Questions tagged [twisted-pair]

Most commonly a type of transmission line that consists of two individual wires twisted together. Its differential nature attenuates common-mode interference present in the environment, which is useful in the transfer of differential signals (even low-frequency ones). It is commonly used for differential digital communication protocols such as ethernet.

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2answers
64 views

Twisted pair's effect on power supply rise time

I am having a tough time wrapping my head around this question. I am well aware of the benefits of using a twisted pair for signal wires: the cancellation of common mode noise coupled onto the wires, ...
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58 views

How does twisted pair turn rate affect interference rejection bandwidth?

I'm curious to know how the turn rate of a twisted pair affects the frequency of crosstalk interference rejection. It's clear that an untwisted pair has no inherent rejection. Alexander Graham Bell ...
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72 views

Impedance Control in Twisted Pairs and PCB

Why do differential signal traces on a PCB require a reference plane to have a controlled impedance? Whereas, in an unshielded twisted pair there is no reference, there are only the two conductors? ...
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1answer
57 views

Shielded Twisted Pair noise immunity

If I am correct in assuming a twisted pair cable is used to provide reduced susceptibility to noise. What is the benefit in having the cable twisted when it is inside a foil screen/shield? Would ...
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75 views

Twisted pair with shield and drain wire

Ive been posed with a problem regarding calculating the characteristic impedance of a shielded twisted pair with a drain wire. While I understand how to calculate this for a "normal" shielded twisted ...
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43 views

Quadrax routing on a PCB

When connecting twisted pair wires to a printed circuit board, I hope I am right in thinking that differential pair routing is used on the board in either a stripline or a microstrip configuration to ...
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1answer
62 views

Questions about CAN

I'm trying to build a network of interactive LED matrices which will communicate to each other. Each node will be a circular PCB containing an 8x8 RGB LED matrix that is connected through a vertical ...
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1answer
54 views

Running STP and high-current AC cables together

I am about to install a backup generator about 40m away from my house. There is no question what cables to run for the AC current (which will be 230V 50Hz up to 30A) — doubled 10AWG (6mm2) to keep ...
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1answer
63 views

Structure of Pairs inside a Cat Cable

Is there a standard arrangement for the pairs inside a Cat7|6|5 Ethernet Cable? As shown in the picture, they are in the sequence Orange-Green-Brown-Blue, or the Orange Brown always as opposite pairs,...
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71 views

Ethernet connection using only one twisted pair

For my degree work, i make some reseaches for different bus systems and i've found ethernet a bit different than others: The old 10Base5 and 10Base2 ethernet used only one pair of conductor to ...
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1answer
121 views

3 wire signal to 4 core shielded twisted pair

So I have some flow sensors, which have a 3 wire interface. The three wires are 5V, signal, and ground. Signal is pulse output that varies between 5V and ground at a maximum frequency of about 200 Hz....
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1answer
999 views

The CAN bus in this vehicle has only one 120 ohm termination resistance. What problems would this provoke?

This vehicle that I've started co-developing is designed with only a 120 termination resistor on the CAN bus. Obviously there should be two of those resistors on two ends of the bus. I will be making ...
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1answer
171 views

Shielded twisted pair balanced transmission line implementation

I want to send a signal from board 1 to 2 through 20 cm line. I have four channel in differential, First I add them, can I send them through shielded twisted pair like this: Do I need a buffer? why? ...
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1answer
103 views

Power over ethernet and common-mode termination

I have a non-standard Power over Ethernet application (connector, and devices are not ethernet standard but we are using ethernet pairs and protocol for communications). On looking at PoE schematics I ...
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2answers
312 views

Using optocouplers at the end of a twisted pair

I am designing a dumb "isolation box" that is to sit between a computer and medical data acquisition equipment. The purpose of this box is to inject power and to provide communications and digital ...
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4answers
3k views

CAT5 for telephony

I wish to extend my incoming telephone connection using CAT5 as I've heard it could provide better performance than standard single stranded telephone wire over long distances. There are only two ...
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1answer
193 views

Locating pairs on an LVDS cable

For a 2-row connector intended to interface a cable to a PCB, which method is preferable for twisted pair LVDS signals? Horizontal Pairs: LVDS1-    LVDS1+    ...
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4answers
269 views

Analog Audio Signal over dedicated Ethernet/Twisted Pair Cable

I need to send an audio signal over 3 meters and back again on the same line (the plan is to put an on/off switch and a volume regulator at the end of the line). Additionally I would like to send 12 ...
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1answer
334 views

Can I use a twisted pair for 5V and ground?

I'm going to use a RS485 modbus connection which requires a twisted pair. Now I also need power, that will be a 5V line and a ground. The distance will be about 3 meters max. Can i use a twisted pair ...
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1answer
2k views

Will RS-485 work over non-twisted pair?

I have a project coming up that requires serial data comms across a large vehicle with two trailers connected in train. The total length of the vehicle is 100ft, and I need to install several nodes ...
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2answers
3k views

Which RJ45 pins should I use for power supply?

I'm somewhere in a process of creating mini automation system for hobby use. I've already put CAT 5e cables with RJ-45 connectors in walls. They are somewhere between 5 - 30 meters long. On one side ...
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3answers
452 views

Is cross talking caused by cables acting as antennas?

Why does cross talking happen between different cables? Is it because any electrical cable has the capability to act as an antenna? And most important, why do twisted pair of cables have less cross ...
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1answer
270 views

Cable shielding groundloop

I am trying to connect a encoder to a motor controller which runs very close to the motor that it controls (30+ amps). Due to the risk of high EMI of the motor inducing on the encoder signals, we send ...
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0answers
174 views

How do I choose a twisted pair shielded cable?

The charging/discharging of a battery (1u to 30 mA) and remote voltage measurement is to be performed over 2 pairs of 2 m cable. In order to reduce picked up common mode noise I intend to use shielded ...
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1answer
74 views

Does differential sending benefit current sensing circuits in the same way as differential voltage sending?

I'd like to send two currents along a long twisted pair (well, ~5m, but I want to be very careful about noise in this experiment). The two currents are produced by two photodiodes with equal and ...
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2k views

When should twisted pair wires be used?

I know several applications where twisted pairs are used and why they are used in those applications, but I would like to know more about the advantages and disadvantages of using twisted pair wires ...
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3k views

Does using twisted pair wiring make sense only for differential signalling?

I read that the twisted-cable wiring is used for eliminating the common mode noise. As far as I know, in differential signalling the two wires carry their mirrored images so any common mode noise like ...
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2answers
539 views

Arduino power and networking over cat6

I plan to run about 4-5 arduino pro micro in my backyard to handle controlling of solenoid valves for garden watering based on measurements of soil (so we keep it well watered). My question regards ...
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779 views

Attaching Cat7 (S/FTP) Cable to PCB

We are planning on using Cat7A twisted pair cable for an application with which high bandwidth (~800MHz) analogue signals are being transferred over around about 3 metres. At the moment the cable ...
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1answer
589 views

Parallel differential signals

I need to send some I2C data through RJ45 cable between Arduinos. One ATMEGA2560 as master and 1-4 328P's as slaves. I've seen some different configurations and I think for my application the solution ...
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3answers
1k views

Crosstalk between Wires in a single Twisted Pair

I was reading about the Twisted Pair Cables, and how they implement Balanced Line methodology to cancel out all the noise. All fine and good. However, I just couldn't grasp this one simple doubt: ...
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1answer
362 views

Sending two serial signals down a single twisted pair?

Let's say I have two serial signals that need to be sent down a cable. This cable features a twisted pair along with a single common wire. If I were to place each serial signal onto one of the twisted ...
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2answers
2k views

What are the effects of single ended signals on twisted pair conductors?

I'm currently using a cable that has multiple twisted pair conductors. I'm attempting to send a several single ended signals down some of these conductors at a frequency of 12.5MHz. Essentially, I'm ...
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1answer
149 views

Changing Direction of twist in a twisted pair (24V 4A)

I have two wiring harnesses one going to my power supply (24V at 5A) and the other harness going to my main board, there is a motor controller on the board so it can draw a few amps. I noticed that ...
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3answers
5k views

Does the twisting in a twisted pair reduce attenuation?

i'm doing networking and trying to understand if the twisting in twisted pair reduce attenuation. I know that the cable can't be longer than 100 meters and the book says this From Microsoft ...
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776 views

Twisted pair impedance

I've got a twisted pair cable that I'd like to use for connecting distributed systems that use 1Mbps CAN network. The problem is that I don't have a clue what's the impedance of this cable and I know ...
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2answers
426 views

Twisted pair for long distance voltage measurement

I want to measure the voltage drop across a shunt, but the ADC performing the measurement will be far from the actual shunt - perhaps five meters. I'll need to measure voltage drops across the shunt ...
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3answers
2k views

Why didn't 1000BASE-TX gain more popularity than 1000BASE-T?

1000BASE-T uses all 8 wires in a twisted pair to both RX and TX at the same time. It does it using (what seems to me) a complicated process known as echo cancellation. Details here. 1000BASE-TX ...
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4answers
3k views

How is a Twisted Pair's +-2.5v used to send a 1 or a 0?

This is a multi-part question that I'm asking as a follow on to this answer from my other question. I know 100BASE-TX transmits through a pair of wires, that are twisted around each other so that the ...
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7answers
4k views

What if there are an odd number of twists in a twisted pair cable?

I am not an electrician, or a student of the field. I am a Network Engineer with a curiosity bug and that has recently taken me to exploring cabling and Twisted Pair specifically. I say this to plead ...
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1answer
2k views

What is the effect on noise immunity of a floating shield on a shielded twisted pair

We have an installed system where resistive sensors are connected to some electronics by shielded cables of between 2 and 10 metres. The cable is a twisted pair sheathed in a stainless steel braid. ...
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1answer
362 views

Is It Okay to Run a Single-Ended 5V Pulse Train through One Strand of a Twisted Pair?

Okay, I have a motion control application that I want to wire up. The motor drives run from single-ended step and direction signals. I am designing a circuit board, and was thinking of using 8-pin ...
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1answer
554 views

LVDS cable - Impedance measurement

I am using twisted pair cable for LVDS communication between the Host and the display. It was recommended that the differential impedance of cable should be 100ohm (+/-5%). Let me know how to ...
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1answer
241 views

Single cable for dual Ethernet plus power (PoE)

I would like to run two 100 Mbit Ethernets including a common PoE over a single cable which will be about 3-5m long. Since 100 Mbit needs 4 wires I will need 8 plus some wires for the PoE which is at ...
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1answer
376 views

Guidelines for twist cables

Which are the guidelines for chose which cables should I twist as a pair? For example, suppose the case in which I have 3 cables. One of Vcc, one of GND and another of signal. Which ones should I ...
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3k views

factors influencing capacitance of a cable

I am out of my depth here so I am looking for a simple explanation. If you have twisted pair cables of differing makeup, varying in conductive material, diameter of the conductor, number of twists per ...
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2answers
392 views

Role of “HDMI Baluns”?

I understand that an HDMI cable contains essentially 4 shielded twisted pairs, along with additional control lines. Each of the twisted pairs is specified, to my understanding, to be a balanced ...
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1answer
900 views

Twisted pair coil embedded on a PCB

Has anyone tried twisting very thin wires(of order 100 microns) and then sandwiching it in between 2 layers of a multilayer PCB? I have a problem of EMI and looks like twisted pair is the only ...
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3answers
1k views

When do I twist the wires going to transformer winding terminals, and why do I do it?

I sometimes see the wires of winding are twisted outside of the transformer (or inductor), as seen in the images below. What is the purpose of this? When should I twist winding wires and when shouldn'...
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3answers
748 views

Why does Ethernet on UTP have much greater range than other modern protocols?

OCuLink, SATA, USB 3, and Displayport all provide on the order of a few Gbps per signaling pair, and are limited to a cable length of just a couple meters. Ethernet via comparable cabling provides ...