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电话机测试仪是维修电话机必备的仪器。本文介绍的测试仪突出的特点是简单、实用,并且很容易自制。 一、工作原理 测试仪电路见附图,由四部份组成。 1、振铃信号源 振铃信号源由电源变压器次级N_1绕组的80V交流电压提供。电压较高,以便使本仪器发出的振铃信号和交换机发出的大小相当,这样能更有效地检查出振铃电路的某些故障,如局部击穿等。R_101是限流保护电阻,以保证振铃高压不会损伤电话机。
Telephone tester is an essential instrument for telephone repair. This article describes the outstanding features of the tester is simple, practical, and very easy to make. First, the working principle Tester circuit see the photo, composed of four parts. 1, the ring signal source ringing source from the power transformer secondary N_1 winding 80V AC voltage provided. The voltage is high so that the ringing signal emitted by the instrument matches the size of the switch, which can more effectively detect some of the ringing faults, such as partial breakdown. R_101 is the current limiting protection resistor to ensure that the ringing high voltage will not damage the phone.