手持式金(jin)屬(shu)探(tan)測(ce)器被設(she)計(ji)用(yong)來探(tan)測(ce)人(ren)或物體攜帶的金(jin)屬(shu)物，廣泛應用(yong)于(yu)安全檢查、考古、探(tan)礦等方面(mian)。手持金(jin)屬(shu)探(tan)測(ce)器的結構主要由四部(bu)分(fen)組成：

1、高頻振蕩器

由三極(ji)管VT1和高頻變壓器(qi)(qi)T1等組(zu)成，是一種變壓器(qi)(qi)反饋型(xing)LC振蕩器(qi)(qi)。

2、振蕩檢測器

振(zhen)蕩(dang)(dang)(dang)(dang)檢(jian)測器(qi)(qi)(qi)由(you)三(san)(san)極(ji)(ji)管(guan)(guan)開(kai)(kai)關(guan)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)和(he)濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)組成。開(kai)(kai)關(guan)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)由(you)三(san)(san)極(ji)(ji)管(guan)(guan)VT2、二極(ji)(ji)管(guan)(guan)VD2等組成，濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)由(you)濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)阻器(qi)(qi)(qi)R3，濾(lv)波(bo)電(dian)(dian)(dian)(dian)(dian)容器(qi)(qi)(qi)C2、C3和(he)C4組成。在開(kai)(kai)關(guan)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)中，VT2的基極(ji)(ji)與次級線(xian)圈L2的“C”端相連，當(dang)高(gao)頻振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)工(gong)作(zuo)時(shi)，經高(gao)頻變壓器(qi)(qi)(qi)T1耦合過(guo)(guo)來的振(zhen)蕩(dang)(dang)(dang)(dang)信(xin)(xin)號(hao)(hao)，正半周使VT2導(dao)通，VT2集(ji)電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)輸出負(fu)脈沖(chong)信(xin)(xin)號(hao)(hao)，經過(guo)(guo)π型RC濾(lv)波(bo)器(qi)(qi)(qi)，在負(fu)載電(dian)(dian)(dian)(dian)(dian)阻器(qi)(qi)(qi)R4上輸出低電(dian)(dian)(dian)(dian)(dian)平(ping)信(xin)(xin)號(hao)(hao)。當(dang)高(gao)頻振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)停振(zhen)蕩(dang)(dang)(dang)(dang)時(shi)，“C”端無振(zhen)蕩(dang)(dang)(dang)(dang)信(xin)(xin)號(hao)(hao)，又由(you)于二極(ji)(ji)管(guan)(guan)VD2接在VT2發射極(ji)(ji)與地之間(jian)，VT2基極(ji)(ji)被反向偏(pian)置，VT2處于可(ke)(ke)靠的截止狀(zhuang)(zhuang)態，VT2集(ji)電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)為(wei)(wei)高(gao)電(dian)(dian)(dian)(dian)(dian)平(ping)，經過(guo)(guo)濾(lv)波(bo)器(qi)(qi)(qi)，在R4上得(de)到(dao)高(gao)電(dian)(dian)(dian)(dian)(dian)平(ping)信(xin)(xin)號(hao)(hao)。由(you)此(ci)可(ke)(ke)見，當(dang)高(gao)頻振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)正常工(gong)作(zuo)時(shi)，在R4上得(de)到(dao)低電(dian)(dian)(dian)(dian)(dian)平(ping)信(xin)(xin)號(hao)(hao)，停振(zhen)時(shi)，為(wei)(wei)高(gao)電(dian)(dian)(dian)(dian)(dian)平(ping)，由(you)此(ci)完成了(le)對(dui)振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)工(gong)作(zuo)狀(zhuang)(zhuang)態的檢(jian)測。

3、音頻振蕩器

音(yin)頻振(zhen)蕩(dang)器(qi)(qi)(qi)(qi)采用(yong)互(hu)補(bu)(bu)型多諧振(zhen)蕩(dang)器(qi)(qi)(qi)(qi)，由(you)三(san)極(ji)(ji)管(guan)VT3、VT4，電(dian)(dian)阻器(qi)(qi)(qi)(qi)R5、R7、R8和(he)電(dian)(dian)容器(qi)(qi)(qi)(qi)C6組成(cheng)(cheng)。互(hu)補(bu)(bu)型多諧振(zhen)蕩(dang)器(qi)(qi)(qi)(qi)采用(yong)兩只不(bu)同類型的三(san)極(ji)(ji)管(guan)，其中VT3為(wei)NPN型三(san)極(ji)(ji)管(guan)，VT4為(wei)PNP型三(san)極(ji)(ji)管(guan)，連接成(cheng)(cheng)互(hu)補(bu)(bu)的、能夠(gou)強化正反饋的電(dian)(dian)路。在(zai)電(dian)(dian)路工作時，它們能夠(gou)交替地進入導(dao)通和(he)截止狀態，產生(sheng)音(yin)頻振(zhen)蕩(dang)。R7既是(shi)VT3負載電(dian)(dian)阻器(qi)(qi)(qi)(qi)，又是(shi)VT3導(dao)通時VT4基極(ji)(ji)限(xian)流電(dian)(dian)阻器(qi)(qi)(qi)(qi)。R8是(shi) VT4集電(dian)(dian)極(ji)(ji)負載電(dian)(dian)阻器(qi)(qi)(qi)(qi)，振(zhen)蕩(dang)脈(mo)沖信(xin)號由(you)VT4集電(dian)(dian)極(ji)(ji)輸出。R5和(he)C6等是(shi)反饋電(dian)(dian)阻器(qi)(qi)(qi)(qi)和(he)電(dian)(dian)容器(qi)(qi)(qi)(qi)，其數值(zhi)大小影響振(zhen)蕩(dang)頻率(lv)的高(gao)低。

4、功率放大器

功(gong)率(lv)放(fang)大器(qi)由三極管(guan)VT5、揚聲器(qi)BL等組成。從(cong)多諧振蕩器(qi)輸(shu)出的(de)正脈(mo)沖(chong)音頻信號(hao)經限流電阻器(qi)R9輸(shu)入到VT5的(de)基極，使其導(dao)(dao)通，在(zai)BL產生(sheng)瞬時(shi)較強的(de)電流，驅動(dong)揚聲器(qi)發聲。由于(yu)VT5處于(yu)開關工作狀態，而導(dao)(dao)通時(shi)間又(you)非常(chang)短(duan)，因此功(gong)率(lv)放(fang)大器(qi)非常(chang)省(sheng)電，可以利用9V積層電池(chi)供電。