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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Where can I find test labs for FCC and other unintended radio emissions testing? [on hold]

Where can I find labs where I can pre-test or certify an electronic product intended for sale, according to FCC fules?
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43 views

preventing Cell Phone from interfering with car cassette adapter [closed]

My old car has a cassette player and I use an adapter for my MP3 player. I was hearing strange interference occasionally and finally figured out that my cell phone causes that when a call or message ...
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58 views

Maximum Allowed inrush current in Eurpoe

Context: I am designing an device that is placed between the main AC network (230V 50Hz) and some consumer devices (PC, TV, etc..). My device is measuring the current drawn by the consumer device, we ...
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40 views

How to add/sum field strengths given in dBuV/m?

I'm trying to theoretically analyze the resulting field strength, R, from two devices with given field strengths (say r0 and r1), both represented in dBuV/m. My first intuition was to use R = ...
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162 views

Making aluminium conductive for an RF shield enclosure

I'm not sure if it's appropriate to ask here, but I would assume many people in electronics would have experience with this. I'm enclosing an RF sensitive PCB into an sealed aluminium enclosure. ...
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42 views

Dimming LED lights with PWM, driver quite far from LEDs, noise considerations

There were a few questions like this before, however I haven't found ultimate answer yet. I'm going to drive LED lights in my house with multi-channel driver (PWM controller + MOSFET Transistors), ...
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59 views

Basic surge and overvoltage protection

My requirements are: protect the device from surges according to IEC 61000-4-5 Class 2 protect from 400VAC long term overvoltage (working voltage is 220VAC-15%...230VAC+10%) IEC 61000-4-5 Class 2: ...
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51 views

FCC-approval and “modular” integration

I see that a PCB requires certification even if it incorporates a certified RF module, so EMC tests for spurious emissions will still be needed. Is FCC-approval needed if a Raspberry Pi is ...
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53 views

Kick-off Spread Spectrum Clocking

Need of SSC: Spread spectrum clocking (SSC) is a special way to reduce the radiated emissions of digital clock signals. These levels or energy is radiated and therefore this is where a potential EMI ...
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1answer
149 views

Will FCC EMC tests need to be redone?

In light of the new FCC rules that Chinese (and all non-MRA) labs will no longer recognised in July and all EMC tests need to be done at FCC-authorized Telecommunications Certification Bodies, for FCC ...
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3answers
66 views

Changing the value of capacitor

What is the effects of replacing signed capacitors with 4uF ones related to Emi Filter performance (Electromagnetic compatibility issues). We observed that the time with 4uF ones keeps longer (power ...
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56 views

20H rule EMI/EMC effectiveness

I have been doing some research into the effectiveness of applying the 20H rule to 4 layer PCB designs and have been finding some very conflicting information. Some sources (including a few IEEE ...
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47 views

Can I replace this filter with that one?

TL;DR: Can I replace THIS: 0.18uF X capacitor 2500pF Y capacitor 2x3mH inductance 1Mohm resistor 250VAC @ 2A with THIS: ...
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113 views

Transient protection to prevent microcontroller freeze - Selecting MOVs and TVS diodes

I have a circuit which contains an offline switching SMPS circuit (based on viper22a) converting 220V to 5V regulated down to 3.3V using linear regulator IC. This powers up an ESP wifi module and ...
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36 views

TRIAC Circuit triggered due to interference

I have a small circuit designed to switch on the lights in my room using a wifi-enabled microcontroller Particle Photon. The circuit is based on an opto-triac and TRIAC setup where the microcontroller ...
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1answer
75 views

How to protect IC for VCC surge?

I have on my circuit an integrated circuit (IC) that has been destroyed by some event. After the event, the component's Vcc pin was shorted to GND inside the IC. After measurement, it appears that ...
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2answers
190 views

DIY ESD generator (ESD-gun)

Does anyone have a simple ESD generator circuit for pre-compliance testing (3KV-20KV)? e.g. can it be built from the following? ...
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1answer
182 views

Spikes induced on PCB. EMC problem?

I designed the following PCB, where after testing a faced a severe (EMC related?) problem. This board houses an STM32F103 developing board. On the right of the PCB, there are 6 thermistors connected ...
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1answer
129 views

How can I observe rectifier switching noise?

I understand there is such a thing as rectifier switching noise. I would like to observe it on the bench, but I don't understand its causes well enough to design a test setup. Once in hand, I'd like ...
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2answers
41 views

Switcher discontinuous mode - potential EMI problem

I need to design switching mode power supply with input voltage range of 25V-45V and output voltage 5V@2A. Power supply must be ON while the system is in sleep mode(~1mA consumption). In that ...
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630 views

What does the Y capacitor in a SMPS do?

It seems that a well-designed SMPS has a capacitor connecting the ground planes of the primary and secondary sides of the transformer, such as the C13 capacitor here. What is the purpose of this ...
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2answers
416 views

How to measure EMI without special equipment?

I have bought a cheap dashcam to play with, only to discover that my GPS receiver stops working when it's on. After I ruled out power supply issues (both devices have batteries), I'm left with a ...
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1answer
87 views

Blocking RF on same side as PCB antenna?

I have a penta-band GSM transciever on a 4-layer board, along with a matched chip antenna. Similar concept to ...
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2answers
75 views

Will EMI strongly affect my sensor reading

I'm using an Arduino to read analog values from my sensor running at 5V using a voltage divider. The sensor contains a force resistive sheet where the resistance of the sheet decreases as force is ...
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1answer
47 views

Alternative Gigabit Ethernet Connector - considerations for impedance, signal integrity, and EMC considerations?

I have a design that does not have enough vertical clearance for a standard RJ45 socket. I'm hoping to use a connector like this one from Molex. I will use Cat5e cable when building my cable with the ...
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35 views

WIre length in Conducted emission test

What should be the Minimum or maximum input power cable length can be used in Conducted emission test. Length from EUT(DUT) to LISN. What if my product come with input cable length out of MAX limit. ...
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46 views

Transceiver and RF Emissions (Unintentional)

My question is simply what is RF emissions (unintentional) and how does it relate to a device (such as a smart phone) which contains a transceiver or transmitter (baseband IC) ? Which part of a RF ...
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55 views

Expanded standard deviation in logarithmic scale [closed]

Hello and good day to all. Referring to picture attached I have a question. . I am working on different measurements and trying to find the mean and standard deviation values of these ...
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72 views

12V vs 5V servo

I am looking to actuate a throttle on an internal combustion engine. I am using a 5V servo driven by an Arduino Mega2560 at the moment. The throttle is very close to the engines alternator and there ...
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72 views

Avoid EMI in power circuit controled by MCUs

This is a toy project just for fun. As anybody knows, if I want to control a lamp by a simple switch, the circuit is as follows: However, I want to change the circuit so I can control a lamp with ...
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3answers
437 views

EMC testing vs. EMI testing

What is the difference between EMC testing (Electromagnetic compatibility) and EMI testing (Electromagnetic interference)
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161 views

Are these EMI noises?

I have always heard about EMI noises but have not really meet them or measured them. Our system composes a MCU running at 168MHz and a 16-bit DAC which is supposed to provide high-precision voltages ...
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44 views

Image current and return current

I find I'm a little confused about "image current" and "return current" in PCB/EMI/EMC design. Are they equivalent? Many docs use this model when talking return current Exactly, I will treat the ...
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2answers
112 views

Ribbon Cable Noise Susceptibility

As part of a product upgrade we are looking at replacing looms of wires bound together by cable ties or spiral wrap with ribbon cable. We are doing this to try and cut cost and assembly times. We are ...
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171 views

Signal and power integrity - 4 layer board

Let's assume that we need to design Mixed signal PCB with 2 fast integrated circuits(tr_min = 1ns) operating at different voltage levels(3.3V and 4V). There are however other voltage levels on the ...
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26 views

Electric Vehicle Temperature Monitoring

I'm looking to implement a system to monitor the cell temperatures of about 80 cells in a 240-cell battery pack for an electric vehicle (yes, at least 80 cells must be monitored). I'm looking for a ...
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3answers
192 views

What is the thought process for specifying an EMI bypass cap on line transformer secondary?

Update It turns out I had mistakenly interpreted the role of the capacitor in question here as an EMI filter for line noise. It looks like a capacitor in that position actually serves as a snubber ...
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53 views

Is 'RFI' a term in active usage, or is it all 'EMI' now?

I'm studying capacitors in some detail just now, and one of their typical uses, of course, is to bypass high frequency interference at sensitive circuit inputs. I want to get my terms straight, and ...
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56 views

Buck regulator frequency

I am trying to use a buck regulator. Usually I make it use at its Max frequency and then just use it. But now, we want to go for Emi and emc certification. I am hence told that this switching (a few ...
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1answer
50 views

USB 3.0 LC circuit on shield

I am designing a circuit with USB 3.0, and looking at the reference design from Cypress in the link below. SuperSpeed Explorer Kit User Guide (CYUSB3KIT-003) I see on page 47., that the USB ...
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1answer
114 views

Polarity of USB common mode choke

Can I reversely route the data polarity to USB common mode filter below? Namely, connect USB trace D+ to the filter pin D- to simplify layout. ...
1
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1answer
112 views

Switch-mode power supply and EMI on input power line filtering

I'm trying to reduce some switching noise I'm seeing (using LISN & Spectrum Analyzer) on my input power cable. My SMPS operates at 1.2MHz. I have room on the PCB and I'd like to place a SMT common ...
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70 views

Direction of E1 and E2 in phasor diagram of transformer

The phasor diagram of transformer is a bit confusing. Is E1 and E2 have same direction? Different books mention it differently. Please clarify!!
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44 views

EMC shielded box with transparent window?

Is there such a thing? I would like to put my board in a box to isolate it from radiated emissions externally and also limit emissions from the board to the outside. I would also like a transparent ...
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1answer
19 views

redundancy checks and protection on monolithic and MMICs

I am using the ISL8026A chip for voltage regulation from 5 to 3.3V. The datasheet is - datasheet. Now, this is merely an example circuit. Now, I would like to design a power supply for a hi ...
2
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2answers
48 views

EMC Filter and Vintage Electronics

Does anyone have any opinions about using an EMC Filter to protect vintage electronics? I'm referring to very sensitive jukeboxes, pinball machines and this kind of stuff. I have some machines that ...
2
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1answer
75 views

Converting a three-wire system's “EMC filtering configuration” to a two-wire one

I'm designing a board which has -48V input. For the power module, I'm considering using KSTW010A0A Barracuda from GE(DOSA compliant 1/16 brick, Isolated DC-DC Converter) In the datasheet, there is ...
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56 views

EMI RFI housing / protection. capacitive touch

Can i create a effective capacitive touch(hover) button? Since the first day (playing with mcu's) i was impressed about the capacitive touch lib. The first time everything worked perfectly i wanted ...
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1answer
103 views

Conducted Emission Fail at High Frequency

Good Morning All We run Conduction emission Test on Lab with the Line filter and without the line filter. Product was 230V 16A welding Power supply. Below are the graph with line filter and without ...
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Latch-up and ESD protection for power supply and RS-422

I am designing a power supply board that has a switching regulator and four LDOs. Now, I understand that layout details or practices will help reduce switching noise from corrupting the ground and so ...