Questions tagged [shielding]

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

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109 views

Does alumide provide any electromagnetic shielding?

Alumide is a new 3D printing material that contains aluminium dust. It is mechanically stiffer, but little is said about its conductivity and electromagnetic shielding properties. There is probably ...
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1answer
67 views

Basics of board level shielding and grounding

I have been designing MCU based PCB that must be withstand hard EMI tests. This PCB includes ethernet transceivers, can transceivers, rs485 transceivers, II2 chips, 25MHZ oscillators, optoisolators ...
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50 views

Ethernet connectors shielding/ grounding

I am currently trying to derive the relevance of ethernet connections shielding and grounding. This is regarding the robustness of the design (in terms of communication) and eventual ESD ...
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2answers
635 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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1answer
52 views

How good is the idea to place mostly entire copper layer up and down the functional layers in PCB?

My PCB contains PWM - driven LEDs. The specs says the internal oscillator runs at about 5.6 MHz, with currents of 30 mA per line and there are 56 lines in total. As the indicators are very large (10 ...
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26 views

Adding Ground or Earth to the shielded cable

I am using 8 core shielded cable to transfer I2C signal along with analog sensor data. We have connected earth to the shied cable, we have option to connect DC ground also. Everywhere I have read ...
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60 views

Should I (and in what degree) be concerned about EMI/RFI shielding?

I am starting on designing a sort of HAT (like used on the RPi) for the Nvidia Jetson Nano. As I am on my third year of electrical engineering I know little to nothing about EMI and shielding. Should ...
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1answer
35 views

Shielding a signal with both GND and supply? [closed]

What happens if a net is shielded by GND on one side and VCC on the other side inside an IC? Assume that the 3 lines are on the same metal layer. This is an interview question and I would like to know ...
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49 views

Which side is the shield's drain cable connected and why?

I have 2 PCBAs connected using a shielded cable. The cable is transmitting an SPI signal from master PCBA to the slave at 30MHz. I have previously been advised to shield on the driving circuit (master....
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2answers
138 views

Amp circruit from PC speakers, why the connection to cable shielding?

I've taken apart some Logitech PC speakers in order to use the amp inside an bartop Raspberry Pi arcade game I'm making. There's something I don't understand. The donor speakers work as follows: R ...
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1answer
53 views

Which parts of this U.FL laptop wifi antenna need to be exposed?

I got these wifi antennas for use in a small metal computer case. I'm cutting some holes in the case to give the antennas exposure, but I'm not sure what parts of the antenna need to be exposed. As ...
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2answers
176 views

CAN Bus on PCB traces instead of twisted pair cable - points to consider

In order to save cost on the system in one of my current projects (no cables) I would like to eliminate the CAN cable and add traces to the PCB (one pair from left to right to connect the connectors + ...
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27 views

Advice on Bulk Current Injection Testing

I am having trouble getting a new product I'm working on to pass Bulk Current Injection Testing. I had trouble on the 50mA test at around 30MHz where the Ethernet link was not functional. I have a 6 ...
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6answers
7k 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 ...
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58 views

Will a vacuum tank shield against microwaves?

I am working on an experiment that involves 50-250W of microwave radiation. The antenna will be inside a small vacuum chamber (~2ft Dia x 3ft long) with ~1.5" steel walls. There are a handful ...
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4answers
4k 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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1answer
63 views

Would there be a significant difference if a metal shield is connected or not to the circuit ground?

Assuming that we have a sensitive electronics that is battery powered, which consist of a very sensitive 32 bit adc is reading a voltage from a chemical reaction and you place it inside a chunky 1 ...
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1answer
43 views

I/O panel filtering for shielded room

We are looking into setting up a very basic shielded chamber inside a small room at my company to be able to perform some basic relative radiated EMC measurements. We will buy a somewhat cheap ...
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4answers
2k views

75 Ohm Coaxial Cable Used On a 600 Ohm Output

I'm working on restoring an HP 211A square-wave generator and I'm looking to add a shielded cable to the 600 ohm output. I've got some spare 75 ohm RG59 cabling and I was wanting to know if using that ...
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1answer
57 views

How does the shield of a coaxial cable work?

let's consider a coaxial cable with only two conductors (the core and the external metallic shield), and let's consider the case in which it propagates TEM mode at a certain frequency: My question is:...
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9k views

Why does an XLR connector use 3 pins instead of two

Why does XLR connectors use 3 pins instead of just 2. The wiring is Pin Function -------------------------------- 1 Chassis ground(cable shield) 2 hot 3 cold ...
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1answer
64 views

Electromagnetically shield guitar pedal

I've built a few guitar pedals using op-amps, transistors, etc. (with supporting resistors & capacitors of course), and I've generally 3D printed the housing for the components for custom designs. ...
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1answer
53 views

What degree of magnetic shielding does a Kozyrev Mirror require? [closed]

After learning about kozyrev mirrors, I’m curious what types of fields they’re designed to shield. “The earth’s electromagnetic field” was all I could find. But does that mean just earths magnetic ...
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1answer
41 views

Self solder 8-pin din cable

a bit of specific question. I want to build my own cable based on pins stated in the manual of an old camera, so I can capture the video (composite video) and audio signal. Question: Is there ...
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1answer
85 views

What is the “leakage current” between signal and shield?

Consider a coaxial cable with shield not connected to anything. My textbook seems to suggest that there will be leakage current between the "signal" and the "shield". I have two questions: 1) ...
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3answers
145 views

Is there any sense in carrying assembled enclosed electronics in a static-shielding bag?

Say I have a Raspberry Pi enclosed in a metal case, such as this. Would it offer any additional level protection if I put it in a static-shielding antistatic bag whenever I carry it around (e.g. ...
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0answers
44 views

Prevent Reception from an Extended Distance (Beyond Design)

I have a magnetic field that is being induced onto a power line by a transmitter, which is following the length of the power line to the receiver. The receiver communicates via a loosely coupled coil ...
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1answer
273 views

Shielded Ethernet Cables in Office Buildings - Ground Loops?

I have a question related to shielding and grounding of ethernet cabling in industrial environments, offices and datacentres. What I assumed as correct so far (please correct me if I’m wrong): In ...
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5answers
271 views

Considerations for transmitting the signal from a MEMS microphone over a short cable?

In my application I have the signals from 6 analog MEMS microphones (CUI Devices CMM-3729AT-42108-TR), each amplified by a pair of op-amps in a voltage follower -> inverting amp configuration. The ...
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2answers
772 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 ...
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0answers
51 views

Can current absorbed by a shield of a cable be harmful to a human?

I wonder if I should isolate shielding everywhere throughout the system. It is a bit costly because shields are on the outside and tend to touch a bunch of outer metal parts. But then humans can touch ...
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1answer
152 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 ...
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1answer
57 views

Decoupling capacitors on opposite side of board when using PCB mount EMI shield

When using a PCB mount EMI shield, can you put decoupling capacitors on the back side of the board? Well of course you can put them there, but will it make the shield essentially useless? Or will ...
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1answer
182 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 ...
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1answer
59 views

How do I shield PLB signals?

I am trying to refurbish an electronic personal locator beacon (for rescue callouts for stranded hikers/sailors/pilots). To do so to spec most devices require a GPS signal test (activation). There is ...
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3answers
143 views

Is EMC shielding of a grounding wire required?

Consider the following 2 use cases: Fully electric vehicle with 2 different insulated voltage systems: 1 high voltage @1000V DC insulated from chassis and 24VDC system with minus pole (-) at chassis. ...
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2answers
61 views

How to connect a few shields correctly?

There are several shields on my PCB: shield on CAN-bus, on RS485, on Ethernet, on ENCODER motor signals. How do I correctly connect all these shields? If I use the star topology, which filters should ...
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1answer
40 views

4 Pole Connector and USB cable compatibility

USB 2.0 Cable to pass through enclosure boxes. Are such cables able to be cut and connected (soldered) to the connectors pictured, and used without effect on their performance. Are there specific ...
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1answer
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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1answer
61 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 ...
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2answers
85 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 ...
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0answers
193 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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2answers
210 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 ...
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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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59 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 ...
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1answer
93 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 ...
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3answers
25k 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 ...
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74 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 ...
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2answers
1k 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 ...
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1answer
74 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 ...

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