Lightweight and practical multi-core cable (network cable) detection circuit (NE555) ----- Wire Tester

Keywords: NE555, cable test, network cable test Author: Chen Baoxin The circuit can check if the bunch of wire or multi-core cable is the same harm guide or the same cable, which can check if there is a wire or short circuit in a wire or a wire, which can be used for the bundle wire or multi-core cable. Direct line number. The circuit is small, light, simple, easy to use, check fast and accurate, low power consumption, etc., there is a certain reference in practical applications. The working principle of the circuit. The schematic diagram of the circuit is shown in the figure below, and the whole machine is powered by a 9V dry battery. When the power switch S1 is connected, the power supply indicator LED2 is powered, the NE555 integrated chip starts working, its operating state is a multi-harmonic oscillation, and the 3 pin outputs a rectangular pulse of about 50%, LED1 When it starts to flash, the pulse is input to the 14 pin of the CD4017 integrated chip. At this time, the CD4017 starts counting, and the current output is high, and the high level reaches the port of P1 through the resistor. The P1 and P2 are connected in the middle of the multi-core cable. If the lines of the multi-core cable are turned on, the LED3-LED10 is turned on, blinking; if the multi-core cable is disconnected, the corresponding LED light does not illuminate If the line number of the multi-core cable is connected, the order of the diode illuminates is incompatible, and the purpose of detecting the multi-core cable is achieved by this principle. Be Works debugging. Close the switch SL, turn on the power supply, LED2 luminesce, whether the main chip will heat up, no abnormal phenomenon; later found that LED1 does not flash, the problem occurs, the 3 pin of the NE555 chip does not output pulse wave. The oscilloscope is detected, and there is no waveform output. At this time, it is seriously checked whether the welded circuit has a short circuit or disconnect, and the digital multimeter is used to detect whether the connection points are turned on. It is found that the line is not abnormal; check the information about the NE555 chip, especially As a paralletic oscillator, each pin is taken; the 5 foot of the NE555 is not connected to the ground, which is easy to cause high level shattered. Thus, a 4.7μF capacitor is added to the ground, eliminates high-level schurn; again turns on the power, detects the 3 foot waveform of the NE555, and the measurement of 3 foot outputs a duty cycle is about 50%. Pulse wave, then the LED1 flicker appears. Tested with a intact network cable, it was found that the light-emitting diode LED3 ~ LED10 was fluidized, and the exhight of the luminescence can be synchronized with the LED1, that is, the LED1 shines once, and the LED3 ~ LED10 has a lamp, and it is finally made to light the light. One line cut is tested, and the corresponding LED 5 corresponding to the power is not emitted, and the remaining seven LED lights can be lit by one-round, and can be synchronized with the LED1, so that success is successful.