Questions tagged [coil]

A coil is an electrical conductor such as a wire in the shape of a coil, spiral or helix. coils are used in applications where electric currents interact with magnetic fields, in devices such as inductors, electromagnets, transformers, and sensor coils.

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63 views

How to use this 2 coil motor as a hand crank?

I found this used motor coil and got a few questions on how I can make it useable as a hand crank. There are 2 coils with respectively 2 wires each. How exactly do I know the way of how each coil ...
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108 views

How to trigger an 8 channel relay module with an air coil and moving magnet

I just bought this 8 channel relay module on Aliexpress, and I'd like to try to trigger it using an air coil and a moving magnet, but I'm unsure how to connect the coil to the trigger and collect the ...
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100 views

Show polarity of magnetic pulse using two LEDs

I have made this simple circuit: In response to a rapidly changing magnetic field (pulse), the LED blinks. An example of the pulse is shown below: Now I would like to have a circuit with 2 LEDs so ...
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55 views

How does a relay behave when its resistance is increased or decreased? [closed]

I have a relay of coil resistance 200 ohm whose input voltage is 12V DC. Now, under the same 12V DC supply, will the relay be activated when: The relay coil is decreased, say by 100 ohm i.e. new coil ...
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59 views

Determine inductance of large inductor

I asked a similar question before but i am still struggling with this problem. I am trying to measure the inductance of a large (34cm diameter) electromagnetic brake. Important findings to keep in ...
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94 views

Can voltage be increased without coils?

I have a $5 solar lamp. I have recently repaired it. It has a 1.5V rechargeable battery, a small solar panel, a yellow LED, a power switch, a transistor, a diode and some resistors. I am a little ...
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65 views

How to determine electromagnet air-gap using current waveform

I am trying to determine the air-gap of between an electromagnet (coil diameter 34cm) and a metal armature using the current waveform. In the figure below you can see the charging curve of the coil ...
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87 views

Determine electromagnet inductance

I am trying to measure the inductance of a large electromagnetic brake (coil diameter 34cm). I used two methods: LCR meter (100Hz because the brake is activated using a rectified 50Hz AC voltage) (...
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78 views

Is it possible to use 48V relay in 120V circuit by adding current limiting resistor and capacitor. Will this also speed up the response of the relay?

simulate this circuit – Schematic created using CircuitLab title kinda says it all, Was talking to another engineer and didn't quite follow how they said they could get faster trip coil response ...
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1answer
47 views

Current draw of a bilge motor [closed]

What happens at the coil when an electric bilge motor is stuck and stopped from spinning and the current draw increases beyond the rating (from 2 A to 8 A)?
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Is this ringing a problem after "Relay coil fast demagnetization". If so, how to stop

In the question Relay coil fast demagnetisation, a diode and a zener were used in series to quickly remove the energy from an inductor. The question posed an example of a 24VDC 400mW relay, and I ...
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Relay coil fast demagnetisation

In the past few days, I've encountered an application note on the Maxim Integrated website about rapid demagnetisation of an inductive load: https://www.maximintegrated.com/en/design/technical-...
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Coil generator in practice

I am trying to create something like gyroball. Which features LED lights, so the faster the spinning, the more light LEDs emit. This seems like a simple scenario of a coil generator. As an experiment, ...
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45 views

Using a signal generator and power amp to supply >>240VAC to a coil

On Lenz's law, Wikipedia says: Faraday's law states that the EMF is also given by the rate of change of the magnetic flux where epsilon is the electromotive force (EMF) and \$\phi_B\$ is the magnetic ...
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83 views

Total force made by the magnetic fields and the current, it should be zero but as I tried to derive it , the upward components only remains

As shown in the above diagram , the same 2 coils of square are aligined with paralell of same plane . $$ I:=\text{current which flows to each wire of the square } $$ What I am confusing to ...
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148 views

Determining an industrial electromagnet coil's number of turns and wire diameter, etc

I'm a new graduate and fresh hired Electrical Engineer who works in a company building magnetic separators for general industry (including mining, recycling etc.) Normally, we build magnetic ...
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67 views

Briefly switching a coil

We are going to build a telegraph which can communicate to an other telegraph. One of our communication systems exists out of a bell. The idea is that the sender can press a button and the receiver ...
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1answer
68 views

Finding out the magnetic field inside the cross section of the torus which is wrapped by conductive wire and the current flows it

As shown in the diagram , the torus of radius of \$~ R ~\$ exists . The wire is wrapped around the torus . $$ N:=\text{total number of the turns of the wire around the torus } $$ The current is ...
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106 views

Is there a formula to calculate the saturation current of an inductor or is it only obtained experimentally?

I want to make an inductor for my buck converter since I cannot obtain the recommended inductors for the LM2596. How do I calculate the saturation current for this inductor if I use a ferrite core? ...
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1answer
156 views

Can two electromagnetic coils repel and attract with both like poles?

I was playing around with two EM coils where they have a steady flow of DC current through them. Theoretically, both of them should be magnetised to have a stable north and south pole, a typical ...
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54 views

\$\delta n \cdot x + n \cdot \delta x~\$ equation of shrunk coil with incremented number of turns per unit length

The very long coil exists with the following information . $$ a:=\text{radius of the circle of the coil} $$ $$ n:=\text{number of turns of the coil per unit length} $$ $$ x:=\text{lenght of the ...
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54 views

DC Power Relay 12V inrush Current

I have a question regarding 12v dc relay circuit design. About 350mA flows through the relay coil from the 12v power supply, so the pmosfet specification was selected as vds -30v, id -2A class. The ...
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44 views

Does the current or voltage switch when an inductance goes from being a load to a source?

When first S1 is closed to charge the coil the voltage UL and current IL are inline and positive. When the switch S2 closes and S1 opens, does the current or voltage switch direction?
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121 views

How to repair broken coil?

I am working on my Grandpa's rare old watch which was damaged, the damage is with the coil in which one copper strand is cut. Its an enamel coated copper. How to repair the cut wire? and I want to ...
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56 views

Could anyone identify the manufacturer or a similar product to this ~6x7mm inductive charging coil?

I had this smart ring from a company called Oura, and I took my charger apart recently. Inside, I found an incredibly small inductive charging coil printed inside of a little FPC. Could anyone ...
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1answer
53 views

Tesla coil design: primary coil

Background info: I'm trying to create a spark gap tesla coil that uses a ZVS / flyback combo, and so far, given the initial tests with a 12 volt 20 amp power supply, I managed to get it to work, but ...
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48 views

What effect in the current will have the change of the diameter of coil but same length of coil and same magnetic flux?

First image is one coil with the large diameter and a magnet rotating to create current in the coil. Second image is the same set but the diameter of coil is smaller.
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68 views

Reason behind coil melting

Today I managed to melt the ignition coil of my RC engine. First let me describe my circuit, I have also created a diagram, however I could not find all the parts in the designer so I think some ...
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2answers
71 views

Driving electromagnetic coil "out of spec"

I'm designing automatic watering system for my garden. I've bought these bistable electromagnetic valves. But specs are somewhat confusing: voltage range is 3.6-6 V, current consumption is 200-300 mA, ...
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38 views

Can someone explain what is the purpose of connecting the 2 center coils in parallel on my scooter's stator?

Hi. First post here and have this burning question on my mind. I am going to rewind the 2 coils at the output end and the ground end cos I accidentally connected the bike's battery to it and burnt out ...
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1answer
70 views

Electric toothbrush: Role of spring in contact-less charging

I accidentally dropped our electric toothbrush on the floor and the bottom lid came undone. I want to fix the toothbrush and make it watertight again. I would glue the lid back on, but this is impeded ...
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3answers
142 views

Function Generator to Audio Amplifier

I am looking to control a Helmholtz coil with a function generator but I need a waveform amplifier to increase the current and voltage from the function generator. The coil has to be run using low-...
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38 views

Improving coil launcher circuit

I recently constructed this working circuit for a coil launcher project. I'm still working on the optical sensors to shut off the coils. That is not pictured here. I would now like to start beefing ...
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157 views

How many volts is needed to power a coil

I recently encountered and was trying to troubleshoot a device that's not working properly. In tracing the functionally of the device, I isolated the issue with a coil that does not activate. ...
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70 views

what exactly is this component and what the marking on it means?

my car stereo (audi rns-e) showed a blank white screen, took it apart and the outer part of this component was rattling around. i want to replace it to see if it was the problem, but i dont really ...
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279 views

How do you prevent feedback in a relay or contactor (120V coil, 120V contacts) when coil and contact are both connected to one source?

I have a 2NO 2NC 120V coil, up to 400V contacts contactor. (Electrodepot 934022) I need to power both the coil at 120V and the contacts at 120V from the same source. Manufacturer says this is not ...
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3answers
74 views

Induction Motor Wire Size

Capacitor Run Single Phase Induction Motor have very high starting currents, possibly in the order of 35-40 Amps upon startup for a 1 hp device, whereas the nominal current usually lies in the order ...
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2answers
198 views

How to switch a 700A 200V pulse for a coilgun?

I'm working on a coilgun and I need to discharge a capacitor bank through a coil to create a strong magnetic field. My coil has a resistance of 266 milliohms and when fully charged, the capacitors are ...
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99 views

What is a good circuit model for an AC generator?

A very simple electrical AC generator can be made by spinning magnets around a fixed stator coil. The changing magnetic field induces current in the stator winding. It would seem that at a fixed ...
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1answer
83 views

Slayer exciter not drawing from supply

I made a Slayer exciter according to the schematic below. I have done about everything necessary for it to work such as sanding the bottom of the secondary. I have 2000 turns on secondary, and 7 on ...
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42 views

Repurposing auto cigerette lighter heating element

Been trying to solve this and was looking at making custom heating elements with wire but is was getting way too complicated for me. My thought, which would completely solve this assuming I can ...
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1answer
97 views

Torque RPM Characteristics of Single Phase Induction Motor within Maxwell's Equations

A single phase induction motor is constructed of a stator, which contains the stationary main winding, and a rotor, which is a conductive cage which rotates. The stationary main winding is a two pole ...
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80 views

Limiting Power in a Coil

I am currently working on a project to make my own coilgun. But a bit unsure of the driver circuit. Typically, a driver circuit will look something like this: Flyback diode and a mosfet being the ...
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1answer
82 views

Different coil turns

Why there is a different number of turns? Why there is not 8 turns on each side?
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135 views

Flyback diode placement for solenoid valve simulation circuit

I am working on a project where I want to fake the presence of a solenoid valve in a control unit on a car so that the control unit does not give an error message. The output of the control unit is a ...
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3answers
430 views

How to optimise wire gauge selection for electromagnetic applications?

Disclaimer: Hobbyist "maker" with limited experience and no relevant education. Please considerate and answer in detail. Feel free to skip to "Question". Context I have an ...
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170 views

What are the possible reasons this current transformer doesn't work?

On the assembly shown, I have built a current transformer with a toroid coiled with 30 turns of magnet wire. The brown wire is the phase going through, blue is neutral. When I connect a fan onto the ...
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109 views

Why coil at high frequency pass lower current?

I am currently working on a project that uses an H-bridge to output different direction current. I use 2 P-channel MOSFETs (IRF4905), and 2 N-channel MOSFETs (IRF3710) to build my H-bridge. *reference ...
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2answers
72 views

How to understand this formula.?

I am having ferrite core T60006-L2063-W517 Ferrite Toroids /Ferrite Rings Core 63x50x25 58.6uH@10kHz. I wanted to measure inductance of the core from datasheet it shows, Ferrite Rings Core 63x50x25 58....
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66 views

PWM driven MOSFET to power a coil

I need to power a coil (electromagnet to be precise) using a PWM singal generated by an arduino or a 555 timer. I can esily power the coil when the PWM signal is in the HIGH (5v) state using a simple ...

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