Questions tagged [rj45]

For questions about Registered Jack 45, an 8 position 8 contact (8P8C) modular connector commonly associated with Ethernet and category 5 (Cat 5) cables. Consider using in conjunction with associated tags "connector", "ethernet", "cat5", "cables", etc., if applicable.

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Can I use an RJ45 plug designed for UTP with STP wire?

I have a non-standard application (model railroad) where I am planning to use CAT6 wiring between a custom made circuit board and a display panel. The circuit board will have RJ45 ports (using ...
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EtherCAT Communication Testing

I am working on a device that uses EtherCAT. On one side, I have the standard EtherCAT Connector - an RJ45. On the other side, I would like to experiment with different connectors. For starters, I ...
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Understanding 24 V PoE mode B magjack connections

Having just realised I have screwed up my board by stupidly swapping pins 4 & 5 on the magjack output, I have realised I don't properly understand the PoE power pins on the magjack. I wonder if ...
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RJ45 PCB Design Transformer & MagJack

Designing a PCB board that supports RJ45 using W5500, yet I'm confused with two issues: Magnetic jack: Is it required? Is transformer required if Magnetic jack is used? Or are they unrelated? By ...
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Can I punch down regular hookup wire in an RJ45 Keystone Jack?

I'm planning to use CAT5e cable for a model railroad application and on the far end of the wire I am looking to use a keystone jack. My question is whether or not regular hookup wire can be punched ...
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W5500 ethernet controller link problem

My design includes an STM32, a W5500 and this RJ45 connector which has a 1000pF/2kV capacitor. The problem is that when I connect a cable to the RJ45, the orange LED always blinks. This indicates no ...
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9 wires in a CAT5e cable?

I just cut open a CAT5e cable since I wanted it for a project which required several twisted shielded pair cables. To my surprise there were 9 wires with isolation? I was under the impression that ...
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Interfacing RJ45 to 3 pin RMII and bidirectionality

I am trying to add an Ethernet interface to a dev board (This board specifically). From looking at the schematics, I see that it has a 3 pin PHY input (GND, TRX+, and TRX-). From my understanding, a ...
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Ethernet RJ45 M-F cable (socket <-> plug)

During renovation I've asked the electrician to use two long patch cables originally running from my router to create RJ45 sockets with the intent to later connect the router to the socket using a ...
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Not getting linkup on Ethernet with ESP32 MCU

I have an issue regarding ethernet with an ESP32. I have designed a hardware with an ESP32 and DP83848 phy for ethernet connection. The problem is I don't get link up from phy. I am running the ESP32 ...
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What to do with unused pins on a 1000BaseT RJMAG jack

Trying to figure out what to do with the unused wires heading into the magnetics on an RJMG2330A1610ER Ethernet/USB jack. Due to the craziness in manufacturing in the world I am forced to find a ...
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Ethernet Surge Protector Speed

I've been investing in some new surge protectors lately – a fraught process at best given the difficulties of comparing model and brand quality. Things were even trickier when looking into ethernet (...
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How to connect Ethernet Magnetic/RJ45

I am connecting up my PHY to an RJ45 with magnetics and was wondering what I do with some pins on it. Here is the circuit for the Rj45 w/ magnetics. My questions are: do I connect pin 10 to the ...
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Can I convert my dozens of laptop adapters into universal ones by using RJ-11 or RJ-45 connections?

I have accumulated dozens of laptop (and other) power bricks over the years. Some of them belong to a corresponding laptop or device, others just haven't been thrown away yet. I'm trying to make them ...
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protect RS485 from PoE

I have a board with two RJ45 connectors. One is used for an Ethernet port and the other one is for a RS485. The Ethernet is for Power over Ethernet. What are some suggestions to protect the RS485 port ...
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Difference between the two Ethernet magnetic topologies

Background Hello, I'm building up a PCB for a PoE module based on Microchip LAN8720 IC. The recommended schematic is shown in the following figure. I built up a prototype based on the Waveshare ...
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Center Tap (CT) pins in RJ-45 Connector

I'm not an Ethernet connector expert. I was wondering what are the CT pins in RJ-45 connector are used for. From a search in https://www.edaboard.com/ I found this interesting answer from a user ...
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How to connect interfaces' shields?

I am designing a new PCB board these days, and I am confused about how to connect interfaces' shields. The interfaces on the board include USB, RJ45 and D-SUB, should them be connected directly to ...
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Transmitting I2S over 6ft

I've been looking at audio ADCs with most rated at 192Ksps with 24 bit audio. Typically the output is in I2S, but I understand that the signal is not intended to go far. I understand that HDMI can ...
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Manually Use LEDs on RJ45 Connector [closed]

I am using RJ45 connectors(2-406549-1) with built in LEDs, to transmit SPI lines for a microcontroller project(I needed CAT 6 cables for twisted data/ground pairs). I'd like to use those built in LEDs ...
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DMX over RJ45 daisychain extra pins?

Im building a DMX controller that uses RJ45. (Controller as in lights are connected to it) I will obviously have 2 RJ45 jacks for daisy-chaining. What I was wondering is, I've seen that multiple ...
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10Gb link data transfer between FPGA && PC [closed]

I'm trying to transfer data from 10Gb ETH subsystem of FPGA to 10GB ETH card of PC. SFP, RJ45 and ETH cable comprise of this data transfer pipeline. The RTL code is ready for testing and I'm looking ...
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Can I use 2 RJ45 magjacks (PCB mounted) used for pass through..on my PCB?

I need to put a pass through ethernet on my PCB. (rj45 to rj45). My circuit is similar to this guy.. I want to use my existing components. I have space on my chipplacer(yes I have a chipplacer line) ...
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How to fix a RJ45 connector patina without poison or with common tool?

The RJ45 connector from the wall of my house is rusted. The copper pins are covered by thick patina. The patina is so thick that it looks black. It definitely reduces communication quality so I would ...
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2 Ethernet jacks on a Device with ENC28J60 chip in with switch

I have an Ethernet device that works with Microchip's ENC28J60 chip perfectly. So if I want to connect a cable from a switch/controller, to device 1 (that has 2 RJ45 jacks), then have device 1 second ...
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How to properly read current of a PoE Mode A device?

I'm trying to measure the power consumption of a PoE device using Mode A. I assume I would need 2x current readings -- one for pin 1 (I1), one for pin 2 (I2), and then 1 voltage reading of from either ...
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W5500 with POE functionality Link status ON with nothing plugged in?

I am working on a design that uses a W5500 for networking. I followed a reference schematic and believe all my connections are correct, however I am facing issues with the network connectivity. ...
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PCB design for RJ45 jack

I'm designing a PCB to host an Applanix APX15 GPS/inertial navigation device. The hardware integration manual (which seems not to be publicly available) shows that a 10/100 BaseT Ethernet is supported ...
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ENC28J60 Circuit Connected With 2 Magjack in Parallel

I'm using ethernet controller chip ENC28J60 and I need to have it connected to 2 magjack in parallel, but I'm unsure if I made a correct circuit, is this can work? Please advise me, thank you very ...
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Ethernet in MIL-DTL-38999 connector

I am hoping to use a MIL-DTL-38999 circular connector for 10/100 Mb ethernet in acc. to IEEE802.3. So the insulation voltage should be at least 1500VAC for 1 min. Most connectors I have seen during my ...
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How to dial a phone number via DTMF tones?

I want to dial a phone number on a landline with DTMF tones generated by my phone. I tried soldering a 3.5mm audio jack to a phone cable and using my regular phone app, but nothing happened. In this ...
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Designing an Ethernet / RJ 45 disconnector

I am currently in need of a device that is plugged in between a host and a client to cut the connection regularly on a hardware level. This should simulate unplugging the Ethernet cable and plugging ...
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Small connector alternative for 10/100base Ethernet [duplicate]

I have been looking for a small connector that I can use for Ethernet 10/100 base communication. There were some similar discussions here about the same topic, but I couldn't find a solid answer. In ...
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CAT6: Assembling cable: RJ45 connectors

What do I need to check for when assembling RJ45 cables. I had some left over CAT6 cable from when I wired my home, and I bought some CAT6 RJ45 connectors from a local store: I cannot even push the ...
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Touching MOSI on RJ45 connector cleans bus noise

I am using a STM32F767ZI-Nucleo development board from ST. i'm using it to communicate by SPI with a UM7 orientation sensor board. There a register to read in the FW version. Normally I only receive ...
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DP83848C: DP83848 stops working after few month on field

In a product we designed, the LAN drive circuit(MII mode) is composed of LPC1768 and DP83848CVV. The function is very normal. There are no problems with factory testing. After using it in the hands of ...
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In sale or custom made?

RJ45 to 8 pos board connector. Board connector width: 12,4 mm Pin pitch: 2 mm Found inside a plastic card printer. Somewhere to purchase cable? Identification of the board connector?
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Is there a RJ45 with magnetics for PHY less network switch

I have a network switch indoor and camera outdoor. I plan on having a PCB with RJ45 with magnetics. Can any tell me how to choose an RJ45 with transformer for a PHY Less network switch.
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Ethernet with transformer

I have a schematic of Ethernet Transformer that supports POE, and 2.5GBT. I plan on using Ethernet with transformer on my PCB to connect to Network Switch. Are pin VC12 13, VC36 14, VC45 15, VC78 16 ...
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How critical is the magnetics circuit diagram in a magjack RJ45?

I'm looking at an example circuit diagram from ST, and it use sa 48F-01GYDXNL part that I can't find anywhere. It's a gigabit ethernet jack with magnetics, and the datasheet shows a circuit looking ...
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0-10V on RJ45 jack - bad practice?

I'm developing a control unit for ventilation systems. Beside switching those fans with a relay they are often controlled with a 0-10V analog signal. Now I found a product that uses a RJ45-plug to ...
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Can you replace a RJ45 connector with smaller connector?

I'm designing a small board that needs an ethernet connection. However, the RJ45 jack takes considerable space. I would like to reduce the footprint of the connector to safe some space. Would it be ...
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2 votes
3 answers
319 views

Power small microcontroller from motherboard RJ45 ethernet port

I'm wondering if it's possible to power a microcontroller (e.g. ATmega328) from a Ethernet RJ45 motherboard port. Unlike USB, there is no power line, all pins/lines seem to be data only. I am ...
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What can happen if 24vdc is applied to an Ethernet port?

We have a device with two RJ45 ports. One of these ports is for receiving 24vdc on pins 7(-) and 8(+) to power the device. The other RJ45 port is an Ethernet connection. The ports are of course ...
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Is it possible to use the same RJ-45 connector?

Given that the wires are connected to the pins and crimped with a crimp tool; is it possible to "un-crimp" the wires such that they can be unattached from the RJ-45 connector? Whereafter the connector ...
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Can I run DC voltage through RJ45 Connector with Magnetics?

I am designing a PoE (Power over Ethernet) application. My question is can I run 48V DC Voltage through a standard RJ45 Jack WITH Magnetics? or do I need one WITHOUT magnetics? I am planning to use ...
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How to route Ethernet PCB ? [closed]

I am new to PCB routing. In one of my projects, I need to be able to exchange data between nano-computers (https://www.variscite.com/wp-content/uploads/2018/01/DART-6UL_DART-6UL-5G_Datasheet.pdf) ...
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Divide RS-485 Simply without switch

I have an RS-485 input / output from a solar charge controller (SCC) and would like to read the output in two locations, while maintaining its input from one, or hopefully both of those locations (see ...
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3 votes
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DHT22 bad readings on long rj45 cable

Duplicate of https://raspberrypi.stackexchange.com/questions/91781/dht22-bad-readings-on-long-cable, I figured there is chances people here have a solution for me. Hi, I'm preparing a setup with a ...
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USB over RJ45 to USB C [closed]

I am working on an Arcade Stick/Fight Stick enclosure. Internally, the PCB (Brook UFB) runs USB over a standard Ethernet cable, to a Neutrik RJ45 passthrough. I typically then create an RJ45 to USB A ...
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