Are these inductors?

If so, can anybody estimate their ratings? Or is there a way I can measure them? I'm looking for something around a 4mH inductor to use in "Simplest Ever DC-DC Boost 12v to 73v" instructable by "pyrohaz". Also, are these potential inductors the same as the ones found in CFL light bulbs? And one more thing, why does the small one have 4 wires coming out, the medium one has 2 wires, and the big one has 10?

Question by Ke-Bob 8 years ago  |  last reply 8 years ago

dc inductor

Do inductors work with pulsed dc? like would they become more resistive with frequency? Or would they do nothing because it's not ac and the electrons can't "bump" into eachother.

Topic by guyfrom7up 11 years ago  |  last reply 11 years ago

Inductor coils?

How would one go about determining the milihenries value of an inductor coil pulled from an amplifier, well different ones I have found. And living up to it's standards, google has found me no information but what an inductor coil is and it's function, but no information on how to find inductance rating.

Topic by Punkguyta 10 years ago  |  last reply 10 years ago

Inductor winding?

Once again, I come to you for help. I recently became interested in some kind of 555 device metal detector. The schematic calls for a 10mh inductor. However, my local Ripoffshack doesn't carry inductors, and instead I decided I could make my own. It's just a coil of wire right? Right, so I have some formulas to find inductance given things like length and width, and I wondered if there's anything I need to be aware of. Does a ferrite core increase inductance? Where can I get a ferrite core? Do I need one? Is there a sweet spot for inductors? Thanks, Mr. Merino

Question by mrmerino 6 years ago  |  last reply 6 years ago

Inductor Usage

I have an 10mH inductor pressed against the active line of an extension cord connected to a load (a washing machine) that produces 9 amps. How do I measure the voltage produced by the inductor? Does it need to have a current already in order to react to the magnetic field? Does the negative lead produce a negative AC and the positive frequency such that if I attached a voltometer I would get a 0 reading? That's what I am getting even on my voltometer, even on the finest setting. I should be reading 0.09V, I believe.

Topic by watchingmachine 11 years ago  |  last reply 11 years ago

Inductor Heating Problem Answered

I'm having a bit of trouble with an inductor implemented as part of a boost converter. The circuit works fine except for the inductor gets very hot within a few seconds after turning on. There are also noticeable high pitched noises coming from it associated with varying current loads. I'm not really sure what the issues are as the circuit is within the maximum DC current rating (circuit draws around 120mA, inductor is rated for 250mA) and resonant frequency is also quite low (around 1.5kHz). Datasheet for the inductor I used can be found here. Some help would be appreciated in determining what the problem is and in locating a suitable replacement inductor. Thanks.

Question by andy70707 3 years ago  |  last reply 3 years ago

Help With This Inductor Anybody?

Hey. I'm still learning a lot about electronics, and I'm still very new to that kind of thing, but am trying an electronics project for the Green contest anyway. I did some research on how step-up converters work and finally have settled on a circuit that would work for my project. My problem lies with one of the parts. I needed a 68uH inductor. When I ordered it, the picture below was what I got. This didn't seem quite right. It may be the correct thing, I don't know. So what I'm asking is... A. Is this the part I'm looking for? and B. How would I attach this to the PCB I'm etching for the project. Thanks in advance. My pic was a bit blurry so I found something that looked similar from the internet to go along with it.

Topic by Gjdj3 11 years ago  |  last reply 11 years ago

Effects of Inductors Coupling?

This is a follow up post from this thread >> (It was about how to fix my Wah-Wah guitar pedal, it turns out the Inductor was not working, so I replaced it) I replaced a broken 500mh INDUCTOR in my guitar pedal with a new one. It works now. However, I am planning on keeping the broken inductor in my wah wah pedal (because it yielded a cool volume pedal sound). I want to rig up the circuit so that I can switch from from the GOOD conductor to the BAD conductor. My questions are: Will there be any major effects from having two inductors coupling? Should I be wary of the 'winding' of the coils? If so, what should I do in order to be consistent with the winding? And out of curiosity, how could I rig this up?  Here is the schematic >> 500mh Inductor = L1 I have 3 terminal DPST switch. This is how I imagine rigging it up: I'm thinking of having wires from the inductor terminals on the PCB wired to a terminal on the SWITCH, then to the INDUCTOR, and then back to the PCB. The same follows for the other (bad) inductor. If this is not clear, please let me know, or feel free to post a better way to rig this up. In summary for this last question How could I rig this circuit to switch between two inductors? Thanks.

Topic by Grizzly_Bear 5 years ago  |  last reply 5 years ago

Coil inductor make?

I have, what I believe is, a neodymium ring magnet (pictured) that measures approximately 1.6 cm across x 0.3 cm thick and it has an inner diameter of of about 1 cm. I have been debating on what to do with it (also open to suggestions) hence the title. My question is how do I attempt to predict the performance of a coil created with this? 

Question by Dauntless 4 years ago  |  last reply 4 years ago


Question by pranjal12 6 years ago  |  last reply 4 years ago

what is the value of the inductor i have seen?

I have an inductor which has a "562j" written on it. is it 5.6microHenry which has a 5% tolerance.i need your help.thanks!

Question by cons11 9 years ago  |  last reply 9 years ago

how to make an inductor?and how much it (uH)? Answered

I want to make a flyback driver, i need inductor 200 uH

Question by Rendydevara 9 years ago  |  last reply 9 years ago

Can someone please explain to me what a Axial Inductor do?

Axial Inductor- i have a couple of these things, but have no idea what they do.  they look like a resistor.  can someone tell me what are they used for.  thanks

Question by trinidadmike 7 years ago  |  last reply 7 years ago

Digital Capacitance Meter? Answered

Can a digital capacitance meter measure the capacitance of an inductor?

Question by The MadScientist 8 years ago  |  last reply 8 years ago

How to replace an SMD inductor? Answered

I have an 2gen Ipod shuffle which I burnt. Now after a long while I found that an inductor cas destroyed. How can I find it's value?or Can I put a jumper instead?

Question by theVader75 8 years ago  |  last reply 7 years ago

Microcontroller based inductor winder? Answered

 Is there any way, and I'm sure there is but I don't know how to do it, to make an inductor winder that is programable. Any type of microcontroller brand would work, be it arduino, parallax, pickaxe, whatever. Basically what I would need is a code, and a schematic that would drive two servos, one continuos rotation to do the actual winding and one to move the inductor back and forth, to keep an even winding going. The code would have to dictate how many turns the servo does in order to get the desired number of windings. It can even have to be reprogramed for every inductor from the PC, to keep it more simple. --Thanks         P.S. Sorry if this question was difficult to understand, I didn't know how to put into words what I                           had pictured in my mind...

Question by arhodes18 9 years ago  |  last reply 9 years ago

can i use a 470mh inductor instead of a 500mh inductor for a wah pedal? Answered

I am building my own circuit, and i realized that i could buy a similar part for 10 dollars less.  Is this a possible substitute. thanks in advance.

Question by fatfoohy 9 years ago  |  last reply 9 years ago

Can you use standard choke inductors as electromagnets?

I am making a project where I need very small electromagnets to attract and hold a small metal flap closed when the circuit is turned on. Flap is about 1cm from the magnet and returns to this position via a spring when the circuit is off. In theory is it possible to use inductors used in electronic circuits (for interference suppression etc.) as an electromagnet? Thanks.

Question by laquermonkey 9 years ago  |  last reply 9 years ago

How to Identify or Measure Inductance?

I am gathering the parts for an ible, but I am short one part: a 12mH inductor.I can spot some inductors in electronic garbage - the wire coiled around a ferrite loop - but there are also solid state inductors. Plus, the inductors are not usually labelled with their values.How can I measure the inductance of an inductor with a volt-meter and an ammeter, but without access to a sine-wave generator?Is there some simple trick that would get me "close enough" to the true value? What would be really useful (but probably doesn't exist) is a chart or formula where you plug in the size of the core and the number of turns around it and out pops the inductance value. ?

Topic by Kiteman 10 years ago  |  last reply 6 years ago


I am making a project and i needed a bit of help. I needed to make an inductor of 0.35mH and I do not have a shade of an idea how to make it. If anyone of you might help me i would me greatful to you. THANX.

Topic by pranjal12 6 years ago  |  last reply 6 years ago

What is the equation to determine a coil's inductance? Answered

I have been looking for the equation to determine a coils inductance in henries, but I can't find it. I want the one that uses core diameter, wire thickness, and wire length to calculate it. (But I'll take any equation that will allow me to calculate it easily without test equipment) Could someone help me out?                                                                                                                                                         Thanks!

Question by transistorguy 8 years ago  |  last reply 8 years ago

Can anyone help me make sense of a ferrite core datasheet? Answered

I need help understanding a datasheet for some ferrite cores I bought to wind transformers on.  This is the datasheet:  The main thing I need to know is the inductance per turn of wire on the core so I can design the transformers to minimize inductive reactance and such.

Question by UbuntuNinja 9 years ago  |  last reply 9 years ago


Is there any difference between a coil and electromagnet? So, is saying that a dynamic speaker has coil as correct as saying that it has an electromagnet?

Question by .Unknown. 8 years ago  |  last reply 8 years ago

Any tips on winding a toroid properly? Answered

Every time I try to wind a toroid for a circuit, it never works or it is very temperamental and does not cooperate with me. Any advice on how to wind a better toroid?                                                                                                                                                                                                                                                         Thanks! 

Question by transistorguy 8 years ago  |  last reply 8 years ago

Joule thieves?

I am trying to make a joule thief according to many websites and such, but it never seems to work, even if I follow the instructions. The joule thief I'm trying to make is one of the simplest, with a 1K resistor, transistor, tapped coil, etc. I think it may have something to do with the inductor, even though I've tried a whole different types. I got it to work once, though, when the 1K resistor was replace with a 10K resistor accidentally. I heard somewhere that the resistor should be around 1K up to 3K. Any higher and efficiency goes down. Is that true? And why doesn't the joule thief work when I use a 1K resistor instead of a 10K resistor? P.S: I have made many other joule thieves, my first one being from, and my favourite, the supercharged joulethief from

Question by .Unknown. 8 years ago

How to find inductance of an unknown inductor? Answered

I have some inductors harvested from an old power supply.They don't have an induction rating and I want to measure them.How do I do this?

Question by Derin 9 years ago  |  last reply 9 years ago

What are the effects of Henrys in the use of inductors? Answered

I'm looking for information that might help me find a reactor for my variac setup. I noticed that almost every inductor I looked at has a Henry rating, I'm curious as to how this effects the circuit. After reading up on what a Henry is, I'm not sure I understand what it is exactly. I have also heard of people referring to inductors by their inductance, would they be referring to their Henry rating or their voltage/amperage rating? P.S. My variac is a 125/260v 11A military surplus, for all those interested.

Question by pmk222 3 years ago  |  last reply 3 years ago

Can any one tell me how to make this inductor? Answered

Can any one tell me how to make a 0.35mH inductor what will be the turns and what will be the coil dia.? the circuit is shown below.

Question by ubdussamad 6 years ago  |  last reply 6 years ago

Does an inductor start with a magnetic field, or does it only retain one as long as it is powered?

I am trying to figure out how to keep a reed switch on by proximity to a magnet. I read that an inductor stores the current as a magnetic force, so I was planning on just having the reed switch close to the inductor, and just use a small magnet to close the circuit initially. i was hoping the field from the powered inductor would keep the switch closed. Am I on the right track?

Question by redbaron1234 8 years ago  |  last reply 8 years ago

ATTENTION ENGINEERS: Inductor to limit inrush when starting an electric motor?

The situation: I am using a contactor (like a big switch) to start a brushed permanent magnet DC motor. I am not using a motor controller. The motor is a Mars 0909 which draws 4.8 KW continuous and 15KW for 30 seconds The problem: This current can cause arcing at the contactor which can erode the contactor's electrical contact points and perhaps stress the batteries or blow a fuse needlessly. The goal: Reduce inrush while the motor starts up. The question: My teacher suggested I use a large inductor in series with the contactor. Theoretically the inductor would resist the initial inrush of current and then its resistance would go way down. We looked around a bit and didn't find any motors in series with an inductor in series. Is there a reason why inductors an not typically in series with motors? Is this something like a "Peterson coil" or an "arc suppression coil"? Any idea what the formula would be to calculate the size of such a coil?

Question by snotty 7 years ago  |  last reply 7 years ago

Tesla Coil Secondary Winding Question?

Just curious, I'm working on a Tesla coil and I've run out of wire 1/2 way down the secondary coil. Does anyone think I could just continue winding with another spool of wire and solder the 2 ends together?  Thanks!

Question by transistorguy 8 years ago  |  last reply 8 years ago

i want to make a inductor coil for heat metals e.t.c.?

I want to build a inductor coil for heating metals  i want schematics and how build this thank you

Question by silverplated 8 years ago  |  last reply 8 years ago

Transistor and inductor based 1W emergency light.

I made this 1w emergency light circuit for the maximum output (consuming less power to deliver maximum brightnes) from the LED. But during its functioning, i found that the led glows with same brightness as it was without the circuit ( directly connecting it with battery). Please, suggest some alternatives or amendments to be made. I have uploaded an image of my circuit.

Question by ShuvamP 3 years ago  |  last reply 3 years ago

How does an inductor cause current to lag voltage in the case of an alternating current, and why is this bad? Answered

Basically, can someone help me with this: ? What are the EXACT physics behind it?

Question by Xellers 9 years ago  |  last reply 9 years ago

how to measure inductance using a bridge?

My LCR meter can only read inductances of mH to a few Henries. I need to make a 470uH inductor, since in my place inductors are not so common. How can i measure inductances at microhenries if my LCR meter's reading capability only ranges from millihenries to henries? Someone told me to use bridges like wheatstone bridge or maxwell bridge to have an accurate reading, but i don't know how to do it. Can you suggest any reference? I prefer doing wheatstone. Thank you in advance :)

Question by codestroy7 7 years ago  |  last reply 7 years ago


Im kind of interested in messing with some basic electronics (which i know very little about) and my question is if I have 2 dc devices that have a 900ma draw on both like 2 cell phones .... do I need 2 separate circuits that can handle the individual loads or do i need 1 circuit that outputs say 2a they both take what they need from?

Topic by cbubel 4 years ago  |  last reply 4 years ago

What is this mystery electronic component? Answered

I bought an assortment of components: resistors, diodes, capacitors, all mixed together on about a meter of cut tape from a reel for an automatic PCB populating machine. The original reel was marked as surplus from DEC and looks to be about 20 years old. One of the components is this black cylinder, like a very fat resistor, about 5 mm long and 3mm diameter. No resistance or diode action. Brittle and crack off with a pliers like ferrite. They do not melt or burn with a candle flame. The wire lead goes straight through and out the other side. Can be picked up by a magnet, but are not themselves magnets. They have no markings of any kind, but have shiny flecks. Are they some kind of magnetic tape position marker to tell the insertion machine what component is next? Say like a binary code?

Question by iectyx3c 8 years ago  |  last reply 8 years ago

Transformer Technicalities?

Hey guys I need some help from the experts. I am building the microwave transformer ark welder instructable. I have acquired my microwave transformer, and rewound the secondarys. Now here's where it get interesting. I stay in South Africa, and we have 220v, 15amps coming out of the wall. So I figured with so much wall power I probably only need one transformer, cos I already have too many amps (on paper). So from what I understand, I will be putting 3300watts(220v*15Amps) into this transformer. Another interesting detail is that I think my transformer has 200 turns! I put 16 turns on the secondary (although there is space for more, I just don't have a piece of wire long enough). Which means that my out put voltage will be 17.6v, and 187Amps! Ahhhhhh!!!! If I wind a few more turns on the secondary, I could probably squeeze 25 on there, that will bring my output voltage to 27.5v and 120 amps. Which seems like quite a lot? So here's my question: Will this work? If not, and things go bad, what will happen? Is there any chance that the primary coils will melt, or is it only the secondarys that will do that? I don't really want to destroy my transformer, because they are really hard to get here. South Africans won't give you snow in winter. I had to buy a broken microwave! One idea I had: I have a single coil wrapped around a plate iron core, it looks just like a transformer but with only one set of windings. The thing is as big as the microwave transformer, its wire is of a slightly thicker gauge, and it probably has about 600 turns on it (it belonged to a florescent light setup). I thought I could connect this up to the secondary winding, maybe it will bring the amps down, and also serve as an inductor/ark stabilizer. But I'm just guessing, I'm a complete noob to electronics!?

Question by lenny25 9 years ago  |  last reply 7 years ago

Would this work as a flanger pedal for a guitar? Answered

I am wondering if the would work as a flanger guitar pedal. For the variable inductor, I am planning on using a hand wound coil similar to one on an old crystal radio(quaker oat box one)

Question by josh1324 7 years ago  |  last reply 7 years ago

"Joule Thief" LED Night Light Kit is Now Shipping

Thank you so much for those who pre-ordered the kits! I have shipped all orders now, and the kits are in stock. New orders will be shipped within 2 days. To purchase, please go to Please see this post for the pricing and more: Thanks!

Topic by ledartist 7 years ago  |  last reply 3 years ago

"Joule Thief" LED Night Light Kit & PCB

UPDATE: Everything is shipping now. My instructable is here: "Joule Thief" LED Night Light  Check out the new color changing Joule Thief! KIT Pricing is $10.50 for the kit. Kit 5 Pack Save by ordering 5 packs for $39! PCB Pricing is $4.50 for the PCB. Shipping is $5 for USA, $17 for the rest of the world. *** NOTE: The color of the PCB will be green instead of purple shown in some of the pictures. *** Payment To order, please go to my site - Click on "Add to cart" button and check out via PayPal. Please send messages or leave comments here if you have questions. Thanks!

Topic by ledartist 7 years ago  |  last reply 4 years ago

Colour Night Joule Thief kit & PCB

Please see the instructable for the details and video of this project. *** This is a color changing LED version of "Night Joule Thief". Pricing is exactly the same. *** Kit (includes PCB) Pricing is $10.50 for the kit. Shipping is $5 for USA, $17 for the rest of the world. A picture of full contents is shown below. Kit 5 Pack Save by ordering 5 packs for $39! Shipping is $5 for USA, $17 for the rest of the world. PCB only Pricing is $4.50 for the PCB. Shipping is $5 for USA, $17 for the rest of the world. Payment To order, please go to my blog page at You will find buttons to buy, and checkout via PayPal. Please send messages or leave comments here if you have questions. Thanks!

Topic by ledartist 7 years ago  |  last reply 7 years ago

how to decrease the impedance from a battery ?

If i have a battery that give me 16 M ohm and i would like to decrease the amount to a 1 ohm , if i try and put an inductor in parallel with the battery , it does decrease the amount , but the inductor and the battery get hot and may do damage , so i'm looking for a converter maybe to connect a battery to power transistor and then to an inductor or a transformer , not to increase voltage but to decrease impedance , anyone can help me through this? thank you

Question by Ask Alice 3 years ago  |  last reply 3 years ago

Can someone help me build this LC resonant circuit? and explain it to me Answered

"An LCR circuit 1 is comprised of a capacitor 3, inductor 5, transformer T primary winding 9 and resistance 11 connected in series. It is assumed that the electrical conductors connecting the various circuit elements and forming the inductor 5 and primary winding 9 are perfect conductors; i.e., no DC resistance. Resistor 11 is a lump resistance equivalent to the total DC resistance of the actual circuit components and conductors. The inductor 5 is wound on a core 7"

Question by Intercom D 7 years ago  |  last reply 7 years ago

How many more times do you have to wrap a ferrite rod to achieve the same power as a toroid bead?

So recently I found a neat low-voltage fluorescent driver instructable, it calls for a large toroid as its inductor, I dont have any large toroids, but I do have a ferrite rod.  What I want to know is if I have to wind 90 turns of wire on a toroid, how many do I have to wind on the rod?  I know it has to be more because the rod looses EMF through its ends.                                                                                                                                   thanks in advance,                                                                                                                                                             Junits15

Question by junits15 9 years ago  |  last reply 9 years ago

SMPS formulas?

Are there any switched mode power supply formulas? I've been googling but I can't find anything... I need to know relation between duty cycle (I'm using square waves) frequency size (value) of the inductor output voltage output amperage how many amps should the inductor be rated for (is it how much your drawing?)

Topic by guyfrom7up 10 years ago  |  last reply 10 years ago

Oscillator Trouble/Math ?

I have a "step-up" transformer from a DVD player that I really want to experiment with, but I know I need some form of alternating current to use it. I just finished taking a 3-week summer camp at which I learned about electronics, and there I encountered the 555 circuit. It's simple to build; I can just connect all the pieces on a small breadboard, considering I have several 555 chips. But what makes me a little miffed is that anything over 6V could burn out the chip's components. So I gave up on the 555 oscillator, and turned to the simple(-er) LC circuit. I want to have around 60 Hz to simulate the mains frequency, but I have no idea what capacitance or inductance I should use. Furthermore, I don't quite understand how to achieve a specific inductance based on coil turns, coil diameter, coil length, etc. If anybody could clear me up on these concepts, I'd greatly appreciate it.

Question by Umniscient 8 years ago

I already built a metal detector by using 555 timer IC. My problem is 10mh inductor? Answered

Can you give me a details of 10mh inductor? 1. The number of wires? 2. The number of turns? 3. The coil diameter? 4. The coil length? Thank you. I am hoping for your sonnest reply.

Question by teodygwapo 6 years ago  |  last reply 6 years ago