Questions tagged [emi-filtering]
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189
questions
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39 views
What's the difference between these two differential mode EMI filters?
When I search for differential mode input EMI filters (for power supplies), I get two different filter types:
simulate this circuit – Schematic created using CircuitLab
What's the difference ...
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0answers
26 views
Ceramic Capacitor value for 24v 10A DC Motor
I'm running 24v 10A DC motor in my robotic system. For eliminating the EMI, I need to use ceramic capacitors at the terminals on motor side. Can anyone suggest me the the capacitor value to be used at ...
0
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1answer
40 views
EMI Filter for Buck Converter
I'm trying to design an EMI filter for a buck converter and I'm following steps on: AN-2162
Here is the question:
At page:6, for the Cf capacitor; two different capacitor values are calculated and ...
1
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1answer
52 views
Why Does a Shunt Cap Help For Deglitching Digital Signals?
In some of my projects I have digital pulse signals that are sent over fairly long wires (~12in). For example tachometer readings or stepper signals.
I've tried various things to reduce glitches in ...
2
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1answer
69 views
What types of cables do ferrite beads/chokes have a beneficial effect on?
Ferrite beads prevent electromagnetic interference from affecting a cable. Without fundamentally understanding how EMI works, this is obviously a beneficial effect for the stability and integrity of ...
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21 views
Conductive Emission Help needed
Conductive Emission Help needed :
Have a DC to DC converter 28 VDC to 12 V DC 2A , that is loaded by a PWM load , the supply wires contain unwanted Differential and common mode conductive Emission ...
2
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1answer
45 views
How do I choose a value for an X-capacitor?
I am working on designing an EMI input filter, and I was wondering how I should go about choosing a value (capacitance) for the X-capacitor. I found a post (linked below) which talked about ...
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2answers
103 views
Power Supply Input Filter
Can anyone explain why the two capacitors (C8, C9) in the CLC input filter are set up the way that they are? The screenshot is from this reference design:
https://www.ti.com/lit/df/tidryx8a/tidryx8a....
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25 views
What Common Mode Choke choose for EMI filtering at 250v
I'm designing a PCB with a microcontroller that have to handle 3 Relays. The main power source is an AC Inlet socket 250v, the maximum current for all the circuit from this source is 15A (I included a ...
2
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1answer
68 views
EMI Input Filter Design
I have been reading and watching TI's material on EMI input filter design, and I have a few questions.
My basic question is "How do you select the component values for your EMI input filter?"...
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2answers
61 views
Reasons for glitches observed on PCB from physical touch of floating enclosure
I have a circuit on a PCB on which Iām observing āanalogue glitchesā when making physical contact with the enclosure.
This enclosure is from ABS and there is a circular connector on one side for ...
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1answer
147 views
Is a ferrite sleeve better than a low-pass filter in order to protect a PCB from EMI caused by lightning
Follow up from previous post. This post is different because I am now focusing on the power cable and thus the power input of the PCB.
This post is related to the EMI produced. I wrote a different ...
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100 views
Servo motor and EMI noise on peripheral devices (microcontroller)
I have 6 servo motors (DELTA ASD-A2-0121). Peripheral devices are affected by EMI noise (When motors are in on state and have no movement). I have changed the ground system from series mode to ...
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0answers
29 views
EMI input filter for DC/DC converter
In my design I want to convert a 48V input voltage to a 12V output voltage. In order to achieve this I want to use the AVD120-48S12-6L. The following external circuit is stated as recommended:
However,...
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0answers
33 views
EMI about Y capacitor and common mode noise
I do not get how the capacitor localized between the input voltage and the earth can help to reduce the common mode noise as the input voltage is at a voltage which is fixed and the earth voltage is ...
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0answers
33 views
Filtering Ethernet lines
I'm designing a product where we have an ethernet cable from a Raspberry Pi inside the machine going to a PCB with two RJ45 connectors on it placed at the back of the machine. This "routing" ...
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34 views
EMI consideration for Microwave Sensor Module
I'm using Microwave Solutions MDU1720 datasheet with recommendation that The length of leads connecting the MDU to the signal processing circuitry must be minimised, to reduce pick up of ...
2
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0answers
47 views
Which ground plane connection will perform better in terms of EMC? [duplicate]
In figure 12 of these EMI Design Guidelines
for USB Components, I can see that VBUS and Gnd signals from
the USB receptacle are bypassed with ferrite beads and then connected to their respective power ...
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48 views
How to “clean” a DC brushed motor : noise on CANbus even without moving!
We have very odd problem with a DC brushed geared motor that we are driving with a classical H-bridge chopper (20kHz PWM at the moment). The motor kinda looks like a Mabuchi from an R/C car but with ...
2
votes
2answers
162 views
Accuracy problem with simple thermometer project
I have built a simple circuit that should send temperature mesurements using a radio module.
The main component are:
Attiny84a microcontroller
RFM69HW transceiver
LMT86 sensor
The project is powered ...
1
vote
1answer
56 views
How to implement EMI filter in an N-redundant supply?
I am designing a dual supply powered system, where certain loads, depending on some conditions will be powered by one or other power rail, in order to achieve some safety levels.
The problem arises ...
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0answers
49 views
Does adding a line impedance stabilisation network reduce the output of buck converter in simulation in LTSPICE?
I have modelled a 48v to 12v buck converter in Ltspice.When I added a LISN the output reduced from 11v to 6.3v but EMI remains the same.Is it okay if output voltage is reduced?
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1answer
44 views
Interference suppression coils for 9V DC adapter for audio equipment
I am about to add voltage regulation to an unregulated 230V AC to 9V 150mA DC adapter, by adding an L7809 voltage regulator and ceramic 0.33ĀµF and 0.1ĀµF capacitors.
I want to use this adapter to power ...
0
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0answers
65 views
Blown ferrite bead, need replacement
I'm repairing a Nintendo switch dock and I found that a ferrite bead has blown. The problem is that I donĀ“t really know how to identify the ferrite bead that I need. Can anyone help me? If it helps ...
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44 views
Whether a half bridge SMPS based on MOSFET or another one based on BJT will generate more switching noise at the output?
Whether a half bridge SMPS based on MOSFET or another one based on BJT will generate more switching noise at the output?, if other parameters such as output voltage, current, type of transformer core, ...
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0answers
36 views
PH 4502 electrical interference EMI when in aquarium
I'm trying to get a regular ph reading in an aquarium.
The sensor works well when the probe is in a small quantity of water(i.e. a glass) but has large variations in larger water quantities (i.e. ...
1
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2answers
55 views
Do I need to worry about EMI/RFI/etc. for 110V and 12/5V electronics in the same electric panel?
I am building an electric panel (steel) which will house automation equipment in my home. The box is 20x20x10 inches and will include the following (all attached via DIN rail):
12v and 5v switched ...
1
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0answers
35 views
Solution for EMI on signals in a connector?
I have PWM signal and PSU signals coming from switch mode PSU to our machine.
The motor drive boards that run the stepper motors in the machine are located in the PSU.
At the moment the outputs to ...
0
votes
1answer
50 views
Difference between EMI filter and RFI filter
I always see EMI filters on power entereing of machines. They have generally circuit something like a below:
The machine that I investigad has noise limitter filter that called RFI filters on ...
0
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2answers
119 views
EMI Signature in electronics
What do we mean by EMI Signature? (Both theoretically and physically speaking)
1
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2answers
58 views
Why common mode filters are usually found on AC input stage and not the output stage of an isolated smps?
Title explains the question, I believe.
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0answers
58 views
Why does my new, primary side EMI filter capacitors explode?
I have a HP 8568A (+ HP 85662A display module) spectrum analyzer.
In the last 2 days, I had 3 caps that released the magic smoke.
On the following schematics there is a capacitor C1 that I marked. The ...
4
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5answers
1k views
Question on EMI filtering
I have seen people using ferrite beads to suppress EMI from switching power supplies.
Recently, I came across the following blog post where the author successfully re-models a switching power supply ...
4
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2answers
179 views
Why are engine spark plugs w/o resistor so potent killers of electronics nearby them?
I've recreated the ignition coil part of a small Honda ICE (typically used in lawn mowers or single-digit kW gensets).
I use an electric motor to turn a flywheel taken from a dead engine, and I've ...
2
votes
2answers
70 views
Input power protection for PAN4820
We want to design a telecom compatible power entry circuit with 48V 20A rating for a student project (design of a telecom equipment with 48V DC input power) using PAN4820 devices.
The schematic ...
0
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1answer
46 views
What are the types of devices that should use analog ground?
As the title says, what are the components that require a separation from the digital ground?
For example, currently, I have a PCB where the microcontroller is powered and grounded to analog ground ...
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1answer
43 views
snubber circuit or opto isolator with relay
I have a relay module link with a built in opto-isolator circuit.
When there is no load connected to the relays, the relays switch as expected. But when an inductive load (240V 0.5 HP) motor is driven....
3
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3answers
793 views
Reason of using diode between common mode choke legs
I'm investigating SMPS circuits. And I couldn't understand why there is a diode beetween common mode choke legs (I don't know exactly but it seems like signal diode) What is the main reason of using ...
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0answers
162 views
SMPS Grounding and Earthing
I'm trying to design the isolated SMPS circuit. I'm a newbie on power electronics and I'm using a circuit design tool to design SMPS. I have confusion about grounding and earthing. My system will have ...
5
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4answers
3k views
Should a ferrite bead be placed close to the MCU or close to the power supply?
I am trying to design a PCB based around the STM32F446RE microcontroller. I looked at the schematic provided by ST for their Nucleo-64 board, and physical placement of the ferrite bead on the board.
...
0
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1answer
57 views
I/O panel filtering for shielded room
We are looking into setting up a very basic shielded chamber inside a small room at my company to be able to perform some basic relative radiated EMC measurements.
We will buy a somewhat cheap ...
3
votes
1answer
160 views
Connecting USB shield to system ground [duplicate]
I designed a PCB with an STM32 and a micro USB connector. I put a NUF2042XV6T1G between the connector and the STM32 to protect the data lines. The USB shield is connected to system ground via a 120R@...
1
vote
1answer
60 views
How to eliminate electromagnetic interference when counting pulses using a micro controller?
I have written a pulse counter program for ESP32 micro-controller, the counter counts the pulses correctly when there is no EMI interference but as I turn on the small AC drill machine the counter ...
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0answers
62 views
PI Filter After Bridge Rectifier - Inductor at Positive Line or Negative Line
I was reading the InnoSwitch-CE Family Datasheet for a design I'm currently working on.
At the Circuit Board Layout Recommendations section, it's stated that the inductor should be placed between the ...
0
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2answers
101 views
How to get rid of 19kHz electrical fields
The mains of my German flat has 19kHz electrical fields on hot, neutral and! ground wire.
I don't have to get rid of them entirely but I want to achieve 20dB reduction while sitting in front of my ...
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0answers
37 views
Reduce 50 Hz noise from robot-mower charger
I just bought a robot-lawnmower (Husqvarna Automower 105), which is working perfectly.
But the charging station is making a loud 50 Hz noise all the time, even without the robot charging.
I have ...
0
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2answers
157 views
Noise when using SPI LED driver on 2m cable?
I've made a 2 letter 7 segment display using this LED driver
https://www.st.com/en/power-management/stp16cp05.html
when I connect it with a 10-20 cm cable to my MCU board it all works OK, but fails ...
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0answers
118 views
What's a good method for filtering out glitches from stepper motor step signal?
I have a product which contains 2 stepper motors. I've been hardening the system against EMI and ESD.
It used to reset or crash when hit with static. I've been able to mostly eliminate this by ...
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0answers
55 views
Line Impedance Stabilization Network (LISN) ripple to measurement transfer function
While reading about LISNs, I was lost a bit.
The CISPR limits are in dBĪ¼V, so they're voltages. But are these an image of the current following IN the DUT?
Below you're see the LISN transfer ...
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0answers
22 views
Magnetic fields cause common mode noise
Here is the document that I am reading :
https://www.emcfastpass.com/wp-content/uploads/2017/04/an15.pdf
And here is the assertion :
I understand that a current flowing through a trace which ...
