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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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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 ...
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30 views

Noise testing method

I have Electronic board with power supply , control board etc. I wanted to conduct noise test . Is there any standard procedure available. I wanted to check if i induce the noise into power line or ...
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How to perform parasitic extraction in CST Studio?

I'd like as the title suggests to perform a parasitic extraction of an inverter PCB design using PEEC Method in CST Studio Suite but, unfortunately I can't seem to find documentation or resources ...
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50 views

VCC on surface or inner layer on 4-layer board?

If I can get away with, I will use 6-layer design where I get two dedicated GND planes, L2 and L5, which creates strong reference plane for traces on L1, L3 and L6. When you're working with 4 layers,...
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Why are “devices utilized exclusively in any transportation vehicle” exempted from FCC compliance testing?

I was researching whether do we need to do FCC compliance testing for a device we developed for a client. Curiously, it seems to be in the list of exemptions (passage taken from here): A digital ...
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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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102 views

Viable alternative for expensive MLCC capacitor?

I'm thinking of building and selling a product which uses a DC-DC isolator. I've been prototyping with Recom RI3 3W Isolated DC-DC Converter Through Hole, Vin 5 V dc, Vout 9V dc, I/O isolation 1kV. ...
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48 views

Overloading of ESD protection diode on CAN lines through current during Bulk current injection - test

I have a design checklist question for a typical CAN circuit for an automotive application as below : The question is related to the ESD suppressor : "Was a capacitor parallel to the diode considered, ...
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30 views

Placement of RC filter used for slew rate limiting (for EMC)

I've seen RC combinations used on many circuits now which i believe have been included for slew rate limiting. They usually feed off to a connector. Do the placement of these matter in the circuit? ...
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48 views

Which areas do I remove copper pour to reduce noise?

I have a 2 layer PCB that carries a microcontroller (Particle Electron), connects to a sensor with an ADC reading, has an ADC comparator IC, a watchdog timer IC, a PNP switch, an power bus and I2C ...
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52 views

How protect analog input connected to thermistor through long wires

I'm developing a data acquisition board for 8 thermistors hooked up through 3 feet wires. The board is gonna be installed inside a package unit air conditioning. In there, we have compressors, fan ...
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1answer
34 views

Inductance value of PI-filter connectors?

I find myself in the situation of being forced to use filter connectors to solve an EMC issue very late in the project. Normally, this should of course be solved in circuit design, but as projects and ...
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39 views

An electromagnetic wave incident on a closed loop

Consider the following diagram : Both the electric and magnetic fields will induce a voltage in this circuit. In more details, the component of the electric field that is in the plane of the circuit,...
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1answer
36 views

Comb generator vs. known EMC emitter - different measurements in shielded tent vs. 3 meter chamber

I've got an EMC testing setup of a 1 meter shielded tent, and a very high gain EMC antenna. I'm seeing a phenomena that I can't quite explain. I have a known product that was tested in an accredited ...
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26 views

Bulk Current Injection on CAN bus

I'm trying to understand how the Bulk current injection would look like on the CANH and CANL lines, to understand the overloading of the ESD protection diode on the CAN lines and capacitors in ...
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1answer
67 views

SAMD controlling BLDC resets during high current spike; EMI problem?

I have been making a brushless DC motor controller that is controlled through an ATSAMD21E16L and a MIC4609 mosfet driver. At low average currents of 2A or so, I drive the motor just fine, but when I ...
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92 views

High Frequency Characteristics of Solder-Filled Vias

If a via gets plugged with solder, does this destroy its ability to pass high frequency (RF noise) currents? Since there is no longer a surface along which the high frequency currents can travel due ...
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1answer
39 views

Ferrite beads with turns

I need to understand the meaning of this word "2 1/2 turn ferrite bead" ?? What exactly this 1/2 means ? Does this means that the wire is turned twice inside the bead?
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62 views

Common Mode Chokes

Consider the following : If we need to figure out the input impedance seen by the source, it will be equal to --> Zin = jw(30u) -jw(27u)+1k+jw(30u)-jw(27u). The first two terms are due to the drops ...
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Impedance frequency response for a DC motor

Consider the following impedance frequency response for a DC motor : Its equivalent circuit is : Clearly, from the response, there exists a capacitor, inductor, and resistor, but my problem is how ...
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2answers
61 views

Is this quote about interference from wireless charging coils accurate?

This blog post suggests that apple dropped their promised AirPower wireless charging mat because it didn't pass EMI standards, specifically due to the (unconfirmed) idea that they were using a large ...
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1answer
78 views

What is the proper placement of VCC and GND copper pours in 4-layer PCB?

This is my first PCB design and I'm struggling with proper copper pour usage. I would like to copper pour VCC and GND. From what I understand, a copper pour will net multilayer plated through holes ...
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88 views

PCB GND Guard ring

In my design I am using the step-up converter TLV61046a. As this is the switching device, I would like to maximize EMI reduction. I would like to hear your advice if this GND guard ring in my layout ...
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Is my simple atmega2560 based product exempt from EMC testing?

I have designed a product that is essentially a USB HID device for a computer game. It consists of several on off switches and 5v servos run by an atmega2560, all sealed and enclosed in a plastic case....
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26 views

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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1answer
50 views

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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27 views

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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1answer
57 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
50 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
116 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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1answer
44 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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45 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
67 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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950 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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1answer
63 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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2answers
90 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
73 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
216 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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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
57 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
66 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
827 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
125 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
114 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
67 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
39 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
109 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-...