OMG. You must be a teacher. If not then you would make a great one. I always learn a lot from your videos. You are the best i have come across so far on the internet. And the internet is quite large.
Wow. Finally someone who knows what the hell he's talking about. I've asked so many people about everything in this video, and almost no one could tell me the science behind making a coil. Nice job.
I love the way you explain it. Makes it simple to understand. The first time I glanced at the formula, it was very intimidating until you broke it down.
Cool. That's exactly what my goal was so I'm glad to hear my explanation worked. Hopefully you'll be a little less intimidated by formulas in the future since that'll open up whole new worlds.
Thanks, I've been working on Mendocino motors and coils for charging (induction) and signaling (with a hall sensor or a reed relay) a bike light design. This comes in handy!
I like it better when folks use units in physical equations. For example, the 'mysterious' constant 1.26ee-6 is really just the magnetic permeability of free space in units of H/m. As such the distances should also be in meters.
webpage with the inductance calculator. How do you calculate wire gauge or AWG into your equation. Some tesla coils are 28 AWG and 24 AWG what happens to freq. Current isent the only thing.
I don't calculate wire gauge, but it sounds like a good thing to add to the page. Some times I have a coil already so I know the length for the formula. For my small Tesla coil I wrapped a few turns of wire on the core (cardboard paper towel tube) and then measured the length of that, then divided that by the number of turns I'd put on, and that gave me the average thickness of a single turn. I also recall, a long time ago, using my micrometer to measure the thickness of a wire. Regarding frequency, this is just a coil induction calculator. A full blown calculator for a Tesla coil (if that's what you're working on) has already been done so well here www.classictesla.com/java/javatc/javatc.html that I wouldn't even try making one.
Great Video. I wish there was a guide like this when I was a kid :) No doubt I will be linking to this one a lot :) I especially like the mentioning of all the Formulas, including the thumb rules and rounding off's that regularly get used when designing coils. Those little details can get a lot of people stuck on the theory unnecessarily. When they would learn more by just forging ahead and giving it a go so they can see how it works.
Thanks. Yeah, formulas are great guides. They're a lot of knowledge compressed into a small area. There's still a lot they don't say, but they go a long way.
Formulas are easy to google. Its not always so easy to get a quick yet accurate guide to using them. Its very helpful to show how they work and which numbers are constants and which ones can be rounded etc to make it all more user friendly while maintaining an acceptable error margin :) For beginners looking up LC circuits it can be very overwhelming. Now thanks to this video it needn't be :D
Do you mean the thickness of the wire? The only effect the thickness of the wire will have is that thicker wire will mean a longer coil and length is a variable in the equation (see the inductance formula in the video). If you're trying to keep the coil a certain length then a thicker wire will mean that you can fit fewer turns into the same length. If by thickness of the coil you mean the wire thickness' affect on the coil's diameter, then the diameter includes the thickness of the wire. That's because the diameter is measured from the center of the wire on one side to the center of the wire on the other side. The diameter goes into calculating the area variable in the formula.PS. Sorry for the delayed reply. For some unknown reason, UA-cam flagged your comment as spam and then didn't tell me about it until now.
@@RimstarOrg I googled lots of times to find a formula to calculate the inductence but each websites shows different different formulas .Which one is the correct ?Please reply me too.Here are some examples 👉L=MaN^2A/d 👉L=D^2n^2/45D+100l 👉and your formula.
Thank you! That was very inspiring! :) Though... I need to do a specific coil with multiple leyers and on Iron-Silicon sheets ... its for audio crossover, and since this coil that i'm trying to build needs to cross a speaker at about 175 Hz, I definately need Iron core, because by my calculations it has to be around 6.2 mH... its huge if I have to build it on air core! But I do not know what is the permeability of this type of alloy (iron-silicon)... on wikipedia it says its around 19-90! I don't know what to do anymore... my sheets have 15 mm width/ 71 mm in lenght and I have used 30 of them because they are only 0.3 mm thick
Hello ! I enjoyed yor video very much , it teached me a lot but i have one question : What material would you use to build a wind turbine generator ? Congratulations for Your Great Work
I don't know, I've never built a wind turbine generator. I'd imagine you would not use an air core though. Likely ferrite or layers of steel insulated from each other to minimize eddy currents. I'd suggest searching on UA-cam for DIY wind turbine generators -- I know I've seen them around, though I don't recall any details.And thanks.
That's the nice thing about standards... there are so many to choose from. :D I don't know where the MH for microhenries came from, one of those old conventions I guess.
I really found this video to be helpful - thank you. :c)' I am probably going to reveal just how little I know of electronics with this question but here goes. If I were to wrap two layers of coil (lets say equal turns) around a section and connect both inlets and outlets together i.e. connection in parallel - what might I expect to see? How might a dual layered coil, each of 100 turns compare to a longer coil of 200 coils? Thanks for humouring my ignorance. :c)
@RimstarOrg I have two N52 Magnets Size 2"L x 1"W x 3/8"H and Magnet wire 18Awg, I will have One Magnet face North and other South But I need to make One Magnet wire Coil that both Magnets rotating 360 degrees in center of One Coil to produce at least 14 Volt and light up 150 watts light bulb, How many turns of magnet wire I need to do or have to produce what i'm looking for the out put. I look forward to your reply
Here in 2024....learned a lot from you back in the day....Hey can you say...."I'll let you use my light house for message sending if you listen to my tale" its from rick and morty you sound like the character that saids that.
Hi, i saw a coil in an experiment the other day that was no more than 4 inches long and around 1" in diameter, but the guy said it's inductance was 24H ! I thought i knew enough about inductors but i can't see how such a small coil can have such a very high inductance, what are the methods to achieve that ?
I just plugged your numbers into the calculator on my website, using 217 for the number of turns and a magnetic permeability for the core of 100 and I got just 29mH. To get 29H I had to change to permeability to 100,000. I then did a google search for "magnetic permeability 100000" and got mu-metal (en.wikipedia.org/wiki/Mu-metal) and permalloy (en.wikipedia.org/wiki/Permalloy). Perhaps he was using one of those as a solid core? If it was an air core then I don't see how he could have gotten 24H -- an error perhaps.
I think you've got it! I tested a coil that had proper non-grain-oriented steel laminations (about a dozen) with an inductance of 106mH, i cut up the mumetal sheet into rough rectangles like the laminations, and with only 5 strips i got the 105mH, thanks for the heads up.
Thank you for your crystal clear explanations. There is something that I still do not understand, and I hope you will clear it up for me as well. By changing the number of turns, the core material and its area one can tune the receiver. But all that is happening is that a link is then established between the broadcasting station and the receiver. It would be like the switchboards of old where one telephone user was linked to another by the operator. That still does not explain to me how the messages can come across. For example, let us say a station is broadcasting at 1200khz, with your explanations and the formulas, I should be able to build a crystal radio that can link to this station. But how are the messages coded in the 1200khz? I hope I am making sense.
I think your confusion comes from thinking that a link is established between the broadcasting station and the receiver. There isn't any. What's happening is that the 1200khz signal and signals and noise of other frequencies are all arriving at the receiver and the receiver is tuning into just one frequency. I explain it more completely in my How a Crystal Radio Works video here ua-cam.com/video/0-PParSmwtE/v-deo.html
@@RimstarOrg I agree that your image of the receiver just "standing there" with its own frequency is much more accurate. The point I was trying to make is the fact that within the same frequency all kinds of sounds are captured and we have nothing that explains them except the fact that they exist. The wiper of a crystal radio apparently captures those sounds and not the frequency of the coil even though this frequency makes the capture possible.
Does shape affect how an inductor behaves? Not in terms of measured or calculated inductance but in how that inductor responds to changing frequency or loading or in transmitting? For example, if I had two 240uH inductors, one on a round tube, and one on an egg shaped oval tube (say I taped a sharpie to the cardboard tube then wound the coil so I had a nice prominence for my wiper) would there be a difference in how they behaved?
I think it would be close enough to work. Make sure you also check out my tips and tricks page here rimstar.org/science_electronics_projects/crystal_radio_tips_and_tricks.htm
I don't think relay coils are air core inductors. In order for them to create a strong enough electromagnetic field in a small area they usually have a core of some kind (maybe iron or ferrite).
Hi RimstarOrg Thanks a lot for sharing wonderful videos to learn electronics. I am a beginner to learn Radio and circuits . I really appreciate , if you could explain a 1- 2 transistor ( NPN ) Radio transmitter and receiver circuit for AM and FM. and explain why we need a resistor there , why we need a capacitor there , why wee need a inductor there....why we need a transistor there ...... and how electrons / Current/ signal go through .... Currently some U tubers explain Conventional current and Electron movement ... so it is very confusing for for beginners like me ... they never say their explaining using conventional current or electron movement. I think there are lots of people like me around the world , to learn these stuff. I really appreciate if you could post a few videos around this Kind regards, Dinna
Hi Dinna,I sort of have any radio videos that explain radios with transistors. I have a crystal radio explanation, which has the inductor and capacitor but no transistor. That's in my How a Crystal Radio Works video ua-cam.com/video/0-PParSmwtE/v-deo.html. For the transmitting side there's my video about amplitude modulation with a simple transmitter ua-cam.com/video/R04yEKqgGPc/v-deo.html. But I guess if you also watch the video about making an earpiece amplifier for a crystal radio, near the end of it (around 5 minutes in) there's an explanation involving the transistor. The crystal radio and the amplifier videos both use electron flow (and it's clear in the videos that they do), while the amplitude modulation video doesn't involve current flow in the explanation. Cheers, Steve
Hi RimstarOrg Thanks a lot for the reply. I watched all above videos before. They are all really good. Appreciate If you could explain a complete full circuit when you got time. That would be very valuable for lots of people. Kind regards, Dinna
So what if you use graphite as you core, it's permeability is less than air, so that will make the coil bigger for my needs? P.s. I'm still learning, long way to go
I don't know. It's magnetic permeability is only very slightly less than air so it may not make a big difference. However, that also means it's diamagnetic (en.wikipedia.org/wiki/Diamagnetism) and I don't know what the effect is of diamagnetic materials in coils. P.S. As you can see, I'm still learning everyday too.
The wire size affects the length and the number of turns you'll need. So a formula can be made that includes the wire size. On my webpage here rimstar.org/science_electronics_projects/coil_design_inductance.htm I have a section in a calculator that uses the wire size. You can try different sizes until you get the inductance you want.
The wire size plays a part in the length since the length is the number of turns x the wire diameter x the spacing between the wires. The wire size also plays a part in the area because when calculating the area, you measure your circle from the middle of the wire (see one of the diagrams on my webpage here rimstar.org/science_electronics_projects/coil_design_inductance.htm). The wire also has a resistance but when working on calculations for a coil, usually you treat the resistance separately from the inductance.
Oh, I though UA-cam's alogrithm was smarter than that at recognizing links -- it's including the closing parenthesis in the paragraph. Try this: rimstar.org/science_electronics_projects/coil_design_inductance.htm
The diameter plays a part in the length of the coil and the number of turns you can fit into that length. The number of turns and the length both are in the formulas. So when you try to get certain values for those, that's when the wire's diameter becomes important for inductance. Search online for a "wire size" table to help with that.
Resp.sir problem arises when choosing the thickness of the wire.There are no. of wires present for different thickness .How can choose required thick wire for particular inductance?
The thickness of the wire doesn't play a part in the inductance. It indirectly affects the length of the coil and the number of turns you can fit, both of which are part of the inductance formula. At high voltages it can matters since in that case you don't want leakage and so rounder is better at high voltage. But as far as I know it doesn't play a part in inductance.
The thickness of the wire is used in the calculator to figure the length. Ten turns with wire a tenth of an inch dia gives you a length of an inch....and so forth. The wire size is important due to current capacity requirements and desired resistance.
I tried with a 24 gage wire, which was way too thin. I don't think that thin of wire can handle much current before burning out. And it's difficult to connect the wire. You have to use sand paper to remove the plastic coat which is super tedious.
Hi sir, for my project I'll use a lower frequency (trafo), you said I'll have to use a solid core, is there any reason of doing it? or do you have a book reference for this? I want to know the reference for my paper, thank you sir
What are you using the coil for? I try to give some factors near the end of the video but there are lots of different uses. My knowledge largely comes from learning over the years so I don't have a specific reference in mind and the reference would depend on your use. A Tesla coil reference would be different than a reference for a radio coil which would be different than a coil for a filter and so on.
Yes, you'll need to solder them together. You could also just scrape off the insulation and twist the ends tightly together but make sure you twist them well so that they won't come apart.
The transformer already has capacitance due to the distance between the turns where there is insulation. Increasing the distance between turns and layers decreases capacitance. The type of material in that distance has an effect too so using mylar instead of air, for example, would give a bigger capacitance for the same distance. So yes, playing around with the distance and the material does affect capacitance.
Judging by the H in 1.68 H, I think you meant inductance and not impedance. To do it, try playing around with all the parameters until you get what you want. The calculators I mention on my website should help rimstar.org/science_electronics_projects/coil_design_inductance.htm
Yes. Increasing the diameter of the wire will make the overall coil longer and therefore affect the length parameter in the formula. Similarly, decreasing the diameter will decrease the length parameter. Or if you're trying to keep the coil a specific length then you'll have fewer turns, which is also a parameter in the formula.
Question: My circuit consists of a 1 to 30hz oscillator where the output is amplified to drive a 14.3uh flat coil but I wish to substitue the flat coil for a Helmhultz pair with a distance between them of 10 to 12 inches and coil height from between 2 to 12 inches or ideally two separate coils of 2 and 12. What are the calculations for that? ps: The current flat coil design the magnetic field strength is about 3 Gauss for 5% duty cycle and about 34 Gauss for 95% duty cycle.
I saw a coil made by the english guy Robert Murray-Smith on his "TNT" website, he used button or cylindrical neodymium magnets, and I am trying to replicate it. Can you tell me what figure or factor would you say and use for the permeability of these rare earth magnets. I plan to use a joule thief to power this coil to try and get the lowest input possibly. I think the Joule thief description is a misnomer, I think it is more a joule scavenger because it extracts very low voltage or energy from a depleted battery and then enhances the voltage through a transistor (MOSFET), what's your thoughts ?
You can find the permeability here en.wikipedia.org/wiki/Permeability_(electromagnetism) (see the table around halfway down). Regarding the name, Joule thief, it's more formal name is a blocking oscillator circuit en.wikipedia.org/wiki/Blocking_oscillator
@@RimstarOrg Yes, but I'm interested in your subjective and respected personal opinion sir, when the flux in a circuit changes rapidly in a circuit does it actually pick up energy from the "ether" for lack of a better term or is this laughable nonsense. More importantly is this a viable and reliable energy source.
There are countless circuits out there in all sorts of consumer devices and non-consumer devices that have existed for decades that do similar things to this, coils that are fluctuated in countless different ways and none have ever put out more energy than what's been put in. Don't be misled by the name, joule thief, it's just a blocking oscillator circuit. Energy is built up over time in the electromagnetic field in the coils and then dumped in a very short period of time, resulting in a high voltage. It's actually a fairly inefficient circuit, putting out overall much less than what's put into it. That's not to say that one day we won't find a way to convert energy from the "ether", assuming that's possible, but this isn't it.
@@RimstarOrg Ahhhhh, now your talking brother. Your last reply is written with true scientific and factual intent, you are an inspiration sir. I have dabbled and read about most of what you have written about, including the oscillators, the big trouble is putting the right components together in "situ" to make any over unity device (again, perhaps another misnomer) as efficient as possible. That, I have found is bloody hard.
Sir, I found out that 1.26x10^-6 is the permeability of air. Is it any different with ur (Mew r) or the permeability of the core in your given formula?
Yes, it's different than ur. 1.26x10^-6 is u0 (Mew sub 0) which is the permeability constant. ur is the relative permeability. As I said in the video, air has a ur of 1 meaning that it is 1 x u0 or 1 x 1.26x10^-6. Iron has a ur of around 100 meaning that it is 100 x u0 or 100 x 1.26x10^-6. That's why in the formula I show at 5:03 I'm multiplying 1.26x10^-6 on the end of the formula. The real reason it's called the 'relative' permeability is so that we can say things like, iron's permeability is 100 times that of air, it's permeability is 100 relative to air. It also prevents us from having to remember numbers like 126x10^-6 (which is 100x1.26x10^-6). Side note: You may see u0 written as 4pix10^-7 (you'll see the symbol for pi instead). pi is 3.14 and if you multiply that out you get 1.26x10^-6, the same thing.
How can i easily search for a coil under the ground witht the frequency 101.4khz (specifically designed for the telecom branch), is it possible to just use the magnetic sensors of the phone in combination with a khz searching app, or for example a multimeter with a coil? Most of the time we know around what area we have to search and the coil is about 50cm /1 or 2 feet under the ground.
I don't know if it would work but you could experiment with something like my pizza box crystal radio ua-cam.com/video/iunAvz9PbN0/v-deo.html You'd have to do the calculations for the capacitor capacitance and the coil inductance which I explain in this video ua-cam.com/video/tjD9I95RAbw/v-deo.html I have no idea if it's the best way or how well it would work if the source is underground though.
@@RimstarOrg What about just using an app that uses the sensors on the phone? Like this one play.google.com/store/apps/details?id=com.westerlydesigners.rfdetector_radiofrequency
What is not clear is how "area" is derived. Does one use the inside, mean, or outside diameter of the wires that make up the coil. Obviously the result will not be much different with thin wires. But, if one makes a coil with thick wires, the wire's diameter can have a big difference on calculated area, and more especially when the coil's outside diameter approaches the thickness of the conductor. When a coil's (outside diameter)/(inside diameter) >2 but
Since you were just the most recent of quite a few people who've asked me about whether or not the coil should be included in the calculation for the area, I just updated a diagram and added text about it to my webpage here rimstar.org/science_electronics_projects/coil_design_inductance.htm.
Relative permeability part is wrong. You can't use 100 for iron core. If it's not a closed loop (like toroid) effective permeability will be much much less than 100, closer to air permeability because there is huge air gap between the ends of your core rod.
I want to design a tuning circuit for variable frequencies. From the resonant frequency formula, we have L & C. The values are unknown. If I calculate the inductance using the above formula, I still need to know the radius and number of turns.(air core) How do you decide the number of turns and radius of the coil??
I start with the materials I have. For my crystal radio and Tesla coil, for examples, I had the tubes that I was going to wind the coils on, so measuring it gives the radius. There's some trial and error. Putting the formulas in a spreadsheet makes it easy to try a variety of values. If you know the desired frequency range and have some idea of what capacitance you can make capacitors for (or have capacitors for), then you can rearranged the LC resonance formula to solve for L (or use the calculator on rimstar.org/science_electronics_projects/lc_circuit_aka_tank_or_resonant_circuit.htm). Then rearrange the coil inductance formula to solve for the number of turns, though that's kind of hard to do if you don't also know the length. That's where a spreadsheet comes in handy since you can punch in different values until you get what you want. In the spreadsheet, length can automatically be determined from the turns if you know the width of your wire. To get the width of your wire, I wind an inch or whatever length or coil on the tube, measure it and divide it by the number of turns to get the inches per turn.
Do you mean the energy (erg is a unit of energy)? Power is energy per second and voltage * current is power. So sure, by measuring voltage and current in the coil you can get the power, of energy per second.
I don't know off-hand how temperatures that high will affect the coil. I'm guessing they'd increase the resistance and may have some effect but I don't have any formula for it myself.
I have some speakers I need to repair but I'm not sure what gauge/thickness of wire to buy for the voice coils. data I have found: Kapton with 1.005″ inside diameter, 1.125″ form length, 0.437″ windings width, 8 ohms. so what gauge or cross section wire would that be?
The gauge only played a part in determining the length of the overall coil and the number of turns I could fit in that length. So the gauge was involved only indirectly. If the current is high or the voltage is high then the gauge can also be important, but it wasn't in this case.
Superb presentation Sir! If school was like this, the world would be a smarter place.
I’ve seen ALL of UA-cam’s inductor videos and this IS THE BEST of them all. For me. I understood everything you said. Solid content.
the best explanation about inductors design ive ever seen
OMG. You must be a teacher. If not then you would make a great one. I always learn a lot from your videos. You are the best i have come across so far on the internet. And the internet is quite large.
Wow. Finally someone who knows what the hell he's talking about. I've asked so many people about everything in this video, and almost no one could tell me the science behind making a coil. Nice job.
I love the way you explain it. Makes it simple to understand. The first time I glanced at the formula, it was very intimidating until you broke it down.
Cool. That's exactly what my goal was so I'm glad to hear my explanation worked. Hopefully you'll be a little less intimidated by formulas in the future since that'll open up whole new worlds.
This man is what i call A GENIUS !!
THANKS!!!! I was looking for this for a long time... I’m building my own we n low-pass crossover
Thanks, I've been working on Mendocino motors and coils for charging (induction) and signaling (with a hall sensor or a reed relay) a bike light design. This comes in handy!
Hello! that's a wonderful receiver! thank you for sharing.
Superb explanation. Many thanks to you.
Nice this help to find out more about coils, and i might eventualy learn to make my own circuts after my desiger
Thanks! I couldn't find the answer to why Tesla coils use air cores until your video mentioning it! Thankyou!
Thanks for presentation!! That's an awesome lesson!
Thanks Dan! I'm glad you liked it. Thanks for watching all these years.
Great job. Clear and direct. Thanks.
Keep doing what you do! You are helping big time! Thank you :)
Great Video . I request you to make video on tuned transistor amplifier design. It should include , design of biosing resisters , tank circuit etc
Fantastic tutorial - much appreciated! Thanks.
Thanks! I was looking for a guide like this for weeks!
Thanks for the helpful information; how does wire guage/ coil resistance play into this? Appreciate you sharing some great basics
The thinner the wire the less current can flow through
Thank you so much for this. i was mullung over this while trying to build a primitve smps.
I found your calculator online before finding this vid, Its very helpful thanks!!! 👍😎🇬🇧
Glad to hear it helped! Thanks!
Thanks a lot for the calculator. IT really helps.
I like it better when folks use units in physical equations. For example, the 'mysterious' constant 1.26ee-6 is really just the magnetic permeability of free space in units of H/m. As such the distances should also be in meters.
Mond blowing honest explaination...!!!
Really informative, thanks so much!
You are absolutely wonderful! Thank you very much.
Super, very imformative ! 🔥
Good tutorial
Very clear Sir. Thank you.
Completely 100% awesome video. Thank you so much.
thanks, nice and informative information. very useful
very good video helped me learn this beter. thank you
Really useful, thanks!
Nice! Thanks for this knowledge sharing!
Thanks for posting.
webpage with the inductance calculator. How do you calculate wire gauge or AWG into your equation. Some tesla coils are 28 AWG and 24 AWG what happens to freq. Current isent the only thing.
I don't calculate wire gauge, but it sounds like a good thing to add to the page. Some times I have a coil already so I know the length for the formula. For my small Tesla coil I wrapped a few turns of wire on the core (cardboard paper towel tube) and then measured the length of that, then divided that by the number of turns I'd put on, and that gave me the average thickness of a single turn. I also recall, a long time ago, using my micrometer to measure the thickness of a wire.
Regarding frequency, this is just a coil induction calculator. A full blown calculator for a Tesla coil (if that's what you're working on) has already been done so well here www.classictesla.com/java/javatc/javatc.html that I wouldn't even try making one.
Thank you
Thanks really helpful 👍❤️😎
Great Video. I wish there was a guide like this when I was a kid :) No doubt I will be linking to this one a lot :)
I especially like the mentioning of all the Formulas, including the thumb rules and rounding off's that regularly get used when designing coils. Those little details can get a lot of people stuck on the theory unnecessarily. When they would learn more by just forging ahead and giving it a go so they can see how it works.
Thanks. Yeah, formulas are great guides. They're a lot of knowledge compressed into a small area. There's still a lot they don't say, but they go a long way.
Formulas are easy to google. Its not always so easy to get a quick yet accurate guide to using them. Its very helpful to show how they work and which numbers are constants and which ones can be rounded etc to make it all more user friendly while maintaining an acceptable error margin :) For beginners looking up LC circuits it can be very overwhelming. Now thanks to this video it needn't be :D
Do you mean the thickness of the wire? The only effect the thickness of the wire will have is that thicker wire will mean a longer coil and length is a variable in the equation (see the inductance formula in the video). If you're trying to keep the coil a certain length then a thicker wire will mean that you can fit fewer turns into the same length.
If by thickness of the coil you mean the wire thickness' affect on the coil's diameter, then the diameter includes the thickness of the wire. That's because the diameter is measured from the center of the wire on one side to the center of the wire on the other side. The diameter goes into calculating the area variable in the formula.PS. Sorry for the delayed reply. For some unknown reason, UA-cam flagged your comment as spam and then didn't tell me about it until now.
@@RimstarOrg I googled lots of times to find a formula to calculate the inductence but each websites shows different different formulas .Which one is the correct ?Please reply me too.Here are some examples 👉L=MaN^2A/d 👉L=D^2n^2/45D+100l 👉and your formula.
Theese formulas were in my electronics textbooks already 50 years ago. Before UA-cam.
Thank u very helpful 😊
Thank you! That was very inspiring! :) Though... I need to do a specific coil with multiple leyers and on Iron-Silicon sheets ... its for audio crossover, and since this coil that i'm trying to build needs to cross a speaker at about 175 Hz, I definately need Iron core, because by my calculations it has to be around 6.2 mH... its huge if I have to build it on air core! But I do not know what is the permeability of this type of alloy (iron-silicon)... on wikipedia it says its around 19-90! I don't know what to do anymore... my sheets have 15 mm width/ 71 mm in lenght and I have used 30 of them because they are only 0.3 mm thick
This is really helpful ... thank you
Hello RimStar, can you please do calculations video for an induction AC motor ? thank you
great video. lots of neat info.
Very Good Video my friend thanks .
And the correct gauge for the desired current.
Thanks a lot
Can you share the references that you have followed to understand all these..
Oh, I don't really have any that I've noted. Much of this is from knowledge that I've acquired over the years.
what's the size of a 12 volt for a vibrating coil regulator ?
This is a great help and well-explained. I have a slight objection, though; when I see MH, I think "megahenry"
Me too but unfortunately, MH is sometimes used this way.
no, "mega hertz" is shown with "MHz" not with "MH".
Sir, why don't we use two capacitors to achieve the resonance circuit without resorting to the coil
I want to reply thanks
You're a great man god bless
Hello ! I enjoyed yor video very much , it teached me a lot but i have one question : What material would you use to build a wind turbine generator ?
Congratulations for Your Great Work
I don't know, I've never built a wind turbine generator. I'd imagine you would not use an air core though. Likely ferrite or layers of steel insulated from each other to minimize eddy currents. I'd suggest searching on UA-cam for DIY wind turbine generators -- I know I've seen them around, though I don't recall any details.And thanks.
wouldn't MH be mega henry's?
That's the nice thing about standards... there are so many to choose from. :D I don't know where the MH for microhenries came from, one of those old conventions I guess.
mH > micro Henry, MH > Mega Henry
mH is milli Henry. uH is micro (u used as similar to greek mu).
David L. Jones at EEVBlog also told this (MH for microhenries) in one of his videos... can't remember which one.
Munish_4 Kumar he as wrong write ...^^
thanks
full explanation thank u
:O
Omg please please please do one for the capacitance of coils too!
nice content
I hope you keep update :)
I really found this video to be helpful - thank you. :c)'
I am probably going to reveal just how little I know of electronics with this question but here goes.
If I were to wrap two layers of coil (lets say equal turns) around a section and connect both inlets and outlets together i.e. connection in parallel - what might I expect to see?
How might a dual layered coil, each of 100 turns compare to a longer coil of 200 coils?
Thanks for humouring my ignorance. :c)
@RimstarOrg I have two N52 Magnets Size 2"L x 1"W x 3/8"H and Magnet wire 18Awg, I will have One Magnet face North and other South But I need to make One Magnet wire Coil that both Magnets rotating 360 degrees in center of One Coil to produce at least 14 Volt and light up 150 watts light bulb, How many turns of magnet wire I need to do or have to produce what i'm looking for the out put. I look forward to your reply
Here in 2024....learned a lot from you back in the day....Hey can you say...."I'll let you use my light house for message sending if you listen to my tale" its from rick and morty you sound like the character that saids that.
Wowwwwwwwww I love this video Thank you New Sub here. How would this work with a Tesla Bifilar coil that has two wires in each turn?
Thanks You re the best
Hi, i saw a coil in an experiment the other day that was no more than 4 inches long and around 1" in diameter, but the guy said it's inductance was 24H ! I thought i knew enough about inductors but i can't see how such a small coil can have such a very high inductance, what are the methods to achieve that ?
I just plugged your numbers into the calculator on my website, using 217 for the number of turns and a magnetic permeability for the core of 100 and I got just 29mH. To get 29H I had to change to permeability to 100,000. I then did a google search for "magnetic permeability 100000" and got mu-metal (en.wikipedia.org/wiki/Mu-metal) and permalloy (en.wikipedia.org/wiki/Permalloy). Perhaps he was using one of those as a solid core? If it was an air core then I don't see how he could have gotten 24H -- an error perhaps.
RimstarOrg
Sorry yes it had a core, i've got some mumetal sheet i'll roll some into a core and see.
I think you've got it! I tested a coil that had proper non-grain-oriented steel laminations (about a dozen) with an inductance of 106mH, i cut up the mumetal sheet into rough rectangles like the laminations, and with only 5 strips i got the 105mH, thanks for the heads up.
Thank you for your crystal clear explanations. There is something that I still do not understand, and I hope you will clear it up for me as well. By changing the number of turns, the core material and its area one can tune the receiver. But all that is happening is that a link is then established between the broadcasting station and the receiver. It would be like the switchboards of old where one telephone user was linked to another by the operator.
That still does not explain to me how the messages can come across.
For example, let us say a station is broadcasting at 1200khz, with your explanations and the formulas, I should be able to build a crystal radio that can link to this station. But how are the messages coded in the 1200khz? I hope I am making sense.
I think your confusion comes from thinking that a link is established between the broadcasting station and the receiver. There isn't any. What's happening is that the 1200khz signal and signals and noise of other frequencies are all arriving at the receiver and the receiver is tuning into just one frequency. I explain it more completely in my How a Crystal Radio Works video here ua-cam.com/video/0-PParSmwtE/v-deo.html
@@RimstarOrg I agree that your image of the receiver just "standing there" with its own frequency is much more accurate. The point I was trying to make is the fact that within the same frequency all kinds of sounds are captured and we have nothing that explains them except the fact that they exist. The wiper of a crystal radio apparently captures those sounds and not the frequency of the coil even though this frequency makes the capture possible.
Does shape affect how an inductor behaves? Not in terms of measured or calculated inductance but in how that inductor responds to changing frequency or loading or in transmitting? For example, if I had two 240uH inductors, one on a round tube, and one on an egg shaped oval tube (say I taped a sharpie to the cardboard tube then wound the coil so I had a nice prominence for my wiper) would there be a difference in how they behaved?
Using the same number of turns, 25 and 90, would a coil with a radius of 0.75 inches prevent me from picking up a signal?
I think it would be close enough to work. Make sure you also check out my tips and tricks page here rimstar.org/science_electronics_projects/crystal_radio_tips_and_tricks.htm
Which is the website ur referring in your presentation if provide great help to the viewers of this nice video
The webpage with the inductance calculator is here:
rimstar.org/science_electronics_projects/coil_design_inductance.htm
Excuse me sir, i want to know, is the relay can be included in the air core inductor?
I don't think relay coils are air core inductors. In order for them to create a strong enough electromagnetic field in a small area they usually have a core of some kind (maybe iron or ferrite).
Hi RimstarOrg
Thanks a lot for sharing wonderful videos to learn electronics. I am a
beginner to learn Radio and circuits . I really appreciate , if you
could explain a 1- 2 transistor
( NPN ) Radio transmitter and receiver circuit for AM and FM. and
explain why we need a resistor there , why we need a capacitor there ,
why wee need a inductor there....why we need a transistor there ......
and how electrons / Current/ signal go through .... Currently some U
tubers explain Conventional current and Electron movement ... so it
is very confusing for for beginners like me ... they never say their
explaining using conventional current or electron movement. I think
there are lots of people like me around the world , to learn these
stuff. I really appreciate if you could post a few videos around this
Kind regards, Dinna
Hi Dinna,I sort of have any radio videos that explain radios with transistors. I have a crystal radio explanation, which has the inductor and capacitor but no transistor. That's in my How a Crystal Radio Works video ua-cam.com/video/0-PParSmwtE/v-deo.html. For the transmitting side there's my video about amplitude modulation with a simple transmitter ua-cam.com/video/R04yEKqgGPc/v-deo.html. But I guess if you also watch the video about making an earpiece amplifier for a crystal radio, near the end of it (around 5 minutes in) there's an explanation involving the transistor. The crystal radio and the amplifier videos both use electron flow (and it's clear in the videos that they do), while the amplitude modulation video doesn't involve current flow in the explanation.
Cheers,
Steve
Hi RimstarOrg
Thanks a lot for the reply. I watched all above videos before. They are all really good. Appreciate If you could explain a complete full circuit when you got time. That would be very valuable for lots of people. Kind regards, Dinna
So what if you use graphite as you core, it's permeability is less than air, so that will make the coil bigger for my needs? P.s. I'm still learning, long way to go
I don't know. It's magnetic permeability is only very slightly less than air so it may not make a big difference. However, that also means it's diamagnetic (en.wikipedia.org/wiki/Diamagnetism) and I don't know what the effect is of diamagnetic materials in coils. P.S. As you can see, I'm still learning everyday too.
May I know how to select wire size in this inductor?
The wire size affects the length and the number of turns you'll need. So a formula can be made that includes the wire size. On my webpage here rimstar.org/science_electronics_projects/coil_design_inductance.htm I have a section in a calculator that uses the wire size. You can try different sizes until you get the inductance you want.
thank you
i am looking to enter the freq and the wire diameter to spit out the L value. does the wire size not matter?
The wire size plays a part in the length since the length is the number of turns x the wire diameter x the spacing between the wires. The wire size also plays a part in the area because when calculating the area, you measure your circle from the middle of the wire (see one of the diagrams on my webpage here rimstar.org/science_electronics_projects/coil_design_inductance.htm). The wire also has a resistance but when working on calculations for a coil, usually you treat the resistance separately from the inductance.
@@RimstarOrg thanks for the link, unfortunately it goes to an error :(
Oh, I though UA-cam's alogrithm was smarter than that at recognizing links -- it's including the closing parenthesis in the paragraph. Try this: rimstar.org/science_electronics_projects/coil_design_inductance.htm
Sir what would be the diameter of wire which we wound over the core
The diameter plays a part in the length of the coil and the number of turns you can fit into that length. The number of turns and the length both are in the formulas. So when you try to get certain values for those, that's when the wire's diameter becomes important for inductance. Search online for a "wire size" table to help with that.
Resp.sir problem arises when choosing the thickness of the wire.There are no. of wires present for different thickness .How can choose required thick wire for particular inductance?
The thickness of the wire doesn't play a part in the inductance. It indirectly affects the length of the coil and the number of turns you can fit, both of which are part of the inductance formula. At high voltages it can matters since in that case you don't want leakage and so rounder is better at high voltage. But as far as I know it doesn't play a part in inductance.
The thickness of the wire is used in the calculator to figure the length. Ten turns with wire a tenth of an inch dia gives you a length of an inch....and so forth. The wire size is important due to current capacity requirements and desired resistance.
I tried with a 24 gage wire, which was way too thin. I don't think that thin of wire can handle much current before burning out. And it's difficult to connect the wire. You have to use sand paper to remove the plastic coat which is super tedious.
How about the magnet wire Gauge? What formula to calculate
I just do a google search for "wire gauge table" whenever I need to. I've done it a lot.
Is there any formula for calculating the inductance of one-turn saddle-shaped coil?
Hi sir, for my project I'll use a lower frequency (trafo), you said I'll have to use a solid core, is there any reason of doing it? or do you have a book reference for this? I want to know the reference for my paper, thank you sir
What are you using the coil for? I try to give some factors near the end of the video but there are lots of different uses. My knowledge largely comes from learning over the years so I don't have a specific reference in mind and the reference would depend on your use. A Tesla coil reference would be different than a reference for a radio coil which would be different than a coil for a filter and so on.
its because for lower frequency, typically you need a larger inductance, which is easier to obtain by using a high permeability core
Hi sir, I need to make a 1000 turn of coil. 1 roll of coil isn’t enough. So if I add another roll of coil do I need solder it together?
Yes, you'll need to solder them together. You could also just scrape off the insulation and twist the ends tightly together but make sure you twist them well so that they won't come apart.
Will do the twisting method as it is much more convenient haha. Thx a lot sir you just save my day 👍🏻
very nice sir
if i put paper or mylr between the layers would this make the transformer have capacitor ?
The transformer already has capacitance due to the distance between the turns where there is insulation. Increasing the distance between turns and layers decreases capacitance. The type of material in that distance has an effect too so using mylar instead of air, for example, would give a bigger capacitance for the same distance. So yes, playing around with the distance and the material does affect capacitance.
@@RimstarOrg thanks for the info , how can i make a coil with high Impedance like 1.68 H
Judging by the H in 1.68 H, I think you meant inductance and not impedance. To do it, try playing around with all the parameters until you get what you want. The calculators I mention on my website should help rimstar.org/science_electronics_projects/coil_design_inductance.htm
Will it effect the value if I change the diameter of the copper wire?
Yes. Increasing the diameter of the wire will make the overall coil longer and therefore affect the length parameter in the formula. Similarly, decreasing the diameter will decrease the length parameter. Or if you're trying to keep the coil a specific length then you'll have fewer turns, which is also a parameter in the formula.
@@RimstarOrg thanks for your reply sir.
Question: My circuit consists of a 1 to 30hz oscillator where the output is amplified to drive a 14.3uh flat coil but I wish to substitue the flat coil for a Helmhultz pair with a distance between them of 10 to 12 inches and coil height from between 2 to 12 inches or ideally two separate coils of 2 and 12. What are the calculations for that?
ps: The current flat coil design the magnetic field strength is about 3 Gauss for 5%
duty cycle and about 34 Gauss for 95% duty cycle.
What kind of coil do I need to use when I have a esaki oscillator hooked up to a DC to DC boost converter ???
I saw a coil made by the english guy Robert Murray-Smith on his "TNT" website, he used button or cylindrical neodymium magnets, and I am trying to replicate it. Can you tell me what figure or factor would you say and use for the permeability of these rare earth magnets. I plan to use a joule thief to power this coil to try and get the lowest input possibly. I think the Joule thief description is a misnomer, I think it is more a joule scavenger because it extracts very low voltage or energy from a depleted battery and then enhances the voltage through a transistor (MOSFET), what's your thoughts ?
You can find the permeability here en.wikipedia.org/wiki/Permeability_(electromagnetism) (see the table around halfway down). Regarding the name, Joule thief, it's more formal name is a blocking oscillator circuit en.wikipedia.org/wiki/Blocking_oscillator
@@RimstarOrg Yes, but I'm interested in your subjective and respected personal opinion sir, when the flux in a circuit changes rapidly in a circuit does it actually pick up energy from the "ether" for lack of a better term or is this laughable nonsense. More importantly is this a viable and reliable energy source.
There are countless circuits out there in all sorts of consumer devices and non-consumer devices that have existed for decades that do similar things to this, coils that are fluctuated in countless different ways and none have ever put out more energy than what's been put in. Don't be misled by the name, joule thief, it's just a blocking oscillator circuit. Energy is built up over time in the electromagnetic field in the coils and then dumped in a very short period of time, resulting in a high voltage. It's actually a fairly inefficient circuit, putting out overall much less than what's put into it. That's not to say that one day we won't find a way to convert energy from the "ether", assuming that's possible, but this isn't it.
@@RimstarOrg Ahhhhh, now your talking brother. Your last reply is written with true scientific and factual intent, you are an inspiration sir. I have dabbled and read about most of what you have written about, including the oscillators, the big trouble is putting the right components together in "situ" to make any over unity device (again, perhaps another misnomer) as efficient as possible. That, I have found is bloody hard.
What about internal capacitance?
Sir, I found out that 1.26x10^-6 is the permeability of air. Is it any different with ur (Mew r) or the permeability of the core in your given formula?
Yes, it's different than ur. 1.26x10^-6 is u0 (Mew sub 0) which is the permeability constant. ur is the relative permeability.
As I said in the video, air has a ur of 1 meaning that it is 1 x u0 or 1 x 1.26x10^-6.
Iron has a ur of around 100 meaning that it is 100 x u0 or 100 x 1.26x10^-6.
That's why in the formula I show at 5:03 I'm multiplying 1.26x10^-6 on the end of the formula.
The real reason it's called the 'relative' permeability is so that we can say things like, iron's permeability is 100 times that of air, it's permeability is 100 relative to air. It also prevents us from having to remember numbers like 126x10^-6 (which is 100x1.26x10^-6).
Side note: You may see u0 written as 4pix10^-7 (you'll see the symbol for pi instead). pi is 3.14 and if you multiply that out you get 1.26x10^-6, the same thing.
What about multi layer coil. Where radius starts?
I think you treat the whole coil as if it was the thickness of one thick wire. The radius then is to half the thickness of the coil.
Where have you been all my life??? :)
How can i easily search for a coil under the ground witht the frequency 101.4khz (specifically designed for the telecom branch), is it possible to just use the magnetic sensors of the phone in combination with a khz searching app, or for example a multimeter with a coil? Most of the time we know around what area we have to search and the coil is about 50cm /1 or 2 feet under the ground.
I don't know if it would work but you could experiment with something like my pizza box crystal radio ua-cam.com/video/iunAvz9PbN0/v-deo.html You'd have to do the calculations for the capacitor capacitance and the coil inductance which I explain in this video ua-cam.com/video/tjD9I95RAbw/v-deo.html I have no idea if it's the best way or how well it would work if the source is underground though.
@@RimstarOrg What about just using an app that uses the sensors on the phone? Like this one play.google.com/store/apps/details?id=com.westerlydesigners.rfdetector_radiofrequency
@@RimstarOrg thanks for the answer btw, i saw the video, but that (not being offensive at all) looks strange to take it to a work place
What is not clear is how "area" is derived. Does one use the inside, mean, or outside diameter of the wires that make up the coil. Obviously the result will not be much different with thin wires. But, if one makes a coil with thick wires, the wire's diameter can have a big difference on calculated area, and more especially when the coil's outside diameter approaches the thickness of the conductor. When a coil's (outside diameter)/(inside diameter) >2 but
You use the mean. Since I was dealing with thin wire, I didn't think to include it in the video.
Since you were just the most recent of quite a few people who've asked me about whether or not the coil should be included in the calculation for the area, I just updated a diagram and added text about it to my webpage here rimstar.org/science_electronics_projects/coil_design_inductance.htm.
Relative permeability part is wrong. You can't use 100 for iron core. If it's not a closed loop (like toroid) effective permeability will be much much less than 100, closer to air permeability because there is huge air gap between the ends of your core rod.
I want to design a tuning circuit for variable frequencies. From the resonant frequency formula, we have L & C. The values are unknown. If I calculate the inductance using the above formula, I still need to know the radius and number of turns.(air core) How do you decide the number of turns and radius of the coil??
I start with the materials I have. For my crystal radio and Tesla coil, for examples, I had the tubes that I was going to wind the coils on, so measuring it gives the radius. There's some trial and error. Putting the formulas in a spreadsheet makes it easy to try a variety of values. If you know the desired frequency range and have some idea of what capacitance you can make capacitors for (or have capacitors for), then you can rearranged the LC resonance formula to solve for L (or use the calculator on rimstar.org/science_electronics_projects/lc_circuit_aka_tank_or_resonant_circuit.htm). Then rearrange the coil inductance formula to solve for the number of turns, though that's kind of hard to do if you don't also know the length. That's where a spreadsheet comes in handy since you can punch in different values until you get what you want. In the spreadsheet, length can automatically be determined from the turns if you know the width of your wire.
To get the width of your wire, I wind an inch or whatever length or coil on the tube, measure it and divide it by the number of turns to get the inches per turn.
Do (erg)s affect the "air" coil? Or is it really not enough to measure or matter?
Do you mean the energy (erg is a unit of energy)? Power is energy per second and voltage * current is power. So sure, by measuring voltage and current in the coil you can get the power, of energy per second.
Nice video 👉👈
Sir how to calculate the length and thickness of coil to attend the temperature above 300°c
I don't know off-hand how temperatures that high will affect the coil. I'm guessing they'd increase the resistance and may have some effect but I don't have any formula for it myself.
Thx u thx u u are matrix to power
I have some speakers I need to repair but I'm not sure what gauge/thickness of wire to buy for the voice coils. data I have found: Kapton with 1.005″ inside diameter, 1.125″ form length, 0.437″ windings width, 8 ohms.
so what gauge or cross section wire would that be?
data provided is based on replacement coils I can buy but I don't want to buy lol
What determines the size, or gauge, of wire to be used?
The gauge only played a part in determining the length of the overall coil and the number of turns I could fit in that length. So the gauge was involved only indirectly. If the current is high or the voltage is high then the gauge can also be important, but it wasn't in this case.
I can seam to find the permeability of distilled water? I'm going to need to know that
I think in the tables that that is just water. Distilled water is water with the impurities removed.
@@RimstarOrg I know, with no impurities, pure water... what is its permeability?
0.999 992 (source en.wikipedia.org/wiki/Permeability_(electromagnetism)#Values_for_some_common_materials )