門鈴安裝難？專(zhuan)家推(tui)薦各(ge)種實用門鈴電路圖

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(yong)三個月以上，耗電量較低(di)。

圖中的(de)IC便是時(shi)基電(dian)路集(ji)成塊555，它(ta)構成無穩態多諧振(zhen)(zhen)(zhen)蕩器。按下按鈕(niu)AN（裝在門上），振(zhen)(zhen)(zhen)蕩器振(zhen)(zhen)(zhen)蕩，振(zhen)(zhen)(zhen)蕩頻(pin)(pin)率約700Hz，揚(yang)聲(sheng)器發出(chu)“叮”的(de)聲(sheng)音。與(yu)此同時(shi)，電(dian)源(yuan)通(tong)過(guo)二極管D1給C1充電(dian)。放(fang)開(kai)按鈕(niu)時(shi)，C1便通(tong)過(guo)電(dian)阻(zu)R1放(fang)電(dian)，維持振(zhen)(zhen)(zhen)蕩。但由于(yu)AN的(de)斷開(kai)，電(dian)阻(zu)R2被串入電(dian)路，使振(zhen)(zhen)(zhen)蕩頻(pin)(pin)率有所改變(bian)(bian)(bian)，大約為500Hz左右，揚(yang)聲(sheng)器發出(chu)“咚”的(de)聲(sheng)音。直到C1上電(dian)壓放(fang)到不能維持555振(zhen)(zhen)(zhen)蕩為止。“咚”聲(sheng)的(de)余(yu)音的(de)長短可通(tong)過(guo)改變(bian)(bian)(bian)C1的(de)數值來改變(bian)(bian)(bian)。

不用電池的雙音門鈴電路圖

隨著電話機的(de)(de)普及率越(yue)來(lai)越(yue)高，擁有住(zhu)宅電(dian)話(hua)的(de)(de)家庭也(ye)(ye)越(yue)來(lai)越(yue)多(duo)(duo)，但大(da)多(duo)(duo)數住(zhu)宅電(dian)話(hua)使(shi)用(yong)率很低(di)，利用(yong)電(dian)話(hua)入戶(hu)饋線提供的(de)(de)48V（60V）直流(liu)饋電(dian)作(zuo)電(dian)子(zi)門(men)(men)鈴(ling)的(de)(de)工作(zuo)能源是(shi)(shi)經濟(ji)實(shi)用(yong)的(de)(de)。現(xian)介紹一款不(bu)用(yong)電(dian)池的(de)(de)雙音門(men)(men)鈴(ling)電(dian)路(lu)。電(dian)路(lu)原理如圖所(suo)示，不(bu)難看出(chu)，圖中電(dian)路(lu)是(shi)(shi)常(chang)規的(de)(de)電(dian)話(hua)機(ji)(ji)振鈴(ling)電(dian)路(lu)的(de)(de)變型。a、b分別是(shi)(shi)電(dian)話(hua)機(ji)(ji)入戶(hu)線的(de)(de)正(zheng)、負(fu)兩端。AN為常(chang)開型門(men)(men)鈴(ling)按鈕，在電(dian)話(hua)機(ji)(ji)候機(ji)(ji)時(shi)(shi)(shi)，按下AN，程(cheng)控(kong)交(jiao)換機(ji)(ji)提供的(de)(de)48V（或60V）電(dian)壓(ya)，直流(liu)饋電(dian)經VD1、R1對(dui)電(dian)容C1充電(dian)，當C1端電(dian)壓(ya)Vc達到IC1的(de)(de)起控(kong)電(dian)壓(ya)時(shi)(shi)(shi)，IC1起振送出(chu)雙音電(dian)子(zi)鈴(ling)流(liu)使(shi)蜂鳴(ming)器(qi)B發聲，告知主人(ren)有客來(lai)訪。而當電(dian)話(hua)機(ji)(ji)正(zheng)在使(shi)用(yong)時(shi)(shi)(shi)，則圖中a、b之間的(de)(de)電(dian)壓(ya)較低(di)達不(bu)到IC1的(de)(de)起控(kong)電(dian)壓(ya)，此時(shi)(shi)(shi)，即(ji)使(shi)按下AN門(men)(men)鈴(ling)按鈕也(ye)(ye)不(bu)工作(zuo)，這是(shi)(shi)因為由于R1取值較大(da)，遠大(da)于電(dian)話(hua)機(ji)(ji)的(de)(de)阻抗。故AN按下時(shi)(shi)(shi)對(dui)電(dian)話(hua)機(ji)(ji)的(de)(de)正(zheng)常(chang)通話(hua)無影響。也(ye)(ye)對(dui)程(cheng)控(kong)交(jiao)換機(ji)(ji)無不(bu)良影響，僅在使(shi)用(yong)門(men)(men)鈴(ling)時(shi)(shi)(shi)對(dui)其間打入的(de)(de)電(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)講門(men)鈴的(de)電(dian)(dian)路如圖(tu)，其(qi)工作原理如下(xia)：平(ping)時(shi)掛機時(shi)叉簧開關(guan)HS的(de)1、2觸點(dian)接通，用AC220V供電(dian)(dian)，V1有(you)直流(liu)輸出(chu)，此電(dian)(dian)壓既對(dui)電(dian)(dian)池充電(dian)(dian)，也加到音樂IC的(de)③腳(jiao)。如按一下(xia)S，則音樂IC的(de)②腳(jiao)受觸發，④腳(jiao)有(you)音樂信號輸出(chu)，經(jing)V2放(fang)大后(hou)推動(dong)揚聲(sheng)器發聲(sheng)，同時(shi)經(jing)R5推動(dong)Y2、Y3。摘機后(hou)，叉簧開關(guan)HS的(de)1、3接點(dian)接通，通話電(dian)(dian)路接通電(dian)(dian)源，這(zhe)時(shi)可(ke)進(jin)行(xing)對(dui)講。

本對講(jiang)門鈴由于音頻放大器IC2（LM386）的增(zeng)益很(hen)高，容(rong)易(yi)使Y2、Y3產生嘯(xiao)叫(jiao)聲。經筆者實際驗證，只要(yao)在(zai)Y2、Y3兩端并聯一(yi)只幾pF的小電容(rong)，嘯(xiao)叫(jiao)聲即可消除。

不用按鈕的音樂門鈴電路圖

本文介(jie)紹一種不用按鈕(niu)的音樂(le)門(men)鈴，來(lai)人只要站在門(men)鈴前，便可自動發出(chu)門(men)鈴聲。

該音樂門鈴電路(lu)原理如附圖所示。IC1等(deng)元(yuan)件(jian)組成(cheng)紅(hong)(hong)外(wai)發射(she)電路(lu)，由IC1、RP、R1、C1構成(cheng)多諧振蕩頻率，按(an)圖示元(yuan)件(jian)數據，振蕩頻率約40kHz，輸(shu)出電流為(wei)100--200mA，可驅動(dong)紅(hong)(hong)外(wai)發光二極管D1發射(she)出40kHz調(diao)制紅(hong)(hong)外(wai)脈沖。IC2是紅(hong)(hong)外(wai)接(jie)收芯片，靈敏度高、增益高、輸(shu)出波形好，并具有(you)鑒頻功能。紅(hong)(hong)外(wai)接(jie)收管D2接(jie)收到40kHz頻率的紅(hong)(hong)外(wai)脈沖后，轉換(huan)為(wei)電信號，送(song)入IC2第⑦腳(jiao)，經放大(da)和C5、L調(diao)諧以及IC2內部電路(lu)檢波、整形后，由第①腳(jiao)輸(shu)出脈沖信號。

平(ping)時，IC2第(di)①腳輸(shu)出低(di)電瓶，D3截止，音(yin)樂集成(cheng)電路IC3無(wu)觸(chu)發(fa)脈沖，不(bu)產生音(yin)樂信號(hao)輸(shu)出，揚聲器B不(bu)發(fa)聲。當有人(ren)站在門前遮擋D1發(fa)射的(de)紅外信號(hao)時，IC2第(di)①腳電位瞬間由(you)低(di)電平(ping)變為高電平(ping)，經D3觸(chu)發(fa)IC3輸(shu)出音(yin)樂信號(hao)，由(you)V放大推動揚聲器發(fa)聲。

IC1選(xuan)用(yong)NE555，IC2為μPC1373，IC3選(xuan)用(yong)9300系列音(yin)樂集成電(dian)路(lu)。D1可(ke)用(yong)SE303A或LM66R型5mm圓形(xing)紅外發光二(er)極管(guan)(guan)，D2可(ke)用(yong)PH302方形(xing)紅外接收二(er)極管(guan)(guan)。V為9013NPN管(guan)(guan)，β≥100。B選(xuan)用(yong)YD58--1型、8Ω/0.25W小(xiao)口徑(jing)揚聲器。L用(yong)?0.08mm高強度漆包線，在小(xiao)型晶體管(guan)(guan)收音(yin)機的中(zhong)頻變壓器骨架(jia)上密繞(rao)30匝即可(ke)。

兩種無按鈕音樂門鈴電路圖

門鈴均(jun)需安裝(zhuang)(zhuang)按(an)裝(zhuang)(zhuang)，因而存在著安裝(zhuang)(zhuang)麻煩(fan)和易于丟失(shi)損(sun)壞等問題。用復合(he)開(kai)關管代替機械(xie)觸發開(kai)關制作的音樂(le)門鈴，即可克服(fu)上述弊端。

圖1為振動(dong)式。當(dang)有(you)人用手敲門(men)時(shi)，安裝在門(men)內側(ce)的(de)壓電(dian)陶瓷(ci)片(pian)YD受到振動(dong)而產生相應的(de)音(yin)頻電(dian)壓，使復合(he)管(guan)開(kai)關(guan)BG1和BG2導通，音(yin)樂電(dian)路CIC受到觸發即演奏一段(duan)樂曲。壓電(dian)陶瓷(ci)片(pian)以采用直徑較大的(de)為宜，用502膠水將其粘合(he)在門(men)內偏上(shang)的(de)中(zhong)心位置即可(ke)。

圖2為觸(chu)摸式。當用手指觸(chu)摸電(dian)路A點(dian)時，人(ren)體感應電(dian)壓使復合管BG1和BG2導(dao)通，音(yin)樂電(dian)路CIC受到觸(chu)發即演(yan)奏一段樂曲(qu)。觸(chu)摸電(dian)極A可用一大小適中的金(jin)屬片固(gu)定在門框上(shang)即可。

觸摸式門鈴電路圖

本文(wen)介紹的觸摸式(shi)門鈴，用觸摸方式(shi)代替(ti)機(ji)械開關，它簡單可靠，實用有(you)趣。

工作(zuo)原理：電(dian)(dian)(dian)(dian)(dian)(dian)(dian)原理圖(tu)如圖(tu)所示。555時(shi)(shi)基(ji)集成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)工作(zuo)在單穩狀態，平(ping)(ping)時(shi)(shi)③腳(jiao)和⑦腳(jiao)均為(wei)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)．當用手觸(chu)摸一(yi)下金屬感應(ying)片M時(shi)(shi),人體的感應(ying)信號通(tong)過0.1μF電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)加(jia)(jia)至555時(shi)(shi)基(ji)集成電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的②腳(jiao)，使電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)翻轉(zhuan)進入暫穩態，這時(shi)(shi)③腳(jiao)輸出高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)直(zhi)接(jie)加(jia)(jia)到門鈴(ling)芯(xin)片的觸(chu)發(fa)端，芯(xin)片被(bei)觸(chu)發(fa)并通(tong)過三(san)極管推動揚聲(sheng)(sheng)器發(fa)聲(sheng)(sheng)。同時(shi)(shi)⑦腳(jiao)也變為(wei)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)通(tong)過100KΩ電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻對4.7μF電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian),當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)上的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓充至2/3電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓時(shi)(shi)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)又翻轉(zhuan)，暫穩態結(jie)束，③腳(jiao)又變為(wei)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)。待再(zai)觸(chu)摸一(yi)次M時(shi)(shi)，上述工作(zuo)過程周而復始(shi)。因此(ci)每(mei)觸(chu)摸一(yi)次M，門鈴(ling)就被(bei)觸(chu)發(fa)一(yi)次。③腳(jiao)上的0.01μF電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)為(wei)抗干擾電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong),可防止(zhi)門鈴(ling)被(bei)誤觸(chu)發(fa)。

元器件選擇(ze)與制(zhi)作(zuo)：本(ben)電(dian)(dian)(dian)路(lu)的(de)(de)門(men)鈴芯片(pian)(pian)(pian)(pian)選用“叮咚”（HL9300）芯片(pian)(pian)(pian)(pian)，它(ta)每被觸(chu)(chu)發(fa)一次，盡(jin)管③腳變為(wei)低電(dian)(dian)(dian)平后，它(ta)仍可(ke)連續發(fa)出三次“叮咚”聲。如(ru)選用的(de)(de)是需要觸(chu)(chu)發(fa)端(duan)一直為(wei)高電(dian)(dian)(dian)平才可(ke)發(fa)聲的(de)(de)芯片(pian)(pian)(pian)(pian)（如(ru)音樂芯片(pian)(pian)(pian)(pian)），應(ying)適當(dang)調(diao)整⑦腳上的(de)(de)阻容時(shi)間(jian)常數來(lai)調(diao)整暫(zan)穩態的(de)(de)時(shi)間(jian)，使(shi)③腳的(de)(de)高電(dian)(dian)(dian)平足(zu)以使(shi)芯片(pian)(pian)(pian)(pian)發(fa)出一曲完(wan)整的(de)(de)音樂后才變成低電(dian)(dian)(dian)平。另外還(huan)應(ying)通電(dian)(dian)(dian)測(ce)量一下(xia)門(men)鈴芯片(pian)(pian)(pian)(pian)推(tui)動(dong)三極管的(de)(de)基(ji)極電(dian)(dian)(dian)位(wei)，如(ru)靜態（不發(fa)聲）時(shi)為(wei)低電(dian)(dian)(dian)平，則改用NPN型三極管作(zuo)推(tui)動(dong)管，目的(de)(de)是防止靜態動(dong)耗，延長電(dian)(dian)(dian)池(chi)使(shi)用壽(shou)命(ming)。觸(chu)(chu)摸(mo)片(pian)(pian)(pian)(pian)的(de)(de)引線太長時(shi)最好使(shi)用屏蔽線并(bing)將屏蔽層接地。本(ben)電(dian)(dian)(dian)路(lu)制(zhi)作(zuo)簡單，只要安裝無誤即可(ke)正常工(gong)作(zuo)。本(ben)電(dian)(dian)(dian)路(lu)還(huan)可(ke)擴展為(wei)觸(chu)(chu)摸(mo)開(kai)關、觸(chu)(chu)摸(mo)報(bao)警器等(deng)實用電(dian)(dian)(dian)路(lu)。

簡便電子雙音門鈴電路圖

本文介紹(shao)一(yi)種采用時基集(ji)成電(dian)(dian)路構成的雙音門鈴，電(dian)(dian)路如下圖所示，其核心部分是SL555時基電(dian)(dian)路。

兩用聲控門鈴電路圖

本文介紹(shao)一(yi)種簡易聲(sheng)控(kong)電路。元器(qi)件(jian)較少，靜態電流僅為(wei)1mA。該電路可(ke)用于聲(sheng)控(kong)門(men)鈴(ling)和聲(sheng)控(kong)玩具。

工(gong)作原理(li)(li)：這種聲(sheng)控(kong)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)(de)(de)原理(li)(li)如(ru)(ru)下圖(tu)所示(shi)。它由聲(sheng)控(kong)傳感器、接收(shou)放大器、射(she)極(ji)(ji)(ji)輸出(chu)器、音(yin)樂(le)集(ji)成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)、發(fa)光(guang)二(er)極(ji)(ji)(ji)管(guan)、揚聲(sheng)器等組成(cheng)。外界(jie)產生的(de)(de)(de)(de)聲(sheng)音(yin)控(kong)制信號，由駐極(ji)(ji)(ji)體電(dian)(dian)(dian)(dian)(dian)(dian)容傳聲(sheng)器BM轉變(bian)為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)信號，并經電(dian)(dian)(dian)(dian)(dian)(dian)容C1耦合至三(san)極(ji)(ji)(ji)管(guan)VT1進(jin)行電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)放大。VT1的(de)(de)(de)(de)輸出(chu)信號經二(er)極(ji)(ji)(ji)管(guan)VD2驅動三(san)極(ji)(ji)(ji)管(guan)VT2導通，使電(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)加到音(yin)樂(le)集(ji)成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)IC的(de)(de)(de)(de)②腳（觸發(fa)端），音(yin)樂(le)IC③腳發(fa)出(chu)音(yin)樂(le)信號，經VT3放大后，驅動揚聲(sheng)器BL發(fa)出(chu)宏亮的(de)(de)(de)(de)樂(le)聲(sheng)。與些同時，發(fa)光(guang)二(er)極(ji)(ji)(ji)管(guan)VD3、VD4隨(sui)著(zhu)音(yin)樂(le)的(de)(de)(de)(de)大小而頻(pin)頻(pin)閃光(guang)，猶如(ru)(ru)洋(yang)娃(wa)娃(wa)兩(liang)只閃亮的(de)(de)(de)(de)大眼睛。調節電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)位器RP的(de)(de)(de)(de)阻值，可(ke)以(yi)改變(bian)BM的(de)(de)(de)(de)工(gong)作電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，從而起到改變(bian)聲(sheng)控(kong)靈敏度的(de)(de)(de)(de)作用。電(dian)(dian)(dian)(dian)(dian)(dian)容C2是防止誤觸發(fa)，避免浪涌電(dian)(dian)(dian)(dian)(dian)(dian)流沖擊(ji)面(mian)設(she)置的(de)(de)(de)(de)。

元(yuan)(yuan)器件選擇：VT1～VT3選用(yong)9014高(gao)增益三極管，其穿(chuan)透電流(liu)要(yao)小(xiao)，β＞80。BM可選用(yong)CN－15E或阻抗為1KΩ的(de)其它駐極體(ti)傳(chuan)聲器。音樂集(ji)成電路IC選用(yong)KD－152等工作電壓為3V的(de)高(gao)電平觸發(fa)(fa)的(de)音樂集(ji)成片(pian)。VD3、VD4選用(yong)工作電壓低、導通電流(liu)小(xiao)而發(fa)(fa)光(guang)效率(lv)高(gao)的(de)發(fa)(fa)光(guang)二極管。其余元(yuan)(yuan)件均按(an)圖中標注的(de)值選取，并(bing)無特殊(shu)要(yao)求。

安裝與使用：

（1）如(ru)家有(you)音樂門鈴，則(ze)不必(bi)再制作電(dian)路(lu)外(wai)殼，可按圖加裝控制電(dian)路(lu)即(ji)可。

（2）駐極體傳聲器BM，裝在外門框上，高(gao)度可視人高(gao)矮而定。為使BM保(bao)持清潔，可(ke)用一塊(kuai)小花布遮掩并標注“聲(sheng)控”二字(zi)，即(ji)可(ke)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具有適當(dang)的靈敏度(du)，以人(ren)嘴離駐極體傳聲器BM為30mm左右能觸(chu)發門鈴為宜。

（4）發(fa)光二(er)極管(guan)用于聲控門鈴時，只須一只發(fa)光管(guan)，將其裝(zhuang)在門外顯(xian)眼(yan)處。當人發(fa)聲時，如發(fa)光管(guan)顯(xian)示，則告訴外人，請(qing)放心電路工(gong)作正(zheng)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裝入兩只眼睛中，只要兒童發(fa)聲，洋(yang)娃(wa)娃(wa)便會閃動著大眼睛唱歌，頗有情(qing)趣。

（6）兒童不玩時，取出電池。最好選用4.7K帶開(kai)關的電位(wei)器，即可調節(jie)又能開(kai)關，這樣(yang)可節(jie)省(sheng)靜態耗(hao)電。

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(ta)的外部再加裝幾只電(dian)子(zi)元件，便可組(zu)成觸摸(mo)式音樂門鈴。電(dian)路工(gong)作電(dian)流為60mA，靜態電(dian)流幾乎(hu)為零。

該電(dian)(dian)(dian)路如下圖所(suo)示。VT1、VT2組成(cheng)觸摸靈敏開(kai)關。當手輕觸摸金屬片A時，人(ren)體給(gei)VT1的(de)柵極(ji)(ji)注(zhu)入一感(gan)應(ying)信號(hao)，使(shi)VT1的(de)漏(lou)(lou)極(ji)(ji)電(dian)(dian)(dian)流(liu)減小(xiao)，其漏(lou)(lou)極(ji)(ji)與源(yuan)極(ji)(ji)間電(dian)(dian)(dian)阻增(zeng)大(da)，C點(dian)變(bian)(bian)為高電(dian)(dian)(dian)位(wei)，VT2導通，發(fa)光(guang)二極(ji)(ji)管VD1亮。這(zhe)時D點(dian)變(bian)(bian)為低(di)電(dian)(dian)(dian)位(wei)，KD－482的(de)SW端被低(di)電(dian)(dian)(dian)平觸發(fa)振蕩工(gong)作，由(you)VT3放大(da)的(de)信號(hao)驅(qu)動揚聲器BL發(fa)聲。手離(li)開(kai)時A時，VT1的(de)漏(lou)(lou)極(ji)(ji)電(dian)(dian)(dian)流(liu)變(bian)(bian)大(da)，其漏(lou)(lou)、源(yuan)極(ji)(ji)間電(dian)(dian)(dian)阻減小(xiao)，C點(dian)變(bian)(bian)為低(di)電(dian)(dian)(dian)平，VT2截止，VD1熄滅，D點(dian)變(bian)(bian)為高電(dian)(dian)(dian)位(wei)。BL播完一首(shou)樂曲后(hou)將(jiang)會自動停止。

元器(qi)件選(xuan)擇(ze)(ze)：場效應晶(jing)體(ti)管(guan)VT1除3DJ6E外(wai)也(ye)可(ke)采用其它的結型場效應晶(jing)體(ti)管(guan)，但要求飽和漏極電流小于1mA。發光二極管(guan)VD1的型號可(ke)任意(yi)選(xuan)擇(ze)(ze)，為使(shi)效果更(geng)佳，VD1應選(xuan)擇(ze)(ze)工作電壓在2～2.5V．發光效率高的發光管(guan)。金屬片的面積為300mm左(zuo)右(you)。

調(diao)試：電(dian)路(lu)按下(xia)圖(tu)接(jie)好后(hou)，先將電(dian)源(yuan)的負極(ji)與(yu)(yu)SW端(duan)用一根(gen)金屬線(xian)短接(jie)一下(xia)（KD－482為(wei)低電(dian)平觸發），BL放出音樂(le)即可。控制電(dian)路(lu)只稍加(jia)調(diao)整(zheng)，未(wei)觸摸A之前，將萬用表打在直(zhi)流1V檔(dang)位，測量VT2的基極(ji)b與(yu)(yu)發射極(ji)e兩端(duan)電(dian)壓應小于0.7V，然后(hou)再用手輕觸A，此時(shi)指針指示要大(da)于或等于0.7V。如達(da)不到該值(zhi)，可適當改變一下(xia)R2或R3的阻值(zhi)，兩個電(dian)阻最好配合(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(gu)可省去電源開關。A與(yu)VT1的(de)柵極(ji)之間(jian)的(de)距離可根(gen)據實際情(qing)況而定，最好不(bu)要超過1m。發光(guang)二極(ji)管(guan)VD1最好與(yu)觸(chu)摸(mo)片A裝在門外(wai)顯眼處，當門外(wai)人觸(chu)摸(mo)到(dao)A時，VD1即(ji)刻發光(guang)顯示(shi)，就表示(shi)電路工作(zuo)正常(chang)。在觸(chu)摸(mo)A時，有時偶爾會出現電路不(bu)工作(zuo)情(qing)況，這時VT1與(yu)VT2應選擇放大(da)倍數大(da)一(yi)些的(de)管(guan)子。

該電(dian)路也可(ke)用(yong)于(yu)(yu)防(fang)盜，將VT1柵極的(de)(de)(de)接觸(chu)線安裝(zhuang)(zhuang)在門拉手(shou)或門鎖(suo)等金屬部位，當(dang)盜賊的(de)(de)(de)手(shou)一(yi)接觸(chu)即可(ke)報警。該電(dian)路經改動后可(ke)用(yong)于(yu)(yu)觸(chu)摸兒童玩具。KD－482的(de)(de)(de)E、E'兩(liang)端原來是(shi)接蜂(feng)鳴陶(tao)瓷片的(de)(de)(de)，如加以改進接上兩(liang)只發(fa)光(guang)二極管(guan)VD2、VD3（如下(xia)圖所示），而(er)發(fa)光(guang)二極管(guan)VD1裝(zhuang)(zhuang)在前額中間尤如三(san)只眼，這樣(yang)不(bu)僅集聲．光(guang)、色于(yu)(yu)一(yi)體新穎有(you)趣，而(er)且更會招來兒童們的(de)(de)(de)喜愛。其中VD1是(shi)用(yong)于(yu)(yu)來控制明暗的(de)(de)(de)，VD2．VD3是(shi)隨音(yin)樂(le)聲的(de)(de)(de)大小而(er)頻頻閃爍的(de)(de)(de)。