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笔者照97年第7期28页的电子查线器原图制作时,发现BG1、BG2组成复合放大管时不如改进后的效果明显。另外,用感应极片感应到的噪音太大,耳机里“吱吱”、“咝咝”的干扰声太多太大,而对电线的感应交流声很难判别。分析: 1.对原图的电子元件没有改动,只是把R1阻值降低到270kΩ,以提高灵敏度。 2.把连接感应电极的单股线改为屏蔽线。屏蔽线的外层与电源负极相接,减少干扰杂音,使耳机感应到电线的交流信号
The author according to the 97th of 7 28 pages of the electronic thread checker production, it was found that BG1, BG2 composition of the composite amplifier tube as improved effect is obvious. In addition, the sensor with induction pole noise is too large, the headset “creak”, “咝 咝” interference sound too much, but the induction of the wire is difficult to distinguish the sound. Analysis: 1. No change to the original electronic components, only reduce the R1 resistance to 270kΩ, in order to improve the sensitivity. 2. Change the single wire connecting sensing electrode to shielded wire. Shield the outer layer of the power supply and negative phase, reducing interference noise, so that the headset to the wire AC signal