Questions tagged [ferrite-bead]

A ferrite bead is a passive electric component, which is commonly used for suppressing high frequency noise in electronic circuits.

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24
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5answers
14k views

Ferrite bead vs common mode choke

simulate this circuit – Schematic created using CircuitLab I inherited the top circuit from a previous designer on my robotics team. The circuit uses two ferrite beads, a zener, a TVS and a ...
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2answers
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Why not use a ferrite bead around an RS-232 cable?

This is from the instruction manual of a printer: As you can see, one is not supposed to wrap the supplied bead around the serial cable. What is the reason for this?
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Ferrite bead position

I wish to use some extra power supply filtering for my DAC, ADC, CPLD and OpAmp devices. In this question I got the point about the global locations for ferrite beads. If I understood correctly, the ...
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1answer
9k views

How to select a good Ferrite Bead

I am building a USB project and I want to use a Ferrite Bead in the USB 5V rail. I am looking for 1206 Ferrite Beads. How to select them properly? Which impedance at 100MHz is a good one?
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EMI Filtering on LVDS lines

This question is slightly related to: What's radiating on my PCB? These are Beckhoff's EtherCAT industrial IO modules. Each module is connected to its neighbours by 100mbps LVDS. Each module contains ...
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2answers
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What's the purpose of a ferrite bead inductor on this circuit?

I'm studying the analog voltage reference circuit described in the AVR450 Application Note - Battery Charger for SLA, NiCd, NiMH and Li-Ion Batteries, which schematic is below (copied from page 38). ...
8
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1answer
3k views

How do I choose a ferite bead for power supply filtering?

I want to put a ferite bead on positive SMPS supply rail that goes to analog part of the mixed digital/analog circuit. Now on parametric search at Digikey I can see several parameters: Current ...
7
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3answers
5k views

North American standard symbol for ferrite bead?

Many of the schematics I've seen in reference schematics use an the symbol of an inductor as the symbol for a ferrite bead (makes sense). But I've also seen other variants of it as well. I don't have ...
7
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1answer
240 views

What frequency is Ferrite Bead reactance usually given at?

I've noticed on schematics at work, when I was at uni, and on datasheets that Ferrite Beads usually (90% of the time) are only given with their designator (FB? or L?), then the reactance (XOhms) and ...
6
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1answer
2k views

What is the component on the schematic indicated by the symbol of a diagonal rectangle with a line through it?

I can't for the life of me, figure out what these diagonal rectangles are... Help?
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603 views

Regarding Ferrite Bead

What is a ferrite bead? How is it different from an inductor? How is it rated? What are its important parameters? What allows me to chose between an inductor or ferrite bead to filter out frequencies ...
6
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1answer
3k views

What does 100Ohm @ 100MHz exactly mean in ferrite beads?

I am trying to understand the parameters of ferrite beads and having trouble in understanding the impedance vs frequency parameter. What does 100Ohm at 100MHz exactly mean? Does it mean that the ...
6
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1answer
2k views

When has to be used a ferrite bead in power supply?

I'm designing a PCB with a Telit GL865 GSM/GPRS module. I find this example in Internet and I am wondering why has it got a ferrite bead on 3.3V power supply line. Some extre values from datasheet: ...
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1answer
212 views

Do ferrite beads need snubbing diodes?

Inductors, when applied as inline power filters, need a parallel snubbing diode so that when the load opens, the current can be safely discharged. In certain contexts, ferrite beads such as the Laird ...
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2answers
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Ferrite instead of LDO

Currently we are using the following power supply scheme: This solution effectively separates the analog sub-part of the PCB from the noise of the digital sub-part. Now we are going to use the ...
5
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1answer
242 views

Are bypass caps reason why uC don't have flyback diode across ferrite bead in the sample schematics?

Often the IC datasheet recommends putting a ferrite bead before AVCC pin. First I started wondering if I don't need a flyback diode but than I realized that capacitor is probably able to absorb the ...
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3answers
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Understanding Ferrite Chokes

I am looking to clean up the power supplied to a video transmitter on the UAV I am building. The video transmitter consumes about 200mA of current at 16V DC. The 16V line has noise from motors and ...
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3answers
26k views

Does the position of the Ferrite bead matter?

Often I will see a ferrite bead a couple of inches from one end of a cable. Does the position of a ferrite bead really matter?
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2answers
1k views

Why does this low-cost battery powered device use ferrite beads on the power input?

I have just opened up a small, low-cost motion-activated (by PIR) LED light as I am planning on just using the casing for another project. The PCB inside is clearly designed to be very cheap. It uses ...
4
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3answers
1k views

Fighting overshoots/undershoots using ferrite beads does not help?

I posted relative problem a while ago here but we came to conclusion that the overshoots were just artifacts. Later, when I extended the signal lines, the overshoots increased and were about 2V of ...
4
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1answer
507 views

Ferrite Beads Design

Currently learning about ferrite beads. I have noticed that on the data sheets they have graphs of impeadance vs frequency. to ensure you have the best ferrite for the job I assume you want to get ...
4
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1answer
2k views

How use ferrite bead to reducing noise from charge pump?

Old senior design project and in schematic I see he uses ferrite bead and capacitor after charge pump voltage output befor connecting to opamp input Circuit very simple: charge pump uses MAX232 to ...
4
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1answer
2k views

Ferrite bead for use for filtering a microSD card's Vcc

I am hoping to use a microSD card in an AVR project and am just trying to find values for all my components. However, I am not sure what value of ferrite to use here. The few microSD schematics that ...
4
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1answer
248 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 ...
4
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2answers
1k views

Where to connect shield and ferrites in PCB with isolated planes

I have a device which has two sections of the PCB completely isolated form each other, but connected by an isolator IC (PN: ????). I think I need to shield the whole device for reducing EMI because ...
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2answers
488 views

Magnetic core transfer loops (logic)

I have an interest in "alternative" logic gates, as in not silicon transistors. I have built RAM in a little game called "Powder Game", constructed "one-off" logic gates out of exploding lattices of ...
3
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2answers
212 views

Ferrite bead for high-speed digital IC

Although I've seen numerous recommendations for the use of FBs on the power supply rails of noise-sensitive analog circuitry, the opinions regarding their use with high-speed digital circuitry are ...
3
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1answer
790 views

EMI suppression low frequency

I'm dealing with a PWM generator which drives a load at 12V with pretty high currents (5-10A) The PWM frequency is in the band of 100-200 Hz. Which is the best choice and right configuration of ...
3
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1answer
218 views

Surface mount bead core

I am experimenting with surface mount components for a project. All the other components seem to be OK and I have deduced that it is the surface mount bead core that is the problem. When I remove ...
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2answers
520 views

Characteristics of Ferrite cores

Why can't ferrite cores be used at lower frequencies like 50Hz? To my knowledge, they can only operate at high frequencies.
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1answer
2k views

What is the effect of Saturation on a Ferrite Bead Inductor?

This circuit shows the "current channel" of an energy meter. IA_IN are the two inputs for a shunt (typically 250 uOhms) while TP1 is the connection to the energy measurement IC, which uses the 3.3 V ...
3
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1answer
446 views

Placement and values for ferrite bead/capacitor ESD protection / transient suppression filter

I've been researching but found it difficult to find a clear answer on this. I need to add ESD protection to my circuit, in this Texas Instruments video it talks about combining a TVS diode with a FBC ...
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3answers
155 views

Inductor : how to choose toroidal ferrite core material

I want a 2.2mH toroid inductor working at 200kHz switching frequency able to keep 2A saturated current. I found a ferrite core provider with these possibilities : - Core FT50-61 (12.7x7.15x4.9) with ...
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2answers
913 views

Ferrite Bead: How much impedance do I need?

I understand that ferrite beads can be used to reduce noise from a power supply input to an IC. I understand that one selects ferrite beads based on its resistance at the noise frequency one wishes ...
2
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2answers
143 views

Is there an easy way to find out if my 0805 SMD components are ferrite beads?

I ordered SMD 0805 components among other items and I received a package with the SMD components but there is no description at all. Also, there is no identification on the components itself. Is ...
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2answers
936 views

Can smd ferrite beads be avoided [closed]

I am redesigning an input interface circuit for digital input. Its a basic signal conditioning circuit for reverse polarity protection, EMI ESD protection, and filtering voltage surges. For EMI EMC, ...
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1answer
3k views

Ferrite Bead Simulation in SPICE

I am reading this link about ferrite beads and in page 2, figure 2, there is a SPICE circuit to emulate the ferrite beads frequency response. Why there is an AC Current Source in the circuit? Why ...
2
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1answer
355 views

How can I identify ferrite bead material?

I am working my way through the book "The Electronics of Radio" by David B Rutledge", which details experiments on the various parts of the circuit as one builds a "Norcal 40A" transceiver, as a ...
2
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1answer
2k views

LC filter and ferrite bead

Suppose I've a circuit that is affected by EMI noises that have a freq. less than 80khz and noises above 2ghz. I want to cut off this noise freq. before they reach my ICs. The circuit is powered by 5 ...
2
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2answers
4k views

Ferrite beads in Quasi-Resonant Switch-Mode Power Supply (QRSMPS) primary?

I am using the Fairchild FSCQ series and I am shocked that nowhere is there any guide for sizing the bead on the drain. The frequency range is 24kHz min. to (looks like) 90kHz. There is also another ...
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3answers
341 views

Won't the ferrite bead (L3) will restrict sudden power requirement of bluetooth module (U4)

I know the circuit is well tested by STm but, I think, C15 should not be able to provide enough instantaneous power. Does noise suppress by this ferrite bead (cross-over frequency 12MHz) will be same ...
2
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1answer
207 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 ...
2
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1answer
113 views

Voltage Regulator for GPS vs. BMP280

I am using the Bosch BMP280 pressure sensor and the FGPMMOPA6H GPS chip together on a PCB. I am using the reference designs from Adafruit's breakout boards for each chip (found via the product links: ...
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0answers
368 views

Adding a ferrite bead to source of mosfet (smps)

We are designing a SMPS (ultra low noise) based on TI schematics http://www.ti.com/lit/df/tidrgc2/tidrgc2.pdf (5V, 15W quasi resonant) In order to reduce EMI (we have some ringing across Mosfet when ...
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2answers
182 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
901 views

Choosing ferrite bead in Henry

How can I choose a ferrite bead if on schematics it's marked as 100uH? On Mouser all ferrites have only Impedance value. How can it be compared to inductance in Henry? JIC, in BOM it also commented ...
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1answer
2k views

Why do some computer power cables not have ferrite beads? What type is usually used?

Admittedly I'm clueless when it comes to electrical engineering. I felt compelled to add a ferrite bead/choke/clamp to my computer's power cord since it was missing one. Would it be helpful? What kind ...
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5answers
185 views

What is the purpose of the ferrite bead on DC Adaptors?

According to WikiPedia: Ferrite bead suppress high frequency noise. In the case of wall power adaptors, are they trying to protect the device being powered or are they protecting the PSU from high ...
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1answer
162 views

Should ferrite beads be closer to the stepper motor or to the motor driver?

Stepper motor, cable with ferrite bead, and dual H-bridge driver: I noticed that the cable that came with these motors had the bead closer to one end. Does it matter which way it's wired as far as ...
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2answers
2k views

How to check ferrite beads?

I faced with a problem of checking ferrite bead with parameters: The measurements for two reels of this component have difference in Resistance and inductance: Reel 1: Resistance: 170 mOhm, ...