Use the CD4017 to do a network cable tester, Network Cable Tester
Keywords: Network cable tester with CD4017
The CD4017 is a very wide range of Johnson Decade Counters / Pulse dispensers. The timing waveform diagram of the CD4017 and the pins arrangement are shown in Figure 2 and the lower right, respectively. It can be seen from the waveform, which has two clock pulse inputs, ie CP and INH, both respectively, the rising edge and the falling edge trigger input pulse, CR is an asynchronous clear zero enable end, when Cr = 1, Y0 is 1 Level, Y1-Y9 is O level; each Y port has decoded output when Cr = 0. The 1 piece CD4017 can form a sequential pulse generator of 10 cases, and if the output Yn (N ≥ 2) is directly connected to the CR, the sequential pulse output of the n-piece shooting can be obtained in the Y0 1 y (n-1) segment.
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Most local area networks use non-shielded twisted pair UTP as a wiring transmission medium. The network cable consists of two RJ45 crystal heads from a twisted pair of a certain length. The twisted pair is divided into 4 pairs of two different colors. In order to test the disconnection of each line and its line, it is understood by the drawings that the circuit is divided into two parts: the host circuit and the secondary circuit. The 1-8 terminals in the host circuit and the 1-8 terminals in the secondary circuit are respectively connected to two RJ45 heads of the network cable (9, 10 terminals in the host circuit, 9, 10 wiring in the secondary circuit). The ends correspond to two BNC headers connected to the received network cable, respectively. The light-emitting diode LED1O-LEDL7 and 8 ordinary diode VD1O-VD17 are used. Mainly in conjunction with the host circuit. After the power is turned on, the NE555 is powered, generates square wave, and LED0 is shining. Its square wave rising edge triggers the CP end of the CD4017. When the CR ground of the CD4017, each Y is a decoded output. The output (YO-Y9) has only one high level cycle, and the rest is low. According to the upper circuit diagram, the following loop is configured: the light-emitting tube LED1 → the first root of the measured network cable → one of the radius lines LEDs 10 → VD11 → VD17 → another 10-mesh cable → host VD2-VD8. so. If the LED1 in the host circuit is lit, the LED 10 in the secondary machine is also lit, and the first root line of the measured network cable is "pass", the other case. When detecting the network cable, if the LED1-LED8 has a hieraser, it means that this path is not available. If the LED 10 LED17 is in a non-order, it indicates that the line is incorrect. In addition, after testing, it is also possible to determine the quality of the network cable according to the luminous strength of the light-emitting diode. BNC coaxial cable detection is the same. This tester will continue to automatically repeat the network cable. In this circuit, IC1 uses NE555, IC2 to select CD4017. LED0 uses φ5mm red luminous tube, LED1-LED18. φ3mm green luminous tube. In addition, in order to facilitate the connection test network cable, two RJ45 socket boxes should be prepared. The power supply uses a 9V laminated battery. There is no special requirements for other components. After the circuit debug is passed, 10 holes are drilled in the front panel of the RJ45 socket box of the host housing, respectively. On the front panel of the RJ45 socket box of the secondary machine case, 9 holes are drilled according to the diameter of the light emitting diode. First, the light-emitting diode card is in the hole, then press the circuit diagram to weld each component. Finally, according to the line sequences 568a and 568b of the two twisted pairs specified in the wiring of EIA / TIA, one of the criteria is selected, and 8 pin sequences on the RJ45 socket should be welded to the host, 1 1 -8 terminal. This serial is very important when the network line is forwarded, and it cannot be mistaken. Since the maximum transmission distance of the twisted pair is generally 100m. Therefore, in online debugging, one can be used. 10M cable tests around 100M.
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