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西德电子学杂志1971年第4期报道了一种简易金属搜索仪,它具有一定的特点。介绍如下:利用二块CMOS集成电路、二个晶体管、一个扬声器和几个无源元件可以组装成一台简易的金属搜索仪。通过一个12pF的电容器把频率在50～200kHz范围内可调的振荡器和LC振荡电路相连接。LC谐振频率约为80kHz。把振荡器的频率调到接近谐振频率。调整P_1,以使经硅二极管连接的变换电路刚好处于切换装置之前。由于黑色金属和有色金属在接近探索线圈L时对谐振频率的影响不一样,所以,通过切换开关S及相应地调整P_1及P_2,来选择指示是那一种金属。
West German Journal of Electronics, 1971, No. 4 reported a simple metal search device, it has certain characteristics. The introduction is as follows: Using two CMOS integrated circuits, two transistors, a speaker and several passive components can be assembled into a simple metal searcher. Oscillator with adjustable frequency in the range of 50 ~ 200kHz is connected to the LC tank via a 12pF capacitor. The LC resonance frequency is about 80 kHz. Adjust the frequency of the oscillator close to the resonant frequency. Adjust P_1 so that the silicon-diode-connected conversion circuit is just in front of the switching device. Since ferrous and non-ferrous metals have different effects on resonant frequency as they explore coil L, the indication of which metal is by selecting switch S and adjusting P_1 and P_2 accordingly.