Networking - Delphijustin industries

Resistor RJ45 Tester

Justin Roeder — Fri, 08 Dec 2023 20:01:40 +0000

This is a simple network cord tester that uses just 8 unique resistors. The values/wattage doesn’t matter as long as the meter can read them. They should be in the kiloohm range. I have made an Excel spreadsheet file that you can enter all 8 of the resistors and get the total parallel resistance. The pins are listed as binary 1s and 0s. J1 and J2 are the RJ45 connectors. I even entered the ones I’m using. It doesn’t tell you if it’s a patch cord, crossover or rollover, but tells you if the pins used on the cord are making connection. To tell what type of cord it is just look at the 2 ends.

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The post Resistor RJ45 Tester first appeared on Delphijustin industries.

Audio over telephone

Justin Roeder — Sat, 14 Jan 2023 22:07:10 +0000

Heres a simple circuit that takes a audio signal(from ham radios,computers or cd players) and converts them into a telephone signal. It powers the phone line with 22vdc(It doesn’t have to be 22vdc, different voltage means different resistor is needed). The phones can run as high as 48v. If you use cordless phones the converter will still need power. WARNING DO NOT CONNECT THIS TO A REGULAR TELEPHONE LINE OR LANDLINE THOSE LINES PROVIDE AC AND THE CAPACITOR WON’T BLOCK THE VOLTAGE. THIS CIRCUIT IS TO TAKE AUDIO FROM THE HEADPHONE JACK AND INJECT IT INTO CORDLESS PHONES WITHOUT A TELEPHONE COMPANY. I use mine to listen to IRC chat 1000ft away from my computer. This could also work with corded phones. I believe you connect them in series, where the lamp is. I don’t have any corded phones to experiment with, the resistor may need to be lowered for 2 corded phones. I tried connecting two cordless phone bases together but the handset said No Line and also you could hear them or hear the tone when you press number buttons. When I made this circuit the No Line message went away and you could hear the computer and tones for the number buttons could be heard.

The capacitor should be no more than 1uF of capacitance and non-polarized. And yes the cord is safe to touch since its not hooked up to a real phone line. The resistor should be 1/2W instead of 20W. I had extra of those so I used it.

In the circuit diagram the 44KHz is the Audio Signal and the lamp is the phone

The way I wired it. Part of the audio cord is behind the RJ11 and the other one by GND
The schematic

I have two cordless phones but no splitter or second RJ11 connector. I will try talking over them when I get those stuff

The post Audio over telephone 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:

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