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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Are my calculations wrong?
So I'm trying to make relatively large square coil antenna that will operate at 125khz frequency. The width and height of antenna are 300mm (30cm) and wire diameter is AWG24 (0.51mm) and I'd like to ...
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1answer
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can I use a choke 150uH inductor for my AM transmitter circuit?
I am trying to develop an AM transmitter but I am having problems with getting a variable capacitor and inductor (for the rf circuit) in my location. I was able to find a choke coil with an inductance ...
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42 views
Protection for transistor driving a coil
I recently purchased a few electromagnets. I want to drive these with transistors, but I want to build in protection, as these don't have any available specs re: max operating temp, duty cycle, etc. (...
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1answer
57 views
Magnetic Field around step-down converters [closed]
I'm courious how strong is magnetic field around step-down conveter? My plan is to use one LM2596 @ 12V(1A at maximum load) and one LM2596 @ 5V for STM32.
I Know that coils generate MF around itself ...
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42 views
Detecting both short and open circuit voice coils in coil driver
I'm building a voice coil driver for a science experiment. The coils are in an environment where both coil shorts and coil open circuits are common problems. I'd like to build in a fault indicator to ...
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1answer
51 views
How to power an electric motor
I would like to attempt to assemble an outrunner BLDC motor from scratch. Its working principle seems ridiculously simple and I'm up for the challenge. There is one thing that I would like to clear up ...
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88 views
Magnetic circuit diagramming
What software makes magnetic circuit diagrams such as the one pictured?
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75 views
How does Rühmkorff induction coil start and periodically produce sparks?
I found the following pictures and equivalent circuit of the Rühmkorff induction coil:
Can someone explain the operating of this coil in a step by step fashion?
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2answers
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Power output of ignition coil - 2.0 [duplicate]
There was an older question about "Power output of ignition coil".
The system would not let me comment on that question.
So, I'll ask here. In regards to a ignition coil (non specific).
OK,you have ...
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45 views
Linear antenna: with electromagnetic coil, trap circuit
I am trying to understand the concept of the linear antennas.
I have read that the linear antennas are the simplest form of the antenna in the case of asymmetrical (coaxial) feed.
what happens if I ...
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52 views
Designing a Flex PCB as a wireless charging coil
I am designing an inductive charging circuit to power up a small device with an odd shape. None of the off-the-shelf coils fit the dimension specified. I figured I needed to design my own coils like ...
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29 views
Current transformer damage
Can a current transformer be damaged with an open secondary coil even if it is powered with an extremely low current?
e.g a small spark gap is made, though no plasma stream is created due to the ...
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1answer
83 views
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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1answer
62 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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1answer
60 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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1answer
37 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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1answer
56 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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47 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
68 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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1answer
50 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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1answer
93 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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2answers
52 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
115 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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1answer
49 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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2answers
252 views
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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1answer
48 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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1answer
53 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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0answers
82 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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1answer
151 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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1answer
55 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
111 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
109 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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5answers
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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
56 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
55 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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0answers
59 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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1answer
55 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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1answer
149 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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1answer
130 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
143 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
69 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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3answers
162 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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0answers
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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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1answer
68 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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1answer
85 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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2answers
276 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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1answer
972 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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1answer
64 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
190 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) ...
