一、手持金屬探測儀由哪幾部分組成
手持式金屬探測器被設計用來探測人或物體攜帶的金屬物，廣泛應用于安全檢查、考古、探礦等方面。手持金屬探測器的結構主要(yao)由四部(bu)分組成：
1、高頻振蕩器
由(you)三極(ji)(ji)管(guan)(guan)VT1和(he)高(gao)頻(pin)(pin)變(bian)壓(ya)(ya)器(qi)(qi)T1等(deng)組成，是(shi)一種變(bian)壓(ya)(ya)器(qi)(qi)反(fan)(fan)(fan)饋(kui)型LC振(zhen)(zhen)(zhen)蕩(dang)器(qi)(qi)。T1的(de)(de)(de)(de)(de)初級(ji)線圈(quan)L1和(he)電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)(qi)C1組成LC并聯振(zhen)(zhen)(zhen)蕩(dang)回路(lu)(lu)，其(qi)振(zhen)(zhen)(zhen)蕩(dang)頻(pin)(pin)率(lv)約200kHz，由(you)L1的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)感(gan)量和(he)C1的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)容(rong)(rong)量決(jue)定(ding)(ding)。T1的(de)(de)(de)(de)(de)次(ci)級(ji)線圈(quan)L2作(zuo)為振(zhen)(zhen)(zhen)蕩(dang)器(qi)(qi)的(de)(de)(de)(de)(de)反(fan)(fan)(fan)饋(kui)線圈(quan)，其(qi)“C”端接振(zhen)(zhen)(zhen)蕩(dang)管(guan)(guan)VT1的(de)(de)(de)(de)(de)基極(ji)(ji)，“D”端接VD2。由(you)于(yu)VD2處于(yu)正向導通(tong)狀態(tai)，對高(gao)頻(pin)(pin)信號(hao)來說(shuo)，“D”端可視為接地。在(zai)高(gao)頻(pin)(pin)變(bian)壓(ya)(ya)器(qi)(qi)T1中，如(ru)果“A” 和(he)“D”端分別為初、次(ci)級(ji)線圈(quan)繞線方(fang)向的(de)(de)(de)(de)(de)首端，則從“C”端輸(shu)入到(dao)振(zhen)(zhen)(zhen)蕩(dang)管(guan)(guan)VT1基極(ji)(ji)的(de)(de)(de)(de)(de)反(fan)(fan)(fan)饋(kui)信號(hao)，能(neng)夠使電(dian)(dian)(dian)(dian)路(lu)(lu)形成正反(fan)(fan)(fan)饋(kui)而產生自(zi)激高(gao)頻(pin)(pin)振(zhen)(zhen)(zhen)蕩(dang)。振(zhen)(zhen)(zhen)蕩(dang)器(qi)(qi)反(fan)(fan)(fan)饋(kui)電(dian)(dian)(dian)(dian)壓(ya)(ya)的(de)(de)(de)(de)(de)大(da)(da)小(xiao)與線圈(quan)L1、L2的(de)(de)(de)(de)(de)匝(za)數比(bi)有關，匝(za)數比(bi)過(guo)小(xiao)，由(you)于(yu)反(fan)(fan)(fan)饋(kui)太弱，不容(rong)(rong)易(yi)起(qi)振(zhen)(zhen)(zhen)，過(guo)大(da)(da)引(yin)起(qi)振(zhen)(zhen)(zhen)蕩(dang)波形失真(zhen)，還會使手持(chi)金屬(shu)(shu)探(tan)測(ce)器(qi)(qi)靈敏度大(da)(da)為降低。振(zhen)(zhen)(zhen)蕩(dang)管(guan)(guan)VT1的(de)(de)(de)(de)(de)偏置(zhi)電(dian)(dian)(dian)(dian)路(lu)(lu)由(you)R2和(he)二(er)極(ji)(ji)管(guan)(guan)VD2組成，R2為VD2的(de)(de)(de)(de)(de)限流(liu)電(dian)(dian)(dian)(dian)阻(zu)。由(you)于(yu)二(er)極(ji)(ji)管(guan)(guan)正向閾(yu)值(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)恒(heng)定(ding)(ding)（約0.7V），通(tong)過(guo)次(ci)級(ji)線圈(quan)L2加到(dao)VT1的(de)(de)(de)(de)(de)基極(ji)(ji)，以得到(dao)穩定(ding)(ding)的(de)(de)(de)(de)(de)偏置(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)。顯然，這種穩壓(ya)(ya)式(shi)的(de)(de)(de)(de)(de)偏置(zhi)電(dian)(dian)(dian)(dian)路(lu)(lu)能(neng)夠大(da)(da)大(da)(da)增(zeng)強VT1高(gao)頻(pin)(pin)振(zhen)(zhen)(zhen)蕩(dang)器(qi)(qi)的(de)(de)(de)(de)(de)穩定(ding)(ding)性(xing)。為了進(jin)一步提高(gao)手持(chi)金屬(shu)(shu)探(tan)測(ce)器(qi)(qi)的(de)(de)(de)(de)(de)可靠性(xing)和(he)靈敏度，高(gao)頻(pin)(pin)振(zhen)(zhen)(zhen)蕩(dang)器(qi)(qi)通(tong)過(guo)穩壓(ya)(ya)電(dian)(dian)(dian)(dian)路(lu)(lu)供電(dian)(dian)(dian)(dian)，其(qi)電(dian)(dian)(dian)(dian)路(lu)(lu)由(you)穩壓(ya)(ya)二(er)極(ji)(ji)管(guan)(guan)VD1、限流(liu)電(dian)(dian)(dian)(dian)阻(zu)器(qi)(qi)R6和(he)去耦電(dian)(dian)(dian)(dian)容(rong)(rong)器(qi)(qi)C5組成。振(zhen)(zhen)(zhen)蕩(dang)管(guan)(guan)VT1發射極(ji)(ji)與地之間接有兩(liang)個(ge)串聯的(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)位器(qi)(qi)，具有發射極(ji)(ji)電(dian)(dian)(dian)(dian)流(liu)負反(fan)(fan)(fan)饋(kui)作(zuo)用(yong)，其(qi)電(dian)(dian)(dian)(dian)阻(zu)值(zhi)越大(da)(da)，負反(fan)(fan)(fan)饋(kui)作(zuo)用(yong)越強，VT1的(de)(de)(de)(de)(de)放(fang)大(da)(da)能(neng)力也就(jiu)越低，甚(shen)至于(yu)使電(dian)(dian)(dian)(dian)路(lu)(lu)停振(zhen)(zhen)(zhen)。RP1為振(zhen)(zhen)(zhen)蕩(dang)器(qi)(qi)增(zeng)益的(de)(de)(de)(de)(de)粗調電(dian)(dian)(dian)(dian)位器(qi)(qi)，RP2為細調電(dian)(dian)(dian)(dian)位器(qi)(qi)。
2、振蕩檢測器
振(zhen)蕩(dang)檢測器(qi)由(you)(you)三極管開(kai)關電(dian)路(lu)(lu)和濾(lv)(lv)(lv)波(bo)電(dian)路(lu)(lu)組(zu)成(cheng)(cheng)。開(kai)關電(dian)路(lu)(lu)由(you)(you)三極管VT2、二極管 VD2等組(zu)成(cheng)(cheng)，濾(lv)(lv)(lv)波(bo)電(dian)路(lu)(lu)由(you)(you)濾(lv)(lv)(lv)波(bo)電(dian)阻器(qi)R3，濾(lv)(lv)(lv)波(bo)電(dian)容器(qi)C2、C3和C4組(zu)成(cheng)(cheng)。在(zai)開(kai)關電(dian)路(lu)(lu)中，VT2的基(ji)極與次級線圈L2的“C”端(duan)相(xiang)連，當高(gao)頻振(zhen)蕩(dang)器(qi)工作時(shi)，經(jing)高(gao)頻變壓器(qi)T1耦(ou)合過(guo)(guo)來的振(zhen)蕩(dang)信號(hao)(hao)(hao)(hao)，正(zheng)半周使(shi)VT2導(dao)通，VT2集(ji)電(dian)極輸出(chu)負脈沖信號(hao)(hao)(hao)(hao)，經(jing)過(guo)(guo)π型(xing)RC濾(lv)(lv)(lv)波(bo)器(qi)，在(zai)負載電(dian)阻器(qi)R4上(shang)輸出(chu)低電(dian)平(ping)信號(hao)(hao)(hao)(hao)。當高(gao)頻振(zhen)蕩(dang)器(qi)停(ting)振(zhen)蕩(dang)時(shi)，“C”端(duan)無振(zhen)蕩(dang)信號(hao)(hao)(hao)(hao)，又由(you)(you)于二極管VD2接在(zai)VT2發射極與地之間，VT2基(ji)極被反向偏置(zhi)，VT2處于可(ke)靠的截止狀(zhuang)態，VT2集(ji)電(dian)極為高(gao)電(dian)平(ping)，經(jing)過(guo)(guo)濾(lv)(lv)(lv)波(bo)器(qi)，在(zai)R4上(shang)得(de)到(dao)高(gao)電(dian)平(ping)信號(hao)(hao)(hao)(hao)。由(you)(you)此可(ke)見，當高(gao)頻振(zhen)蕩(dang)器(qi)正(zheng)常工作時(shi)，在(zai)R4上(shang)得(de)到(dao)低電(dian)平(ping)信號(hao)(hao)(hao)(hao)，停(ting)振(zhen)時(shi)，為高(gao)電(dian)平(ping)，由(you)(you)此完成(cheng)(cheng)了對振(zhen)蕩(dang)器(qi)工作狀(zhuang)態的檢測。
3、音頻振蕩器
音頻振(zhen)(zhen)蕩(dang)器(qi)(qi)(qi)采(cai)用(yong)(yong)互補(bu)型(xing)多(duo)諧振(zhen)(zhen)蕩(dang)器(qi)(qi)(qi)，由三(san)(san)極(ji)管VT3、VT4，電(dian)(dian)阻(zu)器(qi)(qi)(qi)R5、R7、 R8和(he)電(dian)(dian)容器(qi)(qi)(qi)C6組成(cheng)。互補(bu)型(xing)多(duo)諧振(zhen)(zhen)蕩(dang)器(qi)(qi)(qi)采(cai)用(yong)(yong)兩只不同類型(xing)的三(san)(san)極(ji)管，其中VT3為NPN型(xing)三(san)(san)極(ji)管，VT4為PNP型(xing)三(san)(san)極(ji)管，連接成(cheng)互補(bu)的、能(neng)夠強化正反(fan)饋的電(dian)(dian)路。在電(dian)(dian)路工作時，它們能(neng)夠交(jiao)替地進入導通和(he)截止(zhi)狀態，產生(sheng)音頻振(zhen)(zhen)蕩(dang)。R7既是(shi)VT3負載電(dian)(dian)阻(zu)器(qi)(qi)(qi)，又是(shi)VT3導通時VT4基極(ji)限流電(dian)(dian)阻(zu)器(qi)(qi)(qi)。R8是(shi) VT4集電(dian)(dian)極(ji)負載電(dian)(dian)阻(zu)器(qi)(qi)(qi)，振(zhen)(zhen)蕩(dang)脈(mo)沖(chong)信號由VT4集電(dian)(dian)極(ji)輸(shu)出。R5和(he)C6等(deng)是(shi)反(fan)饋電(dian)(dian)阻(zu)器(qi)(qi)(qi)和(he)電(dian)(dian)容器(qi)(qi)(qi)，其數(shu)值(zhi)大小(xiao)影響振(zhen)(zhen)蕩(dang)頻率的高(gao)低。
4、功率放大器
功率放(fang)大(da)器(qi)(qi)由(you)三極管VT5、揚聲器(qi)(qi)BL等(deng)組成。從多諧振蕩(dang)器(qi)(qi)輸出的正脈沖(chong)音頻(pin)信號經(jing)限(xian)流(liu)(liu)電(dian)(dian)阻(zu)器(qi)(qi)R9輸入到VT5的基極，使其導通，在BL產生(sheng)瞬時較強的電(dian)(dian)流(liu)(liu)，驅(qu)動揚聲器(qi)(qi)發聲。由(you)于(yu)VT5處于(yu)開關工(gong)作(zuo)狀態，而導通時間又非(fei)(fei)常(chang)短，因此(ci)功率放(fang)大(da)器(qi)(qi)非(fei)(fei)常(chang)省(sheng)電(dian)(dian)，可以(yi)利(li)用(yong)9V積層電(dian)(dian)池供(gong)電(dian)(dian)。
二、手持式金屬探測器原理是什么
了(le)(le)解了(le)(le)手持金屬探測(ce)器的(de)結構(gou)，接下來就(jiu)可以介紹金屬探測(ce)器的(de)工作(zuo)原理了(le)(le)：
手持金屬探測器利用電(dian)磁(ci)感(gan)應的(de)原理，利用有(you)交(jiao)流(liu)電(dian)通過的(de)線圈，產生迅速變化(hua)的(de)磁(ci)場。這個磁(ci)場能在金屬物體內部能感(gan)生渦(wo)(wo)電(dian)流(liu)。渦(wo)(wo)電(dian)流(liu)又會產生磁(ci)場，倒過來影(ying)響原來的(de)磁(ci)場，引發(fa)探測器發(fa)出鳴聲。
工(gong)作時，其內(nei)部探測器會(hui)發出某一頻(pin)(pin)率(lv)的(de)電(dian)磁(ci)波，由(you)于金屬有(you)自感，會(hui)使這一頻(pin)(pin)率(lv)發生(sheng)偏(pian)移，當它再接收到有(you)偏(pian)差(cha)的(de)電(dian)磁(ci)波時，就把差(cha)頻(pin)(pin)放大，發出信(xin)號報警。
