Questions tagged [inductor]

An inductor is a 2 terminal passive device that stores energy in a magnetic field.

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2 answers
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How to guess the particular solution form from forcing function?

$$2\frac{dv(t)}{dt}+v(t)=5t\sin(t)$$ According to the general equation for first-order differential circuits, \$5t\sin(t)\$ is my forcing function. My task here is to find the particular solution. I ...
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Filtering USB +5V and filtering battery (also +5V) before and after LDO

I have a development board project where I want to use USB as the power source when plugged in and then switch off the battery - and vice versa. Then I am running it through a 3.3V fixed LDO (AMS1117-...
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Why does a ground plane change the radiation pattern for a PIFA antenna?

I have designed a PIFA antenna as shown below. The problem is that the radiation pattern changes as a function of my ground dize. I know that if the ground plane is large enough then the radiation ...
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1 vote
1 answer
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L and R function in the vicinity of a SMPS output

What is the Inductor L and Resistor R function in a SMPS output vicinity below after transormer T output? What are the two values supposed to be calculated with respect to each other and to the two ...
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Alternative inductor for evaluation boards kit DC2781A (using LT8316)

I want to build the DC2781A evaluation board by Analog Devices. Most of the passive parts I already have, so the building cost would be much cheaper for me. However, I wasn't able to find a ...
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Common mode choke and inductor for inverter circuit

I am building an inverter that uses an H-Bridge and PWM to generate something that should get close to a sine wave. My original design only included a common mode choke, however now that I am doing ...
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Difference between D, D+Z and TVS for inductor surge suppression

Let's say I have a switched inductive load (e.g. a lift/hold electromagnet, electromagnetic actuator, or relay coil). IIUC, when the switch/EMR/SSR opens, the collapsing magnetic field can cause the ...
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7 votes
1 answer
178 views

How to check the polarity of a common-mode choke?

I purchased some common-mode chokes and the documentation provided states: As this pinout does not correspond to other chokes of the same format, I have doubts about the position of the dots (pins 1 ...
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2 answers
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Unshielded inductor in EMI filter

When it comes to power transmission elements, e.g. in DC-DC converters, using shielded inductors makes perfect sense to me. I am not sure the same is true for LC filters at the input of these ...
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3 votes
3 answers
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Intuition about inductor/transformer core shape nomenclature and performance impact

Due to some future projects, I feel I have to get more accustomed to winding my own transformers/inductors, so I have been reading about ferrite cores lately. One thing I can't really develop a ...
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1 answer
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Inductors at a DC motor's terminals

While tearing down an RC toy to scavenge the DC motors, I found an unusual circuit attached to the motor that turns the car right or left. It seems that it has two inductors but I am not exactly sure. ...
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2 answers
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LC filter in inverter

I am in the process of creating a high-current inverter, with a current rating of 100A. I have completed the simulation, but am having difficulty finding an inductor with a high enough current rating ...
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2 answers
199 views

Unexpected output from LC circuit

I am trying to get back into some electrical engineering basics, and had a quick question regarding an unexpected output I am seeing. I am trying to learn about RLC circuits again, and wanted to build ...
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LED bulb driver

I am trying to make a non-isolated LED bulb driver and while reverse engineering I found the driver's inductor has three pins: one is connected to ground, one is connected to the FB pin of the driver ...
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6 answers
712 views

Inductor polarity

Let's say an inductor has DC current going through long enough for it to completely build it's electro magnetic field. If the source voltage then goes lower, the inductor will 'use' the energy stored ...
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2 answers
92 views

Where to find huge solenoid inductors (~25 H) or cheap magnet wire? [closed]

I am on an energy harvesting project, and it would require a 25 H solenoid inductor (width 0.3 mm max). The only issue is that I am completly unable to find any inductors of that size on the internet. ...
5 votes
1 answer
441 views

Why is an inductor kickback wave-like?

I though that an inductor, when it doesn't have current flowing through it anymore, would quickly discharge in the opposite polarity. More precisely, I was expecting one quick peak in a negative ...
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2 answers
190 views

Why doesn't the voltage at the resonance frequency go above the input frequency of a sine wave source?

I have performed a simple RLC parallel circuit experiment to determine the resonance frequency. I used the voltage as the magnitude. Experimentally, the magnitude at the resonance frequency tops at ...
5 votes
2 answers
265 views

Parallel RLC time domain response, with two specified initial conditions and no driving source -- it is an homogeneous system

This question is inspired from Andy Aka's question from almost 5 years ago. It is also a nod of my respect to Andy. But what I wrote there is kind of muddled. And it only addresses the under-damped ...
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2 votes
2 answers
194 views

Inductor impedance

I feel like I'm missing/forgotten something fundamental with regards to impedances. For an inductor \$X_L=2πfL\$, so for a 68uH at 500kHz \$X_L = 2π \times 500\text{ k} \times 68\text{ u} = 214Ω\$. So ...
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1 answer
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Can SMD 22uH (shielded) inductor cause health hazards? [closed]

I'm planning to add MT3608 boost converter to gloves, for experimental purposes. I'm planning to use SMD 22uH (shielded) for it, because I have seen such a schematic in many places, and its allowed by ...
4 votes
3 answers
664 views

If inductors opposes any change in electrical current, how can the magnetic field vary with time if the current is varying with time?

When I looked the definition of the inductors, I saw that: It opposes any change in electrical current. If the current is varying with time, the magnetic field is varying with time. So if 1. ...
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6 answers
126 views

How does an inductor behave alone with a voltage source?

I am trying to understand inductors, and Kahn Academy said that the current on the following circuit would be 300t, where t is time and initial time is 0. There would be an increasing current, but ...
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1 answer
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Sense small variations in inductance in AC for a metal detector circuit

I am currently working on the design of a metal detector circuit. I am relying on the method that the coil's inductance would change when a metal is close to it (due to eddy currents.) I have tried ...
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1 answer
59 views

what voltage rating do I have to observe at resonant frequency?

This is the schematic of the resonant switched capacitor cell balancing circuit. The problem is that at the resonant frequency when the capacitor and inductor impedances become equal and the total ...
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1 answer
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Voltage drop in a switching circuit with two storage elements

There is a switch between Vs and V1 that closes the circuit at t=0. The resulting circuit is shown below. When analyzing this circuit for t>0, why is the voltage drop across Vs and V1 not zero? ...
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1 answer
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Non Symmetrical Inductor Current

I'm doing an LTSpice simulation of a basic inverting op-amp. The output of the op-amp is driving a 53uH inductor. The ESR for the inductor is very small. My problem is when I try to measure the ...
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Impedance matching transformer simulation

Here is an example of a transformer that converts 10Ohm load into 1kOhm And the AC simulation result From my understanding the source sees the transformer as an inductor in parallel with a converted ...
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1 answer
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How does the Skin Effect at RF frequencies affect wire ampacity?

Through simulation we can find the current going through an inductor that is part of a filter network and this 1-sheet paper points out that ampacity diminishes with higher frequency because of the ...
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1 vote
2 answers
121 views

Multisim results not matching handwritten results

I was given a project with the following question: I calculated the current going through inductor 2 in transformer 2 as 4 phase angle -30. \$Vs = 1440 V RMS\$ \$V_1 = \frac{1}{3} * V_S = 480 V RMS\$ ...
2 votes
2 answers
189 views

Choosing LC oscillator components

I understand that the frequency of a simple LC oscillator can be selected by using $$f=\frac{1}{2\pi\sqrt{LC}}$$ Say that I am trying to get an oscillator to operate at some arbitrary frequency of 60 ...
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1 answer
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Cascode amplifier does not provide gain properly

I'm trying to build a Cascode amplifier on ads but I think I have a problem with my tank oscilator. Here's the complete circuit The inductor is an air-core inductor from coilcraft and the transistor ...
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2 answers
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Short circuit behavior in very complex circuits (First Order RL and RC circuit problems)

I do know that a resistor is by passed when parallel to a short circuit or wire with no branches. However what if it was within a complex circuit and not just in the outer loop how does that by-passed ...
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2 answers
163 views

Why do power supply module's capacitor and inductor blow up?

I developed a power supply module. The instant I connected the PCB to mains, the capacitor and inductor blew up. Does anyone know how to debug the problem? The ratings of the components are good ...
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How would you go about finding the full response i(t) for a circuit with an inductor in series with a CCVS?

My process for other questions similar questions so far has been to first find i(o), then find steady state current and plug into the equation i(t)=i + (i-i(o))e^-at where a is 1/timeconstant. But I'm ...
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2 votes
2 answers
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Air core inductor impedance vs frequency graphs

I wanted an inductor with at least 100 μH, so I used a PVC pipe and some enamelled wire (AWG 21 if I recall correctly) to create an inductor. The inductor does serve its purpose fine as a load ...
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6 answers
201 views

Why does a diode placed in series before an inductor not protect from surge?

I checked some posts that explain quite well the concept of a freewheeling diode, but all of them seem to place the diode in parallel with the inductor. Why doesn't placing the diode right before the ...
2 votes
0 answers
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Square vs Round Air-core Inductors for RF filters: When would you use one vs. the other?

The Kyocera AS-series Square Core Inductors boast that "the unique square cross section of the air core inductor provides better performance, and offers manufacturing advantages over toroidal ...
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1 answer
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Will an AC voltmeter show deflection if connected across a pure inductor in an AC LCR circuit?

I'm asking this on behalf of one of my classmates. My thoughts: It will, as if there is current flowing backwards, there needs to be an EMF developed, and if there is no voltage drop, Kirchhoff's laws ...
1 vote
1 answer
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Inductor positioning in switching power supply

I'm designing a switching power supply which outputs -24V using this MAX629ESA+ from Maxim. (Figure 3 - page 7). Is it generally a good/ok idea to put the inductor on the other side of the PCB as I ...
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2 answers
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Can I connect low current inductors in parallel to get high current boost converter

The image below is a 680uH and 4A inductor: Can I use 5 of them in parallel to make a boost converter which has input current of 15A and inductance of 136uH. The converter is made of discrete ...
3 votes
2 answers
309 views

Boost converter design guide

I am making a TL494-controlled boost converter from discrete components which has these specs: Max output power: 120 W Max output voltage: 100 V Max output current: 10 A Supported input voltage: 7-...
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1 answer
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Induced EMF polarity of inductor from bar magnet

I can't understand the polarity of an induced emf of an inductor from a bar magnet. I understand inductor voltage polarities in normal closed circuits in that an inductor produces a voltage drop when ...
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3 answers
113 views

What could be causing my wire terminals to burn off so often? [closed]

Every 3 to 8 months, my 20-year-old dryer stops producing heat. It started happening about 4 years ago. To repair it, I replace either a thermostat or a thermal fuse. Often, the wire is charred at the ...
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2 answers
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Concerns with operation of ZVS circuit

I'm looking to build my first ZVS circuit to use for future projects. But before doing so I want to fully understand how and why the circuit works the way it does. So I built a model in LT SPICE which ...
5 votes
2 answers
323 views

How to calculate the natural frequency of a series LC circuit?

The below question is just to exemplify what I mean, I don't need help with this question, but rather the concepts behind it From the wwikipedia article on natural frequency I concluded that for an LC ...
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3 answers
98 views

Calculating reactors for parallel connection of thyristors (SCRs)

I have been looking for more information on how to connect two thyristors in parallel in order to balance the load. From what I have found there are two options: either using balancing resistors, ...
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0 answers
104 views

Calculate multi-layer coil inductance

I tried to calculate the inductance of an existing multi-layer air core. Since it is covered in some kind of insulating tape I cannot see the coil form or the actual extent of the coil. Some data: ...
4 votes
1 answer
172 views

Does a parallel air gap increase or decrease maximum energy stored in magnetic field of an inductor?

I understand that a serial air gap increases the amount of energy that can be stored in an inductor. The reasoning is as follows: according to Gauss's law for magnetism, divergence of B-field is zero. ...
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1 vote
1 answer
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I want to calculate the cut off frequency and bandwidth of the following circuit. I need it for EMI/EMC testing

I want to calculate the bandwidth and cut off frequency of this circuit for the following inputs: Supply - 230VAC, 50Hz. Components used ...

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