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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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2
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3answers
2k views

Why is a caseless PC not an EMI problem?

As I understand it, the case of a PC is metal so that it can form an EMI enclosure around the electronic parts. My view is reinforced by there being conductive fingerstrips around the mating edges. ...
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4answers
239 views

Blocking cell phone interference on LM386 amp

I built a small amplifier using an LM386 on a protoboard. The problem I have however is that it makes those typical cell phone sounds if my mobile phone is close to it. Since I want to 3d print an ...
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2answers
1k views

DMX: What should I do with ground and shield?

I'm currently developing a DMX interface (master interface) with USB and Ethernet connections. The power for my device I'm retrieving from the 5V of the USB connector. The shield of the USB connector ...
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2answers
2k views

How can I make a diy anechoic chamber?

I'd like to make a small anechoic box for RF measurements. I need roughly a 30x30x30cm cube of usable space, and I'd like the reflections from the walls to be attenuated by 10dB or more from 100MHz ...
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1answer
59 views

If I run electrical current through the conductors in a magnetic shield, can It be used to shield stronger magnetic fields?

I'm wondering if running electrical current through a shield amplifies its effect to a significant extent, effectively making it into a shield you can "turn on and off" for stronger magnetic fields ...
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1answer
45 views

Current Rating of Stepper Shield Ground Wire

I have a 2 phase bipolar stepper motor; https://catalog.orientalmotor.com/item/all-categories/20mm-pkp-series-2-phase-bipolar-stepper-motors/pkp214d06a-2 Its 4 power wires are wrapped in a shielded ...
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3answers
183 views

EMI shielding without shield? [closed]

Hi I sorted of had an epiphany when thinking about EMI shielding a PCB... If the frequency of the system on a PCB was constant ( lets 20MHz digital system or something) could I take advantage of that ...
5
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2answers
994 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 ...
2
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1answer
82 views

Which one of these shielded scenarios is correct?

I have a system were both the signal generated and the sensing equipment is sharing the same ground. Which one of these shield terminations scenarios is correct? (if any). I searched the internet for ...
0
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1answer
127 views

How should I connect a braided shield 2-core cable with a headphone plug with three cores

I'm a beginner in Electronics. The cable has two cores and a braided shield. What should I do about the ground?
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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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1answer
852 views

ungrounded chassis shielding

I'm looking into whether an ungrounded metal box provides good/bad EM shielding. This thread seems like a definite "good", for reasons of the box acting as a faraday cage : How much shielding does an ...
2
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1answer
567 views

Shielded breadboard jumper cable wires

Does it exist a shielded version of 2.54mm pitch breadboard jumper cable wires? Thin flexible wires, Gauge AWG 24-28. I want use shielded wires for JTAG cable, to reduce electrical noise from ...
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2answers
416 views

How to determine quality of headphone earbuds by spec sheet?

I have been doing some work with cheap headphone earbuds for quite a while now. I was wondering, when buying earbuds in bulk, if there was any way to tell what the sound quality would be before ...
0
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1answer
439 views

USB OTG Cable Shielding

I just soldered a USB OTG cable to connect a keyboard (regular USB-A) to a Raspberry Pi Zero (micro-USB). How to wire the VCC, GND, D- and D+ pins was obvious and the cable works. However both ...
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1answer
267 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 ...
8
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3answers
1k views

Why does my GPS and Wi-Fi work inside a sealed copper clad box?

I have just finished assembling a Raspberry Pi-based project into a DIY box made from copper clad FR4 PCB, with the edges soldered together and the copper surface connected to ground. I expected, ...
0
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1answer
119 views

Should it be expected that some shielded wire is not good at data transmission?

I have recently purchased a reel of this specification screened wire from RS Components to use in I2C communications, expecting it to be very well suited to purpose. I am running at approximately 400 ...
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0answers
170 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
468 views

Encapsulating an inductor with epoxy and ferrite powder

Say I have some SMD inductors and I'm trying to limit their EMF from the rest of the board, can I simply potty it with epoxy mixed with ferrite powder (or perhaps iron filings), if I make sure the ...
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3answers
617 views

Connect signal ground to safety ground?

We are designing a product which has to meet EMC directives. It consists of metal backplate folded into a chasis (the front is open). on the backcover there is a SMPS mounted. and on top of this we ...
3
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2answers
3k views

Should I connect a cable's shield to the ground layer of board when it's isolated from earth?

I have a controller board powered by DC that may or may not be isolated from earth ground. The chassis of the device is non-metallic. This board connects through a long (30-40m), shielded cable to a ...
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1answer
53 views

Calculate field strength for shielded isotropic transmitter

How to calculate the field strength of a shielded theoretical isotropic transmitter, if there is a hole in the shield for example. I am looking for a complex formula that also takes into account the ...
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3answers
188 views

Is the “antenna aperture” the same as the “hole in the shield”?

Is the concept of the "Antenna Aperture" the same as a hole in a electromagnetic shield? The wikipedia article is quite vague, and I am a newbie in this field. For example if we have an electric ...
11
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2answers
905 views

Purpose of bare copper perimiters on HF PCBs

I have seen many RF PCBs with a thick, rounded area of exposed copper going all around the PCB, like in this example: My intuitive thought is that this is for some kind of grounding or shielding can, ...
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4answers
265 views

Can an alternating magnetic field be “informationally” shielded?

I have asked previously about the properties & shielding of the "static" magnetic field previously, where I have determined that static fields are hard to shield. However what I am really ...
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4answers
222 views

Can a “static” magnetic field carry Information? [closed]

Information is electronically represented as some energy that is changing, therefore we measure an on state (1) and an off state (0), to create a (0,1) binary representation of the information. Now a ...
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3answers
2k views

Does Shielding “Electrically” shield “Magnetically” too?

I know it sounds like a newbie question but I can't wrap my mind around it. An electromagnetic field is electric + magnetic field. So this means that when shielding an equipment offensively, for ...
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3answers
55 views

Is better to have holes on different sides of the shield instead of the same side?

I suppose the best is to have no hole on the shield, but that is practially impossible if you have to let cables come out of it. So I read somewhere that having the holes on different sides of the ...
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3answers
2k views

How do I properly shield wires to my stepper motors?

I have a project where I need to run stepper motors within a few centimeters of wireless RF transmitters and receivers. On the breadboard I have experienced some strong interference. I am purchasing ...
10
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1answer
3k views

USB 3.0 Hub shield connection

This is about the seemingly controversial shield to ground connection. The system is basically a body-worn intel-based computer, powered by a battery. Two USB 3.0 (or 3.1 Gen1) cables come out to a ...
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1answer
396 views

Minimize crosstalk using shield/guard trace with capacitor ground

I'm designing a PCB using this component http://www.ti.com/lit/ds/symlink/afe4403.pdf And from the datasheet page 90 layout guidelines I found point(2) which says If the INP, INN lines are required ...
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2answers
865 views

How does current flow through a mono (TS) guitar cable?

My basic understanding of electronics says there must be a complete circuit for electricity to flow, so does that mean there is both a + and - wire inside a mono guitar cable? Or does electricity flow ...
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1answer
114 views

Inductance of Shielded Helical Resonators

I found an equation in a thesis which calculates the inductance for a helical coil inside of a cylindrical shield: $$L = (\pi N d_{coil})^{2}\frac{1}{l_{coil} +0.45 d_{coil}}\left(1 -\frac{d_{coil}^{...
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1answer
338 views

High impedance op-amp using guard ring to drive a shield

http://imgur.com/a/GSALb http://imgur.com/gallery/9QrWO So I'm looking at the first picture and I'm trying to figure out now the whole shielding part of the circuit works right now. The second image ...
8
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1answer
2k views

Does an ungrounded shielded cable shield at all?

Does a shielded cable provide any shielding if the shield isn't grounded? Would it be practically different than an unshielded cable?
4
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3answers
2k views

What properties of metal makes make them suitable as EMF shielding material?

What properties of metals make them effective at shielding against EMF, and which metals are typically used? How does Aluminium, Steel, Copper and Lead compare?
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3answers
583 views

Db9 shield connection? in plastic hood!

at my work there are a network of identical devices each of which control some 50 location-guidance light units. These devices or controllers are all linked together and then to a main server/computer ...
11
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3answers
2k views

What is a more effective shield for magnetic fields between 300 and 500kHz Solid copper or copper mesh?

I am working on a PCB that is very crowded, and has high gain amplifiers working between 300kHz and 500kHz Typically I would use Mu metal or similar for shielding at this frequency, but obviously ...
2
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1answer
828 views

How do I deal with multiple, separate shields?

With HDMI or USB3.0/3.1, a cable assembly, in addition to the main braided shield, has multiple separate shields for each differential pair, here an example of a USB3.0 cable: Image source The inner ...
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1answer
86 views

Are one side signals affected by other side signals on multilayer PCBs?

Designing a 4 layer board I've found that if I place some power lines running on top layer I can easly keep them wide and route them without headaches. But this lines are very noisy becouse they ...
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0answers
118 views

Shielding from inductive charging in simple PCB

I am going to design a fairly simple binary LED wrist watch. For a cool feature and a good learning experience I want it to have wireless charging capabilities so I purchased this wireless charging ...
0
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3answers
825 views

How can I shield signal cables in an electrically noisy environment?

I have been playing with a four-channel EEG neurofeedback device. There is some evidence, not conclusive but respectable, that coding performance is improved by neurofeedback on the ratio of beta ...
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2answers
967 views

Ethernet shielding termination

With regard to termination of ethernet shielding I have been taught always to terminate only ONE end of the shielding to ground to prevent ground loops occurring. Is this best practice? and is there ...
2
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1answer
460 views

Advice for Grounding and Shield Placement

I am working on a board design which includes an ADC and a DAC. The board attaches to the headers of the Mojo V3 Spartan 6 FPGA Dev Board. The ADC has to pick up a quiet signal at the same time as the ...
0
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1answer
997 views

How to double-shield a cable properly?

I have a shielded cable, but the shield is not very efficient because the EM radiation leaked from the cable still interferes with nearby equipment. It is still better than a no shielded counterpart, ...
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2answers
2k views

How does shielding work in VGA cables?

Hello I am confused about how EM shielding works, especially after checking out my VGA cable. The end of the VGA cable has a metal chassis around the 15 pins, covered by a plastic coat, and 2 screws ...
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4answers
8k views

Reduce interference over 3.5 mm to cassette tape adapter

I have one of those cheap 3.5mm > cassette adapters, to use in my car. I've purchased high-end ones (around $40) and I've purchased cheaper ones like this ($20) but I always get static/feedback from ...
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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 ...
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2answers
585 views

Aluminum plate for EMI shielding

I'm on a job where some folks are attempting to use aluminum plates to separate weld power cables from ethernet/serial comm. To be clear, it's just wires in a cable tray separated by an aluminum plate....