門(men)鈴(ling)安裝難？專家推(tui)薦各種實用門(men)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(ge)月以上(shang)，耗電量較低。

圖(tu)中的(de)(de)IC便(bian)是時(shi)基電(dian)(dian)(dian)路集成塊555，它構成無穩態(tai)多諧(xie)振(zhen)(zhen)蕩(dang)(dang)器(qi)。按(an)下按(an)鈕AN（裝(zhuang)在(zai)門(men)上），振(zhen)(zhen)蕩(dang)(dang)器(qi)振(zhen)(zhen)蕩(dang)(dang)，振(zhen)(zhen)蕩(dang)(dang)頻率約700Hz，揚(yang)聲(sheng)器(qi)發出“叮”的(de)(de)聲(sheng)音。與此同時(shi)，電(dian)(dian)(dian)源(yuan)通過二極管D1給(gei)C1充電(dian)(dian)(dian)。放開按(an)鈕時(shi)，C1便(bian)通過電(dian)(dian)(dian)阻R1放電(dian)(dian)(dian)，維持(chi)振(zhen)(zhen)蕩(dang)(dang)。但由于AN的(de)(de)斷開，電(dian)(dian)(dian)阻R2被串入電(dian)(dian)(dian)路，使(shi)振(zhen)(zhen)蕩(dang)(dang)頻率有所(suo)改(gai)變(bian)，大約為500Hz左右，揚(yang)聲(sheng)器(qi)發出“咚”的(de)(de)聲(sheng)音。直到C1上電(dian)(dian)(dian)壓放到不(bu)能(neng)維持(chi)555振(zhen)(zhen)蕩(dang)(dang)為止。“咚”聲(sheng)的(de)(de)余(yu)音的(de)(de)長短可通過改(gai)變(bian)C1的(de)(de)數(shu)值來(lai)改(gai)變(bian)。

不用電池的雙音門鈴電路圖

隨著電話機的(de)(de)普及率(lv)越(yue)來(lai)(lai)越(yue)高，擁有(you)住宅(zhai)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)的(de)(de)家庭也(ye)越(yue)來(lai)(lai)越(yue)多(duo)，但大多(duo)數住宅(zhai)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)使用率(lv)很低，利用電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)入戶(hu)饋(kui)線(xian)提供的(de)(de)48V（60V）直流(liu)(liu)(liu)饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)作電(dian)(dian)(dian)(dian)(dian)(dian)子門(men)鈴(ling)的(de)(de)工(gong)作能源是經濟實用的(de)(de)。現介紹一款不(bu)用電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)雙音(yin)(yin)門(men)鈴(ling)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)。電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)原理如圖(tu)所示(shi)，不(bu)難看出，圖(tu)中電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)是常規的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)機(ji)(ji)振鈴(ling)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)變型。a、b分(fen)別(bie)是電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)機(ji)(ji)入戶(hu)線(xian)的(de)(de)正(zheng)、負兩端。AN為常開型門(men)鈴(ling)按(an)(an)鈕，在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)機(ji)(ji)候機(ji)(ji)時(shi)(shi)(shi)，按(an)(an)下AN，程控(kong)(kong)交換(huan)機(ji)(ji)提供的(de)(de)48V（或(huo)60V）電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，直流(liu)(liu)(liu)饋(kui)電(dian)(dian)(dian)(dian)(dian)(dian)經VD1、R1對電(dian)(dian)(dian)(dian)(dian)(dian)容C1充電(dian)(dian)(dian)(dian)(dian)(dian)，當C1端電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)Vc達到IC1的(de)(de)起控(kong)(kong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)時(shi)(shi)(shi)，IC1起振送(song)出雙音(yin)(yin)電(dian)(dian)(dian)(dian)(dian)(dian)子鈴(ling)流(liu)(liu)(liu)使蜂鳴器B發聲，告知(zhi)主人有(you)客來(lai)(lai)訪。而當電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)機(ji)(ji)正(zheng)在(zai)使用時(shi)(shi)(shi)，則圖(tu)中a、b之(zhi)間的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)較低達不(bu)到IC1的(de)(de)起控(kong)(kong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，此時(shi)(shi)(shi)，即使按(an)(an)下AN門(men)鈴(ling)按(an)(an)鈕也(ye)不(bu)工(gong)作，這是因為由于R1取值(zhi)較大，遠大于電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)機(ji)(ji)的(de)(de)阻抗。故(gu)AN按(an)(an)下時(shi)(shi)(shi)對電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)機(ji)(ji)的(de)(de)正(zheng)常通話(hua)(hua)(hua)無影響。也(ye)對程控(kong)(kong)交換(huan)機(ji)(ji)無不(bu)良(liang)影響，僅在(zai)使用門(men)鈴(ling)時(shi)(shi)(shi)對其間打(da)入的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)遇忙。

一種對講門鈴電路圖的剖析及改進

有(you)一種對(dui)講(jiang)門鈴的(de)(de)電路如圖(tu)，其(qi)工(gong)作原(yuan)理如下(xia)：平時掛機時叉(cha)簧(huang)開關HS的(de)(de)1、2觸點接(jie)(jie)通，用AC220V供電，V1有(you)直(zhi)流輸出(chu)，此(ci)電壓既(ji)對(dui)電池充電，也(ye)加到音(yin)樂(le)(le)IC的(de)(de)③腳。如按一下(xia)S，則(ze)音(yin)樂(le)(le)IC的(de)(de)②腳受觸發，④腳有(you)音(yin)樂(le)(le)信號輸出(chu)，經(jing)V2放大后推動揚聲(sheng)器發聲(sheng)，同時經(jing)R5推動Y2、Y3。摘(zhai)機后，叉(cha)簧(huang)開關HS的(de)(de)1、3接(jie)(jie)點接(jie)(jie)通，通話電路接(jie)(jie)通電源，這(zhe)時可進行對(dui)講(jiang)。

本對講門鈴由于音(yin)頻放大器IC2（LM386）的增益很高，容易使Y2、Y3產生嘯(xiao)叫聲。經筆者實(shi)際驗(yan)證，只要在Y2、Y3兩端(duan)并聯一只幾pF的小電(dian)容，嘯(xiao)叫聲即可消除。

不用按鈕的音樂門鈴電路圖

本文介紹一種不用按鈕的音樂門鈴，來(lai)人只(zhi)要站(zhan)在門鈴前，便可(ke)自動發出門鈴聲。

該音樂(le)門鈴(ling)電路(lu)原理如附圖所示。IC1等(deng)元件(jian)組成紅外(wai)(wai)(wai)發(fa)(fa)射電路(lu)，由(you)IC1、RP、R1、C1構成多(duo)諧(xie)振蕩(dang)(dang)頻(pin)率(lv)，按(an)圖示元件(jian)數據，振蕩(dang)(dang)頻(pin)率(lv)約40kHz，輸出電流為100--200mA，可驅動(dong)紅外(wai)(wai)(wai)發(fa)(fa)光二極管(guan)D1發(fa)(fa)射出40kHz調制紅外(wai)(wai)(wai)脈沖。IC2是紅外(wai)(wai)(wai)接收(shou)芯片(pian)，靈(ling)敏度高、增益高、輸出波(bo)形好，并具有鑒頻(pin)功能。紅外(wai)(wai)(wai)接收(shou)管(guan)D2接收(shou)到40kHz頻(pin)率(lv)的紅外(wai)(wai)(wai)脈沖后，轉換(huan)為電信號，送(song)入(ru)IC2第⑦腳，經放(fang)大和C5、L調諧(xie)以及IC2內部電路(lu)檢波(bo)、整形后，由(you)第①腳輸出脈沖信號。

平時，IC2第(di)①腳輸(shu)(shu)出(chu)(chu)低電瓶(ping)，D3截止，音樂(le)集成電路IC3無觸(chu)發(fa)(fa)脈沖，不(bu)產(chan)生音樂(le)信號(hao)輸(shu)(shu)出(chu)(chu)，揚聲(sheng)器B不(bu)發(fa)(fa)聲(sheng)。當有人站在門(men)前遮(zhe)擋D1發(fa)(fa)射的(de)紅外(wai)信號(hao)時，IC2第(di)①腳電位(wei)瞬(shun)間(jian)由低電平變為高電平，經D3觸(chu)發(fa)(fa)IC3輸(shu)(shu)出(chu)(chu)音樂(le)信號(hao)，由V放(fang)大推動揚聲(sheng)器發(fa)(fa)聲(sheng)。

IC1選(xuan)(xuan)(xuan)用(yong)NE555，IC2為μPC1373，IC3選(xuan)(xuan)(xuan)用(yong)9300系列音樂(le)集(ji)成(cheng)電路。D1可(ke)用(yong)SE303A或LM66R型(xing)5mm圓(yuan)形紅外(wai)發光二極(ji)管(guan)，D2可(ke)用(yong)PH302方形紅外(wai)接收二極(ji)管(guan)。V為9013NPN管(guan)，β≥100。B選(xuan)(xuan)(xuan)用(yong)YD58--1型(xing)、8Ω/0.25W小口徑揚聲器。L用(yong)?0.08mm高強度漆包線，在(zai)小型(xing)晶(jing)體管(guan)收音機的中頻(pin)變壓器骨架(jia)上密繞(rao)30匝即(ji)可(ke)。

兩種無按鈕音樂門鈴電路圖

門(men)鈴(ling)均需安(an)(an)裝按裝，因而存在著安(an)(an)裝麻煩和易于丟失損壞等問題(ti)。用復(fu)合開關管(guan)代替機械觸(chu)發開關制作的音樂門(men)鈴(ling)，即可(ke)克服上述弊端。

圖1為振(zhen)動式。當有人用手敲門(men)時，安裝在(zai)門(men)內側(ce)的壓(ya)電(dian)陶瓷(ci)(ci)片YD受到振(zhen)動而產生相應的音頻(pin)電(dian)壓(ya)，使復合(he)管(guan)開關BG1和BG2導通，音樂(le)電(dian)路CIC受到觸(chu)發即(ji)演奏一段樂(le)曲(qu)。壓(ya)電(dian)陶瓷(ci)(ci)片以采用直(zhi)徑較大(da)的為宜，用502膠水將(jiang)其粘合(he)在(zai)門(men)內偏上的中(zhong)心位(wei)置(zhi)即(ji)可。

圖2為(wei)觸摸式。當用(yong)手指觸摸電(dian)路(lu)A點時，人體感(gan)應(ying)電(dian)壓使復合管BG1和(he)BG2導(dao)通(tong)，音樂電(dian)路(lu)CIC受到觸發即(ji)演(yan)奏一段(duan)樂曲。觸摸電(dian)極A可用(yong)一大小適中的金(jin)屬片(pian)固定在門框(kuang)上即(ji)可。

觸摸式門鈴電路圖

本(ben)文介紹(shao)的觸(chu)(chu)摸(mo)式門(men)鈴(ling)，用觸(chu)(chu)摸(mo)方(fang)式代(dai)替(ti)機械開關，它簡單可(ke)靠，實用有(you)趣。

工(gong)(gong)作(zuo)原理：電(dian)(dian)(dian)(dian)原理圖如(ru)圖所示。555時(shi)(shi)基集成電(dian)(dian)(dian)(dian)路工(gong)(gong)作(zuo)在單穩狀態(tai)，平時(shi)(shi)③腳和⑦腳均為(wei)(wei)低(di)電(dian)(dian)(dian)(dian)平．當用手觸(chu)(chu)摸一下(xia)金屬感應片(pian)M時(shi)(shi),人(ren)體的(de)感應信號(hao)通過0.1μF電(dian)(dian)(dian)(dian)容(rong)(rong)加至555時(shi)(shi)基集成電(dian)(dian)(dian)(dian)路的(de)②腳，使電(dian)(dian)(dian)(dian)路翻(fan)轉(zhuan)進入暫(zan)穩態(tai)，這時(shi)(shi)③腳輸出(chu)高(gao)電(dian)(dian)(dian)(dian)平直接加到(dao)門鈴芯(xin)片(pian)的(de)觸(chu)(chu)發(fa)(fa)端，芯(xin)片(pian)被觸(chu)(chu)發(fa)(fa)并(bing)通過三極(ji)管推(tui)動揚(yang)聲器發(fa)(fa)聲。同時(shi)(shi)⑦腳也(ye)變為(wei)(wei)高(gao)電(dian)(dian)(dian)(dian)平，電(dian)(dian)(dian)(dian)源(yuan)通過100KΩ電(dian)(dian)(dian)(dian)阻(zu)對4.7μF電(dian)(dian)(dian)(dian)容(rong)(rong)充(chong)電(dian)(dian)(dian)(dian),當電(dian)(dian)(dian)(dian)容(rong)(rong)上的(de)電(dian)(dian)(dian)(dian)壓(ya)充(chong)至2/3電(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)壓(ya)時(shi)(shi)，電(dian)(dian)(dian)(dian)路又翻(fan)轉(zhuan)，暫(zan)穩態(tai)結束，③腳又變為(wei)(wei)低(di)電(dian)(dian)(dian)(dian)平。待再觸(chu)(chu)摸一次(ci)M時(shi)(shi)，上述工(gong)(gong)作(zuo)過程(cheng)周而復始。因(yin)此每觸(chu)(chu)摸一次(ci)M，門鈴就被觸(chu)(chu)發(fa)(fa)一次(ci)。③腳上的(de)0.01μF電(dian)(dian)(dian)(dian)容(rong)(rong)為(wei)(wei)抗干擾電(dian)(dian)(dian)(dian)容(rong)(rong),可(ke)防止門鈴被誤觸(chu)(chu)發(fa)(fa)。

元(yuan)器件選擇與制作(zuo)：本電(dian)(dian)(dian)路的(de)(de)(de)門鈴芯(xin)片(pian)(pian)選用(yong)(yong)“叮咚(dong)”（HL9300）芯(xin)片(pian)(pian)，它每被觸發(fa)(fa)一次，盡管(guan)(guan)③腳(jiao)變為(wei)(wei)低電(dian)(dian)(dian)平后，它仍可(ke)連續發(fa)(fa)出三(san)次“叮咚(dong)”聲。如(ru)選用(yong)(yong)的(de)(de)(de)是需要觸發(fa)(fa)端一直為(wei)(wei)高電(dian)(dian)(dian)平才(cai)可(ke)發(fa)(fa)聲的(de)(de)(de)芯(xin)片(pian)(pian)（如(ru)音樂(le)(le)芯(xin)片(pian)(pian)），應適當調整(zheng)⑦腳(jiao)上的(de)(de)(de)阻容(rong)時間(jian)(jian)常數來調整(zheng)暫穩態的(de)(de)(de)時間(jian)(jian)，使③腳(jiao)的(de)(de)(de)高電(dian)(dian)(dian)平足以使芯(xin)片(pian)(pian)發(fa)(fa)出一曲完整(zheng)的(de)(de)(de)音樂(le)(le)后才(cai)變成低電(dian)(dian)(dian)平。另(ling)外還應通電(dian)(dian)(dian)測量一下門鈴芯(xin)片(pian)(pian)推(tui)動三(san)極(ji)管(guan)(guan)的(de)(de)(de)基(ji)極(ji)電(dian)(dian)(dian)位，如(ru)靜(jing)態（不發(fa)(fa)聲）時為(wei)(wei)低電(dian)(dian)(dian)平，則改用(yong)(yong)NPN型三(san)極(ji)管(guan)(guan)作(zuo)推(tui)動管(guan)(guan)，目的(de)(de)(de)是防止靜(jing)態動耗，延長電(dian)(dian)(dian)池使用(yong)(yong)壽(shou)命。觸摸片(pian)(pian)的(de)(de)(de)引線太長時最好使用(yong)(yong)屏蔽(bi)線并(bing)將(jiang)屏蔽(bi)層(ceng)接地(di)。本電(dian)(dian)(dian)路制作(zuo)簡單，只要安裝無誤即可(ke)正常工作(zuo)。本電(dian)(dian)(dian)路還可(ke)擴展為(wei)(wei)觸摸開關(guan)、觸摸報(bao)警器等實用(yong)(yong)電(dian)(dian)(dian)路。

簡便電子雙音門鈴電路圖

本(ben)文介紹一種采(cai)用(yong)時基集成(cheng)(cheng)電路(lu)構成(cheng)(cheng)的雙音門鈴(ling)，電路(lu)如下圖(tu)所示，其核(he)心部分(fen)是SL555時基電路(lu)。

兩用聲控門鈴電路圖

本文介紹一種簡易聲控電路。元器件較少，靜態電流(liu)僅為(wei)1mA。該(gai)電路可用于聲控門鈴和(he)聲控玩具。

工作原理(li)：這種(zhong)聲(sheng)控電(dian)路的(de)(de)原理(li)如(ru)下圖所示(shi)。它由(you)聲(sheng)控傳(chuan)感(gan)器、接收放(fang)大(da)(da)(da)器、射(she)極(ji)(ji)輸(shu)(shu)出(chu)器、音(yin)樂(le)(le)(le)集(ji)(ji)成電(dian)路、發光二極(ji)(ji)管(guan)(guan)、揚(yang)聲(sheng)器等組成。外界(jie)產(chan)生的(de)(de)聲(sheng)音(yin)控制信(xin)號(hao)，由(you)駐極(ji)(ji)體電(dian)容傳(chuan)聲(sheng)器BM轉變(bian)為電(dian)信(xin)號(hao)，并經電(dian)容C1耦合至(zhi)三(san)極(ji)(ji)管(guan)(guan)VT1進行電(dian)壓(ya)放(fang)大(da)(da)(da)。VT1的(de)(de)輸(shu)(shu)出(chu)信(xin)號(hao)經二極(ji)(ji)管(guan)(guan)VD2驅動三(san)極(ji)(ji)管(guan)(guan)VT2導(dao)通，使電(dian)源電(dian)壓(ya)加到音(yin)樂(le)(le)(le)集(ji)(ji)成電(dian)路IC的(de)(de)②腳（觸(chu)發端），音(yin)樂(le)(le)(le)IC③腳發出(chu)音(yin)樂(le)(le)(le)信(xin)號(hao)，經VT3放(fang)大(da)(da)(da)后，驅動揚(yang)聲(sheng)器BL發出(chu)宏亮的(de)(de)樂(le)(le)(le)聲(sheng)。與些同時(shi)，發光二極(ji)(ji)管(guan)(guan)VD3、VD4隨著音(yin)樂(le)(le)(le)的(de)(de)大(da)(da)(da)小而頻頻閃(shan)光，猶如(ru)洋(yang)娃娃兩只閃(shan)亮的(de)(de)大(da)(da)(da)眼睛。調節電(dian)路中電(dian)位器RP的(de)(de)阻值，可以改(gai)變(bian)BM的(de)(de)工作電(dian)壓(ya)，從(cong)而起到改(gai)變(bian)聲(sheng)控靈敏度(du)的(de)(de)作用。電(dian)容C2是(shi)防止誤觸(chu)發，避免浪涌電(dian)流沖擊(ji)面設(she)置的(de)(de)。

元(yuan)器(qi)件選(xuan)(xuan)擇：VT1～VT3選(xuan)(xuan)用9014高(gao)增(zeng)益三極(ji)(ji)管，其穿透電(dian)流要小(xiao)，β＞80。BM可選(xuan)(xuan)用CN－15E或阻抗為1KΩ的(de)其它駐極(ji)(ji)體傳聲器(qi)。音(yin)樂集成電(dian)路IC選(xuan)(xuan)用KD－152等工作電(dian)壓(ya)為3V的(de)高(gao)電(dian)平觸(chu)發的(de)音(yin)樂集成片。VD3、VD4選(xuan)(xuan)用工作電(dian)壓(ya)低、導通(tong)電(dian)流小(xiao)而發光效率高(gao)的(de)發光二極(ji)(ji)管。其余(yu)元(yuan)件均按圖中標注的(de)值選(xuan)(xuan)取，并無特(te)殊要求。

安裝與使用：

（1）如家有(you)音樂(le)門鈴(ling)，則不必再(zai)制作電路外(wai)殼，可(ke)按(an)圖加裝控制電路即(ji)可(ke)。

（2）駐極體傳聲器BM，裝在外門框(kuang)上，高度可(ke)視人(ren)高矮(ai)而定。為使BM保持清潔，可用(yong)一(yi)塊小花(hua)布(bu)遮(zhe)掩并標注“聲控”二字，即可裝飾(shi)，又引人注目。

（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(shi)當的靈敏度，以人嘴離駐極體傳聲器BM為30mm左右能(neng)觸發門鈴為宜(yi)。

（4）發光(guang)二極管(guan)用于(yu)聲控門鈴時，只須一只發光(guang)管(guan)，將其裝在(zai)門外(wai)顯(xian)眼(yan)處(chu)。當人發聲時，如(ru)發光(guang)管(guan)顯(xian)示，則告訴外(wai)人，請放心電路工作(zuo)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裝入兩只(zhi)眼(yan)睛中，只(zhi)要兒童發聲，洋娃(wa)(wa)娃(wa)(wa)便會閃動著大眼(yan)睛唱歌，頗有情趣。

（6）兒童不玩時，取出電池。最好選用4.7K帶開關(guan)的(de)電位(wei)器，即可調節(jie)又能開關(guan)，這樣可節(jie)省(sheng)靜態耗電。

觸摸式音樂門鈴電路圖

KD－482常用于石英(ying)鐘(zhong)整點時(shi)，如在它的外部再加裝幾(ji)只電子元件(jian)，便可組(zu)成(cheng)觸摸式音樂(le)門鈴(ling)。電路工作(zuo)電流為60mA，靜(jing)態(tai)電流幾(ji)乎為零。

該電(dian)(dian)(dian)路如下圖(tu)所示。VT1、VT2組(zu)成(cheng)觸(chu)摸靈(ling)敏開關。當手(shou)輕觸(chu)摸金屬片A時(shi)，人體給VT1的(de)(de)(de)柵(zha)極(ji)注入一感(gan)應(ying)信號(hao)，使VT1的(de)(de)(de)漏極(ji)電(dian)(dian)(dian)流減小(xiao)(xiao)，其(qi)漏極(ji)與源極(ji)間電(dian)(dian)(dian)阻增(zeng)大，C點變(bian)(bian)為高電(dian)(dian)(dian)位(wei)，VT2導(dao)通，發光二極(ji)管VD1亮。這(zhe)時(shi)D點變(bian)(bian)為低(di)電(dian)(dian)(dian)位(wei)，KD－482的(de)(de)(de)SW端被低(di)電(dian)(dian)(dian)平觸(chu)發振蕩工作(zuo)，由VT3放大的(de)(de)(de)信號(hao)驅(qu)動揚聲器BL發聲。手(shou)離開時(shi)A時(shi)，VT1的(de)(de)(de)漏極(ji)電(dian)(dian)(dian)流變(bian)(bian)大，其(qi)漏、源極(ji)間電(dian)(dian)(dian)阻減小(xiao)(xiao)，C點變(bian)(bian)為低(di)電(dian)(dian)(dian)平，VT2截(jie)止，VD1熄(xi)滅，D點變(bian)(bian)為高電(dian)(dian)(dian)位(wei)。BL播(bo)完一首樂曲后(hou)將(jiang)會自動停止。

元器件選擇：場效(xiao)(xiao)應晶體管(guan)(guan)VT1除3DJ6E外也可(ke)采用(yong)其它的結型(xing)場效(xiao)(xiao)應晶體管(guan)(guan)，但要求(qiu)飽和漏(lou)極電流小于1mA。發光二極管(guan)(guan)VD1的型(xing)號(hao)可(ke)任(ren)意選擇，為使效(xiao)(xiao)果更佳，VD1應選擇工作電壓在2～2.5V．發光效(xiao)(xiao)率高(gao)的發光管(guan)(guan)。金屬片的面積(ji)為300mm左(zuo)右(you)。

調試：電(dian)路按(an)下(xia)圖接(jie)好(hao)后(hou)，先將(jiang)電(dian)源的(de)負極與SW端用一(yi)根金(jin)屬線(xian)短接(jie)一(yi)下(xia)（KD－482為(wei)低電(dian)平觸發(fa)），BL放出音樂即可(ke)(ke)。控制電(dian)路只稍加調整，未觸摸A之前，將(jiang)萬用表打在(zai)直(zhi)流(liu)1V檔位，測(ce)量VT2的(de)基極b與發(fa)射極e兩端電(dian)壓(ya)應(ying)小于(yu)(yu)0.7V，然(ran)后(hou)再用手輕觸A，此時指針(zhen)指示(shi)要大于(yu)(yu)或(huo)等于(yu)(yu)0.7V。如達不(bu)到(dao)該值，可(ke)(ke)適當改變一(yi)下(xia)R2或(huo)R3的(de)阻(zu)值，兩個電(dian)阻(zu)最(zui)好(hao)配合調整。

安裝與調試：

由于該電(dian)路(lu)靜態耗電(dian)流極(ji)(ji)微，故可省(sheng)去電(dian)源開關。A與VT1的(de)(de)柵極(ji)(ji)之(zhi)間的(de)(de)距離可根據實(shi)際(ji)情況(kuang)而(er)定(ding)，最好不要超過(guo)1m。發光二極(ji)(ji)管VD1最好與觸摸片A裝(zhuang)在門(men)(men)外(wai)顯眼處，當門(men)(men)外(wai)人觸摸到A時，VD1即(ji)刻發光顯示(shi)，就表示(shi)電(dian)路(lu)工(gong)作(zuo)正(zheng)常。在觸摸A時，有時偶爾(er)會出(chu)現(xian)電(dian)路(lu)不工(gong)作(zuo)情況(kuang)，這時VT1與VT2應選擇放大倍數大一些的(de)(de)管子。

該(gai)(gai)電(dian)路也可用于(yu)防盜(dao)，將VT1柵(zha)極(ji)的(de)(de)接(jie)觸線安(an)裝(zhuang)在門拉手或門鎖等(deng)金屬(shu)部位，當(dang)盜(dao)賊的(de)(de)手一接(jie)觸即可報警(jing)。該(gai)(gai)電(dian)路經改動后可用于(yu)觸摸兒童(tong)玩具。KD－482的(de)(de)E、E'兩(liang)端原(yuan)來(lai)是接(jie)蜂(feng)鳴陶瓷片的(de)(de)，如(ru)(ru)加以(yi)改進接(jie)上兩(liang)只發光二極(ji)管(guan)(guan)VD2、VD3（如(ru)(ru)下圖所示(shi)），而(er)(er)發光二極(ji)管(guan)(guan)VD1裝(zhuang)在前額中(zhong)間尤如(ru)(ru)三只眼，這(zhe)樣不僅集聲．光、色(se)于(yu)一體新穎有趣，而(er)(er)且更會招(zhao)來(lai)兒童(tong)們(men)的(de)(de)喜愛。其中(zhong)VD1是用于(yu)來(lai)控制明(ming)暗的(de)(de)，VD2．VD3是隨(sui)音樂聲的(de)(de)大小而(er)(er)頻頻閃爍(shuo)的(de)(de)。