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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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1answer
85 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-...
4
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2answers
67 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 ...
2
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0answers
71 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, ...
2
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3answers
100 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
69 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 ...
1
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1answer
54 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 ...
0
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1answer
45 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 ...
0
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1answer
38 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
61 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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0answers
64 views

CAN transceiver - resistor on TXD,RXD lines

could someone please tell me why series resistors are used on the TXD, RXD lines of a CAN transceiver while interfacing it with a microcontroller. I've read a few application notes where they suggest ...
0
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1answer
37 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 ...
0
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1answer
60 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 ...
0
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0answers
20 views

Emc filter servo drive

This is a circuit diagram for a Lexium 28 servo drive and associated BCH2 motor. The manual states that the drive should be fitted with a VW3A4420 EMC filter Can anyone please confirm if the ...
0
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1answer
62 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: ...
0
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0answers
30 views

Input filters on AC/DC converter

I am using a board mount AC/DC converter and after adding an LC filter at the DC output of the converter to remove high frequency noise going to the circuitry, the noise is now reflecting back down ...
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1answer
83 views
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1answer
57 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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0answers
52 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 ...
0
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1answer
44 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 ...
0
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1answer
46 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 ...
0
votes
1answer
75 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 ...
2
votes
1answer
79 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 ...
3
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1answer
66 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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0answers
25 views

VITA 46.0 VPX grounds isolation requirement

VITA 46.0 VPX standard demands: Rule 3-15: Plug-in modules shall provide a minimum dielectric withstanding voltage of 500VDC +/-10V and a minimum resistance of 1 megaohm between safety ground and ...
0
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1answer
75 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
48 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 (...
3
votes
2answers
125 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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0answers
88 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
85 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 ?
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2answers
80 views

What could cause impulse noise on switch closure

I have a simple SPST NO Tact switch which is creating a noise pulse in a very sensitive receiver. Moving the switch, shielding etc is not possible. I need to understand how the switch is creating ...
0
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1answer
44 views

Unit conversion: dBμV to dBm, including measured frequency

I'd like to ask for help with conversion of measured voltage V=10dBμV to dBm units. Voltage is measured on frequency ...
1
vote
1answer
91 views

Automotive battery input EMI filtering

I'm reviewing the schematics for an evaluation board, which uses an LC filter on the DC input as shown here: PWR_IN is defined for the evaluation board as being 7-27V. The issue I'm facing, is where ...
0
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1answer
41 views

Non-isolated DC power distribution for an appliance

I am building an appliance where we have a device where we need to have a +48 V/300 W DC power rail and a +24 V/300 W DC power rail. The AC (mains) should be world-compatible (both low- and high- ...
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0answers
41 views

CAN Isolator function

Why is a CAN isolator used? Known background theory: The CAN isolator is used in order to protect against surges / EFT's, reduce the effect of ground loops (common mode EMI) and eliminates voltage ...
1
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2answers
51 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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2answers
95 views

Legal to use non FCC-approved radio devices purchased locally?

Does anyone know if it's legal to use non FCC-approved radio devices which are purchased locally? For instance, if the device is purchased from a local eBay seller, is it still legal to use it in any ...
0
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1answer
63 views

Using neighboring traces for PCB return current

I am developing a 2-layer board for a 3-channel BLDC motor driver. I am using an IC for the driver (DRV8313). I will PWM it at 20kHz with around 10% or less duty cycle. Current is less than 1A. It ...
0
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1answer
66 views

PC monitor flickers/resets when washer motor switches on or off [closed]

My room is next to our laundry and I've recently got a new PC monitor. I've noticed each time the motor in the washing machine is switched on or off, my monitor flickers/resets. The monitor is 32" but ...
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0answers
33 views

Switching a power contactor from an arduino / raspberry

I'd like to switch a power contactor (such as this one : https://www.legrand.fr/pro/catalogue/31925-bipolaires-250-v/contacteur-de-puissance-cx3-bobine-230v-sans-commande-manuelle-2p-250v-25a-contact-...
4
votes
3answers
214 views

Class D power supply filtering for conducted emissions

I have recently designed an audio player that uses the TI TPA3112D1 power amplifier, and mostly based it on the reference design and schematic. I find however, that the design is failing the ...
0
votes
1answer
64 views

Feed through capacitor

I have 2 feed through capacitor NFM21PC475B1A3 & NFM21PC105B1C3. These haven't the same capacitance. I want to separate them but I can't measure. Help me what should I do?
0
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1answer
104 views

Impedance mismatch in LISN for EMI/EMC test

I am currently designing LISN for CE-102 test.The schematic of the circuit is provided below. When I connect the circuit to the network analyzer the impedance is coming as shown below expected graph ...
0
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1answer
67 views

Routing the signal across the slot opening in the power plane

What happens when we rout a signal trace across the slot opening in the underlying power plane ? Can you please explain the signal integrity issues generated by this mistake ? And what will happen if ...
2
votes
1answer
117 views

Suppressing “travelling” EMI spikes

I am working on a circuit with a AC to DC power supply module and wireless MCU module. The MCU operates at 240MHz and on the power input to the module there are 2 x 0.1uF capacitors and a 22uF ...
1
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1answer
62 views

EN 50121-3-2:2016 radiated immunity frequency range gap

I was just reading EN 50121-3-2 (Railway Applications – Electromagnetic compatibility – Part 3-2: Rolling stock – Apparatus) and noticed in Table 5 that there is a gap in the test frequency between 2....
0
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1answer
63 views

Connector's placement - EMC [closed]

Why placing connectors on the same edge of the PCB is recommended as an EMC design guideline? As mentioned in https://learnemc.com/pcb-layout All connectors should be located on one edge or on one ...
4
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3answers
280 views

PCB design - signal loops

I've read about loops that a PCB designer should avoid them "mostly about ground loops" but i think I've read also about power. so in this case, is this wrong: ???
0
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1answer
50 views

Car 12V Supplied device - Requirements

I am currently designing a device that is intended to be used outside the car and supplied by car 12V socket (also during the drive). The question is: Are there any specific requirements for example ...
1
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1answer
65 views

How to perform conducted emissions testing for electric generator?

I am doing pre-compliance EMC testing on an electric generator. The standard I am reading explains how to test devices that get power from mains, but it doesn't explain the testing procedure for a ...
0
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1answer
26 views

Netfilter (230VAC) without protective earth (PE)

I need to filter my mains input, but I don't have any protective earth (PE). Will a mainsfilter (schaffner for example) still be usefull? I think so. I think the mains filter despite of not being ...