Skip to main content

Questions tagged [magnetics]

Important to inductors, transformers, generators, motors, magnetic fields, inductive heating, magnetic storage, permanent magnets

Filter by
Sorted by
Tagged with
0 votes
0 answers
50 views

How is slope compensation implemented in the UC3843?

I was reading about slope compensation in the datasheet of UC3843 and I have watched this tutorial on youtube which gave me a general idea and overview about what slope compensation is. Now regarding ...
AbdAllah Talaat's user avatar
0 votes
1 answer
95 views

Magnetic field in a tape

This is a theoretical question. Let's guess we have an unknown magnetic tape cassette, no brand, no numbers or other signs. The question is: do tools exist, that are able to analyze the magnetic field ...
john_smith's user avatar
1 vote
1 answer
61 views

How does a Current Injection clamp work from a physics persepective?

Current injection clamps are normally described as a transformer with a single turn secondary, which is all fine and good, but the construction of a transformer is different from a current clamp. ...
EricEverton's user avatar
0 votes
0 answers
45 views

Can I deduce the saturation current of a transformer from the rated wattage and maximum frequency?

I have an SMPS transformer EE10, but am not sure about the saturation current it has, I tried doing some internet research, all what I can get is this so far : I am trying to deduce the saturation ...
AbdAllah Talaat's user avatar
0 votes
0 answers
29 views

Measurement bias of Hall sensors with moving permanent magnets

I want to measure the magnetic flux density produced by a moving permanent magnet. In my case, the magnet would move left and right alternatively at speed of 10 mm/s, with a constant vertical distance ...
booo's user avatar
  • 1
4 votes
2 answers
98 views

Energy stored in a saturating inductor

We all know that the energy stored in an ideal inductor is \$E=\frac{1}{2}LI^2\$. However, real inductors with a ferromagnetic core don't have constant inductance. Particularly, when a specific field ...
AnttiP's user avatar
  • 209
7 votes
2 answers
416 views

Inductance after core saturation

Looking at the datasheets of some drum core inductors, at higher currents the inductance drops significantly due to ferrite core saturation. But it seems inductance asymptotically approaches a value ...
ac47's user avatar
  • 71
0 votes
1 answer
100 views

Why are common mode chokes used in Ethernet magnetics

I’m trying to understand the reason the common mode choke is required in Ethernet magnetics. To understand, if we look at the schematic, with the common mode choke (horizontal coils) removed, we are ...
EricEverton's user avatar
5 votes
1 answer
259 views

Does hysteresis still occur if saturation is not achieved in a core?

When looking at a BH curve, what happens if the H field is raised to some level below saturation. For example we apply an H field that is only half way to saturation. On a BH plot this will trace a ...
EricEverton's user avatar
0 votes
3 answers
107 views

Inductance Computed As Length in Historical Document

In "Formulas and Tables for the Calculation of Mutual and Self-inductance.", many equations compute the inductance of an arrangement as a length. For example, Equation 95, on p. 150, states,...
Terry's user avatar
  • 9
1 vote
1 answer
128 views

What are sources of extra low frequency magnetic field in a car with IC engine? [closed]

ELF analyser (16 Hz - 2 kHz) shows a magnetic field around 300- 2000 nT (at some position exceeding that) in car when petrol or diesel engine work. When RPM increase from idle to 2500 RPM, magnetic ...
user avatar
0 votes
2 answers
96 views

Transformer losses due to eddy currents. Why these losses are compensated by the transformer?

Here is my understanding of a transformer. Let's assume that we have the following ideal circuit, in which a coil is wrapped around a core and there are no core losses⎯excuse my crude drawing.         ...
ganymede's user avatar
  • 267
2 votes
1 answer
92 views

Magnetic Force Equation

Is there any equation where I can take a metal with a given volume/mass, with a certain amount of magnetic flux in it (in teslas) and find out how much force (in newtons) it exerts a given distance ...
Ombrezz's user avatar
  • 173
5 votes
3 answers
1k views

How can single phase induction motor's direction be reversed?

My house has a ceiling fan which has 2 wires which are connected to a capacitor, and Iam able to control the velocity and direction. After looking about these motors on the web I found out its ...
Gatonito's user avatar
0 votes
0 answers
50 views

Magnetization of an Electric Guitar String

I'm trying to calculate the magnetic field generated by electric guitar strings of various gauges. The strings are made of some ferromagnetic material (pure steel or pure nickel). They are magnetized ...
Rod Hobbs's user avatar
0 votes
1 answer
47 views

If I have two magnets repelling each other, will they always form a peak in the middle?

If I have two identical magnets, aligned so they repel each other a distance of X apart and at a height of Z I have Hall effect sensor, the peak of the magnetic field sensed will be at the distance X/...
Ari Guðmundsson's user avatar
0 votes
0 answers
68 views

Energy stored in a magnetically coupled circuit

In the circuit shown, inductors $$L_1,L_2$$ are magnetically coupled with the mutual inductance being $$M$$. The red dots are for dot convention. Normally,the energy stored in such a circuit is $$\...
green_blue's user avatar
1 vote
3 answers
135 views

How does all (well most of) the flux in the primary side get into the secondary side in a transformer?

I had a follow up question to this: How does a magnetic material "confine" a magnetic field? In the above question, it asks how the magnetic flux is "confined" by the core. The ...
Jonathan Lee's user avatar
7 votes
1 answer
212 views

Equation for the force created by a solenoid

I'm trying to make an electro-magnet and I want to figure out what core and wire I need using math instead of trial-and-error. I want it to produce ~1.5 newtons of force at ~1.5 inches from the magnet....
Ombrezz's user avatar
  • 173
3 votes
3 answers
78 views

Characterize ferrite cores, e.g. core losses

How can I characterize ferrite cores? I can measure saturation, but how can I measure core losses so I can decide what frequency to run them at? I could charge a primary winding to a certain current, ...
darsie's user avatar
  • 199
10 votes
2 answers
2k views

Finger magnets and MRI

A few years ago in the biohacking community there was a phase where people (mostly engineers) were having small magnets embedded in a fingertip in order to sense magnetic fields. I was slightly ...
Dirk Bruere's user avatar
0 votes
0 answers
71 views

Are 10GBASE-T ethernet magnetics modules compatible with 1000BASE-T?

I am designing a board with a 1000BASE-T ethernet PHY and I want to use a discrete magnetics module since I will be using a non-standard connector. However, I am constrained with space and I found a ...
Matias B's user avatar
1 vote
1 answer
112 views

Transformer design and calculations

I am trying to find correct way of determining the transformer parameters. I provided a simple schematic of a PSFB (phase-shifted full bridge) converter below. How do we determine thr primary ...
Mhan's user avatar
  • 377
1 vote
2 answers
103 views

Core demagnetisation - What is the condition?

Consider forward converter topology. What is necessary for core to be successfully demagnetised? Does the magnetising current has to reach absolute zero amps, or even little negative is advantage? How ...
Michal Podmanický's user avatar
-1 votes
1 answer
78 views

Would a electromagnet be used to detect the presence of a permanent magnet?

I was wondering if there is any way I could use an electromagnet to detect the presence of a permanent magnet. I am specifically thinking of using a planar type small coil. Maybe use a core or ...
assasinchop7's user avatar
4 votes
3 answers
2k views

How to design a 12V to <100mV 15A DC-DC converter?

My project requires a constant current source of at least 13A for a minimum of 1s (preferably capable of longer such as 5s). The primary use of this current is to produce a B-field. The current would ...
Kristen22423's user avatar
0 votes
2 answers
135 views

Reluctance concept

I would like to appeal question, where the correct answer was given as option (B) 'Cross-sectional area.' However, I believe that option (D) 'Permeance' is also inversely proportional to reluctance. ...
Dragnovith's user avatar
5 votes
1 answer
490 views

How Should I Model Eddy Currents in a Magnetic Core?

simulate this circuit – Schematic created using CircuitLab I'm primarily a VHDL and DSP guy, so I apologize in advance if this question is dumb. I have wire wrapped around a magnetic core. The ...
James Strieter's user avatar
1 vote
2 answers
163 views

Electromagnet design and powering it up? (Fault prevention of DC supply for a small coiled Electromagnet)

I want to create an array of multiple electromagnet which I will be controlling using a microcontroller. I will have around 100 such magnets lined in a squared grid 10x10. Only three or five at a time ...
Kush_Uttam's user avatar
0 votes
1 answer
120 views

Problem acquiring B-H curve

I'm trying to acquire the BH curve of a toroidal current transformer in saturation, having the primary and secondary current. The formulas I am using are: B = (1/NsS) Integral(Vs(t)dt) H = (Ip*Np)/l $...
Fe2321's user avatar
  • 1
1 vote
2 answers
314 views

Ethernet Magnetics Polarity Swapping

Can I on the same pair (for Example A) to swap polarity on opposite side of transformer/magnetics? Update 1: Currently i use cross-over method to make lanes shorted and more easy to layout. Update 2:...
Radu G.'s user avatar
  • 23
4 votes
1 answer
183 views

Boost Inductor Design for three phase Diode Bridge Rectifier for PFC operation

I am doing a simple DCM based control for power factor correction. Please see the topology below . Specifications are as below: 1.) Power 5KW 2.) Input Voltage is 415V L-L Nominal 3.) Inductor ...
Archit Asthana's user avatar
2 votes
2 answers
156 views

Does winding a solenoid around a copper pipe reduce the net magnetic flux at all?

I want to wind an air core solenoid around a copper tube. One end of the solenoid is soldered to the copper tube. (See picture above). Will a magnetic field be induced in the copper tube that cancels ...
James Strieter's user avatar
1 vote
2 answers
205 views

How is the holding force of this electromagnet so large?

I am designing a system that uses the magnetic force to fix an object in its place. I plan to connect an I-core to my object and fix it to a fixed C-core by letting a magnetic flux flow through both ...
Arad's user avatar
  • 91
3 votes
1 answer
1k views

Design Ethernet capable board without RJ45 socket

I have been tasked to design the schematics of a board of an ECU which provides 4-pin Ethernet on its 58 pins connector, for a 100Base-T implementation; I have been mandated the use of TI's DP83822 ...
Jack's user avatar
  • 417
1 vote
2 answers
107 views

I am wondering if magnets can be safely used to connect power from one to the other? [closed]

I am thinking of trying to create a extension cord that can be taken apart or separated as needed. And rejoined at any length of cord but connected only through magnetic connections. So I'm wondering ...
HEO's user avatar
  • 11
3 votes
2 answers
420 views

Why are induction motor cores laminated to prevent eddy currents?

The permeable iron alloy cores of induction motor rotors are formed from thin laminated sheets, designed to prevent eddy current flow and thus "reduce losses", but isn't the whole point of ...
PersonWithName's user avatar
0 votes
0 answers
71 views

Any information on magnetic braking with copper?

I have an engineering project where I have to design and build a model of a drop tower from a theme park. The tower itself can be no taller than 40cm. I plan to use magnetic braking with copper to ...
18jbrana's user avatar
2 votes
2 answers
125 views

Does operating an iron core near its saturation field reduce performance?

I am sizing an iron core for an electromagnet, and I am uncertain if there are disadvantages to operating close to the saturation flux density. If the saturation field is X, would it be better (more ...
Arad's user avatar
  • 91
1 vote
1 answer
61 views

How Far Should Mu Metal Be From An Inductor to Leave Its Internal Behavior Unchanged?

I have an air core inductor. Since its magnetic field will be large, and it will turn on and off rapidly, I assume it will make a lot of noise. I don't want that noise to disturb the PCB's nearby, so ...
James Strieter's user avatar
0 votes
0 answers
71 views

Magnetics part with and without auto-transformer

I have 2 magnetics part. One magnetics is this (Circuit A configuration magnetics) & the other magnetics is this When I use the Halo part, the ethernet link is not up. But when I just replace the ...
Freshman's user avatar
6 votes
5 answers
1k views

Why do metal finders not use any sensors other than search coils?

I was wondering why metal finders do not use any other sensors to recieve the magnetic signal instead of search coils. I have been looking at MEMS sensors used as digital compasses, for example. As ...
Ron Vaisman's user avatar
1 vote
1 answer
75 views

Is there any practical purpose of placing read only memory (ROM) chip near a hard drive?

Premise: a PCB file has ROM chips (I think they are masked ROMs?) placed beside standard 3.5" HDDs, which has lead me to a few questions. While the product is off, I understand that the magnets ...
CodingFryCook's user avatar
0 votes
1 answer
1k views

Calculate motor flux of a PMSM

I am struggling with the calculation of the motor flux for a RPX22-042V24 PMSM. I know back EMF, Torque constant and several other values from the datasheet. But I found different ways to calculate ...
hanss's user avatar
  • 147
0 votes
0 answers
80 views

Want someone to review my Helmholtz coil design to see if I am missing something obvious before I fabricate it?

I am planning to construct a Helmholtz coil and wanted electrical engineers to take a look just so I know I am not overlooking anything. The max field strength I am looking for is 200 Gauss. I ran ...
assasinchop7's user avatar
1 vote
1 answer
46 views

Useing a PoE RJ45 ICM Magnetics but not using it for PoE?

I plan on using the Bel G27-122T-015 (PoE ICM RJ45) but I don't need it for PoE. Can I just leave these pins unconnected? The ICM already has an internal Bob Smith termination.
miggyEE's user avatar
  • 45
0 votes
1 answer
190 views

Metal detector coil wire gauge [duplicate]

Many designs of metal detector coils use different gauges of wire for the TX and RX coils - why is that? Does the wire thickness influence other parameters rather then just the resistance and current ...
ron vais's user avatar
5 votes
1 answer
271 views

What role does permanent magnet strength play in BLDC/PMSM performance?

It seems to me like stronger permanent magnets are preferred by motor designers, but my current understanding of what role they play in performance is fuzzy at best. I would assume that stronger ...
TheDarkSaint's user avatar
2 votes
1 answer
66 views

What types of inductor cores exhibit magnetization?

My understanding of magnetization in core memories is as follows: a bit is written to an inductor's core by magnetizing it, by applying a large current. Later, the bit is read by observing the effect ...
personal_cloud's user avatar
0 votes
0 answers
71 views

What is the best material for 200Hz power inductor?

I am looking for inductor core material working at about 200Hz. The inductor current is DC only, close to triangle with 5A average. I read for such purpose the amorphous alloys have a good performance,...
Michal Podmanický's user avatar

1
2 3 4 5
13