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在說(shuo)蜂(feng)鳴器驅動(dong)電路前，我們(men)首先需要了解一(yi)下蜂(feng)鳴器的分類。

按(an)照發(fa)聲原理的(de)不同可以把蜂(feng)(feng)鳴器(qi)(qi)分為電磁(ci)式蜂(feng)(feng)鳴器(qi)(qi)和壓電式蜂(feng)(feng)鳴器(qi)(qi)。

按照驅(qu)動方式不同又(you)可分為有源蜂(feng)鳴(ming)器(qi)(內含驅(qu)動線路)和無源蜂(feng)鳴(ming)器(qi)(外部(bu)驅(qu)動)。

壓電(dian)(dian)(dian)(dian)(dian)式(shi)蜂(feng)鳴器使(shi)(shi)用(yong)的(de)(de)是壓電(dian)(dian)(dian)(dian)(dian)材料的(de)(de)壓電(dian)(dian)(dian)(dian)(dian)效應來發(fa)聲(sheng)的(de)(de)。壓電(dian)(dian)(dian)(dian)(dian)材料的(de)(de)特性(xing)為當受到外(wai)力導致其(qi)(qi)變(bian)形(xing)時(shi)，會產生電(dian)(dian)(dian)(dian)(dian)荷(he)，同樣的(de)(de)，當給壓電(dian)(dian)(dian)(dian)(dian)材料通電(dian)(dian)(dian)(dian)(dian)時(shi)，也會使(shi)(shi)其(qi)(qi)變(bian)形(xing)。當壓電(dian)(dian)(dian)(dian)(dian)材料按照一(yi)定的(de)(de)頻率變(bian)形(xing)，配(pei)合特殊的(de)(de)共(gong)振腔設計，即可發(fa)出聲(sheng)音。

電(dian)磁式風蜂鳴(ming)器使用的是電(dian)磁感應(ying)現象，為音圈接入交變(bian)電(dian)流后形成的電(dian)磁鐵與永磁鐵相(xiang)吸或相(xiang)斥而推動振膜(mo)發(fa)聲。

不(bu)論是電磁(ci)蜂(feng)(feng)(feng)(feng)鳴(ming)器(qi)(qi)還是壓電式蜂(feng)(feng)(feng)(feng)鳴(ming)器(qi)(qi)都包含有源(yuan)(yuan)(yuan)蜂(feng)(feng)(feng)(feng)鳴(ming)器(qi)(qi)和無(wu)(wu)源(yuan)(yuan)(yuan)蜂(feng)(feng)(feng)(feng)鳴(ming)器(qi)(qi)。有源(yuan)(yuan)(yuan)和無(wu)(wu)源(yuan)(yuan)(yuan)這里(li)的(de)(de)“源(yuan)(yuan)(yuan)”不(bu)是指電源(yuan)(yuan)(yuan)，而是指震蕩(dang)源(yuan)(yuan)(yuan)。也(ye)就(jiu)是說，有源(yuan)(yuan)(yuan)蜂(feng)(feng)(feng)(feng)鳴(ming)器(qi)(qi)內部帶(dai)震蕩(dang)源(yuan)(yuan)(yuan)，所(suo)以只要一通(tong)電就(jiu)會叫(jiao)(jiao)。而無(wu)(wu)源(yuan)(yuan)(yuan)內部不(bu)帶(dai)震蕩(dang)源(yuan)(yuan)(yuan)，所(suo)以如果用直(zhi)流信號無(wu)(wu)法(fa)令其(qi)鳴(ming)叫(jiao)(jiao)。必須用2K~5K的(de)(de)方波去驅動它。有源(yuan)(yuan)(yuan)蜂(feng)(feng)(feng)(feng)鳴(ming)器(qi)(qi)往往比無(wu)(wu)源(yuan)(yuan)(yuan)的(de)(de)貴，就(jiu)是因為(wei)里(li)面多(duo)個震蕩(dang)電路。

由于壓(ya)電(dian)式(shi)蜂鳴器和(he)電(dian)磁式(shi)蜂鳴器的(de)(de)原理(li)不(bu)同，所以它們的(de)(de)驅動電(dian)路也(ye)是(shi)不(bu)一樣的(de)(de)。

對(dui)于壓電(dian)式蜂(feng)鳴(ming)器，由(you)于其(qi)原理是利用(yong)壓電(dian)材料的壓電(dian)效應來發聲(sheng)(sheng)的，所(suo)以其(qi)只要通(tong)直流(有源蜂(feng)鳴(ming)器)或者一定頻率(lv)的交流(無源蜂(feng)鳴(ming)器)即可發聲(sheng)(sheng)，原理圖(tu)如下圖(tu)圖(tu)一所(suo)示：

圖一

MCU通(tong)(tong)過(guo)控(kong)制三極管的(de)通(tong)(tong)斷(duan)來給蜂鳴器供電。如果是有源(yuan)蜂鳴器，使(shi)三極管導通(tong)(tong)即可讓(rang)蜂鳴器鳴叫(jiao);如果是無源(yuan)蜂鳴器，需要MCU控(kong)制三極管按照一定(ding)頻率通(tong)(tong)斷(duan)即可使(shi)蜂鳴器鳴叫(jiao)。

對(dui)于電(dian)(dian)(dian)(dian)磁式蜂(feng)鳴(ming)(ming)器(qi)(qi)，由(you)于使用的是電(dian)(dian)(dian)(dian)磁感(gan)應原理，蜂(feng)鳴(ming)(ming)器(qi)(qi)相當于一個電(dian)(dian)(dian)(dian)感(gan)器(qi)(qi)件(jian)(jian)。如果是電(dian)(dian)(dian)(dian)磁式無源(yuan)蜂(feng)鳴(ming)(ming)器(qi)(qi)，當三極管由(you)導通變(bian)為關斷狀態(tai)時，蜂(feng)鳴(ming)(ming)器(qi)(qi)會產生感(gan)應電(dian)(dian)(dian)(dian)動勢，對(dui)電(dian)(dian)(dian)(dian)子元器(qi)(qi)件(jian)(jian)產生沖擊，嚴重(zhong)可(ke)能(neng)損壞電(dian)(dian)(dian)(dian)子元器(qi)(qi)件(jian)(jian)，所(suo)(suo)以需要在蜂(feng)鳴(ming)(ming)器(qi)(qi)上并(bing)聯一個反(fan)向(xiang)二(er)極管，進行續(xu)流(給(gei)感(gan)應電(dian)(dian)(dian)(dian)動勢一個釋放路徑)，減弱(ruo)對(dui)電(dian)(dian)(dian)(dian)子元器(qi)(qi)件(jian)(jian)的損害，特(te)別是對(dui)于無源(yuan)的電(dian)(dian)(dian)(dian)磁式蜂(feng)鳴(ming)(ming)器(qi)(qi)。所(suo)(suo)以原理圖如圖二(er)所(suo)(suo)示：

圖二

對于有源的電(dian)磁式蜂鳴器，因為不(bu)需要頻(pin)繁(fan)的開啟關斷三(san)極管，所以影響(xiang)不(bu)大，既(ji)可以使用圖(tu)一驅動電(dian)路(lu)，也可以使用圖(tu)二驅動電(dian)路(lu)。

由(you)于蜂鳴器(qi)是(shi)(shi)流控器(qi)件，所以需要使用(yong)三(san)極(ji)管(guan)來作為開(kai)關管(guan)控制(zhi)通(tong)斷(duan)。使用(yong)NPN三(san)極(ji)管(guan)或PNP三(san)極(ji)管(guan)均可，不同的類型(xing)三(san)極(ji)管(guan)，只是(shi)(shi)控制(zhi)其通(tong)斷(duan)的高低電平不同而已。

總的(de)來說蜂(feng)鳴(ming)器的(de)驅動(dong)電(dian)路(lu)還是(shi)比較簡(jian)單的(de)，只需依照不同(tong)的(de)蜂(feng)鳴(ming)器原理(li)來選擇(ze)不同(tong)的(de)驅動(dong)電(dian)路(lu)即可。