門鈴(ling)安裝難？專(zhuan)家推(tui)薦各種(zhong)實用門鈴(ling)電路(lu)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上，耗電量較低。

圖中的(de)IC便是時(shi)(shi)基電(dian)(dian)(dian)路集成(cheng)塊(kuai)555，它構成(cheng)無穩態多諧振(zhen)蕩(dang)(dang)器(qi)。按(an)下(xia)按(an)鈕AN（裝在門上），振(zhen)蕩(dang)(dang)器(qi)振(zhen)蕩(dang)(dang)，振(zhen)蕩(dang)(dang)頻(pin)率約700Hz，揚聲(sheng)器(qi)發(fa)出“叮(ding)”的(de)聲(sheng)音。與此同(tong)時(shi)(shi)，電(dian)(dian)(dian)源(yuan)通過(guo)二極管D1給(gei)C1充電(dian)(dian)(dian)。放(fang)(fang)開(kai)按(an)鈕時(shi)(shi)，C1便通過(guo)電(dian)(dian)(dian)阻R1放(fang)(fang)電(dian)(dian)(dian)，維(wei)(wei)持(chi)(chi)振(zhen)蕩(dang)(dang)。但由于AN的(de)斷開(kai)，電(dian)(dian)(dian)阻R2被(bei)串(chuan)入電(dian)(dian)(dian)路，使振(zhen)蕩(dang)(dang)頻(pin)率有所改變，大約為500Hz左右，揚聲(sheng)器(qi)發(fa)出“咚”的(de)聲(sheng)音。直到C1上電(dian)(dian)(dian)壓(ya)放(fang)(fang)到不能(neng)維(wei)(wei)持(chi)(chi)555振(zhen)蕩(dang)(dang)為止。“咚”聲(sheng)的(de)余音的(de)長短可(ke)通過(guo)改變C1的(de)數(shu)值來改變。

不用電池的雙音門鈴電路圖

隨著電話機的(de)(de)(de)(de)普及率(lv)越(yue)來(lai)越(yue)高，擁有住宅(zhai)電(dian)(dian)(dian)(dian)(dian)話(hua)的(de)(de)(de)(de)家庭也越(yue)來(lai)越(yue)多，但(dan)大(da)多數住宅(zhai)電(dian)(dian)(dian)(dian)(dian)話(hua)使用(yong)率(lv)很低(di)，利用(yong)電(dian)(dian)(dian)(dian)(dian)話(hua)入(ru)戶饋(kui)線提供的(de)(de)(de)(de)48V（60V）直流饋(kui)電(dian)(dian)(dian)(dian)(dian)作電(dian)(dian)(dian)(dian)(dian)子(zi)門(men)鈴(ling)的(de)(de)(de)(de)工(gong)(gong)作能源是經濟實用(yong)的(de)(de)(de)(de)。現介紹一款不(bu)用(yong)電(dian)(dian)(dian)(dian)(dian)池(chi)的(de)(de)(de)(de)雙(shuang)音門(men)鈴(ling)電(dian)(dian)(dian)(dian)(dian)路(lu)。電(dian)(dian)(dian)(dian)(dian)路(lu)原(yuan)理(li)如圖(tu)所示，不(bu)難看出，圖(tu)中電(dian)(dian)(dian)(dian)(dian)路(lu)是常規(gui)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)話(hua)機振鈴(ling)電(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)(de)(de)變(bian)型。a、b分別是電(dian)(dian)(dian)(dian)(dian)話(hua)機入(ru)戶線的(de)(de)(de)(de)正、負兩(liang)端(duan)。AN為常開型門(men)鈴(ling)按(an)(an)鈕(niu)，在電(dian)(dian)(dian)(dian)(dian)話(hua)機候機時(shi)(shi)，按(an)(an)下(xia)(xia)AN，程(cheng)控(kong)(kong)交換(huan)機提供的(de)(de)(de)(de)48V（或(huo)60V）電(dian)(dian)(dian)(dian)(dian)壓(ya)，直流饋(kui)電(dian)(dian)(dian)(dian)(dian)經VD1、R1對電(dian)(dian)(dian)(dian)(dian)容C1充電(dian)(dian)(dian)(dian)(dian)，當(dang)(dang)C1端(duan)電(dian)(dian)(dian)(dian)(dian)壓(ya)Vc達到(dao)IC1的(de)(de)(de)(de)起控(kong)(kong)電(dian)(dian)(dian)(dian)(dian)壓(ya)時(shi)(shi)，IC1起振送出雙(shuang)音電(dian)(dian)(dian)(dian)(dian)子(zi)鈴(ling)流使蜂(feng)鳴器B發聲，告知(zhi)主(zhu)人有客來(lai)訪。而(er)當(dang)(dang)電(dian)(dian)(dian)(dian)(dian)話(hua)機正在使用(yong)時(shi)(shi)，則圖(tu)中a、b之(zhi)間的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)較(jiao)低(di)達不(bu)到(dao)IC1的(de)(de)(de)(de)起控(kong)(kong)電(dian)(dian)(dian)(dian)(dian)壓(ya)，此時(shi)(shi)，即使按(an)(an)下(xia)(xia)AN門(men)鈴(ling)按(an)(an)鈕(niu)也不(bu)工(gong)(gong)作，這(zhe)是因為由(you)于(yu)R1取值較(jiao)大(da)，遠大(da)于(yu)電(dian)(dian)(dian)(dian)(dian)話(hua)機的(de)(de)(de)(de)阻抗(kang)。故AN按(an)(an)下(xia)(xia)時(shi)(shi)對電(dian)(dian)(dian)(dian)(dian)話(hua)機的(de)(de)(de)(de)正常通話(hua)無(wu)影響。也對程(cheng)控(kong)(kong)交換(huan)機無(wu)不(bu)良影響，僅在使用(yong)門(men)鈴(ling)時(shi)(shi)對其間打入(ru)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)話(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)電(dian)(dian)(dian)路如(ru)圖，其工作原理如(ru)下：平時掛機(ji)時叉簧開關(guan)HS的(de)1、2觸點(dian)接(jie)(jie)(jie)通(tong)，用(yong)AC220V供(gong)電(dian)(dian)(dian)，V1有(you)直流輸出(chu)，此電(dian)(dian)(dian)壓既對(dui)電(dian)(dian)(dian)池充電(dian)(dian)(dian)，也(ye)加到音(yin)(yin)樂IC的(de)③腳。如(ru)按一下S，則音(yin)(yin)樂IC的(de)②腳受觸發，④腳有(you)音(yin)(yin)樂信號輸出(chu)，經V2放大后推動(dong)揚(yang)聲(sheng)器(qi)發聲(sheng)，同時經R5推動(dong)Y2、Y3。摘機(ji)后，叉簧開關(guan)HS的(de)1、3接(jie)(jie)(jie)點(dian)接(jie)(jie)(jie)通(tong)，通(tong)話(hua)電(dian)(dian)(dian)路接(jie)(jie)(jie)通(tong)電(dian)(dian)(dian)源，這(zhe)時可進行對(dui)講(jiang)。

本(ben)對(dui)講門鈴(ling)由于音頻放大(da)器IC2（LM386）的(de)增益很高，容易使Y2、Y3產(chan)生嘯叫聲。經筆(bi)者實際驗證，只(zhi)要在Y2、Y3兩端并聯一只(zhi)幾(ji)pF的(de)小電容，嘯叫聲即(ji)可消除。

不用按鈕的音樂門鈴電路圖

本文(wen)介紹(shao)一種不用按鈕(niu)的音樂門鈴，來(lai)人只要站在門鈴前，便(bian)可自動發出門鈴聲(sheng)。

該音樂門鈴電(dian)路(lu)原理如附(fu)圖(tu)所示。IC1等(deng)元(yuan)件組成(cheng)紅外(wai)(wai)發射電(dian)路(lu)，由(you)IC1、RP、R1、C1構成(cheng)多諧振蕩頻(pin)率，按圖(tu)示元(yuan)件數據，振蕩頻(pin)率約40kHz，輸(shu)出(chu)電(dian)流為100--200mA，可驅(qu)動紅外(wai)(wai)發光二極管(guan)D1發射出(chu)40kHz調制紅外(wai)(wai)脈沖。IC2是紅外(wai)(wai)接(jie)收芯片，靈敏度高、增益高、輸(shu)出(chu)波形(xing)好，并(bing)具有(you)鑒頻(pin)功能。紅外(wai)(wai)接(jie)收管(guan)D2接(jie)收到40kHz頻(pin)率的紅外(wai)(wai)脈沖后，轉換為電(dian)信(xin)號，送入IC2第⑦腳，經放大和C5、L調諧以(yi)及IC2內(nei)部電(dian)路(lu)檢波、整形(xing)后，由(you)第①腳輸(shu)出(chu)脈沖信(xin)號。

平(ping)時(shi)，IC2第(di)①腳輸(shu)出低電瓶，D3截止，音樂(le)集成(cheng)電路IC3無觸發(fa)脈沖，不產生(sheng)音樂(le)信號輸(shu)出，揚(yang)聲(sheng)(sheng)器B不發(fa)聲(sheng)(sheng)。當有人站(zhan)在(zai)門前遮(zhe)擋D1發(fa)射的紅(hong)外信號時(shi)，IC2第(di)①腳電位瞬間由低電平(ping)變為高電平(ping)，經(jing)D3觸發(fa)IC3輸(shu)出音樂(le)信號，由V放大推(tui)動揚(yang)聲(sheng)(sheng)器發(fa)聲(sheng)(sheng)。

IC1選用(yong)NE555，IC2為μPC1373，IC3選用(yong)9300系列音樂(le)集成(cheng)電路。D1可(ke)用(yong)SE303A或LM66R型(xing)5mm圓形(xing)紅(hong)外發光二(er)極管(guan)，D2可(ke)用(yong)PH302方形(xing)紅(hong)外接收(shou)二(er)極管(guan)。V為9013NPN管(guan)，β≥100。B選用(yong)YD58--1型(xing)、8Ω/0.25W小(xiao)口徑(jing)揚聲(sheng)器(qi)。L用(yong)?0.08mm高強度漆包線(xian)，在小(xiao)型(xing)晶體管(guan)收(shou)音機(ji)的中頻變(bian)壓器(qi)骨(gu)架上(shang)密繞(rao)30匝即可(ke)。

兩種無按鈕音樂門鈴電路圖

門鈴均需(xu)安裝(zhuang)按裝(zhuang)，因而存(cun)在(zai)著安裝(zhuang)麻煩和易于丟失損壞(huai)等問(wen)題(ti)。用(yong)復(fu)合(he)開關管代替機(ji)械觸發開關制作的音樂(le)門鈴，即可克服上述弊端。

圖1為振動(dong)式。當有(you)人用手敲門(men)時，安裝(zhuang)在(zai)門(men)內側(ce)的壓(ya)電(dian)陶(tao)瓷(ci)片YD受到(dao)振動(dong)而產生相應的音頻電(dian)壓(ya)，使復合管(guan)開關BG1和BG2導通，音樂(le)電(dian)路CIC受到(dao)觸(chu)發(fa)即演奏一段樂(le)曲。壓(ya)電(dian)陶(tao)瓷(ci)片以采用直徑較大的為宜，用502膠水將其(qi)粘合在(zai)門(men)內偏上的中心位置即可(ke)。

圖2為觸(chu)摸式。當用手指觸(chu)摸電(dian)(dian)路(lu)A點時，人(ren)體感(gan)應電(dian)(dian)壓使(shi)復合(he)管BG1和BG2導(dao)通，音樂(le)電(dian)(dian)路(lu)CIC受(shou)到(dao)觸(chu)發(fa)即(ji)演奏一(yi)段樂(le)曲。觸(chu)摸電(dian)(dian)極A可用一(yi)大小適中(zhong)的金屬片固定在門框上即(ji)可。

觸摸式門鈴電路圖

本(ben)文介紹的觸(chu)(chu)摸式門(men)鈴，用觸(chu)(chu)摸方式代替機械開關，它(ta)簡單(dan)可靠，實用有趣。

工作原理(li)：電(dian)(dian)(dian)(dian)(dian)(dian)(dian)原理(li)圖(tu)如圖(tu)所示。555時(shi)基集(ji)(ji)成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路工作在單穩(wen)(wen)狀態，平(ping)時(shi)③腳(jiao)(jiao)和⑦腳(jiao)(jiao)均為低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)．當用手觸(chu)(chu)摸一下金屬(shu)感應(ying)片(pian)M時(shi),人體的感應(ying)信號(hao)通過(guo)0.1μF電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容加至555時(shi)基集(ji)(ji)成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路的②腳(jiao)(jiao)，使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路翻轉進入(ru)暫穩(wen)(wen)態，這時(shi)③腳(jiao)(jiao)輸出高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)直(zhi)接加到(dao)門(men)鈴芯(xin)片(pian)的觸(chu)(chu)發端，芯(xin)片(pian)被觸(chu)(chu)發并通過(guo)三極管(guan)推(tui)動揚聲器(qi)發聲。同時(shi)⑦腳(jiao)(jiao)也變為高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)通過(guo)100KΩ電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻對4.7μF電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian),當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容上的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓充(chong)至2/3電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓時(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路又翻轉，暫穩(wen)(wen)態結(jie)束(shu)，③腳(jiao)(jiao)又變為低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)。待再觸(chu)(chu)摸一次(ci)M時(shi)，上述工作過(guo)程(cheng)周(zhou)而復始。因此(ci)每(mei)觸(chu)(chu)摸一次(ci)M，門(men)鈴就被觸(chu)(chu)發一次(ci)。③腳(jiao)(jiao)上的0.01μF電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容為抗干(gan)擾電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容,可防止門(men)鈴被誤觸(chu)(chu)發。

元(yuan)器件選擇與(yu)制作(zuo)：本電路的(de)(de)(de)門鈴(ling)芯(xin)片(pian)選用(yong)“叮(ding)咚”（HL9300）芯(xin)片(pian)，它每被觸(chu)發(fa)一(yi)次，盡管(guan)③腳(jiao)(jiao)變(bian)(bian)為(wei)低電平(ping)后(hou)，它仍可(ke)連續發(fa)出三次“叮(ding)咚”聲(sheng)。如(ru)選用(yong)的(de)(de)(de)是(shi)需要觸(chu)發(fa)端一(yi)直(zhi)為(wei)高電平(ping)才可(ke)發(fa)聲(sheng)的(de)(de)(de)芯(xin)片(pian)（如(ru)音樂芯(xin)片(pian)），應適當調(diao)整(zheng)⑦腳(jiao)(jiao)上的(de)(de)(de)阻容時(shi)間(jian)(jian)常(chang)數來調(diao)整(zheng)暫穩態的(de)(de)(de)時(shi)間(jian)(jian)，使(shi)③腳(jiao)(jiao)的(de)(de)(de)高電平(ping)足以使(shi)芯(xin)片(pian)發(fa)出一(yi)曲完整(zheng)的(de)(de)(de)音樂后(hou)才變(bian)(bian)成低電平(ping)。另外(wai)還(huan)應通電測量一(yi)下門鈴(ling)芯(xin)片(pian)推動三極管(guan)的(de)(de)(de)基(ji)極電位，如(ru)靜態（不發(fa)聲(sheng)）時(shi)為(wei)低電平(ping)，則改用(yong)NPN型三極管(guan)作(zuo)推動管(guan)，目的(de)(de)(de)是(shi)防止(zhi)靜態動耗，延長(chang)(chang)電池使(shi)用(yong)壽命。觸(chu)摸(mo)(mo)片(pian)的(de)(de)(de)引線太長(chang)(chang)時(shi)最好(hao)使(shi)用(yong)屏蔽線并將屏蔽層接(jie)地。本電路制作(zuo)簡(jian)單，只要安裝無誤(wu)即可(ke)正(zheng)常(chang)工(gong)作(zuo)。本電路還(huan)可(ke)擴展為(wei)觸(chu)摸(mo)(mo)開關(guan)、觸(chu)摸(mo)(mo)報警(jing)器等(deng)實用(yong)電路。

簡便電子雙音門鈴電路圖

本文介紹一種采(cai)用(yong)時基集成電路構成的雙(shuang)音門鈴，電路如下圖所示，其(qi)核心部分是SL555時基電路。

兩用聲控門鈴電路圖

本文介紹一種簡易聲(sheng)控電路。元器件較少，靜態電流僅為1mA。該電路可(ke)用于聲(sheng)控門鈴和聲(sheng)控玩具。

工(gong)作(zuo)原(yuan)(yuan)理(li)：這種聲(sheng)控電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的原(yuan)(yuan)理(li)如下圖所示。它由聲(sheng)控傳感器(qi)(qi)(qi)(qi)、接收放大器(qi)(qi)(qi)(qi)、射極(ji)(ji)輸(shu)出器(qi)(qi)(qi)(qi)、音(yin)(yin)樂(le)集(ji)成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)、發(fa)光(guang)二極(ji)(ji)管、揚聲(sheng)器(qi)(qi)(qi)(qi)等(deng)組(zu)成(cheng)。外界(jie)產生的聲(sheng)音(yin)(yin)控制(zhi)信號(hao)，由駐極(ji)(ji)體(ti)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)傳聲(sheng)器(qi)(qi)(qi)(qi)BM轉變(bian)為電(dian)(dian)(dian)(dian)(dian)(dian)信號(hao)，并經電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)C1耦合至三(san)極(ji)(ji)管VT1進行電(dian)(dian)(dian)(dian)(dian)(dian)壓放大。VT1的輸(shu)出信號(hao)經二極(ji)(ji)管VD2驅(qu)動(dong)三(san)極(ji)(ji)管VT2導通，使電(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)壓加到音(yin)(yin)樂(le)集(ji)成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)IC的②腳（觸發(fa)端(duan)），音(yin)(yin)樂(le)IC③腳發(fa)出音(yin)(yin)樂(le)信號(hao)，經VT3放大后(hou)，驅(qu)動(dong)揚聲(sheng)器(qi)(qi)(qi)(qi)BL發(fa)出宏亮的樂(le)聲(sheng)。與些同時(shi)，發(fa)光(guang)二極(ji)(ji)管VD3、VD4隨(sui)著音(yin)(yin)樂(le)的大小而頻頻閃光(guang)，猶(you)如洋(yang)娃(wa)娃(wa)兩(liang)只閃亮的大眼睛。調節電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中電(dian)(dian)(dian)(dian)(dian)(dian)位器(qi)(qi)(qi)(qi)RP的阻值，可以改(gai)變(bian)BM的工(gong)作(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)壓，從而起到改(gai)變(bian)聲(sheng)控靈(ling)敏度的作(zuo)用。電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)C2是防止誤觸發(fa)，避免浪涌電(dian)(dian)(dian)(dian)(dian)(dian)流沖擊面設置的。

元(yuan)器(qi)件(jian)選(xuan)(xuan)擇：VT1～VT3選(xuan)(xuan)用(yong)9014高增(zeng)益三極管，其穿透電(dian)流要小，β＞80。BM可選(xuan)(xuan)用(yong)CN－15E或阻抗為(wei)1KΩ的(de)其它駐(zhu)極體(ti)傳聲器(qi)。音(yin)樂(le)集(ji)(ji)成電(dian)路IC選(xuan)(xuan)用(yong)KD－152等工作電(dian)壓為(wei)3V的(de)高電(dian)平觸發(fa)的(de)音(yin)樂(le)集(ji)(ji)成片。VD3、VD4選(xuan)(xuan)用(yong)工作電(dian)壓低、導通電(dian)流小而發(fa)光效(xiao)率高的(de)發(fa)光二極管。其余元(yuan)件(jian)均按圖中(zhong)標(biao)注(zhu)的(de)值選(xuan)(xuan)取(qu)，并(bing)無(wu)特(te)殊要求(qiu)。

安裝與使用：

（1）如家有(you)音樂(le)門鈴(ling)，則不必再(zai)制(zhi)作電(dian)路外殼，可按圖加裝控制(zhi)電(dian)路即(ji)可。

（2）駐極體傳聲器BM，裝在外(wai)門框上，高度可視人(ren)高矮而(er)定。為(wei)使BM保持(chi)清(qing)潔，可用(yong)一塊小花布遮掩并標(biao)注(zhu)“聲控”二字，即(ji)可裝飾，又(you)引(yin)人注(zhu)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(ju)有適當的靈敏度，以人(ren)嘴離駐極體傳聲(sheng)器(qi)BM為30mm左右(you)能觸發門鈴為宜。

（4）發光(guang)二極管用于聲控門鈴時(shi)，只(zhi)須一只(zhi)發光(guang)管，將其裝在門外(wai)(wai)顯(xian)眼(yan)處。當人(ren)發聲時(shi)，如發光(guang)管顯(xian)示(shi)，則告(gao)訴(su)外(wai)(wai)人(ren)，請放心(xin)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(zhuang)入兩只(zhi)眼睛(jing)中，只(zhi)要兒童發聲，洋娃娃便會閃動著大眼睛(jing)唱歌，頗有情趣。

（6）兒童不玩時，取出電池。最好選用4.7K帶開關的電(dian)位器，即(ji)可調節(jie)又能開關，這樣(yang)可節(jie)省靜態耗電(dian)。

觸摸式音樂門鈴電路圖

KD－482常用(yong)于石英鐘整點時，如在它的外部再加裝(zhuang)幾(ji)只電子元件(jian)，便可組成觸摸(mo)式音樂門(men)鈴(ling)。電路工(gong)作電流為60mA，靜態電流幾(ji)乎(hu)為零。

該電(dian)(dian)(dian)路如下(xia)圖(tu)所示。VT1、VT2組成觸(chu)(chu)摸靈(ling)敏開關。當手輕觸(chu)(chu)摸金屬片A時(shi)，人(ren)體給VT1的(de)柵極(ji)注入一感應信號，使(shi)VT1的(de)漏(lou)(lou)極(ji)電(dian)(dian)(dian)流(liu)減(jian)小，其漏(lou)(lou)極(ji)與源極(ji)間電(dian)(dian)(dian)阻增(zeng)大(da)(da)，C點(dian)變為(wei)(wei)高電(dian)(dian)(dian)位(wei)，VT2導通(tong)，發光二極(ji)管VD1亮。這時(shi)D點(dian)變為(wei)(wei)低電(dian)(dian)(dian)位(wei)，KD－482的(de)SW端被低電(dian)(dian)(dian)平(ping)觸(chu)(chu)發振(zhen)蕩(dang)工作(zuo)，由VT3放大(da)(da)的(de)信號驅動揚聲器(qi)BL發聲。手離開時(shi)A時(shi)，VT1的(de)漏(lou)(lou)極(ji)電(dian)(dian)(dian)流(liu)變大(da)(da)，其漏(lou)(lou)、源極(ji)間電(dian)(dian)(dian)阻減(jian)小，C點(dian)變為(wei)(wei)低電(dian)(dian)(dian)平(ping)，VT2截止，VD1熄滅，D點(dian)變為(wei)(wei)高電(dian)(dian)(dian)位(wei)。BL播完(wan)一首樂曲后將會自動停止。

元(yuan)器件選擇：場(chang)效應晶體(ti)管(guan)(guan)VT1除3DJ6E外也(ye)可采用其它的結型場(chang)效應晶體(ti)管(guan)(guan)，但(dan)要求(qiu)飽和漏(lou)極電流小于1mA。發光二(er)極管(guan)(guan)VD1的型號可任意選擇，為使效果更佳，VD1應選擇工作電壓在2～2.5V．發光效率高(gao)的發光管(guan)(guan)。金屬(shu)片的面(mian)積為300mm左右。

調試：電路按下圖接好(hao)后，先將電源的(de)(de)負極(ji)(ji)與SW端用(yong)一根金屬線短接一下（KD－482為低電平觸(chu)發），BL放(fang)出音樂(le)即(ji)可。控(kong)制電路只稍加調整，未(wei)觸(chu)摸A之前，將萬(wan)用(yong)表打在直流1V檔位，測量VT2的(de)(de)基極(ji)(ji)b與發射極(ji)(ji)e兩端電壓應小于0.7V，然(ran)后再用(yong)手輕觸(chu)A，此時指針指示(shi)要(yao)大于或等于0.7V。如達(da)不到該值，可適當(dang)改變一下R2或R3的(de)(de)阻值，兩個電阻最好(hao)配(pei)合(he)調整。

安裝與調試：

由(you)于該電(dian)(dian)路(lu)靜態耗電(dian)(dian)流極微(wei)，故(gu)可省去電(dian)(dian)源開(kai)關。A與(yu)VT1的(de)柵極之(zhi)間的(de)距離可根據實際(ji)情況而定(ding)，最(zui)好不要超(chao)過1m。發(fa)光二極管VD1最(zui)好與(yu)觸(chu)摸(mo)片A裝在(zai)門外(wai)顯(xian)(xian)眼處(chu)，當門外(wai)人觸(chu)摸(mo)到A時(shi)，VD1即刻發(fa)光顯(xian)(xian)示，就表示電(dian)(dian)路(lu)工(gong)作正常。在(zai)觸(chu)摸(mo)A時(shi)，有(you)時(shi)偶爾(er)會(hui)出現電(dian)(dian)路(lu)不工(gong)作情況，這(zhe)時(shi)VT1與(yu)VT2應(ying)選擇放大(da)倍(bei)數大(da)一些的(de)管子。

該電路也可(ke)用于防盜，將(jiang)VT1柵極的(de)(de)接(jie)觸(chu)線安裝在門拉手(shou)或(huo)門鎖等金屬部(bu)位，當盜賊(zei)的(de)(de)手(shou)一(yi)(yi)接(jie)觸(chu)即可(ke)報(bao)警。該電路經改動后可(ke)用于觸(chu)摸兒童玩具(ju)。KD－482的(de)(de)E、E'兩(liang)端原來(lai)是接(jie)蜂(feng)鳴陶瓷片的(de)(de)，如加以改進接(jie)上兩(liang)只(zhi)發光(guang)二極管VD2、VD3（如下(xia)圖所示），而發光(guang)二極管VD1裝在前(qian)額中(zhong)間尤如三只(zhi)眼，這樣(yang)不僅集聲(sheng)．光(guang)、色于一(yi)(yi)體新穎有(you)趣，而且更會招來(lai)兒童們的(de)(de)喜愛。其(qi)中(zhong)VD1是用于來(lai)控制明暗(an)的(de)(de)，VD2．VD3是隨音樂聲(sheng)的(de)(de)大(da)小而頻頻閃爍的(de)(de)。