(fu)上述弊端。

圖1為振動式。當有(you)人用手敲門時，安裝在(zai)門內(nei)側(ce)的(de)(de)壓電(dian)陶瓷(ci)片YD受到振動而產生相應的(de)(de)音(yin)頻電(dian)壓，使(shi)復合(he)管開關BG1和BG2導通(tong)，音(yin)樂電(dian)路CIC受到觸發(fa)即(ji)演奏一段樂曲。壓電(dian)陶瓷(ci)片以采(cai)用直徑較大的(de)(de)為宜，用502膠水將其粘合(he)在(zai)門內(nei)偏(pian)上的(de)(de)中心位置(zhi)即(ji)可。

圖(tu)2為觸(chu)摸(mo)式。當用手(shou)指觸(chu)摸(mo)電(dian)路A點時，人(ren)體感應電(dian)壓使(shi)復合管(guan)BG1和BG2導通(tong)，音(yin)樂電(dian)路CIC受到觸(chu)發即(ji)演(yan)奏一(yi)段樂曲。觸(chu)摸(mo)電(dian)極A可用一(yi)大小(xiao)適中的金屬(shu)片固定在門(men)框(kuang)上即(ji)可。

觸摸式門鈴電路圖

本文介紹(shao)的觸(chu)摸式門鈴，用觸(chu)摸方式代(dai)替機械(xie)開關(guan)，它簡單可靠，實用有趣。

工作原理：電(dian)(dian)(dian)(dian)(dian)原理圖(tu)如圖(tu)所示(shi)。555時(shi)(shi)基集成(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)路(lu)工作在單穩狀態，平時(shi)(shi)③腳(jiao)(jiao)和⑦腳(jiao)(jiao)均(jun)為(wei)低電(dian)(dian)(dian)(dian)(dian)平．當用手(shou)觸摸(mo)一(yi)下金(jin)屬(shu)感應(ying)片(pian)M時(shi)(shi),人體的(de)感應(ying)信號通過(guo)0.1μF電(dian)(dian)(dian)(dian)(dian)容加(jia)至555時(shi)(shi)基集成(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)路(lu)的(de)②腳(jiao)(jiao)，使電(dian)(dian)(dian)(dian)(dian)路(lu)翻轉進入(ru)暫(zan)(zan)穩態，這時(shi)(shi)③腳(jiao)(jiao)輸出高電(dian)(dian)(dian)(dian)(dian)平直接加(jia)到門(men)鈴(ling)芯片(pian)的(de)觸發(fa)端(duan)，芯片(pian)被(bei)觸發(fa)并通過(guo)三(san)極(ji)管推(tui)動揚(yang)聲器發(fa)聲。同時(shi)(shi)⑦腳(jiao)(jiao)也變(bian)為(wei)高電(dian)(dian)(dian)(dian)(dian)平，電(dian)(dian)(dian)(dian)(dian)源通過(guo)100KΩ電(dian)(dian)(dian)(dian)(dian)阻對4.7μF電(dian)(dian)(dian)(dian)(dian)容充電(dian)(dian)(dian)(dian)(dian),當電(dian)(dian)(dian)(dian)(dian)容上的(de)電(dian)(dian)(dian)(dian)(dian)壓充至2/3電(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)壓時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)路(lu)又翻轉，暫(zan)(zan)穩態結(jie)束，③腳(jiao)(jiao)又變(bian)為(wei)低電(dian)(dian)(dian)(dian)(dian)平。待再觸摸(mo)一(yi)次(ci)M時(shi)(shi)，上述工作過(guo)程周而復始。因(yin)此(ci)每觸摸(mo)一(yi)次(ci)M，門(men)鈴(ling)就被(bei)觸發(fa)一(yi)次(ci)。③腳(jiao)(jiao)上的(de)0.01μF電(dian)(dian)(dian)(dian)(dian)容為(wei)抗干(gan)擾電(dian)(dian)(dian)(dian)(dian)容,可防止門(men)鈴(ling)被(bei)誤觸發(fa)。

元器件選擇與(yu)制(zhi)作：本(ben)電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)門(men)鈴芯(xin)片(pian)(pian)選用(yong)(yong)“叮咚”（HL9300）芯(xin)片(pian)(pian)，它每被觸發一(yi)次，盡管③腳變(bian)為低電(dian)(dian)(dian)(dian)平(ping)后(hou)，它仍可(ke)連(lian)續發出三次“叮咚”聲。如選用(yong)(yong)的(de)是需要觸發端(duan)一(yi)直為高電(dian)(dian)(dian)(dian)平(ping)才(cai)可(ke)發聲的(de)芯(xin)片(pian)(pian)（如音樂芯(xin)片(pian)(pian)），應適(shi)當調(diao)整⑦腳上的(de)阻容時間常(chang)數來調(diao)整暫(zan)穩態的(de)時間，使(shi)③腳的(de)高電(dian)(dian)(dian)(dian)平(ping)足以使(shi)芯(xin)片(pian)(pian)發出一(yi)曲(qu)完(wan)整的(de)音樂后(hou)才(cai)變(bian)成低電(dian)(dian)(dian)(dian)平(ping)。另外還應通電(dian)(dian)(dian)(dian)測量(liang)一(yi)下(xia)門(men)鈴芯(xin)片(pian)(pian)推(tui)動(dong)三極(ji)管的(de)基極(ji)電(dian)(dian)(dian)(dian)位，如靜態（不發聲）時為低電(dian)(dian)(dian)(dian)平(ping)，則改用(yong)(yong)NPN型三極(ji)管作推(tui)動(dong)管，目(mu)的(de)是防止靜態動(dong)耗，延長電(dian)(dian)(dian)(dian)池使(shi)用(yong)(yong)壽命。觸摸(mo)片(pian)(pian)的(de)引線太長時最(zui)好(hao)使(shi)用(yong)(yong)屏(ping)蔽(bi)線并將屏(ping)蔽(bi)層接地。本(ben)電(dian)(dian)(dian)(dian)路(lu)(lu)制(zhi)作簡單，只要安裝無誤即可(ke)正常(chang)工作。本(ben)電(dian)(dian)(dian)(dian)路(lu)(lu)還可(ke)擴展為觸摸(mo)開(kai)關、觸摸(mo)報警器等實用(yong)(yong)電(dian)(dian)(dian)(dian)路(lu)(lu)。

簡便電子雙音門鈴電路圖

本文介紹(shao)一(yi)種采用(yong)時(shi)基(ji)集成電路(lu)構成的雙音門鈴，電路(lu)如下(xia)圖所(suo)示，其(qi)核(he)心部分是SL555時(shi)基(ji)電路(lu)。

兩用聲控門鈴電路圖

本文(wen)介紹(shao)一種簡易聲(sheng)控(kong)電(dian)(dian)路(lu)。元器件(jian)較少，靜態電(dian)(dian)流(liu)僅為(wei)1mA。該電(dian)(dian)路(lu)可用(yong)于聲(sheng)控(kong)門(men)鈴和(he)聲(sheng)控(kong)玩具(ju)。

工(gong)作(zuo)原理：這(zhe)種(zhong)聲(sheng)(sheng)控(kong)(kong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)原理如(ru)下圖所(suo)示。它由(you)聲(sheng)(sheng)控(kong)(kong)傳感器、接收(shou)放大器、射極輸出器、音(yin)樂(le)(le)集成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路、發(fa)(fa)光二(er)極管、揚聲(sheng)(sheng)器等組成。外界產(chan)生的(de)(de)聲(sheng)(sheng)音(yin)控(kong)(kong)制(zhi)信號(hao)，由(you)駐極體(ti)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)傳聲(sheng)(sheng)器BM轉(zhuan)變為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)信號(hao)，并經電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C1耦合(he)至三極管VT1進行電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)放大。VT1的(de)(de)輸出信號(hao)經二(er)極管VD2驅動三極管VT2導(dao)通，使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)加到(dao)(dao)音(yin)樂(le)(le)集成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路IC的(de)(de)②腳（觸發(fa)(fa)端），音(yin)樂(le)(le)IC③腳發(fa)(fa)出音(yin)樂(le)(le)信號(hao)，經VT3放大后，驅動揚聲(sheng)(sheng)器BL發(fa)(fa)出宏亮(liang)的(de)(de)樂(le)(le)聲(sheng)(sheng)。與些同時，發(fa)(fa)光二(er)極管VD3、VD4隨著音(yin)樂(le)(le)的(de)(de)大小而頻(pin)頻(pin)閃光，猶如(ru)洋娃娃兩只閃亮(liang)的(de)(de)大眼睛。調節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位器RP的(de)(de)阻(zu)值，可以(yi)改變BM的(de)(de)工(gong)作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，從而起(qi)到(dao)(dao)改變聲(sheng)(sheng)控(kong)(kong)靈敏度的(de)(de)作(zuo)用(yong)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)C2是防止誤(wu)觸發(fa)(fa)，避免浪涌電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流沖(chong)擊面設置(zhi)的(de)(de)。

元器件選擇：VT1～VT3選用(yong)9014高增(zeng)益三(san)極(ji)管，其(qi)穿透電(dian)(dian)流(liu)要小，β＞80。BM可選用(yong)CN－15E或阻抗為(wei)(wei)1KΩ的(de)其(qi)它駐(zhu)極(ji)體傳聲器。音(yin)樂集(ji)成電(dian)(dian)路IC選用(yong)KD－152等工作(zuo)電(dian)(dian)壓為(wei)(wei)3V的(de)高電(dian)(dian)平觸(chu)發(fa)的(de)音(yin)樂集(ji)成片。VD3、VD4選用(yong)工作(zuo)電(dian)(dian)壓低、導通電(dian)(dian)流(liu)小而發(fa)光效率高的(de)發(fa)光二極(ji)管。其(qi)余元件均按圖(tu)中標注(zhu)的(de)值選取，并無特殊要求。

安裝與使用：

（1）如家有音樂門鈴，則不必再制作電路外殼，可按圖(tu)加裝控制電路即(ji)可。

（2）駐極體傳聲器BM，裝在(zai)外門(men)框上(shang)，高度(du)可視人高矮而定。為使BM保持(chi)清潔，可用(yong)一塊小花布遮掩并(bing)標注“聲控”二字，即可裝(zhuang)飾，又引人注目(mu)。

（3）為防止外界聲音的干擾而引起誤工作，要調節RP，使BM具有適當(dang)的(de)靈(ling)敏度，以人嘴離(li)駐極體傳聲器BM為(wei)30mm左右(you)能觸發(fa)門鈴為(wei)宜。

（4）發光二(er)極管用(yong)于聲控門鈴(ling)時，只(zhi)須一只(zhi)發光管，將其裝在(zai)門外(wai)顯眼處。當(dang)人(ren)發聲時，如發光管顯示，則告訴外(wai)人(ren)，請放心電路工作正常。

（5）如作兒童玩具，選用一只空心塑料或毛絨絨的玩具，將VD3、VD4裝(zhuang)入(ru)兩只眼睛中，只要兒童(tong)發聲，洋(yang)娃娃便會閃動著大眼睛唱(chang)歌，頗有情趣。

（6）兒童不玩時，取出電池。最好選用4.7K帶開(kai)關(guan)(guan)的電(dian)位(wei)器，即可(ke)調節(jie)又能開(kai)關(guan)(guan)，這樣可(ke)節(jie)省(sheng)靜態耗(hao)電(dian)。

觸摸式音樂門鈴電路圖

KD－482常用于石英鐘整點時，如在它的外部再加裝幾只電子元件，便(bian)可組成觸摸式音樂門鈴。電路(lu)工作電流(liu)為60mA，靜態(tai)電流(liu)幾乎為零。

該電(dian)(dian)(dian)路(lu)如下圖所示。VT1、VT2組成(cheng)觸摸靈敏開關。當(dang)手輕觸摸金屬片A時，人體(ti)給VT1的(de)柵極(ji)(ji)(ji)(ji)注入(ru)一感應信號，使(shi)VT1的(de)漏極(ji)(ji)(ji)(ji)電(dian)(dian)(dian)流減小(xiao)，其(qi)漏極(ji)(ji)(ji)(ji)與源(yuan)極(ji)(ji)(ji)(ji)間電(dian)(dian)(dian)阻(zu)增大，C點(dian)變為(wei)高(gao)電(dian)(dian)(dian)位(wei)，VT2導通(tong)，發(fa)光二極(ji)(ji)(ji)(ji)管VD1亮。這時D點(dian)變為(wei)低(di)(di)電(dian)(dian)(dian)位(wei)，KD－482的(de)SW端被低(di)(di)電(dian)(dian)(dian)平觸發(fa)振蕩工作，由VT3放大的(de)信號驅動揚聲器BL發(fa)聲。手離開時A時，VT1的(de)漏極(ji)(ji)(ji)(ji)電(dian)(dian)(dian)流變大，其(qi)漏、源(yuan)極(ji)(ji)(ji)(ji)間電(dian)(dian)(dian)阻(zu)減小(xiao)，C點(dian)變為(wei)低(di)(di)電(dian)(dian)(dian)平，VT2截止，VD1熄滅，D點(dian)變為(wei)高(gao)電(dian)(dian)(dian)位(wei)。BL播完一首樂曲(qu)后將會自動停(ting)止。

元器件選擇(ze)(ze)：場(chang)效應晶體管VT1除3DJ6E外(wai)也可采用其(qi)它的(de)結型(xing)場(chang)效應晶體管，但要求飽和漏極(ji)電流小于(yu)1mA。發(fa)光(guang)二極(ji)管VD1的(de)型(xing)號可任意(yi)選擇(ze)(ze)，為使(shi)效果更佳，VD1應選擇(ze)(ze)工作電壓在2～2.5V．發(fa)光(guang)效率高的(de)發(fa)光(guang)管。金屬片的(de)面(mian)積為300mm左右。

調(diao)試：電(dian)路(lu)按(an)下圖接好后，先將(jiang)電(dian)源的(de)負極與SW端(duan)用一(yi)根金(jin)屬(shu)線短(duan)接一(yi)下（KD－482為低電(dian)平觸發），BL放(fang)出音樂即可。控制電(dian)路(lu)只稍加調(diao)整(zheng)，未觸摸A之前，將(jiang)萬用表打在直流1V檔(dang)位，測量VT2的(de)基(ji)極b與發射(she)極e兩端(duan)電(dian)壓應小于0.7V，然(ran)后再用手輕觸A，此時指針指示要大于或(huo)等于0.7V。如達(da)不到(dao)該值(zhi)，可適當改(gai)變一(yi)下R2或(huo)R3的(de)阻值(zhi)，兩個(ge)電(dian)阻最(zui)好配合(he)調(diao)整(zheng)。

安裝與調試：

由于該電路靜(jing)態耗電流極(ji)微，故可(ke)省去(qu)電源(yuan)開(kai)關(guan)。A與VT1的柵極(ji)之(zhi)間的距離可(ke)根(gen)據實際情況(kuang)而定，最(zui)好(hao)不(bu)(bu)要超過1m。發光(guang)二極(ji)管VD1最(zui)好(hao)與觸(chu)摸片(pian)A裝在門(men)外顯(xian)(xian)眼處，當門(men)外人觸(chu)摸到A時(shi)，VD1即刻發光(guang)顯(xian)(xian)示，就表示電路工作正常。在觸(chu)摸A時(shi)，有時(shi)偶(ou)爾會出現電路不(bu)(bu)工作情況(kuang)，這時(shi)VT1與VT2應選(xuan)擇放大倍數大一些的管子。

該(gai)電路(lu)也可用于(yu)防(fang)盜，將VT1柵極的(de)接觸(chu)線安裝在(zai)門(men)拉手(shou)或門(men)鎖等(deng)金屬部(bu)位，當盜賊的(de)手(shou)一接觸(chu)即可報警。該(gai)電路(lu)經改(gai)動后可用于(yu)觸(chu)摸(mo)兒童玩具(ju)。KD－482的(de)E、E'兩端(duan)原來是(shi)接蜂(feng)鳴(ming)陶(tao)瓷片的(de)，如加以(yi)改(gai)進接上(shang)兩只(zhi)發光二極管(guan)VD2、VD3（如下圖所示），而發光二極管(guan)VD1裝在(zai)前額中間尤(you)如三只(zhi)眼(yan)，這(zhe)樣(yang)不僅集聲(sheng)．光、色于(yu)一體(ti)新穎有趣，而且更會招(zhao)來兒童們的(de)喜愛(ai)。其中VD1是(shi)用于(yu)來控(kong)制明暗的(de)，VD2．VD3是(shi)隨音樂聲(sheng)的(de)大小而頻(pin)頻(pin)閃(shan)爍的(de)。