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2
votes
3answers
240 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
votes
2answers
135 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
votes
2answers
233 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 ...
5
votes
1answer
333 views

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 ...
1
vote
1answer
90 views

Different voltages with Ferrite Beads

I am checking the datasheet of one complex component, and the schematics of one demo board, and I find a difference that I would like to ask here. It is a 100Base-tx switch. The chip uses 3.3v for ...
1
vote
1answer
132 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 ...
1
vote
1answer
141 views

Ferrite Beads - Maximum DC current and resistance

I'm building a PupDAC (http://www.diyforums.org/PupDAC) and am looking into two different Ferrite beads. The plan for the PupDAC calls for this Vishay/Dale model (link 1) while I'm looking into this ...
3
votes
1answer
292 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 ...
6
votes
1answer
294 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 ...
2
votes
2answers
616 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 ...
4
votes
1answer
1k 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?
2
votes
1answer
130 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 ...
3
votes
2answers
173 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 ...
2
votes
1answer
364 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 ...
15
votes
2answers
693 views

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?
3
votes
1answer
109 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 ...
3
votes
1answer
736 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 ...