本文介绍的电话分机提机指示灯,可解决主、分机与外线的通话混乱,可实现只要分机一提起,另一部电话机上的提机指示灯便会迅速点亮指示,从而避免重复提机:还可以通过指示灯指示电话线路是否被他人盗用。电路原理提机指示灯的电路原理图如图1所示。L1、L2直接并联在电话机的外线上,VD1～VD4组成电流极性自动换向器,因此这个小装置与电话外线相连时可以不必考虑电话线路的正负极性。通常电 This article describes the extension telephone extension lights, to resolve the main, extension and outside the chaos of conversation, as long as the extensions mentioned, the other phone on the indicator light will quickly light instructions, to avoid duplication of the machine : You can also indicate if the phone line is being stolen by an indicator. Circuit diagram The circuit diagram of the elevator lights as shown in Figure 1. L1 and L2 are directly connected to the outside of the telephone. VD1 to VD4 form a current polarity automatic commutator. Therefore, the small device can be connected to the outside of the telephone without considering the polarity of the telephone line. Usually electricity