Questions tagged [shielding]

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

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3answers
56 views

Extra pin for shielding with CAN bus connector

I am presently using a 4 wire bus for CAN (CANH,CANL,PWR,GND). This is used all across the design for various boards. Now the cable needs to be shielded. Would this imply using 5 pin connectors and ...
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1answer
51 views

What's are the material properties that distinguish a magnetic containment disk from an induction cooker?

My picture below shows a coil carrying AC current, generating an alternating magnetic field. On top of the coil I've drawn a disk of high-permeability metal. Such as carbon steel, or mu-metal. If the ...
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1answer
85 views

What is the plastic barrier surrounding this choke for?

I disassembled the mains power supply from an audio mixing desk. Immediately after the switch and inrush protection NTC is an Epcos B82722 10mH / 1A choke (the blue component in the photo below). The ...
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5answers
2k views

Cable shielding adequate for video, but not audio frequencies

I am no expert in audio equipment, but to educate myself I have been studying. In the process, I came across a video which tests the audio frequency shielding of a purported shielded video cable. (I ...
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1answer
55 views

Why do (magnetic) absorber sheets work?

I understand how/why graded absorbers work - you achieve a match with free space by gradually varying the electromagnetic properties from "almost air" to strong absorption (either ...
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2answers
94 views

Holes in RF shield, what frequencies can escape?

So this is part of a theoretical design problem that I've come across not too long ago, and still can't find a satisfactory answer for it. Assume a large (infinite) metal plane with a round hole in it ...
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0answers
30 views

Raspberry Pi : White/Blank screen with new shielded cable

I'm currently passing EMC tests at a test lab. For the purpose of the tests, I made a custom DSI cable for the official Raspberry Pi 7" screen with shield against EMI as the PCB of the official ...
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0answers
51 views

Cable Issues with USB HS

We’re working on a product that makes use of USB HS, and are having some connection and consistency issues. Originally, our product was USB FS-based and we had no connectivity issues; with this second ...
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0answers
47 views

What metal(s) are old game console RF shields made of and coated with?

I'm restoring my old game consoles (like NES) and am having trouble finding what the RF shields are made out of and coated with so I can sand out the corrosion and re-plate them. I thought it might be ...
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0answers
39 views

Wireless charging with metal plate on back of phone: eddy currents wasting energy and heating up?

I just got a car mount for my phone which uses a small magnet stuck to the back of my phone. I'm not sure the material, but I'm guessing it's conductive. My concern is with wirelessly charging my ...
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0answers
39 views

Basic shielding practice for simple passive audio project in an enclosure?

I'm a tinkerer but not an electrical engineer. I'm constructing a stereo->mono summing box for my stereo (to listen to Beatles LPs properly, natch). I'm using the design & schematic here for ...
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1answer
45 views

Connecting USB shielding of two hosts and one peripheral

I'm making a simple project regarding switching USB connection between two computers. I would like to know if it is safe to connect USB shielding for pc1, pc2 and peripheral together, while keeping ...
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4answers
612 views

Active guard shielding for instrumentation amplifier

I want to use the the AD8221 amplifier as a conditioner for my load cell. I saw that to reduce noise I can use an "active guard shield driver" between the "REF" of my amplifier and ...
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1answer
51 views

Avoiding ground loop through d-sub like connector shield over metal enclosure

I have to pass a couple of analog signals between separately grounded systems over a HPDB68 cable. Ground loops have been a major issue previously, so the signals are passed differentially and ...
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2answers
90 views

RFID antenna beam direction and how to control it

I've been working on some RFID stuff lately and I'm wondering if someone could help me understand how the beam direction works? I'm having problems with my RFID reader picking up signals from tags ...
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1answer
41 views

How to connect interfaces' shields?

I am designing a new PCB board these days, and I am confused about how to connect interfaces' shields. The interfaces on the board include USB, RJ45 and D-SUB, should them be connected directly to ...
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2answers
38 views

In wifi modules what does the shield have to protect?

All wifi modules have a shield over the chip but what I’m wondering is if the track to the antenna need to be shielded or is it just the chip that needs shielding ? Thanks Ben
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0answers
32 views

Should via-stitched polygons connect to adjacent analog grounds?

I am putting together an analog PCB. I am reading an audio signal and using large gain to clip it (effectively a crude digital signal 0-5V) using a differential amplifier. It is a 2-layer PCB with the ...
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1answer
266 views

Is an aluminum foil wrap working as a shield in my spliced USB cable?

I'm preparing to cut apart a non-trivial $ device and try to extend a 4-conductor cable, so I have been practicing my splicing skills. I figured a USB cable would be a good test. I spliced, heat-...
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1answer
225 views

How to shield your microphone the best way

I hope this is not a too simple question for this forum. I have an issue with EMI/RMI on a microphone I am building. It's picking up noice from wifi hubs, computer screens and mains. I do not want to ...
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0answers
28 views

Wiring Stepper Motor / Placement of Stepper Motor Driver

I'm making a CNC-like machine and I'm in the process of designing PCBs for the head assembly. Currently I have stepper motor driver (with 100uF caps on the power line) on the head assembly and I'm ...
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0answers
100 views

Where to properly terminate 4-20mA cable shield in ungrounded low voltage DC system?

Preface: I read both: ungrounded chassis shielding and: RS485: Where to connect the cable shield in a battery-powered system? A sensor system I'm working on is getting installed in a 20x20' cement ...
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7answers
319 views

Frame grounding, data & power - EMI

I'm looking into building some large robotics with (ofcourse) a frame, (shielded) data/communication cables - EtherCAT, and power lines. Now different 'experts', websites and people say all different ...
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1answer
134 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
359 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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1answer
116 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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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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0answers
33 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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0answers
65 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
42 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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1answer
77 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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1answer
61 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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0answers
36 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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2answers
160 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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2answers
701 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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0answers
60 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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1answer
72 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
59 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
103 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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1answer
186 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
87 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
54 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
198 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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1answer
548 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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0answers
45 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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5answers
293 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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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
84 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
61 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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