手(shou)持(chi)式金屬探測器被設計用(yong)(yong)來(lai)探測人或物體攜帶的金屬物，廣泛應用(yong)(yong)于安全(quan)檢查、考古、探礦等方面。手(shou)持(chi)金屬探測器的結構主要由四部(bu)分組成：

1、高頻振蕩器

由三極管VT1和高頻變壓(ya)器(qi)T1等組成，是一種變壓(ya)器(qi)反(fan)饋(kui)型LC振蕩器(qi)。

2、振蕩檢測(ce)器

振(zhen)(zhen)蕩(dang)檢測器(qi)由三極(ji)(ji)管開關電(dian)(dian)(dian)(dian)路(lu)和(he)濾(lv)波電(dian)(dian)(dian)(dian)路(lu)組(zu)成(cheng)。開關電(dian)(dian)(dian)(dian)路(lu)由三極(ji)(ji)管VT2、二極(ji)(ji)管VD2等組(zu)成(cheng)，濾(lv)波電(dian)(dian)(dian)(dian)路(lu)由濾(lv)波電(dian)(dian)(dian)(dian)阻器(qi)R3，濾(lv)波電(dian)(dian)(dian)(dian)容器(qi)C2、C3和(he)C4組(zu)成(cheng)。在(zai)開關電(dian)(dian)(dian)(dian)路(lu)中，VT2的基極(ji)(ji)與(yu)次級線圈(quan)L2的“C”端相連，當(dang)高(gao)頻(pin)(pin)(pin)振(zhen)(zhen)蕩(dang)器(qi)工(gong)作時(shi)，經(jing)(jing)高(gao)頻(pin)(pin)(pin)變壓器(qi)T1耦合過(guo)(guo)來的振(zhen)(zhen)蕩(dang)信(xin)號(hao)(hao)，正半周使(shi)VT2導通(tong)，VT2集電(dian)(dian)(dian)(dian)極(ji)(ji)輸(shu)出負脈沖信(xin)號(hao)(hao)，經(jing)(jing)過(guo)(guo)π型RC濾(lv)波器(qi)，在(zai)負載電(dian)(dian)(dian)(dian)阻器(qi)R4上輸(shu)出低電(dian)(dian)(dian)(dian)平信(xin)號(hao)(hao)。當(dang)高(gao)頻(pin)(pin)(pin)振(zhen)(zhen)蕩(dang)器(qi)停(ting)振(zhen)(zhen)蕩(dang)時(shi)，“C”端無振(zhen)(zhen)蕩(dang)信(xin)號(hao)(hao)，又由于(yu)二極(ji)(ji)管VD2接在(zai)VT2發射極(ji)(ji)與(yu)地之間，VT2基極(ji)(ji)被反(fan)向(xiang)偏置，VT2處于(yu)可靠的截(jie)止狀(zhuang)態，VT2集電(dian)(dian)(dian)(dian)極(ji)(ji)為高(gao)電(dian)(dian)(dian)(dian)平，經(jing)(jing)過(guo)(guo)濾(lv)波器(qi)，在(zai)R4上得到高(gao)電(dian)(dian)(dian)(dian)平信(xin)號(hao)(hao)。由此可見，當(dang)高(gao)頻(pin)(pin)(pin)振(zhen)(zhen)蕩(dang)器(qi)正常工(gong)作時(shi)，在(zai)R4上得到低電(dian)(dian)(dian)(dian)平信(xin)號(hao)(hao)，停(ting)振(zhen)(zhen)時(shi)，為高(gao)電(dian)(dian)(dian)(dian)平，由此完成(cheng)了對振(zhen)(zhen)蕩(dang)器(qi)工(gong)作狀(zhuang)態的檢測。

3、音頻振蕩器

音頻(pin)振(zhen)(zhen)(zhen)蕩器(qi)(qi)(qi)(qi)采用(yong)互補型多諧振(zhen)(zhen)(zhen)蕩器(qi)(qi)(qi)(qi)，由三極(ji)管(guan)VT3、VT4，電(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)R5、R7、R8和電(dian)(dian)容器(qi)(qi)(qi)(qi)C6組成。互補型多諧振(zhen)(zhen)(zhen)蕩器(qi)(qi)(qi)(qi)采用(yong)兩只不同類(lei)型的三極(ji)管(guan)，其中VT3為NPN型三極(ji)管(guan)，VT4為PNP型三極(ji)管(guan)，連(lian)接成互補的、能夠強化(hua)正(zheng)反(fan)饋(kui)的電(dian)(dian)路(lu)。在電(dian)(dian)路(lu)工(gong)作(zuo)時，它(ta)們能夠交替地進入導(dao)通和截止狀態，產生音頻(pin)振(zhen)(zhen)(zhen)蕩。R7既是(shi)VT3負載電(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)，又是(shi)VT3導(dao)通時VT4基極(ji)限流電(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)。R8是(shi) VT4集電(dian)(dian)極(ji)負載電(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)，振(zhen)(zhen)(zhen)蕩脈沖信(xin)號由VT4集電(dian)(dian)極(ji)輸出。R5和C6等是(shi)反(fan)饋(kui)電(dian)(dian)阻(zu)(zu)(zu)器(qi)(qi)(qi)(qi)和電(dian)(dian)容器(qi)(qi)(qi)(qi)，其數值(zhi)大小影響振(zhen)(zhen)(zhen)蕩頻(pin)率的高(gao)低。

4、功率放大器

功率(lv)放(fang)大(da)器(qi)由(you)三極管VT5、揚(yang)(yang)聲器(qi)BL等組成。從多諧(xie)振蕩器(qi)輸出的正脈沖音頻信號經限流(liu)電阻器(qi)R9輸入到VT5的基極，使(shi)其導通(tong)，在BL產生瞬時(shi)較強(qiang)的電流(liu)，驅動揚(yang)(yang)聲器(qi)發聲。由(you)于(yu)VT5處于(yu)開關工作狀態，而(er)導通(tong)時(shi)間又非常(chang)短，因此功率(lv)放(fang)大(da)器(qi)非常(chang)省電，可以利用9V積層電池供電。