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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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Effect of a coil before DC motor

I am wondering what effect a coil before a DC motor has. It's a 3 AA battery powered (4.5V) small RC car. I cut off the cables going to the motor and connected the motor to the battery directly (I ...
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54 views

How to measure the impedance of a given coil? [duplicate]

What's the best way to measure the resistance and inductance of a coil at a given frequency? I need these parameters for my LTSpice-Simulation which assumes an RL series circuit. The coil has 8 ...
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56 views

Output problems with lm124 opamp

I am using this circuit to supply current through R1 which is a 50Ohm coil. Opamp is Lm124 supplied as shown in the schematic. Vin is a voltage that can be between 2.5V and 3.5V. Everything works fine ...
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35 views

Coil causing spike and circuit reset?

I built a circuit that pulses a 50-ohm electromagnet when a 'trigger' magnet passes over a hall-effect sensor. This circuit swings a pendulum and simultaneously plays an audio clip as long as the 555 ...
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50 views

Control a fan motor (with PWM IC burned out) [closed]

After the IC fan controller burned out by a voltage error I pulled it out to see what the motor coils were like. They are so I think: 4 series coils, but I'm not sure if it's the 4 coils in series. ...
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43 views

RLC circuit with intial conditions

The circuit I have is given by the following schematic: simulate this circuit – Schematic created using CircuitLab I know a few things: The current in the circuit at \$t=0\$ equals \$\text{I}...
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2answers
65 views

yesinductane heating stainless steel bolts [closed]

I wish to heat 303 stainless 10 mm bolt to form an eye with 10 mm ID. My gas torch just doesn't get the bolt hot enough for me to hammer it into the shape I need. So I would like to make an ...
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46 views

Relay Circuit Explanation

I am trying to understand relay circuits better. I have two circuits in question below. Left Image I understand Pins 2 and 9 are the coil contacts. I would wire a microcontroller outpin pin to a ...
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79 views

Does the lack of a primary DC blocking capacitor cause my tesla coil driver to explode?

Lately I've been tinkering with an SSTC half-bridge driver. I've ran a couple of tests using relatively low input voltages ~50V and the IGBTS seemed to do fine, there was no noticeable heating at all. ...
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44 views

Transformer windings order

I have several transformers for audio amps, with single thiner primary and dual larger area secondary windings, for lower voltage higher current. They are toroidal, all by different manufacturers, but ...
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3answers
87 views

Xenon Flash thyristor trigger

I'm building a xenon flash unit with a power of 50Ws (300V 1000uF capacitor). I need to trigger it from a microcontroller. For that I use a MOC3041 to opto isolate my µC from the HV circuit and ...
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47 views

Magnetize a thin cobalt steel rod

I need to magnetize a 1/16" x 4" cobalt steel ( drill) rod to its maximum strength. I plan to heat the rod past its curie temp before magnetizing for maximum effect. Can I do this with straight DC ( ...
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Mutual inductance vs coupling coefficient

Question regarding this and this question about mutual inductance and coupling coefficient. I'm trying to analyse a two coil system: It consists of two coils like in the picture with 2 cm air gap ...
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Location of secondary winding on long rod core transformer with full length primary winding

On a Rod iron Core transformer or Induction coil pair, if the primary is wound 1 layer deep from end to end of the core, say a 10 cm long coil from end to end, and the secondary is 1 layer and only 2 ...
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47 views

Transformer safety concern

I have a a transformer for my speaker (230VAC -> 9VAC). The primary of the transformer is basically a coil. Is it not dangerous to pull out the transformer from the outlet? I know that in coils if ...
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43 views

How Does Line Frequency Affect Coils of a Contactor?

I am using a generator as my source voltage, which produces 240VAC @ 240Hz. I was planning to use the following contactor from TE: CONTACTOR 4PST 40A 240V In the datasheet it says this contactor's ...
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79 views

How to know Number of turns

In closed magnetic circuit, How many turns are when a conductor winded around a square mild steel core with permeability (Ur=2410)? The outer length is 20 cm and inner length is 16 cm. The current ...
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107 views

Tesla coil - my primary circuit doesn't work

I would like to make a Tesla coil, so I bought a 10 kV 120 W 30 mA neon sign transformer from Aliexpress. First potential problem, while playing with it, I noticed that when it stops ...
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A few questions about copper coils, magnets and induction

So I've been into electronics and electricity in general, lately. I've been trying to understand induction. Here's a few questions I had pertaining to it. In what way are coils connected together to ...
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52 views

How to optimze a coil for needed voltage?

Faraday's law for a coil is : V = A * M * N Where: V = Peak output-voltage A = Area of the cross-section of the wire M = Rate of change of magnetic flux in the coil N = Number of turns of the ...
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3answers
109 views

Amplifying a pulsed current

I need to pulse a current through a coil, to create relatively short magnetic pulses. I would like to know if I can use a function generator as the source of the pulses and amplify the current that ...
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1answer
88 views

Overvoltage protection for AC relay dilemma

I am currently designing a safety-related device that has to open a relay when a certain event occurs. During most of its life, this relay will be closed, and only open if the safety event occurs, ...
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2k views

H-Bridge with emitter followers

I am currently reverse engineering a circuit which requires controlling of a magnetic field. For that, the circuit has a pair of D882 and B772 each. The PCB traces suggest that the transistors are ...
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1answer
54 views

“3 phase” Type of winding I am not aware of, help? not wye or delta, maybe eFed up generator?

I bought a few 30 watt 3 phase motor/generators in supposedly delta configuration from a ali express. the motor did have only 3 wires coming out, plus the manual stating it, I am pretty sure this was ...
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2answers
53 views

Why is the common lead of unipolar motor connected to the high level voltage?

I'm trying to gain a deeper understanding of DC stepper motor because I'm using them for an arduino project. I was wondering about why the common lead of unipolar stepper motors is usually (always?) ...
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58 views

Capacitors discharging into Coil

I have 2 capacitors charging in parallel and then switching them in series to discharge into a wound coil of known inductance. My capacitors are 4nF 2000V and the charging voltage is 1000V. So at the ...
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53 views

How does adding more coils to an AM tuner coil allow it to tune Shortwave?

I have seen several tutorials about how to turn an AM radio into a Shortwave radio. They add more coils to the inductor (is that the correct name for the tuning coil?). Here is one example, https://...
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110 views

Mounting orientation recommendations for PCB spring antenna?

I have been looking at 868MHz through-hole spring antennas for an application, but I can't seem to find any sort of information in datasheets regarding layout recommendations. Here's the most ...
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155 views

Magnetic field - spiral flat coil in A (0,0,z>0)

I need to derive and draw a formula for the magnetic field in the center of a flat spiral coil shown in Figure 1, but at a distance on the Z axis other than zero. fig.1. I know that the formula in ...
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1answer
100 views

Voltage induced in aircraft high-tension magneto ignition system

Why is there no voltage induced into the secondary winding (in high-voltage step-up transformer) when the ignition switch is closed (OFF)? When the current flows in the primary winding of the coil a ...
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3answers
138 views

Can a transformer have no secondary stages?

While disassembling the power for the spindle of my hobby CNC mill, I came across something peculiar which I think warrants a question on this site. The input is standard 220V AC. Phase 1 (brown) ...
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1answer
63 views

Three phase RC unit

I found this component connected in parallel with an inductive load ( three phase coil used to disengage a mechanism ) the load keeps heating and burning after a while ( had to rewind it ) and no ...
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134 views

What's the minimum amount of transistors I need to operate a stepper motor?

I would like to know the minimum amount of transistors to operate a stepper motor.Could I pilote it with one transistor or I need one transistor for every coil? Thanks in advance! Edit: the minimum ...
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Resonant circuit: Inductor resticts discharge of capacitor?

Following schematic: simulate this circuit – Schematic created using CircuitLab Let's assume the capacitor has a charge of 10V in the moment t = 0, and the overall voltage of the system is ...
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61 views

Moving a magnet through coils wound in the opposite direction

Suppose I want to harvest kinetic energy by moving a magnet back and forth through a coil assembly. Faraday flashlights work by this principle, but to my knowledge those usually only have one coil. ...
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64 views

Build a simple coil generator

I know that if I want to create a powerful electromagnet, then I'd better put a ferromagnetic material inside the coil I build. So I was wondering if the same applies in the inverse scenario, that is ...
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196 views

UHF Tesla coil powered by low voltage?

I want to know if it is possible to use a 2.4 GHz magnetron as a oscillator for a Tesla coil circuit. The idea is to use a oscillating relay-driven step up transformer (12 V to 10 kV) and then charge ...
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773 views

Making a nail electromagnet with bare copper wire?

When creating a simple electromagnet, all you need is a nail and some copper wire, and a battery. I did this using non-coated copper wire, and after thinking about it for a bit, I was confused as to ...
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62 views

Continue winding using another wire

While winding a coil my wire snapped, I would like to complete winding of the coil and still have a functioning coil? Will it have any effect on the performance of that coil? It’s being wound ...
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1answer
149 views

IRGB14C40L and MC33153

I want to drive a power ignition IGBT (IRGB14C40L), and for this a driver MC33153 has been chosen. I have several questions about my supposed schematics, shown below: 0) This design will (allegedly) ...
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Different coil configurations and how they affect effi

I am a novice when it comes to electronic systems so forgive my ignorance. I was wondering if different stator coil configurations affect efficiency in a magnet and coil set up. Specifically what ...
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1answer
100 views

Winding a custom transformer with coil former

For a project I'm building a DC/DC convertor for converting 600VDC to 5VDC. Through the use of the TI Webench I was able to create a design, but it requires a custom wound transformer. The transformer ...
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75 views

Will a loop antenna work with only two turns?

I am considering the design of a manually-wound AM loop antenna roughly following this guide. It must be tunable in three ranges - 3.33MHz, 7.85 MHz and 14.67 MHz. The highest range would simply have ...
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3answers
135 views

Circuit approximation of Induction in guitar pickups

I was trying to learn the way basic guitar circuits work, the other day, and I stumbled upon a thing that I couldn't fully understand. According to this site, a simple guitar circuit can be made as ...
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2answers
46 views

Alimented coil close to a passive coil

If I build a coil A, of 10cm height with iron core and a 4cm diameter, and alimented it with a DC 15v,6amp source, it will produce a magnetic field. Let’s say A is set vertically. Will building ...
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1answer
48 views

Discharge of a coil powered by parallel transformers

I have the following circuit: I basically have 2 transformer, one is 230V-8V the other one has a ratio of 1:1, so 230V on the secondary. I'm rectifying the two signals with two full bridge ...
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1answer
63 views

Does the resistance of a coil increase if it gets burnt?

If a coil gets burnt, does its resistance necessarily increase? The reason I'm asking this is that I have a vape, and burnt coils are common in vaping. The vape has an LCD that shows the resistance of ...
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2answers
157 views

Approximate Capacitance of a Toroidal Coil

I'm interested in an expression for the capacitance or resonant frequency of a Helmholtz like (the windings are parallel to the plane of the coil) of circular cross section and of the order 1 meter in ...
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341 views

12 v watt heater with nichrome coil [closed]

i am new here. First of all I am sorry for my bad english. I want a help from those who know about nichrome heater coil. I want to make a 12v dc incubator using nichrome wire as heating element, all ...
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29 views

What is the canonical form based on sinus of the autoinduced EMF in a coil

I am stuck with this exercise as I can't really find the expressions I need in order to solve this. Please help me & guide me theoretically, so I can finish this. Deduce the canonical form based ...