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 ...

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Quasi-peak detector

This is the circuit of a quasi-peak detector: simulate this circuit – Schematic created using CircuitLab where \$ V_{sig}\$ is the input signal. When the diode is open-circuited, the ...
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36 views

Deliberate Shoot-Through in H-bridge for EMI reduction

today I was analysing an H-bridge driver circuit in a commercial product which is used to drive a DC motor (approx 24V/4A) over an unshielded cable with about 1.5m length. When I did a simulation of ...
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76 views

How do I properly size components for an EMC filter for a variable frequency drive power supply?

One of the products my company designs is, essentially, common bus power supplies for variable frequency drives (VFDs). Thus far we have only sold into the United States. We are considering selling ...
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2answers
636 views

Why are caps configured this way in EMC filters?

Every EMC filter I've seen has capacitors between the AC lines and earth, configured like this: simulate this circuit – Schematic created using CircuitLab Why are the caps not configured ...
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41 views

Does inductive back-EMF create significant radiated emissions on long load wires?

So, lets say you have a switch connected to a small inductive load (say, a single speed ceiling fan) via a long wire (1000' of NM). When the switch is turned off, how much of the energy from the ...
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65 views

X-rated capacitors required for DC input voltage circuits

In my project I am using 12V DC from external power supply and EUT will load max 2A; in which I am using EMI EMC filter. I have considered Input MOV’s for common mode and differential modes, ...
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1answer
31 views

questions on shielding static magnetic field

It seems that using ferromagnetic materials is the easiest way to shield static magnetic field. But is it still working in strong field strength(up to 5T)? Another question is that are mu-metal ...
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40 views

Possible ways of protecting comparator input from coupling?

Overview So as I'm implementing some logic with a comparator, I've run into the problem of the output swing coupling with one of the inputs, and now I'm searching for possible ways to minimize or ...
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1answer
149 views

How serial resistors actually reduce EMI?

I am recently working with a GSM based system, and there was this advice in the datasheet of the GSM module: 22Ω resistors should be connected in series between the module and the SIM card so as ...
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16 views

EMC simulation using FEKO

I am trying to simulate a lens antenna using feko by illuminating it with a Yagi-Uda antenna radiation pattern. The problem is that the simulation can't be completed because radiation pattern (in ...
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2answers
83 views

Perpendicular tracks in 2 different layers (PCB)

Many times ago I heard it's not good to have 2 perpendicular track in 2 different layers of 2 layers PCBs(I mean one track in one side become perpendicular to another track in other side of the pcb) . ...
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63 views

EMI filtering at end of a long copper wire transmitting high DC power

I have a long (20 - 50 m) copper wire for supplying DC power. One one end there is a AC-DC converter supplying 600W-1000W of power at 60V output. At the other end I have a switching type (100-140 kHz) ...
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1answer
83 views

How do electric and magnetic fields affect electronic circuits?

I have come across those requirements: "The equipment shall not be susceptible to DC magnetic fields of up to 60 μT." "The equipment shall not be susceptible to electric fields of up to 140dBuV/m ...
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1answer
63 views

Function of Glass bead on EMI Filter Legs

I am looking at a PCB that has tiny glass beads on the input and output legs of an EMI filter. The middle pin goes to GND. What is the purpose of the glass beads? Couldn't get the focus quite right ...
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42 views

Preventing High Frequency EMI on Headphone Output

I am working a project with the following final power amplifier for audio output. What is best practice to prevent injecting RF EMI onto the cable from the MPU(tens of Mhz) and another radio ...
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1answer
53 views

Thermocouple temperatures change drastically when my whole system is powered vs when just my arduino is powered

I apologize in advance if this should instead go in the Arduino stack exchange, but I feel it should be here. I'm using this thermocouple / amplifier pair with my Arduino Uno. I am trying to make my ...
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1answer
71 views

Placing Ground Vias To Improve EMI

Placing ground vias all over the PCB (stiching) to improve the EMI. Have all ground vias to be spaced the same distance? Or may they be separated different distances if it is under lambda/8? I ...
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2answers
110 views

EMC considerations for driving a solenoid via PWM over a long cable

We're designing a circuit which essentially has the topology shown below. We're driving an inductive load (24V, 3.8Ohm solenoid - max avg current = 2A, but peak current can be 6.3A) using PWM. ...
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24 views

Switching power supplies, EMI and wireless communication (FSK)

I am writing to gather information about switching power supplies and EMI and its effect on wireless communication. Currently, I am involved in a project and I have to design and realize an FPGA and ...
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1answer
43 views

Shielded sleeve?

Does anyone know of sleeving that is basically a hollow tube with a metal shield? Something like coax but without the core? I need to take some unshielded wires and run them through a flexible RF ...
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2answers
54 views

What's the most effective way to prevent EM noise from coupling onto a cable and radiating out?

I've a PCB radiating noise inside a metal enclosure (this is Product 1 from this question here). Unfortunately, I can't change the PCB itself, so I'm having to tackle the problem by other means. I ...
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1answer
28 views

EM compatibility of single board computers and laptops

Like a lot of people on this site, I own some single board computers (SBC) and microcontroller boards (UDOO, Raspberry Pi, Arduino, Atmel boards, etc.). I wonder about the electromagnetic emissions ...
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2answers
101 views

How to convert 12v dc to smooth, as if coming from a battery, 6v dc (EMI – RFI free)

I’m an electronics newbie. I did a very simple project. In order to convert 12v dc to 6v dc I used one of those step down converters. Unfortunately what I’m trying to power is an AM radio. It power on ...
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2answers
115 views

unbalanced audio - shielding and ground loop for 2 ch

I have a 3 conductor wire that are all wrapped in a foil shield with wire conductor, for a total of 4 wires. I am connecting the 3 inside wires to audio left, right, and ground. This is an unbalanced ...
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1answer
51 views

I have read that a design which fails signal integrity shall have EMC issues

I have read that if a design has EMC issues and is emitting a lot of radiation, then there is a relationship with some signal paths not being properly terminated and/or there being signal integrity ...
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1answer
220 views

Resistance and Inductance of a ceiling fan motor needed to spec snubber

I'm looking to specify (well, suggest) a RC snubber network for someone over on diy.se who is having EMI problems with his ceiling fan knocking out his TV briefly on turn-off: ...
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1answer
150 views

EMI/ESD protection for USB interface?

I'm a student making a simple Arduino-compatible board similar to the Pro Micro and am going to put a USB connector on the board. The schematic in the above link doesn't show any kind of EMI/ESD ...
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1answer
174 views

Reducing EMI Radiated & Conducted

I have a switching regulator that operates at switching frequency of 260Khz that steps down a 28vdc to 3.3Vdc. The switching regulator output will supply current as high as 1 amp for the initial 5 ...
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2answers
200 views

Can a toroidal transformer be wired as a common mode choke?

I am looking to build an ac power line conditioner. It was suggested that I use a transformer with dual 6.3v secondaries wired in a common mode choke configuration. This is done by using the in-phase ...
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82 views

How to shield a USB device from high EMI

What is the best way to keep a USB device from disconnecting when exposed to a high EMI environment, such as when connected to a high voltage power supply under test? For example, in debugging a ...
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2answers
344 views

Electrical noise on guitar pickups from computer. Due to radio interference, or inductive coupling?

When I point my guitar pickups towards my desktop computer from several feet (2 1/2 - 3) away, I can hear a lot of buzzing/clicking, depending on what the computer is doing (idling vs, say, playing ...
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2answers
156 views

SMPS transformer orientation with respect to PCB: what's best for EMC?

I have the option of either using a vertical or horizontal bobbin for a flyback SMPS transformer, and I can't conclusively decide which would be best for minimal radiated interference to be picked up ...
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446 views

How to fix EMC problems for existing designs?

I'm going to be looking at a few products that have failed EMC radiated emissions testing and will need to apply fixes in order to make them pass (unfortunately, in these cases, two of the designs ...
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2answers
81 views

EMC, resistors and trimpots

I trying to get EMC certification and stumbled upon problem. In the above circuit, they will apply ESD to the exposed part of the trim pot, and it permanently changes the value of the trim pot and ...
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1answer
73 views

interference proof voltage regulated current source

I want to dim some LEDs, using the PWM output from a microcontroller. There are some more LEDs than in the schematic, already wired, so that they need nearly 12 V to give maximum light at about 50 mA. ...
3
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1answer
72 views

Making conducted EMI measurements in the presence of building-wide ground-fault protection for personnel?

As is documented here among other places, the Line Impedance Stabilization Networks used to make measurements of conducted EMI as per CISPR 22, FCC Part 15, and suchnot contain large line-to-ground ...
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3answers
102 views

Effect Of Electronic Devices In Close Proximity

From reading other posts, it seems like electromagnetic induction is the greatest threat to electronic devices these days with either traditional HDDs or newer SSDs. Since current in a wire creates ...
0
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0answers
64 views

EMI/EMC filters for different frequency sub-circuits

I am designing a PWM based solenoid controller. The PWM controller works at 23kHz with an average circuit consumption of 23-45mA. The PWM controller is powered by a non-isolated SMPS with 12V output ...
0
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1answer
54 views

Cable screen terminations for enclosure containing SMPS and instrumentation signal conditioners

I'm looking for some help with some screening and cable termination decisions I need to make. I'd be grateful for any advice, and I'll do my best to explain myself clearly. I am building a control ...
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1answer
82 views

Earth alternative

I'm designing an industrial machine which is AC motor derived. There are sensitive analog sensors (e.g. Load cell) in the system and in the user's site, Unfortunately earth connection is not ...
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222 views

How to calculate EMI filter (ferrite bead) specs for digital signal?

I have a small project of mine that deals with plain old VGA output (d-sub). In my project I'm using a CM2009 IC between actual VGA controller and VGA output connector. It's mentioned in the datasheet ...
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0answers
92 views

EMI & ESD protection for 3.3V signal

I am looking into options to protect the outgoing signals against ESD events and EMI issues. The device will be battery powered but GPS and radio modem are likely to be operated close-by. Frequent ...
0
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1answer
43 views

What's the correlation between spectral graphs produced using near field probes and ones produced using an antenna?

I've been looking at getting some equipment for EMC-precompliance on a budget (about £5k). I understand that I can get a spectrum analyser with some EMI options and some near-field probes (about £2k) ...
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4answers
840 views

What is the purpose of holes on edge of the PCB?

Here is a photo of one of Texas Instrument's RF EVMs. Please pay attention to edge of the PCB that has multiple tiny holes. I marked 3 of them with a red circle on the photo. What is the ...
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2answers
70 views

Suppressing interference in a pressure sensor circuit

I just looked over a circuit designed by my predecessor, which is used to interface with a pressure sensor. It works, but I have some doubts about the way the input filtering is done. The simplified ...
0
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1answer
62 views

Magnetic flux outside a solenoid perpendicular to the direction of axis of solenoid

I know that using straight forward Biot-Svart law it is possible to calculate field inside a solenoid or at a point on an axis away from the circular coil. Now is it possible to calculate the Flux ...
4
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2answers
102 views

Why the \$F_{knee} = 0.5 / T_{r}\$?

In "High-speed Digital Design - A handbook of black magic" p. 2, The knee frequency for any digital signal is related to the rise (and fall) time of its digital edges, but not to its clock rate: ...
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2answers
82 views

Thickness of low frequency Mu shield calculation

I am dealing with a low frequency varying magnetic field, say 10 - 100Hz with a magnitude of 0.8T. It seems shielding at this frequency gets tricky. Even though Mu is capable of doing it, there should ...
3
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1answer
132 views

Switching power supply using faraday cage and EMI protection?

Several switching power supplies in the market use this kind of cages to protect the circuit, however, i have this question, A) Is this used as a faraday cage due to the high frequency used by it? ...
4
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2answers
137 views

How to maintain EMI shielding whilst penetrating the shield with cables?

I'm trying to shield an ip camera from EMI generated image noise for low light photography. It's enclosed within a metal box that is then grounded. The subject is also inside the box. The camera ...