# Tagged Questions

Inductance is the property by which a change in current in a conductor induces a voltage both in the conductor itself and nearby inductors, the latter being the basis upon which transformers operate. Discrete inductors are also available that have many applications including filtering and energy ...

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### What is the purpose of varying lengths of coils in large coil guns?

I am considering building a coilgun similar to Virgil Rigsby's. There's patents available on google, and was wondering what the purpose of shortening the coil lengths was, and if anyone could please ...
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### Calculation Inductance Voltage in book 'Practical Electronics for Inventors'

I'm curious is calculation in screen right? I assume Voltage from 2-3 sec must be -0.2V, because dI/dt=(-1)-1=-2A, not -1A. Am I right?
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### Estimating inductance change by eddy currents

I have a planar coil with inductance L, operating at a given frequency. Now I want to estimate the eddy currents, which are induced in a piece of metal, which is placed in front of the coil, and the ...
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### Will an inductor wound using wire of 0.6438 mm (22 AWG) be close enough to 0.508 mm (25 SWG) for a neglectable difference?

Degi-Key has 25SWG as an obsolete item. While the instructions for a project say to use, "25cm length of 25SWG wire. Wrap the wire around a cylindrical object of 6mm diameter and take it out after ...
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### A question on an approximate calculation of an ideal transformer inductance

I have a 230V to 6V step-down transformer. I'm trying to calculate the inductance of the primary side 'roughly' in an easy way. Here is what I have in my mind: For that I added some illustrations ...
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### Is a flyback diode necessary for a small sg90 servo motor?

I am powering a small sg90 servo motor (see datasheet) directly using a 12V battery and a simple circuit to step down the voltage to the appropriate one for the servo. I noticed the servo has some ...
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### Why is breakthrough voltage of a TVS-diode decreasing when in parallel with an inductance

in our lab we are testing a circuit which has an inductance and a TVS-Diode in parallel. The task is it to determine the breakthrough voltage of the diode. The test works like this: We apply a ...
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### Current flow through inductor (large inductance) in AC circuit

I fail to understand why does the current flow in one direction only initially at t=0 in an AC circuit.. also when inductance is increased the time take for the current to stabilize and move in equal ...
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### Influence of a magnetic field on coil impedance

If you take a coil and make a current flow through it, the coil creates a magnetic field. This field induces a voltage into the coil that produces a counter current that weakens the primary current ...
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### How do I stop coiled (telephone) wire blocking signal?

This circuit is working just fine if the output signal uses a straight wire, even if it is a very long wire with say a 1K resitor added to the end of it. However, the signal does not get through when ...
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### The physical meaning of inductance

What is the the physical meaning of inductance? We know that the resistance "R" of a conductor is how easily the electrons flow through it...etc but what about the inductance "X" ?
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### Reverse Current in N Channel Power Mosfet

I am designing a bidirectional current source to drive a large (~60A) current through a large inductive load (100's mH) and facilitate very fast switching times (as close to an 1A/us as possible). My ...
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### Multiple output flyback converter simulation in Advanced Design System

I am trying to simulate with Advanced Design System (ADS) a multiple output (one primary winding, three secondary windings) flyback converter (see the image). But I cannot find a component in ADS ...
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### Techniques for driving inductive load, e.g DC motor, with PWM and constant current

I'm having trouble getting full torque out of a DC motor at anything other than full speed with a PWM driving circuit. Assuming the problem is inductance of the coils, what can be done besides ...
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### If I used the primary coil as an inductor, does the secondary coil affect it?

I've read this question. It's about how to obtain the maximum inductance from a transformer: How do I use a transformer as an inductor? Now, I would like to use the primary coil only as an inductor ...
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### State Space Model for Variable Mutual Inductance

This is a hell of a request, but today I have recently introduced myself to the concept of the 'State Space' model. I've understood, to a basic level, how state space models work and I am convinced ...
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### Induction Coil Diameter

I am currently building an induction heater to anneal brass casings. I have bought a 1000W induction heater with coil and a 36V 16.6A PSU to run it. Everything works well, I can put in a screwdriver ...
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### Inductance values over the frequency

Does inductance vary over frequency in passive components. Consider a Coax cable for example, does the inductance value change as a function of frequency, lets say from 5GHz to 100GHz, does the ...
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### Wy are speakers rated by impedance instead of inductance?

Audio speakers contain coils which product sound by vibrating a cone. Why are speakers rated by impedance instead of inductance?
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### Artful Coils: How will changing the shape of coiled wire change the resistance?

"Vape Mods" are a type of atomizer used in e-cigarets. These "mods" can be built basically from scratch. The simplest mods consist of little more than a battery and a coil shorted over the battery ...
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### Crosstalk in current loops

I'm trying to understand the interaction between two signal lines. The image below shows two planes (left and right) which have connector pins (bold lines). The top signal line is the "driving" line ...
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### How to stay well grounded?

After some read about ground plane breaks and inductor loops, now I am totally confused about how to design good PCBs. I made a small example of a two layer PCB. Blue is the big ground place. Red are ...
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### converting inductance to electromagnetic force

How might one determine the amount of electromagnetic force produced by an unshielded inductor? E.g. How much holding force does a 600uH unshielded inductor posses? Or alternatively in reverse: How ...
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### PCB Trace Layout to Minimize Inductance

I was wondering what the intuition was behind widening PCB traces to minimize the inductance between a trace and its ground plane. Many high speed design guides cite this without providing much of an ...
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### Find the inductance using function generator, oscilloscope, capacitors, resistors, multimeter, voltage generator

I am trying to find the inductance of a inductor. I have tried many different methods such as putting the inductor in parallel with a capacitor to form a tank circuit and in series with a resistor ...
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### 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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### Calculating voltage spike of an inductor

Suppose there is a circuit like this where the inductor has no resistance In this circuit, if Switch 1 is initially closed, then there is 10/100 = 0.1 A of current flowing through the inductor. ...
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### Can you run wires to an inductive heating coil or will that be a bad idea and why?

I have an inductive heating circuit that runs at around 5A at 24V (I'm estimating here). Is it possible to place the inductive heating coil a distance away from the circuit and connect the circuit to ...
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### Why does current flow in circuit when dc voltage is applied to inductor?

I read in my textbook that when dc voltage source like a battery is connected to inductor,it develops an emf which opposes the increase of current in the circuit.On applying kirchoff's law in the loop,...
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### Relation between frequency and inductor current

I have a question regarding frequency and inductance. What is the relation between frequency of an applied voltage that is square wave, over an inductor, and the average current that would flow ...
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### How can I describe mathematically what is happening in my home made LVDT variant?

I've built an LVDT (Linear Variable Differential Transformer) that is a little different than how it is conventionally done with 2 secondary coils positioned adjacent to a primary coil. My design is a ...
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### Is it possible to measure inductance without LCR Meter/OSC/FG

Like the question, i don't have an oscilliscope/Function Generator/LCR Meter. I do have a multimeter and a lot of "scrap inductors" that i would like to measure. I have searched a lot on the web and ...
527 views

### How does an inductor block frequency?

I know the basics of self-inductance, and how an inductor creates a voltage/current that opposes the increase or decrease in current. I can't find anything on how it reacts to/blocks certain ...
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### Induced voltages and flux within a transformer and their polarities

This is a multifaceted question, and is more to see if I understand what happens inside a transformer. I understand the general idea behind transformers: Alternating voltage that is applied to the ...
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### Design for a small shop 240-volt induction heater?

I am interested in finding a design for the electronic/electrical components of an induction heater for a small shop using a 220V 60Hz input. I do not need designs for the coils and cooling system, I ...
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### Are low ESR SMD capacitors with jumper wires between their legs and the circuit OK?

I have a board with two super low ESR SMD electrolytic capacitors which came off the switching power supply of a notebook motherboard. The legs of the capacitor are still soldered on the board. One of ...
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### Spaced air core inductor wire size effect?

I'm intrigued by the second circuit in Spehro's answer and/or it's precursor (FM Crystal Radio) http://electronics.stackexchange.com/a/217086/33670 But I don't happen to have any 18 Ga solid wire, ...
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### How signficant is leakage inductance in a flyback converter?

In designing some flyback DC-DC converters (to give us isolation), we have been simulating potential designs in LTSpice, which has gone well. (Isn't LT great at documentation? Pretty much perfect ...
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### Finding L and R in AC circuit

Ammeter readings: A1 = 4A A2 = 2A A3 = 3A Voltmeter reading 24V. Circuit is in AC. I have to find R1,R2 and L. While calculating R1 (R1 = 24V/2A= 12 Ohm) seems to be easy, next steps are not ...
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### AL value: nH/N² vs. nH/T²

I'm in the process of sizing some toroidal ferrites. My problem is that I am seeing the AL value on the datasheets shown two different ways as nH/N² or nH/T². Are these two units identical? I believe ...
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### Meaning of infinite self inductance

I am reading about the characteristics of an ideal transformer and it is mentioned that self inductance of each coil is infinite. Could someone help me to understand the physics behind it? When self ...
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### Why is inductance negative in this triphase mutual inductor?

Suppose I have a threephase circuit with a mutual inductor on the first and second phase (V2 and V3). One way of solving the circuit (ie finding the phase currents) would be the following: convert the ...
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### equivalent inductance

If two circuits 1 and 2, are coupled through the coils of inductance L1 (in circuit 1) and L2 (in circuit 2), how does the inductance value of L2 affect L1 ? and what is the inductance value seen by ...
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### equivalent inductance

I have a basic doubt in understanding the concept of equivalent inductance. When two inductor coils are in series the equivalent inductance is calculated as $L_{eq} = L1+L2 \pm 2M$ (depending on ...
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### Where should I look for transformer inductance discrepancy?

I'm experimenting with this smallish (~15VA) toroidal line transformer as a "lab" exercise as I'm learning about transformers. Right now it has its original 115V primary winding only; I "unwound" and ...
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### inductance of multi-stranded wire

The inductance of a single loop of wire will increase in inverse proportion to its diameter. Are there exceptions to this rule when applied to multi stranded wire (not litz wire). I should make it ...
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### Welding Transformers?

I was thinking of making a carry handle for two microwave oven transformers in series, and also so that they can share a common ground without having to split the ground wire. I thought about bolting ...
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### How to choose the correct inductor for my application

I am planning on using induction to power some game pieces in a project I am building. My plan is to use identical coils in board and piece, so they will be small (2" max diameter). My problem is ...
If I have two inductors, with inductances $L_1$ and $L_2$. I put them really close to each other to make a transformer. Are their individual inductances still $L_1$ and $L_2$? Or has the ...