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

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How does inductance change with presence of different directional magnetic fields?

If I design a coil driver for a certain application, I assume there is a fixed load right? It may have drive any inductance between an interval but you can not drive any coil, because the driver is ...
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1answer
35 views

Ferromagnetic core with air gap

N=200 I=N*8A l=20cm=2*10^-1 d(delta)=1mm=10^-3 M=? M=(B/μ)-H How can I get the vector of magnetization? The relative permeability is not known. Everything I ...
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1answer
67 views

electromagnet repelling permanent magnet [closed]

I have an electromagnet (turned off) with an iron core in front of a permanent magnet. At this stage they attract each other. Will any current do if I want them to repel each other, or is there a ...
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6answers
7k views

What is the difference between the magnetic H field and the B field?

Wikipedia provides a mathematical explanation. Can I get the intuitive one? I'd like to, for example, understand a ferrite datasheet. These usually have graphs of H vs B, and the definition of ...
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1answer
824 views

How internal capacitor stud finders work?

I don't understand how can a non magnetic object like wood be detected using a stud finder For instance, stud finders find wood from dielectric constance, but I don't understand the princible. The ...
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3answers
152 views

low frequency 1-10Hz transformer

I have a 20V, 2 Amp Max, 10Hz sine wave generator, I would like to be able to connect a transformer to step up and down the voltage. How would I go about finding a transformer that I could connect to ...
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33 views

In electromagnetic inductance, which one is more efficient, to focus all power to move one part or split it to move both at the same time?

Assuming equal force is used, which one would be more efficient when it comes to generating current through electromagnetic induction: to use 100% of available force to move the permanent magnet only ...
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39 views

3-phase, 2-circuit transmission line calculations

I am trying to assess different positions for 6 conductors of a 3-phase, 2-circuit transmission line. The aim is to minimise the intensity of the magnetic field (H) at the edge of the ROW, 1m above ...
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4answers
13k views

What is the difference between a transformer and a coupled inductor?

Transformers and coupled inductors seem very similar. Is there a difference in construction? Or only in use? This question asks something similar, but the answers don't address my question: Coupled ...
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2answers
4k views

Saturation current of my inductor not agreeing with formulas

I have wound my first inductor and I have verified the inductance with 2 methods. However, when I test its saturation current, its much lower than the formula gave me: \$B_{peak} = \dfrac{V\cdot T_{...
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2answers
105 views

How to properly wind a high frequency / high voltage transformer?

Please, is there any practical tip / caveat I should be aware, when winding a high-frequency transformer? I'm used to wind 50/60Hz transformers and they do work ok, but now I'm trying to make a high ...
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69 views

Magnets in Transformers Desgin

What is the advantages, and disadvantages of using neodymium magnets instead of ferrite cores in transformers? How would the magnetic flux density vary of such a transformer utilizing a neodymium ...
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37 views

Why compass module is affected by its x,y position, if my phone's compass work in the same environment?

I am using hmc5883L on an autonomus robot. It shall remain in a 1 meter squared area. I have recently discovered that its reading changes up to 20 degrees on different positions even when it is facing ...
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1answer
90 views

using a magnet to trigger a traffic light

Here is the link to the Traffic Detector Handbook from the Federal Highway Administration: http://www.fhwa.dot.gov/publications/research/operations/its/06108/02.cfm This will explain more about ...
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1answer
111 views

Where are Ćuk converters

According to "the art of electronics" (p 651) and other internet sources, the ćuk switch converter has the most desirable properties: continuous input and output current waveforms, boosting and ...
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1answer
39 views

Effects on the exterior magnetic field from a field induced by a wire?

I have an experimental set-up where I place a conductive wire in a magnetic field created by an electromagnet like so: There is current flowing in a wire as well(aside from the electromagnet) ...
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1answer
81 views

Reed switch sensitivity

I've built a setup where I've placed a reed switch near the water meter in my house. Every 0.5 litre the switch gets triggered and my Raspberry Pi does the rest of the work. My gas meter also outputs ...
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0answers
23 views

Closed loop shapes with zero mutual inductance?

I have done numerous searches trying to find any mention of theory or experimentation done on determining closed current loop shapes that have zero mutual inductance and...no dice! Of course you can ...
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1answer
40 views

Magnetically shielding an actuator

We need to magnetically shield a solenoid that activates this valve (shown below) Just slipping a mild steel cap over the end does not do the job, nor appears to have any screening effect at all. ...
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1answer
65 views

How to increase an electromagnet's magnetic field size

So i made this electromagnet out of a microwave oven transformer by taking out the secondary coil. It very strong but it can only attract the metals if i bring it really close. How do increase the ...
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1answer
496 views

POE external Magnetics Alternative to magnetic RJ45 jack ieee803af

I can't use a magnetic jack for this POE PD (ieee803af), because we use another connector (M12). Looking for components to replace the internal magnetics, I found that almost all components and ...
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0answers
45 views

Putting together a flyback converter development platform

At this stage of my independent study of off-line flyback topology switching converters, I'd like to start building some working converters to get a hands-on feel for things and to perform ...
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2answers
87 views

Ways to use electromagnets to pick up metal shavings at a distance

I work at a rotor machining plant and there is an issue for shutting a line down to clean up metal shavings, causes too much down time. I was thinking of using a strong electromagnet to have a "pick ...
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1answer
48 views

Formula for electromagnet strength parallel, outside the coil

I am working on a electromagnet project to collect metal shavings off the floor after machining. I have a formula for the magnetic strength at a distance from the ends, but not parallel to the coil. ...
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1answer
93 views

Magnetic switch with no moving parts

Is there a magnetic switch (like a reed switch) but with no moving parts? I need a switch that can be turned on by a magnetic field but won't move around due to tremendous shock absorption.
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3answers
103 views

Core loss appearing in buck converter ripple current

I have been told (and have also seen experimentally) that an inductor with a high core loss will introduce "glitches" to the ripple current in a switch mode power supply. I have tried researching this,...
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3answers
120 views

Hall effect device for circa 1 tesla gaussmeter

I'm thinking about building an unsophisticated bench instrument for measuring magnetic field density, just to support my learning about electromagnetism and building magnetics for power electronics ...
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52 views

Externally toggle relay

Is it possible to force a relay to toggle without changing the input to the coil? i.e. if the relay (a sealed SPDT, say) has 0V on the coil such that NC is connected, it is theoretically possible that ...
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5answers
2k views

Why are reed switches made in glass tubes?

Why are reed switches made in glass tubes? Reed switches sense magnetic fields, and glass is not the only material not affected by a magnetic field. They can use plastic for example. Why are most of ...
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4answers
66 views

Suggestions for moldable ferromagnetic material?

I'm trying to build a sort of three-axis stepper motor that consists of a sphere with a permanent bar magnet embedded in it surrounded by a cube (slightly smaller than the sphere, so that the sides of ...
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3answers
66 views

Magnetic modulation/ induction

I've been looking for a viable means of communication under water (other than sonars), be it short or mid-ranged, and I have come across MM and MI. I am no engineer, so I need help with this, and I ...
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1answer
860 views

How do electric and magnetic fields affect electronic circuits?

I have come across those requirements: "The equipment shall not be susceptible to DC magnetic fields of up to 60 μT." "The equipment shall not be susceptible to electric fields of up to 140dBuV/m ...
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2answers
111 views

Danger of Saturation of Primary Coil in a Flyback

I was reading a book, "switching power supply design - Abraham Pressman", specifically the section about flyback converters. One part I'm not quite sure I understand is where he says that the ...
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13answers
706 views

Tracking rotation with extremely high accuracy

I would like to track the angular position of a fairly slow motorized rotating arm (direct-drive; see illustration below) -- but require angular accuracy of under 0.05°, and similar resolution. As @...
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83 views

Will plastic influence a magnetic field?

First of all sorry for my English. If, for example I will "create" magnet by passing current through a coil. And than I will "wrap" this piece with plastic or some other material, will the "magnet ...
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2answers
193 views

Clamp Meter Working Principle

Basic theory of clamp meter to measure rms of current wave. What I have in mind is that wire creates the changing flux that induces voltage in the meter.This voltage is calibrated ? Also how does the ...
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1answer
124 views

neodymium magnet - how it affects a circuit

I am trying to develop a connector which can join both sides by a magnet. I got the idea of using a neodymium magnet , but I was thinking that if this could in one way or another affect circuit ...
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1answer
53 views

Long Term effects of saturating isolation txfr

I have a 1:1 isolation transformer that's rated for 25VA. I'm consuming 30VA, 20W. I've noticed because I'm saturating it, the txfr is no longer 1:1, it's more like 1:1.1. Other than this issue, for ...
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3answers
116 views

why cannot use permanent magnets for large electricity production

Why cannot use permanent magnets for large electricity generation as they donot require power to produce strong magnneticfield
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41 views

DC MMF and flux density variation in space

If flux density produced by DC current is sinusoidally distributed in space why do we say that DC MMF is space invariant?
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60 views

3 axis magnetometer issue in one axis

I have several 3-axis magnetometers mounted on breadboards, and they all read correctly in the x and z directions. The Y direction is very strange; when turned to read ...
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122 views

Ferrite core characterization

I need to make a dc dc converter and have some ferrite toroids but I don't have the datasheet of the cores so I need to know how much energy are capable do store the core and what current can they ...
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1answer
77 views

Hall effect sensor operational distance from magnet

I want to use a this hall effect sensor to detect the presence of magnet. I'm pretty sure I understand how to use the hall effect sensor, but I'm not sure how to calculate the distance the sensor can ...
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0answers
53 views

Is there a way to shield the fluidics of a solenoid valve from its magnetic field?

Are there any solenoid valves on the market that specifically shield the fluidics from the magnetic field of the solenoid actuation? Either by physically redirecting the fluidics around the coils or ...
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1answer
96 views

Hall-sensor replacement for reed switch

I have a device in which a reed switch is encased in potting compound. (So impossible to identify.) My problem is, that for my application the switch is too slow. I am considering replacing it with a ...
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1answer
90 views

Why don't Inductors have voltage ratings, but transformers do?

Inductors don't have voltage rating, but transformers do... why is that? Why not just put a current, frequency, and turns ratio for transformers and be done?
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2answers
150 views

How is the current induced in this circuit?

Rectangle FBCE is the conducting wire. The circle is where magnetic field exists.The perimeter of the circle is NOT a conducting wire. R1,R2,...are different resistances. If the magnetic field(B) is ...
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1answer
44 views

Opposing EMF's with an odd change…?

A conductor in case 1 has two separate uniform magnetic fields \$B_1\$ & \$B_2\$: The magnetic fields(the blue rectangles are the field regions parallel to the conductor, while X's are the ...
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180 views

Magnet strength in dynamo design

I come from a computer background, and apologies if this question sounds elementary. While designing a dynamo, I came across a problem of how to calculate the the strength of the magnetic field, and ...