DIY cable tester

Justin Roeder — Sat, 27 Aug 2022 13:36:30 +0000

In this blog I will show you two ways to make a cable tester. The 1^st way uses a arduino (software controlled). The 2^nd way uses a decade counter chip(CD4017) and a flashing LED. I am going to order the Dual RJ45 jack to screw terminals from eBay. The other connectors are from parts-express. I couldn’t find one that would tell you that it has screw terminals on parts-express. But starting from 2 dollars off of eBay you couldn’t go wrong! The screw terminals allows secure connections from other types of cords, such as USB and TV coax, whereas punchdown would not be a good choice. The reason for that is each pin on the RJ45 connector will be tied together with the usb cable, coax and rca cables. This tester will tell you which pin on one side is wired to on the other side, tells you if there’s no connection and tells you about any shorts. I ordered connectors that were attached to a cord so that soldering will be easier. It’s basically a LED chaser with two of LEDs in series one for side a and the other one for side b. You can find the arduino code on github. To use simply connect one side of the cord to side a and the other to side b

arduino circuit
4017 chip circuit

Once the parts come in a YouTube video will be uploaded

The post DIY cable tester first appeared on Delphijustin industries.

Passive Ethernet Tap

Justin Roeder — Wed, 29 Jan 2020 03:01:58 +0000

A Ethernet tap allows you to monitor Ethernet communications going through the tap. The circuit uses no power and that is why its called passive. Can be made by cutting Ethernet cords and/or soldering or crimping. This method will make the maximum Ethernet speed 100Mbps, even if its a gigabit Ethernet. Also you could use 2 Ethernet adapters for reading both send and receive lines.

What you will need

2x Ethernet cords(CAT5,CAT6 or CAT5E)

1 pair of scissors or wire strippers

Optional 2x ceramic capacitors(use in case of power over Ethernet)

4x End caps,wiring nuts or solder

Software: Nirsoft SmartSniff with WinPCap

1 pair of pliers( for crimping end caps, if your going to use wiring nuts or solder this is not needed)

Step 1. finding Receive Pair

In order for this circuit to work you must know which wires are the receive pair and ones that are transmit. Patch cords have one of the following color code below.

Pins view

Pinout of the RJ45 Patch cord

If green is closest to pin 1 then receive pair are the orange otherwise it’s green. Also crossover and rollover cords don’t have the same wires connected on both sides. After that you must decide which cable can be use as the monitoring cords. It will use wire 3 and 6

Step 2. Building The Circuit

Connect wire pairs as shown.

Cable wiring

Device A and Device B are the connection to monitor. And Monitor A and Monitor B are the cords that are used for monitoring the connection. Monitoring Cords uses Pin 3 and 6. And Device cords use Pin 1, 2, 3 and 6. Also make sure to use Promiscuous Mode in SmartSniff. If your device uses Power Over Ethernet, just connect one ceramic capacitor on the blue pair and one on the brown pair. Make sure the capacitors are only on the Device side of the cord and not the monitoring.

Step 3. Testing The Ethernet Tap

You will need 2 computers and one Ethernet Router to test this cord. Plug one Device cord up to a router and the other device end to a computer. Hook one of the monitoring cords up to a different computer. Open SmartSniff and select the Ethernet Adapter with the cord connected to it and select WinPCap and Promiscuous Mode. Next on the computer we are spying on ping the router and see if it shows up in SmartSniff(Its protocol will be under ICMP).

Here’s pictures of my Ethernet tap:

The post Passive Ethernet Tap first appeared on Delphijustin industries.

Cat6 - Delphijustin industries

DIY cable tester

Passive Ethernet Tap

Step 1. finding Receive Pair

Step 2. Building The Circuit

Step 3. Testing The Ethernet Tap