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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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Current leak LCD PCB IT-net vs TN-net

I have a LED with LED PCB mounted on a metalic plate that is connected to earth ground. The driver is a cl.2 driver with no earth wire and it's a constand current driver. The lamp is connected to ...
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Common mode filters effectiveness

As we know, there are many types of common mode filters that can be implemented. One of this type is a single element topology where this element can be a series impedance element (usually R or L or ...
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Unbalance effect in differential amplifier

Consider we have the below differential amplifier : Consider that the two resistors R2 are not balanced and the unbalance in this resistors is represented by delta R2. The common mode rejection ...
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EN 300 328 Receiver (RX) Blocking | BLE DTM Implementation with Signaling Analyzers?

We are working through a Nordic NRF 52832 certification, and are getting the device CE tested. We are running into some issues getting our device connected to the R&S CMW 500 signaling analyzer ...
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40 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 ...
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1answer
49 views

Different printed circuit layout for a transistor

The below figure shows a schematic for a transistor where there exists an external magnetic field : This schematic has two layouts to choose from. The first one is shown below : The second layout ...
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2answers
112 views

160MHz Ambient Office Noise?

I've got a shielded tent in our office and I see one ambient element I don't have a good explanation for. We see some ambient noise at 700MHz - 800MHz which I guess is cell-band noise. But there is ...
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42 views

How to create EMI/EMC noise for testing product behavior in noise environment?

We have product which works on three phase AC supply. We were facing issue on I2C interface of external RTC due to noise from external environment. After some inspection, we realized that because of ...
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44 views

Radiated emission limits

The following table represents the FCC radiated emission limits for class A devices at a distance of 10 m : How do we convert this table for a distance of 5 m? Edit : There is an approximation in ...
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44 views

A source generator connected to a receiver with a lossy transmission line

Consider that we have a 50-ohm source generator that is connected to a 300 ohm transmission line. This line has a loss of 10 dB for every 100 ft and is connected to a 50 ohm receiver. The source ...
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4answers
66 views

How is electromagnetic interference possible when measuring voltage difference?

This question is primarily concerned with audio but it's probably applicable to other areas as well. As far as I understand, EMI is caused by electromagnetic waves adding power to wires as they ...
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939 views

Does paint affect EMI ability of enclosure?

This could be a very stupid question, but when it comes to RF you never know. Does painting (non-conductive) over the top of a grounded metal enclosure affect its ability to absorb/block RF ...
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62 views

Wireless phone chargers in a lab environment? [closed]

We are talking about devices that are designed to pump out quite a bit of power in the MHz. Admittedly the chips have comms protocols so they don't spew all the time, and the resonant circuits are ...
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82 views

Routing traces over traces in two layer pcb

I am kind of new to PCB Design. I have a few confusions on my board layout, in order to reduce EMI in routing. I am designing a two-layer PCB design I am aware that when you route traces over ...
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1answer
48 views

Use of internal PCB ground plane as ESD baseplate/EMC reference plane of product in plastic enclosure

I am designing an electronic product which will be housed in a plastic (non-conductive) enclosure. There are a number of, mostly shielded, I/O cables (Copper 10/100/1000Mb/s Ethernet, USB 2.0, RS232, ...
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3answers
196 views

Homemade Faraday Cage?

I'm working in an office with a Wi-Fi router, desktop, and a few cell phones making RF noise. I have an 8 feet long by a 3-feet wide table, and I have an Aaronia BICOLOG 30100 + spectrum analyzer + ...
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49 views

Connecting the secondary side of ignition coil to earth

I have an ignition system used for some application. During the testing I found that spark plug is producing EMI due to spark occurrence and high voltage is traveling through the wire. So to ...
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1answer
51 views

Disabling isolation to reduce noise from EMI

A technician was suggesting we try connecting an isolated ground (described below) to a non-isolated ground suggesting it could reduce EMI noise and possibly fix an issue we're seeing (which we don't ...
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1answer
50 views

ESD Grounding Straps with No Chassis Ground

I've got water pump device that needs to pass ESD testing (IEC 61000-4-2, 8kV contact, 15kV air discharge). On this device (as circled in red), there are these four metal inlets. At 2kV with an ...
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1answer
621 views

Why put capacitor between ground and chassis?

In the product I analyse (an optical fork sensor, rated 10V-35V), there is a sizewise big capacitor between ground and chassis. I measured its value with an LCR meter, it is 60nF. I also broke one by ...
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1answer
119 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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1answer
101 views

Ability of a 100km power transmission line to radiate 50Hz EM waves?

This is about confusion of relating antenna radiation theory to power lines. Assuming a straight 100km or even longer possible power transmisson line with 50Hz frequency. What can be said about the ...
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1answer
54 views

Device's ground riding on a non-ground signal

The question is somewhat conceptual, feel free to close if it's too off-topic. If I take my portable (battery-powered) oscilloscope and try to measure the mains voltage, the connection polarity ...
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1answer
65 views

Stepper motor close to PCB/MCU/ADC

and I apologize if the question is repeated. I tried to search around, but by my keywords main answers are about control of stepper motor with MCU and this is not my problem. In my design I want to ...
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1answer
38 views

Standards for conducted EMI testing

I have some doubts to interpret the CISPR standards, one of them is in relation to the test environment for EMI conducted (150kHz up to 30MHz). The minimum size indicated for the vertical or ...
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1answer
98 views

Which pin of USB-C to use for analog signal?

I am working on a project which connects a microcontroller to an IR sensor device and decided to use a male-male USB C since I need 5 lines (V,GND,SCL,SDA,ADC). Which pin should I use for my single-...
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2answers
94 views

Open-loop Buck LED dimming

About this buck LED driver... TL/DR the questions: 1) I intend to drive the FET from a microcontroller PWM via a suitable FET driver. This open loop control scheme seems too simple. Is it a trap? I ...
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118 views

Flyback Transformer - Grounding the Ferrite Core

Today I dismantled (I hope this is the correct verb) a flyback transformer. The thing that I've never seen is that one end of one of the windings is "glued" to the ferrite core (Before you ask; yes, ...
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3answers
285 views

How to simulate the impedance for this LISN circuit in LTspice?

I tried to simulate the following simplistic LISN circuit: Below is the AC analysis with LTspice for two nodes: But these above plots do not tell me anything related to the purpose of LISN which is ...
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2answers
74 views

Effect of wall location for guided wave attenuation

Pardon my ignorance here if this has already been answered. I'm not fully familiar with the English terminology here so my searches came up empty. If there is any keyword I’m missing or I’m not using ...
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1answer
68 views

I2C bus line over different layers in an arc

I have the following board design in mind: It's a 4 layer, ~5cm diameter board where 10 slave PCB's will be soldered to it that are connected over the I2C bus. The trace line you see is roughly 8 cm ...
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1answer
48 views

Multimeter across Power Line voltage varies wildly

I'm building a single switched AC/DC Forward Converter and have reached to the point where I have steady o/p voltages and currents. However, I am not able to remove noise that goes back into the AC ...
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1answer
40 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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1answer
63 views

When does differential signalling become necessary [closed]

Is there an industry rule of thumb or application note etc for when differential signalling becomes necessary for reliable communication? I'm thinking mainly in terms of distance and signal speed (...
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1answer
53 views

Slew Rate related EMI: How relevant is it for motor control circuits ?

I am designing a 3-phase inverter board for BLDC Motor control. The H-bridges i use are IFX007 from Infineon. The mentioned IC has the possibility to adjust the slew rate. From what i have read, i've ...
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1answer
62 views

noise of high speed serial link

I have an ADC module. The board contains sensitive (10-100MHz) analogue parts and a high speed serial link (Aurora). The link uses scrambling algorithm, and I can choose the bit-rate. (I have much ...
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1answer
67 views

PCB 6-layer stackup trace reference

I am designing a 6-layer board, with stackup like this: 1-TOP slow North/South 2-GND 3-Signal high speed East/West 4-Signal high speed North/South 5-VDD 6-Bottom slow East/West PCB plane spacing is: ...
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89 views
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1answer
64 views

Distance required between two wires to avoid EMI

I am running 3 cables cables from a solar heater down to my apartment (around 12 meters), one to power an electric heater and water pump (around 2000 watts in total), one to control a 12V solenoid and ...
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57 views

Electro magnetic interference with Arduino Uno and a portable radio

I'm surprised when I'm working with Arduino Uno, by just sitting beside a portable radio, like when I was powered on both Arduino & Radio and when they are close to each other I got some noise ...
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1answer
46 views

Issues with designing ground plane for switching relays in high noise environment

I am designing a PC Controlled 8 channel Relay using AVR microcontroller. Here, the relays are on the right side of the board and are controlled by the AVR micro on the left side. The eight TTL ...
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1answer
69 views

Proper connection of choke coil in ethernet magnetics

I need to use the medical ethernet magnetics by Pulse HXU6200NL (it is the only 2MOPP medical-certified PoE magnetics I can find). These are of the rather common transformer/choke coil topology. My ...
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1answer
102 views

How to connect a switch to a microcontroller in an extremly noisy environment

I'm currently working on redesigning the control circuit of a CNC machine (more specific: an Isel milling cutter). Only the digital part will be of interest, I'll keep the old power electronics (motor ...
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1answer
127 views

Converting dBuA to dBuV at 3m and 10m

I'm looking for some advice on converting from dBuA/m to dBuV/m at 10m. I'm trying to convert 10dBuA/m @ 10m. I'm struggling with the uA to uV conversion at distance and can't find online tools to do ...
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1answer
80 views

Problem while simulating EMI Filter for power lines

I was designing an EMI Filter for the CE102 standard. I was a bit confused on how to provide noise source to the circuit, since (as of my knowledge) EMI noise enters our system by parasitic ...
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1answer
122 views

How do I specify a low RFI LED driver?

I bought a bunch of very cheap 18W LED lamps. I love them; they look great and the light is excellent, however the drivers throw out a lot of RFI and is interfering with my radio (quite bad at 50MHz, ...
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2answers
67 views

SPI, RS232 and DMX-512 data signals beneath the ESP8266-WROOM-02 Wifi antenna

I am working on DMX-512 Controller, which will accept commands for driving Addressable LED strip (GE60RGBW8812A) via ESP-WROOM-02 Wifi Controller and I have several data lines (...
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2answers
174 views

EMC Testing, Radiated Emissions

I recently had one of my new rechargeable Lithium Ion products tested (RE pre-compliance scan) and I had a few frequencies (around 150 MHz) pop (7-10 dBuV/m) above the FCC and CISPR limits. I'm not ...
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128 views

In LTspice can I convert the units of an FFT which by default seem to be shown in dBV to dBµV?

In LTspice can I convert the units of an FFT which by default seem to be shown in dBV to dBµV? Cause of reason: The reason for this is that I've a modeled a LISN in LTspice where I want to simulate ...
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1answer
89 views

Need help to newbie to understand MIL-STD-461 [closed]

why only 10khz-10Mhz is used for CE102 test ? why not other frequency range is used for CE102 test ?