Questions tagged [emc]
Electromagnetic compatibility (EMC) is a branch of electronics related to identifying and solving problems caused by electromagnetic interference (EMI) between devices. It encompasses both attempting to prevent unwanted emissions from a device and also ensuring that emissions from another device will not cause spurious operation. EMC depends upon many system-level details; when asking questions, please provide as much information as possible.
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RF signal on Audio/Music/Guitar equipment
It is looking like the standard RF noise from my (new to me) old apartment wiring through my amp to my speakers. Suspected it could be due to poor guitar shielding/grounding, bad cables etc. Started ...
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Auxiliary mechanical anti-ESD measures
If a PCBA within a plastic enclosure is prone to malfunctioning due to ESD air discharge in proximity of enclosure seams and openings, but changing the hardware or plastic design is not an option, ...
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EMC Radiated Emissions, peak vs quasi-peak
This is regarding some Radiated Emissions testing unintentional radiator:
Critical frequency is at 314.986 MHz
Polarization is Horizontal
Peak detector is 53 dBμV/m
Quasi-Peak detector is 56.68 ...
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Inductor of twisted pair cable and of a wire
I found two calculators on internet for calculating the self inductance of a wire and an other calculator for calculating the inductance of twisted pair.
Here are the results for the following ...
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Considerations in board layout for different interface speeds
Currently, I'm working on a design that includes four data buses operating at different datarates.
The signals connect various parts of the system to the central FPGA. I have experience in designing ...
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Monitoring system components affected by interference in EMI testing of wired ethernet
I'm conducting Electromagnetic Interference (EMI) testing on Ethernet setups running Windows and Linux. My primary objective is to identify specific system components affected by interference and ...
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How likely can a Bluetooth IC get damaged if the antenna has a wide bandwidth?
I design a device with a Bluetooth low energy chip (DA14863) that sits at different positions on the human body (minimal distance of 0.7mm). Simulation shows that the human body absorbes up to 95% of ...
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FCC rules for wideband / spread spectrum devices
I'd like to clarify how the FCC measures power in a frequency band (both for intentional and unintentional radiators). There are devices which either frequency hop (output is a sine wave, but center ...
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How to perform conducted emission simulations
I am currently attempting to design an EMI filter for an AC/DC power supply that is too noisy to pass conducted EMI testing for MIL-STD-461 (115Vrms, 50Hz).
In the lab I have measured the DM and CM ...
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Ground loop with oscilloscope probes
I am trying to better understand how ground loops affect a circuit and why it is important to do not have ground loop on a circuit. So I am trying to look at systems with ground loop to further ...
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Common mode choke placement for good EMC performance
I am interfacing a deserializer with Quectels smart module.
The CSI lines of the deserializer are connected to the CSI lines of smart module.
A common mode choke is placed in between them. The ...
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Shielding with Aluminium Foil
I want to shield a capacitive touch sensor circuit from external EMI/RF noise. It's for a commercial product meant to be used in every kind of reasonable environments. I don't have a specific ...
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Do I need to add a filter for an isolated DC-DC converter?
I have purchased three CUI Isolated DC-DC Converters, the models are VHK50W-Q24-S5, VHK150W-Q24-S12 and VFK600-D24-S24. I wonder you could help / guide me to the correct use of them.
Questions:
I saw ...
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Chassis grounding for multiple daisy-chained units
I'm designing a system that provides power/ethernet/serial for up to 5 daisychained units. All of the boxes will be metal and my initial plan is to run power and signal ground through the 14 pin ...
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Ferrite Topology For Motor PWM
Brushed motors are pretty noisy devices, especially when driven with PWM. There are a number of techniques to reduce the transmitted noise (twisting wires, shielding etc) - one of these is using a ...
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Digital signal routing for EMI/EMC
REMOVE THIS WHEN YOU ANSWER THE QUESTIONS IT ASKS
YOUR DESCRIPTION IS UNCLEAR. PEOPLE MAY NOT UNDERSTAND THE QUESTION PROPERLY AND SO WASTE TIME ANSWERING IT. You talk about transcievers and devices. ...
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Test lab noise floor variance and emission limits
I have recently taken part of noise floor measurements for emission tests from two separate EMC labs, both well known and international companies. The thing that shocked me is the dramatic difference ...
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Connecting secondary ground with primary ground
My system must be made of 2 DC/DC converters and a battery (safe voltage level). I already have a DC/DC converter that I bought on internet. It is the following. It is an isolated DC DC converter. I ...
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What is the purpose of connecting your reference ground plane to earth when doing radiated emissions testing?
In most standards it's required to connect the reference ground plane to earth.
However in a lot of cases the reference ground plane is elevated above the earth by a set height.
If you left the earth ...
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Can the Antenna Factor of a passive antenna be improved by adding a pre-amplifier?
If so what are the main considerations with respect to the noise of the amplifier?
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Tight GND plane Pros and Cons
Imagine a typical 2Oz/1Oz, 4 layer PCB with a stack-up, Sig/Pwr, GND, GND, Sig/Pwr. Your typical trace width/space would be 0.2mm/0.2mm, and a prepreg Dk of ~4, ignore the Core. Fastest signal on the ...
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Avoid ground loop for multiboard high-current device
Problem overview
I am designing a multi-board pulser device for ultrasound, and am encountering a conceptual issue when trying to prevent a ground loop in this device. I added a minimal example to ...
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EFT Simulator Duration Time Setting / IEC 61000-4-4 / KeyTek CE 40
I've got an antique EFT simulator, it's a KeyTek CE-40. I'm debugging a device for EFT as per EN 61000-4-4. The manufacturer doesn't provide support for the device anymore and I don't have a product ...
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Reducing EMI with ground plane
I came across this post on how to reduce EMI in a PCB. From this, I learned that there actually exist two types of current. The first is the conductive current (the current that flows through a ...
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Ethernet MLT-3 signall probing
I am getting radiated emission failure in my system, where the emissions were out of limit (~5 dB) for frequencies 125 MHz, 175 MHz, 225 MHz, 275 MHz, 775 MHz, 825 MHz. This sounds like the odd ...
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What is the best practice when replacing a ribbon-cable ferrite clamp with chip ferrite beads?
I'm working on EMC testing a product. We have an internal 30 cm ribbon between 2 boards. One has a MCU and LCD, and the other MOSFETs and a 3 A switching regulator.
We determined that a lot of RF is ...
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Reducing EMI from PWM controlled Led segments
I am currently designing a product that has a ring of LEDs with 7 individually dimmable segments.(all together about 40 standard (blue/white)LEDs max 15mA each) the only supply voltage is 3.3v but I ...
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E field probe or H field probe to detect
I have a board that is failing radiated EMC tests. There are narrowband spikes with 50 MHz intervals (300 MHz, 350 MHz, 400 MHz, etc.)
I believe it has something to do with a clock (I suspect so since ...
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Differerent connection for Y-capacitor (EMI filter)
What is the difference between these two connections Y-capacitor (EMI filter)?
high-voltage side to isolated 12V DC output
isolated 0V DC output rail and a "GND"
Could you tell me the ...
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Common-Mode or Differential-Mode Choke Circuit
This circuit, located at the entrance of our power circuits in the products produced in the company I work for, caught my attention. The design of the circuit was completed a long time ago, and now ...
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Is a DC blocking capacitor required between a GPRS modem and the antenna?
tl;dr
A tracker device which sends GPRS telemetry has EMI issues. The original design had the antenna connected straight to the "ANT" pin of the GPRS chip. When a "0R" resistor on ...
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Do I need to connect a resistor at the output of an isolated DC-DC converter module?
I am using D050505S-1WR3 in my design for powering an isolated CAN transceiver. The can transceiver is the ISO1042BDWV from TI.
Below is the schematic of the power supply and CAN transceiver.
During ...
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DC brush motor EMI
What kind of frequency does a DC brush motor generate? There are a few explanations online as to what causes EMI in DC brush motors (commutator sparking for example) and how to reduce it, but no ...
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PCB Bottom layer GND pour some portion not connected to GND plane
Below is the bottom layer of a 4 layer PCB.The stack up is SIG-GND-Power-Signal.
You can see that there is a floating ground whose some portion is not connected to GND plane.
I have shown that in red ...
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230 VAC 16 A relay Circuit for Reduced EMI
I am designing a PCB that will needs EMI testing from a laboratory. I have a 230 VAC 16 A relay in PCB. I am not sure will it cause EMI issues while switching between loads or not. If anyone as better ...
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What is the tension member in IEC 61000-6-8:2020 Table 6?
In IEC 61000-6-8:2020 3.1.10, an optical fiber port is defined as port at which an optical fiber is connected to an equipment. In Table 6 – Requirements for conducted emissions, other wires ports, it ...
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Why does switching the winding direction on transformer give me a better conducted EMC meassurment?
I am making a charger and I am measuring conducted and radiated EMC.
The circuit is a flyback and the transformer in mention is a sandwich style transformer with 4 windings. Primary windings, ...
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CE Compliance: what is the limit of self-declaration for Industrial Control Panel?
We are a system integrator making custom electrical control cabinets. This is our first time on making panels for European customer, and of course they mandated the CE marking.
The control panel they ...
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Placement of RC filter used for EMC filtering
I've seen RC combinations used on many circuits now which I believe have been included for EMI filtering. They usually feed off to a connector.
Does the placement of these matter in the circuit?
Let's ...
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Can I route PWR signals under RFIC?
I am designing an RF amplifier (< 13 GHz) and want to use a board with two layers. However, the RFIC footprint (16-VFQFN Exposed Pad) has RFIN on the left, VDD on top, RFOUT on the right, and VGG ...
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What to expect from adjusting the suggested EMI filter and surge protection on a DC/DC power supply's application note. 61000-4-5
I am trying to make the CQB50W12-72S12 120VAC input capable by adding a bridge rectifier into the design that is already called out in the application note (app note and data sheet found here: https://...
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Correct way of optical input EMC protection
I tried to find an answer online, but didn't find anything that would make my doubt go away.
The thing is: when you want to protect any input, that is referenced to ground, you use ground-referenced ...
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CMTI of a push pull converter
According to this article, a push converter has good immunity against Common Mode transient :
It is said "The flux generated by the current flowing in one primary coil cancels the flux generated ...
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EMC and Control Area Networks [closed]
With radiated EMI tests, do we need to take into account the communication cabling and its influence on EMI?
I can't seem to find one standard that describes how CAN busses should be configured in EMI ...
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Radiated emissions from WS2812 LEDs
We have a product which is failing EMC testing on radiated emissions. It fails by approx. 25 dBuV at the peaks. The product has a large 550x900 mm opaque 5mm acrylic window. Behind this, at a 50 mm ...
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EN61000-4-5 Surge protection of PCB power supply
I am trying to better understand how EMC testing is simulated and passed. The datasheet of the CQB50W12-72S12 says it pass level 4 line to earth 4kV; and +- line to line 2kV with just a TVS diode (...
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Best placement of bridge rectifier to allow DC/DC convertor to become AC/DC convertor. Does this inhibit surge and EMI performance?
I am trying to use the power supply: CQB50W12-72S12 with AC power without degrading the performance of its recommended filter and surge components. 120VAC peak voltage is 169V and I am worried that ...
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EMI emission of the classical smartphone charger
I would like to ask you about the significance and quantity of electromagnetic interference (EMI) that produce classical mobile phone charger (transformer).
I would like to install one in a turntable ...
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Declaration of conformity to EMC Directive
We need to declare CE compliance of a system consisting of pumps, valves, sensors and control cabinets. I am dealing with the EMC element of the certification.
I have collected the manufacturer's ...
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The way I compute the LC element of the EMC filter using the impedance paper
I am an embedded system engineer. I am not very familiar with the hardware aspects. I am working in the field of embedded systems in C language and I started a project on designing a power supply ...
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