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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251 views

Effects of twisted pair in 120V AC

In Square D's marketing copy for their plug on neutral load centers, they have a photo for demonstrating "cleaner wiring" in which the hot and neutral wires are twisted inside the panel ...
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109 views

Would twisting 3 wires together be as effective (or close) to a twisted pair?

Would twisting 3 wires together like a twisted pair would be as effective as an ordinary twisted pair? Or at least a definite improvement to not twisting them at all? simulate this circuit – ...
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WS2812b data over 35m line

Single WS2812b LED are connected over 35 meters (115 feets) UTP Cat. 5e cable and it's not working as expected. Getting wrong colors. Another WS2812b placed in parallel (not chained) on board close to ...
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39 views

Four wire voltage sensing, all four wires in one cable?

If I twist the power positive and negative wire together and do the same for the sensing wires, can all four wires (two twisted pair) be in one cable or they should be physically separated from each ...
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2answers
61 views

Can I improve serial data signal using reversed output on a twisted pair?

This is a serial data communication with one or several transmitters and one or several receivers. From the transmitter I have one serial data output (D+) and a second, reversed serial data output (D-...
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399 views

PCB equivalent of wire twisting

I've a PCB with quite some electronics including a few motor drivers (30V, 100kHz PWM), and a few brushed DC motors 1 meter further away. These motors each have a quadrature encoder, so next to their ...
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1answer
135 views

Can twisted pair replaced by two wires which are closely placed?

If I have differential signal wires, can I place two wires closely 1mm-2mm gap between them but not twisted? (1mm or 2mm gap is fixed it won't change from place to place ) I am using Differential I2C ...
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1answer
32 views

Data + Power connector and cable suggestion

I need to decide about how to connect two custom designed electronic units. One is main (execution) unit, and the second is hand-controller unit. Those units have to be connected by wire. The ...
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1answer
335 views

Is there any benefit to using twisted pair for short-distance I2C?

I know twisted pairs are important for differential signals, which I2C is not. I also know I2C is not intended to be used over long wires. However, I made a design where I need to use a cable to ...
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324 views

Terminating Resistors on Ethernet Port

I'm using Ethernet (CAT5/5e/6) cables to communicate with the PCA9615 Differential I2C buffer. These cables roughly have a characteristic impedance of 100 ohms, but I have a few questions about ...
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300 views

Swapping out RJ-45 connector on Differential I2C circuit

I'm trying to use Sparkfun's Differential I2C Breakout circuit into my own design, and I'm looking to replace the RJ-45 connector. It's too big (having a footprint size of 15.24 mm x 15.24 mm), and I ...
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77 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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119 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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106 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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84 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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197 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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67 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
66 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
68 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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88 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
251 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
2k 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
197 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
145 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
517 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
8k 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
254 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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485 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
406 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
4k 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
572 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
297 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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193 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
78 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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3k 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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4k 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
628 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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891 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
642 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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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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468 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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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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197 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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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 Windows ...
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823 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
510 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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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
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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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5k 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 ...