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Questions tagged [shielding]

Questions regarding shielding devices against noise, interference, or ESD. Not to be confused with arduino-shield.

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3
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1answer
50 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 ...
0
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1answer
43 views

Purpose of metal sheath in display cable?

I want to repair a display cable which I suspect has some broken wires. The cable seems to be wrapped in a metallized fibre cloth. (I don't know the correct name for it). What purpose, apart from ...
0
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2answers
469 views

How close to a stepper motor do I need to shield the wires?

I am trying to shield the cabling on my CNC mill. The motors, unfortunately, do not have connectors but instead have wire leads coming out from the motor housing. I can cut those wires about an inch ...
1
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2answers
69 views

How can I reduce noise caused by shift register updates?

I have a couple of designs using 74HC595BQ-Q100,115 shift registers. Some are using the SO-16 package, some the DHVQFN16. Some have five shift registers, some have three. ALL have a significant ...
1
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0answers
67 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 ...
1
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2answers
74 views

Shielding and Ground Loops - RF panel jacks for GPS

I've been working on a design that requires me to pass an RF signal through a conductive panel. I'm using SMA jacks for that purpose as they're readily available and also available in an isolated ...
2
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1answer
108 views

Unshielded RJ45 connectors on SFTP Cat5e

I have "inherited" an old SFTP Cat5e cable connecting the basement of my house to the upper floor. There seems to be a break on some of the wires (6 and 7) so it won't even function at 100mbps. I ...
2
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2answers
2k views

SAVR. Is it even possible to reduce environmental EM radiation without using Faraday cage?

Recently I saw a product called SAVR Radiation Reducer in the market by PowerLink claiming the followings: SAVR Radiation Reducer basically scans and detects EMR waves and it generates reverse ...
0
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0answers
31 views

Connecting TVS diodes to a floating shield

I need a little help with shielding for ECG leads. The design I'm working on has 3 leads, about 60mm in length. We use shielded cable for each lead, which all come to a meeting point at the ...
4
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5answers
6k views

Shielded vs Twisted cables

For some reason low voltage, high quality audio interconnects seem to be made of 3 wires braided together, when normal low voltage audio wires are two wires surrounded by a grounding sleeve. I'm a ...
0
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1answer
73 views

Faraday cage - reducing EMI?

I am curious about the working of a Faraday cage as the shield for EMI in many systems. As far as I studied, it depends on Faraday's and Lenz's laws. When the electromagnetic waves are incident on ...
0
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1answer
59 views

How to use shielded audio cable with micro-fit molex connector?

This is typical shielded audio cable which I’m supposed to use with micro-fit molex connector. The problem with that cable is that the ground cable/the shield is not insulated and I found it very ...
9
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3answers
22k views

How important is the shield on an RJ45 connector?

If I am going to use a PCB mount RJ45 connector for 100mbps Ethernet, does it need to be a shielded connector, or can I get away with using an unshielded one? Is there some standard which deals with ...
3
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0answers
44 views

RFI protection for a stepper motor controller

I'm building a remote tuning device for a magnetic loop antenna. It will use a stepper motor to turn the shaft on the mag loop's variable capacitor. The electronics will consist primarily of a ...
5
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2answers
995 views

Confusion in grounding shield wires of transducers

There is a 6-wire Wheatstone bridge type load-cell and one of the wire is called shield and it is electrically connected to the metallic case of the load cell as below(I marked that with yellow ...
0
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1answer
51 views

Grounding and shielding between isolated devices

I have a battery operated micro controller with a hall sensor, mounted on a motorbike. The hall sensor has a shielded cable to counteract spark plug induced EMI. By default, the entire setup is ...
5
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5answers
4k views

What are these metal plates covering parts of PCBs called?

I am trying to fix my wireless router, but one of the parts is under a metal plate. What are these metal plates called? This is what it looks like when it is removed: (The gold coloured plating ...
2
votes
3answers
67 views

If a PEC surface completely reflects an EM wave, why doesn't an ungrounded shield work?

I was thinking about shielding and its effectiveness. An ungrounded shield doesn't work well for either inductive or capacitive coupling. However, if you think about plane wave theory, a PEC surface ...
0
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1answer
78 views

Could shielding (not grounded) affect signal integrity?

I'm trying to shield 6 flat cables that give me some communication issues because I thought that there might be cross-talk or other sources of interference that cause the problem. The shielding is ...
2
votes
1answer
99 views

Motor / VFD / Protective Earth

I have little experience with AC motors since I'm majoring in Mech.E. My team is setting up an AC motor with a VFD to control the movement of an airfoil inside a metal cage we built. I understand the ...
0
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1answer
88 views

Shield ground to metal body or signal ground?

I have a question about grounding. I will have two short shielded cables with signal wires inside, located at the top of a tower. The cables have a grounding wire inside shorted to their foil shields ...
2
votes
1answer
395 views

RFI on the amplifier due to Wifi

I have a board with a sensitive analog amplifier. This amplifier is optical in nature and it has a gain of 6M times. On the same board there is a Wifi module. Somehow when Wifi is transmitting I see ...
4
votes
1answer
190 views

Ground planes disposition in Ethernet connection

I am designing a board that will have sensible analog signals and a processor communicating with the external word via Ethernet and I want to avoid that common mode currents couple into my analog ...
1
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1answer
119 views

Voltage detected across Micro USB cable shielding

I designed a Keyboard PCB using an ATmega32U4 with the data lines wired up to a Micro-USB B Receptacle. Brand: Molex; part number: 1050170001. The USB ground is directly connected to the Micro-USB B ...
0
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1answer
103 views

4 pin connector is melting even with 5 volt and 0.1 amp power supply, Why?

I am using a connector as shown: . I am using this to connect to my camera, which works at 5 volts and 0.1 Amp. But this connector works only for few days and then the plastic portion of the ...
3
votes
4answers
379 views

Electromagnetic shielding and EMP

I've asked several related questions, but I'm afraid that some of the answers that I received, while great answers, might be skewed because of incorrect assumptions or unclarity in my questions. The ...
1
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2answers
101 views

Shielding effectiveness system

I've been working on a Shielding Effectiveness system of 120dB according to IEEE299-2006 standards. The frequency range covered is 9kHz to 40GHz. I've designed it using an analog signal generator, ...
3
votes
1answer
420 views

How much shielding does an ungrounded metal box provide?

How much shielding does an ungrounded metal box provide? That is, a circuit is in a metal box but the box is not connected to either circuit ground nor externally earthed
4
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2answers
81 views

Why is shielding effectiveness different for various hole geometries?

I have run into the equation below in various literature/app notes. (example). I have never seen the derivation for such an equation and don't understand why round apertures are more effective at ...
0
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3answers
128 views

RS422 Full-Duplex Cable Shielding

I need to interface two PCBs via RS422 (250kbps) in full-duplex mode (4-wire, 2-twisted pairs 100ft cable). This system will operate in a noisy (CNC) industrial environment, ie, industrial controls ...
6
votes
1answer
1k views

Running network cable near X-Ray equipment

My mother runs a small veterinary clinic. She is getting a new X-Ray machine that will need a network connection to send digital copies of the X-Ray to the server. I will be installing a wall plate ...
0
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0answers
314 views

Connecting the Chassis Ground and Signal Ground in my PCB

I have been reading alot of questions on this site to clear my understanding on Chassis, Signal Ground, ...
3
votes
1answer
148 views

Analogue (or digital) signal integrity with multiple sources of noise

tldr: Can I transmit an analog signal through a noisy environment without it being corrupted, or should I use a digital signal instead? My requirement is to transmit a signal from a MA3 absolute ...
0
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2answers
146 views

Should I use shielded RJ45 plug by the computers? [closed]

If I have shielded cables, jacks and plugs and I ground the shielding properly, then should I use shielded plugs at the computer's site too? I mean if I do so, then the shielding will be connected to ...
2
votes
2answers
776 views

Shielded cable, to ground or not, in amplifier

I have been looking for an answer on the net about this question but not found it fully answered. The topic has been up here a few times (see links below) as well but I find the answers lacking. My ...
0
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1answer
42 views

ADC wire is picking up noise from cellular antenna [EMC]

I have a 5 wire micro jst cable with a line for ADC readings from an IR sensor that is picking up interference from the cellular antenna of the microcontroller. Will I be able to reduce this noise if ...
0
votes
2answers
105 views

Strategies to reduce EMF radiation

During a long-term, almost six month long, data acquisition in a proximity of scanning electron microscope I have found a significant source of magnetic field noise, which is altering the results. I ...
0
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1answer
262 views

Effects of Neodymium magnets on PCB

I'm currently doing a project that consists of: Arduino Nano. Battery. Buck Boost converter. GPS module. TSL2561 light sensor. BH1750FVI light sensors. LSM6DS3 Accelerometer. HDC1080. MicroSD shield ...
-3
votes
1answer
93 views

how can i attenuate mobile signal completely(maybe 90%) and please suggest me the wall thickness ,as i want to use copper or aluminium [closed]

please help me as i want to make a den for my dog that completely attenuates em waves of phone
1
vote
1answer
268 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 ...
1
vote
1answer
541 views

Why is the usb shield always tied to ground (GND pin)?

The shielding on a cable is to avoid interference from the outside world however it is always tied directly to the GND pin. Not inside the cable itself but inside a device. Every single device I take ...
3
votes
1answer
2k views

Is it OK to place ground plane under transformer?

I have a large transformer (50kHz, ferrite E-core) on the PCB. I want to pass power rails under it on the bottom layer. Should I place a large ground plane on the top layer to shield these power rails ...
0
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1answer
46 views

Testing the integrity of cable shielding for suitability

I am currently working with an ECG cable, is there a way for me to test the integrity of the shielding of the cable without using it directly on an ECG monitor to check for interference.
4
votes
2answers
1k views

Long wires causing Raspberry Pi to die?

I've been working on a simple project involving a Raspberry pi and some switches. I would never thought I would have any problem for something as simple as a switch, but here I am. The 2 wires from ...
1
vote
1answer
658 views

Why do USB data cables have 5 wires, what is the use of shielding wire?

I have always been curious about the 5th wire(aka shield wire) in USB cables. What is its purpose? Does it anyhow affect charging speed for mobiles or data transfer? I do know that it carries the ...
1
vote
1answer
180 views

USB shield for analog and digital ground?

I'm new to Mixed-signal design and I'm having trouble deciding how to connect my digital and analog ground. I'm doing a 4 layer design, so I have a split ground plane. As I understand, since I'm ...
3
votes
2answers
58 views

Help Shielding RF Anechoic Chamber - FM Stations

a collegue and I acquired a surplus small anechoic chamber (8 ft x 8 ft) for making some pre compliance test measurements, and we're running into the issue of FM Stations being only attenuated around ...
1
vote
3answers
271 views

Using shielded audio cable for potentiometer sensor

I'm trying to measure a potentiometer from an Arduino's ADC. The potentiometer has a maximum value of 100k ohms and is located about 1 meter from the Arduino. The potentiometer's wiper is wired to the ...
1
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0answers
45 views

How does the size of a conductor affect a driven voltage?

I'm designing a capacitive sensor which uses an active shield to focus the sensing field. This much works well. Now, in order to most effectively protect the active signal from noise I'd like the ...
2
votes
1answer
563 views

SD card connector chassis grounding

I have been designing a PCB which includes an SD card connector. As I'm not a PCB designer expert, I was looking for a reference design when I came across with the circuit bellow, extracted from Texas ...