手(shou)持(chi)式金屬探(tan)測(ce)器被設計用(yong)來探(tan)測(ce)人或物(wu)體(ti)攜帶的(de)金屬物(wu)，廣(guang)泛應用(yong)于安全檢(jian)查、考古、探(tan)礦等方面。手(shou)持(chi)金屬探(tan)測(ce)器的(de)結構主要由四部分組成：

1、高頻振蕩器

由三(san)極管VT1和(he)高(gao)頻變(bian)壓器(qi)T1等組(zu)成(cheng)，是一種變(bian)壓器(qi)反饋(kui)型LC振蕩器(qi)。

2、振蕩(dang)檢(jian)測器

振(zhen)蕩(dang)(dang)(dang)(dang)檢測器(qi)(qi)(qi)(qi)由(you)三(san)極(ji)(ji)管(guan)(guan)開關(guan)電(dian)(dian)(dian)(dian)(dian)路(lu)和(he)濾波(bo)電(dian)(dian)(dian)(dian)(dian)路(lu)組成(cheng)。開關(guan)電(dian)(dian)(dian)(dian)(dian)路(lu)由(you)三(san)極(ji)(ji)管(guan)(guan)VT2、二極(ji)(ji)管(guan)(guan)VD2等組成(cheng)，濾波(bo)電(dian)(dian)(dian)(dian)(dian)路(lu)由(you)濾波(bo)電(dian)(dian)(dian)(dian)(dian)阻(zu)器(qi)(qi)(qi)(qi)R3，濾波(bo)電(dian)(dian)(dian)(dian)(dian)容器(qi)(qi)(qi)(qi)C2、C3和(he)C4組成(cheng)。在(zai)(zai)(zai)開關(guan)電(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)，VT2的(de)基極(ji)(ji)與次級線圈L2的(de)“C”端相連(lian)，當高(gao)頻振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)(qi)工(gong)作(zuo)時(shi)，經(jing)(jing)高(gao)頻變(bian)壓器(qi)(qi)(qi)(qi)T1耦合過(guo)來(lai)的(de)振(zhen)蕩(dang)(dang)(dang)(dang)信號(hao)，正(zheng)半周使VT2導通，VT2集電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)輸(shu)出負脈沖信號(hao)，經(jing)(jing)過(guo)π型RC濾波(bo)器(qi)(qi)(qi)(qi)，在(zai)(zai)(zai)負載(zai)電(dian)(dian)(dian)(dian)(dian)阻(zu)器(qi)(qi)(qi)(qi)R4上輸(shu)出低電(dian)(dian)(dian)(dian)(dian)平(ping)(ping)信號(hao)。當高(gao)頻振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)(qi)停振(zhen)蕩(dang)(dang)(dang)(dang)時(shi)，“C”端無振(zhen)蕩(dang)(dang)(dang)(dang)信號(hao)，又由(you)于二極(ji)(ji)管(guan)(guan)VD2接(jie)在(zai)(zai)(zai)VT2發射極(ji)(ji)與地(di)之間，VT2基極(ji)(ji)被反向偏(pian)置(zhi)，VT2處于可(ke)靠的(de)截止狀態(tai)，VT2集電(dian)(dian)(dian)(dian)(dian)極(ji)(ji)為高(gao)電(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，經(jing)(jing)過(guo)濾波(bo)器(qi)(qi)(qi)(qi)，在(zai)(zai)(zai)R4上得(de)到高(gao)電(dian)(dian)(dian)(dian)(dian)平(ping)(ping)信號(hao)。由(you)此可(ke)見，當高(gao)頻振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)(qi)正(zheng)常(chang)工(gong)作(zuo)時(shi)，在(zai)(zai)(zai)R4上得(de)到低電(dian)(dian)(dian)(dian)(dian)平(ping)(ping)信號(hao)，停振(zhen)時(shi)，為高(gao)電(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，由(you)此完成(cheng)了(le)對振(zhen)蕩(dang)(dang)(dang)(dang)器(qi)(qi)(qi)(qi)工(gong)作(zuo)狀態(tai)的(de)檢測。

3、音頻振蕩器

音(yin)頻振(zhen)蕩(dang)(dang)(dang)器采(cai)用(yong)互(hu)補型(xing)(xing)多諧(xie)振(zhen)蕩(dang)(dang)(dang)器，由三極(ji)管(guan)VT3、VT4，電(dian)(dian)(dian)(dian)阻(zu)(zu)器R5、R7、R8和(he)電(dian)(dian)(dian)(dian)容器C6組成。互(hu)補型(xing)(xing)多諧(xie)振(zhen)蕩(dang)(dang)(dang)器采(cai)用(yong)兩只不同類型(xing)(xing)的(de)三極(ji)管(guan)，其中(zhong)VT3為NPN型(xing)(xing)三極(ji)管(guan)，VT4為PNP型(xing)(xing)三極(ji)管(guan)，連(lian)接成互(hu)補的(de)、能夠強化正反饋的(de)電(dian)(dian)(dian)(dian)路。在(zai)電(dian)(dian)(dian)(dian)路工作時，它們能夠交(jiao)替地進入導通(tong)和(he)截止狀態，產生音(yin)頻振(zhen)蕩(dang)(dang)(dang)。R7既是VT3負載(zai)電(dian)(dian)(dian)(dian)阻(zu)(zu)器，又是VT3導通(tong)時VT4基極(ji)限流電(dian)(dian)(dian)(dian)阻(zu)(zu)器。R8是 VT4集電(dian)(dian)(dian)(dian)極(ji)負載(zai)電(dian)(dian)(dian)(dian)阻(zu)(zu)器，振(zhen)蕩(dang)(dang)(dang)脈沖信號由VT4集電(dian)(dian)(dian)(dian)極(ji)輸出(chu)。R5和(he)C6等是反饋電(dian)(dian)(dian)(dian)阻(zu)(zu)器和(he)電(dian)(dian)(dian)(dian)容器，其數值(zhi)大小影響振(zhen)蕩(dang)(dang)(dang)頻率的(de)高低。

4、功率放大器

功率放大(da)器(qi)由三(san)極管(guan)VT5、揚聲器(qi)BL等(deng)組成。從多諧(xie)振(zhen)蕩器(qi)輸出的(de)正脈沖音頻(pin)信號(hao)經限流電(dian)(dian)阻器(qi)R9輸入到VT5的(de)基極，使其導(dao)通(tong)，在BL產(chan)生瞬時較(jiao)強的(de)電(dian)(dian)流，驅動揚聲器(qi)發聲。由于VT5處于開(kai)關(guan)工作狀態，而導(dao)通(tong)時間又非(fei)常短，因此功率放大(da)器(qi)非(fei)常省電(dian)(dian)，可(ke)以(yi)利用9V積層電(dian)(dian)池供電(dian)(dian)。