DIY - LAN Cable Tester - With or Without Arduino

There is nothing worse than running your drops only to realize that you have a fault in one of the cable runs. The best approach is to get it right in the first place by using a LAN cable tester. Sometimes cable can also tear because of poor material quality or bad installation or sometimes they get gnawed by animals. In this project I'm going to make a LAN cable tester with just a few basic electronic components. The entire project excluding the battery cost me just a bit over three dollars. With this tester we can easily check RJ45 or RJ11 network cables for their continuity, sequence and if they have a short circuit. For this project we need a perf board, an Arduino Uno Nano whatever is handy, two RJ45 8P8C ethernet ports, nine LEDs, nine 220 ohm resistors, nine 1N4148 fast switching diodes, one SDPD switch, one 555 timer IC, one 4017 decade counter IC, one 10k resistor, one 150k resistor, one 4.7 capacitor, one 18650 battery, one 18650 battery holder, one TP4056 module for charging the battery, few connecting cables and general soldering equipments. A network cable consists of eight wires plus sometimes a shield. These nine connections must be tested one after the other otherwise a shot between two wires or more cannot be detected. In this project I'm only testing the eight wires however just by doing a little bit of modification you can test all the nine wires. The sequential testing is done automatically by multi vibrator and shift register. In principle the circuit is just a running light with the LAN cable in between. If one wire is disconnected the corresponding LED will not light up. If two wires have a short circuit two LEDs will light up and if wires are interchanged the sequence of the LEDs will be interchanged. The 555 timer IC operate as a clock oscillator. The output of the pin 3 goes high every second causing the shift. We can also achieve this by adding an Arduino instead of the 555 IC. Just send a digital high followed by a digital low every second using the blink example from the Arduino IDE. However adding an Arduino will add to the cost but will also reduce the complexity of soldering. The signal from IC 555 or Arduino clocks the 4017 decade counter. As a result the output on 4017 IC are switched sequentially from low to high. The clock pulse generated at the output of IC 555 timer on pin 3 is given as an input to IC 4017 through pin 14. Whenever a pulse is received at the clock input of IC 4017 the counter increments the count and activates the corresponding output pin. This IC can count up to 10 but in our project we only need to count up to 8. So the 9th output from the pin 9 will be fed to the reset pin number 15. Sending a high signal to 15 will reset the counter and it will skip counting the rest of the numbers and will start from the beginning. Let's start by Connect pin 1 to ground. Pin 2 to pin 6. Then connect the 10k resistor to the positive rail and the 150k resistor to the intersection of pin 2 and pin 6. Connect the capacitor to one end of the intersection and the other end to the ground rail. Now connect pin 7 to the intersection of the 10k and 150k resistor creating a voltage divider. Then connect the output pin 3 of 555 IC to the clock pin of 4017 IC. Next connect the pin 4 to pin 8 and then connect them to the positive rail. Add the switch to the positive rail followed by the on off indicator LED. After connecting all the pins of 555 IC it's time for us to connect the pins of 4017 IC. Connect pin 8 and pin 13 to ground. Short pin 9 and reset pin 15 and pin 16 to the positive rail. Once all the above pins are connected it's time for us to connect the LEDs to the circuit. The LEDs will be connected from pin 1 to 7 and on pin number 10 as shown in the diagram. Each of the LEDs will be connected in series with a 220 ohm resistor and in parallel with a 4148 fast switching diode. If you want to test all the 9 pins you just need to repeat this setup 9 times otherwise just use it 8 times. On the terminal end short all the pins together. Now the testing bit. Let's say output 1 is high and all other pins are low. The current flows through the series resistor and LED 1. The diode parallel is in reverse direction and has no influence at all. Because all other outputs now have ground potential so all other parallel diodes will be in forward direction. As all the pins of the terminal socket are connected to each other it will complete the circuit and the LED will light up. Now if you want to do the same with an Arduino you just need to remove the 555 IC and add the Arduino in place of it. After connecting the VIN and ground of the Arduino to the positive and the negative rails respectively connect any one of the digital pins to the pin number 14 of IC 4107. That's it. Easy. I'm not going to explain the code here but I'll provide the link in the description below. Now let's have a look at what I've made. These eight LEDs are to display the status of the LAN cable. Then we have the two Ethernet ports where we are going to plug in the LAN cable. If you want to test a longer cable just have another one of these ports with all its pins connected to each other. One end of the cable plugs into the bottom port and the other end to the third port. I have attached the TP4056 battery charging module to one end of the battery holder to save some space. Okay let's turn on the device and do a quick test. As soon as we turn on the device the on-off indicator LED turns on. Now let's plug in our cable and see what happens. Ta-da! Look at that. If you want you can 3D print a nice looking case for this tester and give it a professional look. However I just left it as is. Thanks again for watching this video. I hope it helps you. If you want to support me you can subscribe to my channel and watch my other videos. Thanks. See you again in my next video. Bye now.