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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Current transformer wire issues

I would greatly appreciate some advice regarding twisted pair conductors for a current transformer. So, according to the manufacturer, whose equipment I am installing, I need to connect 10 AWG, ...
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3 answers
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Why do UTP pairs need different pitches?

Why do unshielded twisted pair cables need a different pitch/twist rate for every pair of wires in a cable? Most of my reading on UTP says that the pairs in a cable must have different pitch or else ...
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Twisting two cables: Does the rotation of each cable play any role?

When twisting two cables (imagine f.e. something like a twisted pair cable), does the rotation of both cables have any importance? I.e., is it important that each cable rotates around its own axis as ...
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8 votes
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Why are coaxial cables typically faster/longer than twisted pairs?

I'm having trouble understand why coaxial cables tend to have higher bandwidth compared to twisted pairs. I couldn't find any source explaining why, they just mention the fact. For instance: "In ...
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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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Why don't oscilloscope probes use twisted pairs?

I was reading online about how Ethernet cables use twisted pairs instead of coaxial cables because it's better in some way. Some websites say that twisted pairs cost less, can carry higher frequencies,...
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How best to allocate signal wires to 4 twisted pairs that best reduces inteference

I have to transmit digital signals 30meters including power. I am going to use a cat 6 ethernet cable with 4 twisted pairs (8 wires in total). I can already assure that my signal gets to the other end ...
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How can a cable tester verify correct shielding/twisting of wires?

Background: The company I work for makes a variety of special-purpose cable assemblies to go with equipment we make. The people who build these cables aren't doing a 100% reliable job, and nobody ...
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Can I use Ethernet UTP instead of COAX for satellite TV

I'm planning on having a satellite TV subscription installed on my home, when the satellite dish is installed they will need to run a coax cable from the satellite dish all the way to the decoder ...
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How does a twisted pair cable reduce inductive coupling compared to non twisted pair cable?

Can anyone explain this concept with figures for both non twisted pair cable and twisted pair cable?
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What is the difference between capacitative and inductive coupling in a twisted pair?

I'm learning about networking and there is this passage: "Twisting cancels out inductive coupling, while the shield eliminates capacitive coupling." What kind of effects are these, ...
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Why we don't use twisted cable in dc power?

I general applications, we don't see DC-Power lines as twisted pairs. Even in standard cables, only the data line pair is generally twisted. Do we assume that DC-power lines are not worth twisting? Or ...
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How to identify a coax connector vs twisted pair connector

I need to have a connector that will bring in COAX input to my PCB. I have this Rosenberger HSD Connector Catalog. On page 33, "99S12D-40MA5-y" - is this connector a twisted pair connector ...
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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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1 vote
2 answers
674 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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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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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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3 answers
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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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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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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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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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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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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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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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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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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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3 votes
1 answer
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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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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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1 answer
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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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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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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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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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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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3 votes
1 answer
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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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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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2 votes
1 answer
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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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5 votes
2 answers
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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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5 votes
4 answers
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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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1 answer
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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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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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1 vote
1 answer
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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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2 votes
1 answer
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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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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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3 answers
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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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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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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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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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8 votes
2 answers
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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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3 answers
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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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