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.

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0answers
42 views

Printed circuit edge trace

I want to know the purpose of copper edge trace in the following circuit:
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2answers
36 views

Automotive filter against voltage spikes

I am building a electric vehicle relay controller. Which controls the High voltage relays among other things. I have built an automotive power supply circuit with strong inspiration from this article: ...
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48 views

Is EMI/EMC still a big concern for a PC case?

I've recently started looking into researching potential concerns when it comes to using a non-metal material for a custom PC case, specifically wood. I've seen people talk about heat, electrical ...
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38 views

Electro magnetic interferences (EMI) generated by power circuit reset low voltage integrated circuits (ICs)

The main question here is (explanation will follow): Is there a way to filter out low voltage oscillations (>10MHz) on pins that have to stay high for the system to function? Oscillations are ...
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What are some quick, cheap hacks for determining the source of EMI in my house?

TL;DR - Without dumping a bunch of money, is there a quick MacGuyver-y way to help diagnose what's causing the EMI in my house? Longer - I have the curse that I'm a little too technical to be helped ...
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43 views

how does it improve EFT immunity

how does this design really improve EFT immunity. where does EFT come from i guess (VDD) as spike ? in my estimation i would say (10k+100nF) is more robust from changes on VDD? in fact the 100pF is ...
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39 views

Design of bias-T (L band,10 MHz,DC)

I want to design a bias-T for satellite application where L band RF (950-2150 MHz),10 MHz, and DC will be multiplexed. I need help in finalizing/selecting the inductor(choke) through which DC (13V/18V,...
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4answers
78 views

How to identify or calculate the electromagnetic interference (EMI) contribution of components on PCB

I am designing a circuit using the Motor Driver IC TB6612FNG. Now I am unaware about how can I calculate the EMI contribution by this IC. I did add the bypass and decoupling, grounding control, ...
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50 views

Placement of damping resistors, closer to driver or load?

I'm connecting an FPGA and MCU and currently optimizing the placement. Does it matter if it's randomly placed? Should I place it like a series terminating resistor and strictly place it close to the ...
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1answer
41 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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Relation of sweep time and number of measurement points in Spectrum Analyzer

My configuration is as follows: RBW: 100 kHz Detector: MAXPEAK Frequency span: 1.1 GHz - 1.8 GHz Spectrum Analyzer: R&S FSV 30 I do not fully understand how the sweep time and number of points ...
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55 views

Atmega MCU freezes when nearby VSD starts. Possible causes and solutions

I have a custom PCB that uses an ATMEGA1280 MCU. The board has a few inputs and a relay output. Inputs are mostly 4-20mA measuring temperature sensors. I also measure VSD current from a VSD mounted ...
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31 views

Should I avoid a switching frequency close to my target SPI or CAN frequency?

I have a kind of an open-ended question. If I'm designing a board with a buck converter and have picked out my peripherals, and say for example I want to run my CAN FD interface at 1MHz baud and maybe ...
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47 views

Filtering out Switching Noise

I'm designing a custom current limiting circuit designed for electric bikes and small electric vehicles. It's purpose is to limit battery current to "dumb" motor controllers so that you can ...
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3answers
38 views

Quartz Crystal with or without metal lid for EMI suppression?

Is there any reason for choosing a quartz crystal with or without metal lid? Some datasheets (this one for instance: link) claim better EMI performance and other do not write at all about it. So is ...
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35 views

Mesh Wire opening size for emi filter at frequency of 30Mhz

I want to use a mesh wire and I wanted to know how do I calculate an opening size of a mesh wire that can filter 30Mhz frequency. Your help is appreciated.
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1answer
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Connecting USB shield to system ground [duplicate]

I designed a PCB with an STM32 and a micro USB connector. I put a NUF2042XV6T1G between the connector and the STM32 to protect the data lines. The USB shield is connected to system ground via a 120R@...
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1answer
38 views

CAN - Tranceiver @ 5V VS Tranceiver @ 3V3 Immunity

I would like to change a 5V CAN transceiver on my board into a 3V3 CAN transceiver. Nevertheless as I am clearly not a specialist of the CAN protocol, I am afraid of doing a big mistake ! I think it ...
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1answer
119 views

Universal Relay Snubber Circuit

I am trying to design the usual remote-controlled relay board for mains usage (I live in Europe, so that means 230VAC). I need to tackle the usual problem of the switching of the relays hanging/...
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1answer
63 views

Ground vias use on no-trace areas at a 4-layer PCB

Background info: I am using a 4 layer PCB stack: Signal, Gnd, Signal+Power, Signal (mostly ground). To avoid out of question issues, I use this set-up due to a reference design on Texas Instruments as ...
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2k views

What is this spongy material?

Hi, while I am tring to repair electronic circuit. I'm encountering this sponge. I wonder what is this sponge? and can I find out what it is used for. I often see this in sensitive circuits like in ...
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Is EMC (FCC and EU) testing performed as sold or as used?

I have a prototype that inserts a fairly weak ISM band RF signal (HF/VHF) as a way of detecting a connection between two metal objects without there being a DC return path (Ideally I would use TDR but ...
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5V tolerant - tolerant to 5V and how many more ? Harsh environnement

There is a lot of questions about this subject... Nevertheless this is not clear to me and clearly I m afraid of putting a signal at the input of a microcontroller which is higher than this supply ...
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47 views

Inverter EMI filter design

I'm designing an inverter with a switching frequency range of 10-40kHz. The inverter will run off of a DC power supply at a relatively low voltage (30-80VDC) and low power (~100W) for motor control ...
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33 views

Reduce 50 Hz noise from robot-mower charger

I just bought a robot-lawnmower (Husqvarna Automower 105), which is working perfectly. But the charging station is making a loud 50 Hz noise all the time, even without the robot charging. I have ...
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61 views

Why are high frequency signals not disturbed by stray fields?

I am trying to design an inductive position sensor based on a high-frequency signal. It is mentioned that using high-frequency signals gives immunity towards stray magnetic fields. Could anyone ...
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1answer
50 views

Conducted Emissions of EV Charging Electronics

I'm building an AC-charging device for electric vehicles (the standard calls it an "ICCPD" or an "In Cable Control and Protective Device") and I'm facing some EMC issues due to the PWM Signal on the ...
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4answers
1k views

Generating 5V from 37V DC with no EMI

I'm making a PCB for an audio amplifier + power supply (circuit here). The power supply voltage rails with my transformer end up being about +/- 37V, and I want to generate a 5V rail from this for ...
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214 views

What kind of inductor for DC-DC converter module's EMC filter?

I'm looking at the datasheets for a number of switching DC-DC converters. They suggest for EMC filtering to add an inductor and a capacitor or two on the input side of the converter. The question: ...
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1answer
81 views

LTspice model of the UC3845 oscillator

I have a circuit whose the purpose is to reduce the EMI by "moving" the switching frequency around a value. I would like to understand how this circuit affects the switching frequency, i.e. how it ...
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99 views

Where does Differential noise come from in a switching power supply

I would like to know where does differential noise come from in an SMPS. I understand where the common mode noise comes from. It mainly comes from the fact that there is capacitance between switching ...
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Line Impedance Stabilization Network (LISN) ripple to measurement transfer function

While reading about LISNs, I was lost a bit. The CISPR limits are in dBμV, so they're voltages. But are these an image of the current following IN the DUT? Below you're see the LISN transfer ...
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Electromagnetic compatibility problem with an hairdryer

I wanted to ask you if you could give me an explanation of this electromagnetic compatibility problem. I connected my (fully working) TV to a certain electrical socket in my house. I have also a ...
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1answer
50 views

4 layer PCB controller below layer query [closed]

I have designed in 4 layer PCB. My Controller placed on the PCB top side / first layer. 2nd layer full ground plane. 3rd layer Power plane (fill or not? please confirm.) 4th layer ground fill.
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58 views

How to read/understand Bode plot of Insertion loss in EMI Filter

I am designing a noise filter with a Target frequency for noise reduction =100KHz and with the help of Murata Noise Filter Designer website. Recommended circuit from Murata with component value is ...
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2answers
64 views

EMC - conducted emissions - unused wires in cable - puzzling coupling

I am trying to understand the impact of unconnected wires in a cable for EMC conducted emissions tests. My product has a shared unshielded cable for supply and communication (I know it's bad practice....
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1answer
53 views

Where to connect TVS clamping Diodes

This question just came up during the review of a design. Should the TVS rather be placed before the feedthrough-cap or after? I would place the TVS before the cap (see A in schematic) because TVS ...
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1answer
171 views

Strange noise at peaks of measured sine waves STM32F103

Please look at this picture: I'm using STM32F103, a popular Blue Pill module. What you can see in the picture are three signals, from bottom: green - AC voltage of 14V RMS, measured with step down ...
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Application circuit G3NA-210B

Simple doubt about EMC directive on page 15. Should I use the varistor, cap and toroidal core on non UTU model? I want it to be compliant with safety directives, but I dont want to interfere with ...
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1answer
67 views

LTSpice - Problem Wurth filter

I am trying to simulate the 810911001 line filter (Wurth Electronik) on LTSpice which I downloaded on the following link : https://www.we-online.com/catalog/en/WE-CLFS/ I tried to simulate the ...
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1answer
149 views

Is it better to route Ethernet on the top layer, or to use vias?

I'm making a circuit board with Ethernet (PoE if that makes a difference) coming in through an M12 connector, passing through magnetics and a PHY and going to a micro. I've always heard that there are ...
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1answer
75 views

How to know if test points can introduce EMC problems

After getting some advices from my PCB manufacturer and from people here, I decided to change the PCB design I'm working on so the PCB could be tested using a bed of nails. To do so, I added test ...
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2answers
65 views

Parallel power traces with PWM and unwanted EMI

I'm in the process of designing a PCB for an RGB LED light source that will allow me to dim each color channel separately using PWM. To help manage the thermal output of the LEDs I'm trying to use an ...
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1answer
110 views

Common Mode Noise filtering for Diff Mode Circuit

I have a circuit that has only two pins and there is no earth ground. However, I have to test it for BCI and design a common mode filter with diff mode. Designing diff mode filter is simple but common ...
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61 views

Relay contact side protection

Do we need any protection on the contact side of the relay (Ex: form C 240V 3A) if the contact side is not powered by the circuit. if we have to protect, then how(Please provide an example). Also, ...
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1answer
215 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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3answers
49 views

Solutions to fix LED light RFI/EMI?

Almost every LED light I've tested (hold an AM or shortwave radio antenna nearby) emits RFI or EMI across a vast frequency range. The EM noise comes either from the base of the bulb, or from some box ...
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1answer
125 views

PWM motor control - weird voltage ringing issue

I'm having some issues with a specific 24V brushed DC motor I'm PWM controlling. I'm seeing some rather nasty voltage spikes and ringing on every PWM on and off cycle. All scope measurements are ...
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1answer
244 views

Routing strategy - 24-bit RGB display on a 4 layer PCB

I'm routing traces between a microcontroller and a TFT display (24-bit RGB, clock frequency at 18 MHz).The stackup is: L1 - Signal L2 - GND (solid layer) L3 - PWR (solid 3.3V in the region of ...
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Questions about grounding schemes when converting a double-insulated audio amplifier into a power supply for a 90vdc treadmill motor

I was given a free Denon AVR3311 AV receiver (a.k.a. audio amplifier) which I immediately gutted and converted to a bench power supply. I combined the "B+" and "B-" rails into a single, ~130Vdc output,...

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