Questions tagged [shielding]

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

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5answers
252 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
49 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
45 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 ...
2
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1answer
57 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
121 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
59 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
36 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 ...
3
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1answer
59 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
51 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
76 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
97 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
90 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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0answers
38 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 ...
1
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1answer
114 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
67 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 ...
3
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0answers
48 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 ...
0
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1answer
56 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 ...
2
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3answers
81 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 ...
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1answer
85 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
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1answer
158 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
121 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 ...
4
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1answer
325 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 ...
2
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1answer
140 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 ...
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1answer
111 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 ...
4
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2answers
84 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 ...
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3answers
198 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 ...
3
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1answer
156 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 ...
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2answers
180 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 ...
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1answer
45 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 ...
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2answers
562 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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2answers
120 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 ...
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1answer
373 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 ...
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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
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1answer
834 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 ...
0
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1answer
47 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
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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 ...
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1answer
770 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
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1answer
202 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
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2answers
61 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
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3answers
345 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 ...
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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
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1answer
696 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 ...
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2answers
104 views

What does metal to metal bottoming mean?

Some connectors datasheets specify the following: Metal-to-metal bottoming for maximum EMI shielding under extreme vibration Reference: Dualok Connectors I have also encountered the following for ...
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2answers
140 views

Does burying a cable shield it?

TL;DR: Does burying a cable provide shielding? I.e., is a shielded cable in air equivalent to an unshielded cable buried ~ 6 inches in soil? Long: I'm a technician at a university. I don't have ...
2
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2answers
954 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 ...
1
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1answer
173 views

How to shield a battery powered instrumentation with USB interface?

I would like to ask for advice on shielding the following setup. I have a measurement target sitting inside a Faraday cage, connected through a shielded cable to a measurement circuit. The cable ...
1
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1answer
80 views

dip switch electric shield

I have ordered a Reed Relay with a diode and electric shield, but I am not sure how to connect the shield to the rest of the circuit because I do not know what the shield does and how does it work in ...
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3answers
101 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. ...
3
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2answers
287 views

How should I use a static-shielding bag prior to opening, and why?

After grounding the ESD mat and wearing the properly grounded anti-static wrist strap, what is the correct process to take the contents out of the static-shielding bag and take it onto the antistatic ...
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0answers
184 views

Can a grounded static-shielding antistatic bag be used as a circuitry work surface to protect from ESD?

Basically, I have looked around about how to take proper care with respect to ESD and I am quite confused. I know an antistatic bag of any type would not provide additional protection from ESD if used ...