试电笔在汽车故障诊断与排除中发挥着重要的作用。如果对其作下述改装 ,它将会有更多的作用 ,如用来鉴别蓄电池的正负极等。具体改装方法是 :先将一红一绿 2只发光二极管和 1只 30 0Ω电阻按图 1所示的电路接好 ,然后取出试电笔中的发光管 ,去掉玻璃管部分 ,将其两端的金属套分 Test pen plays an important role in the diagnosis and troubleshooting of automobile. If you make the following modifications, it will have more effect, such as the battery used to identify the positive and negative and so on. The specific modification method is: First, a red and two green light emitting diode and a 30Ω resistor according to the circuit shown in Figure 1 connected, and then remove the test light pen in the pen, remove the glass tube, the ends of the metal Set points