LC Circuit: Selecting Coil and Capacitor
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- čas přidán 27. 05. 2024
- ERROR!!!! The correction is that whenever the capacitor is discharged, the current it at maximum. At 1:45, 2:37 and 2:49, I remove the arrows to indicate that the current is zero while the capacitor is discharged. I shouldn't have removed them. In fact the arrows are moving in the same direction before and after those points and the arrows are thickest, meaning maximum current! How can it possibly be maximum, then zero, then maximum?! My bad. It's shown better in the animations starting at 3:16.
How to select a coil and capacitor for an LC circuit, using a crystal radio as an example. This also shows about the resonance of the parallel LC circuit.
This video was made possible in part by these Patreon supporters:
Jonathan Rieke
Printable Science
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or make a one-time donation at rimstar.org/donate_support_rim...
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Go to the main channel page here / rimstarorg
See also:
How to Design a Coil for Specific Inductance
• How to Design a Coil f...
How to Make Capacitors - Low Voltage Homemade/DIY Capacitors
• How to Make Capacitors...
How to Make/Build a Crystal Radio
• How to Make/Build a Cr...
Webpage with inductance capacitor for designing coils:
rimstar.org/science_electronic...
Webpage with LC resonance calculators:
rimstar.org/science_electronic...
Where to buy a variable capacitor:
www.midnightscience.com
www.scitoyscatalog.com/categor... (their variable capacitor is 0 to 160pF and is for if your coil has a ferrite core and is smaller than the one in this video)
Follow behind-the-scenes on:
Twitter #!/RimStarz
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A Darker Heart - music by audionautix.com - Věda a technologie
Wow, what a great job explaining! Few people would have gone to the trouble to lay it out like that for the learner; or if they did it would be a team of producers, writers, camera and editors. I never really understood the whole picture of how crystal radios work. Thank you!
i like how you truly understand the fundamentals which means your efficacy in teaching is beyond what others can approach and your tutorials are inspirational ang provide quick realisarions. well done
So many great CZcams channels failed to explain this clearly,and than i found this tiny one with just 100s of sub's that done it! Thank you sir,hat down!
I am an electrical engineering student and this very precise and neat explanation is much better than my professors in my college. I wish you good luck may Allah bless you
This is honestly first time I get it how a resonant circuit works! Thanks mate!
This is the best explanation of how an LC circuit works that I've found so far. Thanks!
The video was amazing. It put everything together perfectly and methodically. I received more straight forward understanding on this circuit than 20 others combined. Keep up the videos!
You can say that again! And again! And again! And again!!
Sorry for the reupload. Had to fix an error with the magnetic field direction.
The repost worked out great for me, I missed the first one but caught the notification on this one :-)
I didn't get it at first: then I realized that you are showing the field outside the coil: the right-hand rule gives the direction of the field inside the coil. :)
Good job.
I caught the error but knew what you were getting at. An excellent tutorial.
you are an amazing teacher!! i subscribed just after watch the joule thief explanation, the perfect match between theoretical and technical
Brilliant, informative video, great explanation with supporting detail. Thank you, for taking the time to make this video.
thank you. THANK YOU THANK YOU THANK YOU! the universe has blessed you with an amazing talent for sharing knowledge in a way that is so simple to understand. i’ve stopped using the “search bar” because your videos are all i need. thank you for sharing and spreading the info. i promise that i will do the same!
Of all the videos on the topic, yours is the best by far. Thank you.
I like how you explain the direction of the current being discharged and charged.
This video helped me bridge a lot of concepts I've been building on (mostly from inductor heating and various astronomy tech), and it was easy to understand!
Great job of teaching, its hard to find a lesson so clear and simple, thank you.
very intuitive way of showing how energy is stored in the coil's magnetic field!
Whoever came up with resonant frequency calculating formulae must have been super inteligent!
Thanks RimstarOrg, out of a hundred videos that i watched only this one made me understand how darn thing works:)
I love your channel!!! Thank you for putting this information out there and presented in such easy and informative way.
hello tesla,i am tesla too.....
Wow a very good explanation in LC circuit and how simple AM radio works ,thank you sir
This video was a life saver thank you so much! Drawing up plans for an induction heater and wanted to make a small one for doing small vac titanium casting but i realised i needed a really high frequency to actually melt titanium. Im that much closer thank you so much again!
Your video on inductance is very helpful to amateur like me !! Thank you Rimstar.org 😊
Thanks for this video. I finally understand the relationship between the capacitor and the inductor in tuning. 😊
That was great!! Very very clear. Your explanation of the lC circuit is great. All the other videos I have watched on LC circuit's neglect to mention that its the collapsing feild the creates the current to recharge the capacitor. Brilliant
Thanks! I'm glad you liked it!
Thank you so much. You really help me understand this radio project for school! I definitely subscribed!
Estos videos son oro puro!
Gracias por la gran explicación
Saludos
Increíble vídeo. Wow.
What an explanation!
Excellent tutorial, thanks for sharing
Awesome video dude. I wish my instructor in school was as clear as you are.
I wish mine had not spent almost an HOUR explaining then he concluded with: "This is NOT the way to do it".
AAARRRGHHHH!!! I hate him!
It's unfortunate, but a lot of professional educators really really suck at teaching--they tend to be presentors of information rather than teachers of it. RimstarOrg is a teacher, and he's so good that he could teach teachers how to teach rather than merely present.
I LEARN GREATLY FROM YOUR VIDEOS!! You helped me here...
At about 1:45 you state that "since the capacitor is discharged, there is no current". ACTUALLY, the instant the capacitor is discharged, current is MAXIMUM (Here, the capacitor's ELECTRIC FIELD is zero and the inductor's magnetic field is MAX). The "inductive momentum" of the coil keeps current flowing, THEN it slows as the capacitor starts to charge in the opposite direction.
The capacitor (thus all) current is ZERO only when it is fully charged. Current must be zero before it can change direction.
I'm glad I helped! Thanks for watching all these years!
Regarding 1:45, whoops, you're right. I even have the direction of the arrows the same before and after the capacitor is discharged. I shouldn't have removed the arrows at that point. I even have the arrows thickest just before 1:45 and again thickest just after 1:45, the thickness representing the amount of current. It's at 2:12 that the current is zero. I notice at around 2:37 I briefly remove the arrows again, which I shouldn't have. Man, it is so hard to get every detail right with all the informational, but also animation and video making details. I wish we could edit them after they're uploaded. I used to put an annotation to denote an error but that feature no longer exists. I'll Heart your comment and put a note in the video description. Thanks!
Well explained and very useful, thank-you.
Nice presentation .Thank you very much.This video is very helpful.I like it.
You rock! :) Great job with the graphics and the explanation. thank you!
Very nice explanation! Thank you so much!!!!!!
Amazing explanation
👏👏👏
Thank you for this nice video!
wowwww!!!!! i just loved it..im in class 12 and u helped me a lot to understand a topic of AC chapter of my book...thanks a lot...i love yaaa
Great! I'm glad it helped!
thanku sir!!!!
That was awesome! You are the best!!!
Ur radio is essentially a very low voltage Tesla coil. TC is an air core transformer where the primary coil is connected to a tank circuit to a cap and the antenna coil is the secondary coil. But the radio is working in reverse by receiving energy from the atmosphere rather then putting energy into the atmosphere.
Nicely explaination
so clear and helpful
that animation is great for explain how that work
Great job
Hello Mr. Rimstarorg, I used to use an RC filter connected to a homemade oscillator of unknown frequency (f). I would then calculate f by the Vout/Vin . Then I would find (L) by connecting the oscillator to an LR filter. I know R and I know f then I would find L from another Vout/Vin Eq for the LR filter.
ma shaa Allah... this is very important ..thank you
Wouldn't it be incredible if every teacher sought to empower and edify their students like this? :(
One thing. I think the arrows on the induced magnetic field are opposite. Because the way they are now, the more magnetic field, the higher the resistance.
Anyway great video, thank you!!
Nope, I'm pretty sure they arrows are pointing in the right direction. I even originally had them the wrong way and had to change them and reupload the video.
🙏🙏🙏🙏thank u so much for knowledgeable video
can the capacitor be housed inside the coil tube, or need it be outside it?
wow thank you so much
from this you can create a self resonating circuit right? by attaching a diode from the output of a coil into a capcitor and then attach another coil right next to or over the existing coil and attach another diode in it and reverse it and attach it to the capacitor and on the negative of both coils attach to ground and then for a second charge that capcitor and the coils will be expanding and contracting while charging the capcitor and the capacitor will charge the other coil which will induce it into the other coil which charges the capcitor again and the cycle repeats
This won't work due to the losses I talk about at 2:52 in the video.
rimstar, what if your trying to figure out what the right capacitor is but you cant see how many turns of wire are on the iron core ? then how do you calculate it? thanks.
If you have an inductance setting out your multimeter then you can measure the inductance. You may be able to find videos that explain other techniques that find it indirectly (search for "how to find inductance").
Hello,
Looking for Ur on a 4B1 200/10 rod.
Do tou have this?
ERROR!!!! The correction is that whenever the capacitor is discharged, the current it at maximum. At 1:45, 2:37 and 2:49, I remove the arrows to indicate that the current is zero while the capacitor is discharged. I shouldn't have removed them. In fact the arrows are moving in the same direction before and after those points and the arrows are thickest, meaning maximum current! How can it possibly be maximum, then zero, then maximum?! It's shown better in the animations starting at 3:16 where the arrows don't disappear when thickest. My bad. You'd think that with only a thousand details to keep track of when making these complex videos, I'd at least not make any mistakes! :-) A huge thanks to dale nassar for catching this and pointing it out.
Great thanks
Your teaching skill is great. I have been trying to wind some coils for radio remote control circuits . I have not been very successful. Can you please guide me on selecting the gauge of the copper wire that is be used for winding such coils. Thanks in advance.
What do you mean by unsuccessful? If you haven't been getting the right inductance then try the hard way, making different coils while changing one thing at a time. Use the formula as a guide for what to change. For example, the number of turns and the length are parts of the formula. Increasing the number of turns affects both the number of turns parameter and the length. But notice that the number of turns is in the top part of the division and is squared while the length is in the bottom but it not squared. So increasing the number of turns will give you a bigger change. Increasing the number of turns increases the inductance. Basically do the same thing you'd do with trying different values in the formula but do it in real life.
Hello… thank you for the great work. One question regarding the antenna coil number of turns, is more turns better for selectivity and sensitivity? What is the optimum? Is there a rule of thumb or equation? Thank you again.
I don't know what goes into the calculation for the number of turns on the antenna coil. I got the number I used from some old plans in a book. One of the purposes of the antenna coil in the circuit I use is to create an electromagnetic field to induce current to flow in the tuning coil. So you need enough turns to do that. The purpose of having the two coils is to help with selectivity at the expense of sensitivity. If you didn't want that improvement in selectivity then you wouldn't use an antenna coil. I talk about that in my video about how a crystal radio works czcams.com/video/0-PParSmwtE/video.html at around ten minutes and forty-six seconds in.
@@RimstarOrg thank you
6:50 I´am eletrician / technican: PERFECT EXPLAINED!!! :-)
Still learning, best video I've seen on this topic. I have two questions:
(1) 6:07 the section of coil you say doesn't matter, that's call the dead-end, yes? Can't it reduce your Q, since it has a complete circuit of its own, and can thus induce EMF back into the part of the coil that you selected?
(2) The antenna coil... it has to induce energy into your tunable coil, and there will be losses involved. Since you don't have a power source other than the antenna, it seems like you'd want to preserve all the input power that you possibly can. So, why not just attach the antenna directly to the tunable coil? (Or, better yet, make the big coil *be* the antenna, and do all your tuning with the capacitor?)
Thanks for any response you care to give.
(1) I've since heard from others in other videos that I may have been wrong about that section. Perhaps I should have left it disconnected from ground. Many years ago, the book I got this circuit from had it the way I show in the video but others in comments have said it would work better disconnected from ground. I haven't tried it that way yet to see.
(2) It's a trade-off. With the separate antenna coil, you get better selectivity i.e. less interference from other frequencies/radio stations. Without the separate antenna coil, you get more volume, as you point out. I talk about it in my how-a-crystal-radio-works video at ten minutes and forty-five seconds in czcams.com/video/0-PParSmwtE/video.html
@@RimstarOrg Thanks for the link! For my first crystal set build, I'm thinking I'll go with a honeycomb litz-wire magnetic loop antenna, sized to complement whatever capacitance range I end up with in my DIY capacitor. But thanks to your reply, I may also add in a bypass-able selector coil, so that I can choose loudness or selectivity, depending on my immediate needs.
Thanks again!
Hi, thanks.
I was wondering : the coil you use is not a resin coil (the ones that are being used in tranformers and motors) ? Your wiper blade does make electric contact with the coil isn't it ?
The coil is made using enamel coated wire, like the ones used in transformers (unless the transformer coils also have an additional coating on them to solidify and protect them further). But I've sanded the enamel off of the very top of the turns so that I can make electrical contact with it. You can see where I do it in my How to Make a Crystal Radio video here czcams.com/video/VqdcU9ULAlA/video.htmlm2s.
thanks
How to make a RF transmitter and receiver module circuit for RC ie. Remote control to drive any DC motor
So how do you get a standing wave
Great explanation. Would I be correct in saying that these calculations should be applied to the Primary Coil in a Loose Coupler?
They're okay for the primary coil on its own but if it's interacting with another nearby coil then I imagine the inductance into the secondary would change things. I don't have formulas for that off-hand. Sounds like a Tesla coil though. If so then I'd recommend the JavaTC calculator. I used it for my Tesla coil czcams.com/video/0SaEPW_iMF8/video.html
@@RimstarOrg circuit diagrams for loose couplers seem to be extremely rare. I am trying to get an idea of wire gauges, number of turns and the capacitors etc. required before I proceed with my build...
Is Resonant freq is equal to filter cut off freq
by adjusting the coil windings ,the lesser the windings the higher the frequency ? or did i misunderstand
That right, you understood it correctly. I once worked on a 300 MHz oscillator that had only a single turn coil.
How ican matching with lower imput impedance mean number of turn secodary coil
Super bro
How do I find out how many turns the smaller antenna coil should be?
I don't know. I got that from the book where I originally got the schematic for it and the book doesn't explain where the number came from.
Did I miss why the antenna isn't directly coupled to the coil, but instead is fed inductively? I heard it was something to do with better selectivity, but I don't understand why.
Yes, it's for better selectivity. I explain why in my How a Crystal Radio Works video czcams.com/video/0-PParSmwtE/video.html at around ten minutes and forty three seconds in. It basically allows unwanted frequencies to influence the path to ground and desired frequencies to influence the tuning coil and capacitor.
would an FM radio work much differently?
Jonathan Covington YES!
Hi,
You mentioned a "reupload" due to an error in B-field direction. Is this video still posted? The reason I ask is that I would love to see the error that someone of your caliber would make! I have found that I can learn the most in virtually all of these cases--especially in a tricky case as this, which I have been studying to understand for so long.
It's no longer around but the only thing wrong was that I had all the arrows on the magnetic field lines drawn in the opposite direction they are now. It was a silly mistake, but an important thing to get right.
I need to watch these like 10 times to understand the math
0:41 why doesn't it just flow using that wire to the capacitor and ignores the second part of the circuit, what determines the path the current will take?
In hindsight, I probably shouldn't have said that section amounts to an unpowered loop of wire. Both paths are in parallel and both are taken. For the explanation of resonance, however, it's simpler to ignore the second section, the "loop" at the end.
@@RimstarOrg I understand, thanks for replying after all this time, I did notice I was commenting on an old video and didn't expect a response honestly. another question is what's the reason to put that wire there, like theoretically speaking it should always run at max frequency as far as that wire is there, I guess? sorry if the question is kinda stupid tho.
That's a good question. I don't have a good answer though.
@@RimstarOrg no worries, thanks again, I appreciate you taking the time to reply.
is this the same process done in the transistor oscillator circuit btw great video cleared my doubt
I'm not sure which transistor oscillator circuit you're referring to, but one that I've played with makes use of a variable resistor and capacitor to determine the timing, and two transistors for the switching.
There are oscillator circuits that use this LC resonance for timing, but in the ones I'm familiar with, the transistor is used as part of the amplifying part of the circuit, the part that feeds the LC circuit extra power to keep it going.
But I'm not familiar with every circuit out there.
RimstarOrg can u just sent me the photo of it or even a diagram wil be helpful
The circuit with the variable resistor and capacitor came from a book, Getting Started with Electronics, By Forrest M. Mims. It's called a Flashing Light circuit in the book. It's very similar to this one I just searched for online www.electroschematics.com/5928/flashing-light-circuit/. I used it a the end of this video to test a DIY electrolytic capacitor czcams.com/video/ml2TdQ2_2mk/video.html but I didn't show any details of the circuit.
For oscillator circuits using LC resonance for the timing, search for hartley oscillator or colpitts oscillator, though there are others too.
Hey Rimstar I got two questions:
1. Can we not use this steady frequency as a timer or clock?
2. Why can we not reverse the induction heat process. Why can't we warm up the coil to produce current? We can reverse a lot of other processes to generate electricity...
1. Sure, that's one use for them in oscillators. Search for hartley oscillator or colpitts oscillator.
2. There is a reversible process with coils and current, it just doesn't have to do with heat. As you saw in this video, running current though the coil produces a magnetic field around the coil. Or, you could instead push a permanent magnet through the coil and produce a current in the coil.
Oh, so just like a motor. Guess you're just "dragging" the electrons in a sense
Follow up question, can we bank the energy from radio waves and use it to charge stuff up? How useful would it feasibly be? Thanks for answering so fast by the way, appreciate what you're doing.
Sure, that's why I got into crystal radios in the first place. I originally planned on making a bunch of small ones to capture the power from the radio waves. But with my first one I quickly learned how little power there was and didn't go further with it. But, I got into crystal radios as a result!
Nice :)
Yup, had to convert it to Farads and Henries. So that's 524,006.85310 Hz (524.00685 Khz).
How do you pick the values of the Capacitor(s) and Inductor(s) when trying to hit a target frequency? (+1 : 415)
I might be misunderstanding your question but choosing inductor and capacitor values is what I talk about at around 6:50 in the video. I assumed a particular capacitance and started trying various inductance values and coil geometries until I got the desired resonant frequency. If you want to try with varying the capacitance too then I have a webpage with a capacitance calculator too rimstar.org/science_electronics_projects/capacitance_formula_capacitance_calculator.htm. So basically, trial by error, adjusting values in the calculators until you get the frequency you want. You can also put the formulas in a spreadsheet instead so that you can try many values and see them all in one place.
So basically adjust the values of the capacitor and inductor until you hit your desired frequency. Thanks for the fast reply.
Yup. It's not as bad as it sounds though. You quickly hone in on the values. It's like looking for a name in a phone book. You don't go through it page-by-page, you quickly narrow it down after looking at only a few pages.
genius!
Yo dawg, I’m tryna build a radio but I’ve spend hundreds on components and got a huge sloper shortwave antenna. I still cant get it to work. Please provide the exact measurements in this scenario, I have access to a 100pF capacitor and also a 365pF if this will work better, I have 36 AWG and 32 AWG enameled magnet wire, I have 1N34A germanium and 1N4148JP silicon diodes, also have plenty different op amps and 555 timers ready to use. I’m finding myself building other devices that are easier to understand and procrastinate on the radio because it’s too complicated please help me know the microhenries and amount of turns on a 1.25” PVC tube for a suitable tuner given the capacitance
I haven't done a shortwave but for a crystal radio, go with you 365pF and your 1N34A germanium (silicon is no good for crystal radios). The rest is in my How to Make a Crystal Radio video czcams.com/video/VqdcU9ULAlA/video.html and the follow-up troubleshooting and tips video czcams.com/video/HZZmKZJrIW0/video.html I then made an amplifier for amplification czcams.com/video/JtPwxbOgBHw/video.html
Hello, can i use any kind of copper wire?
Yes, just make sure it's not bare wire, i.e. it needs to have insulation on it so that the adjacent turns don't short out to each other.
@@RimstarOrg thank you very much. I'm not expecting that you will reply. I really appreciate your response. Thank very much
To work right, the unused portion of the coil should be disconnected from ground.
What animation software did you use?
For the magnetic fields and the 3D modelling I used Blender 2.71 (www.blender.org/). The + and - charges and the blue arrows for the current were drawn as 2D GIF images in OpenOffice draw and inserted one-by-one in the video editor (Sony Vegas Movie Studio 11). You can see my process in my old video celebrating 1 million views czcams.com/video/kZj0_L7lWss/video.html.
Cool. ty.
oh, shoot. I got it!
I don't get the "C" math. 250pF is really like .000000000000025F yet, we can use "250" in the same equation as "Mf" . Which has 3 less zeros.. uH does not have the same amount of zeros. I get the math, just don't under stand why and how everybody can just drop those "0"'s. What is the real number entered in the equation.? I know I ain't no math wiz. I think there's a short cut, idk.
250pF is .000 000 000 250F. Maybe that's where you're going wrong? The seqeuence is, milli, micro, nano, pico.
You don't drop the zeros when you actually plug them in. Many people use scientific notation so you just add/subtract the zeros in the exponent.
at 7:01 you have told 424 but result in formula is 524
Wow! I can't believe I didn't notice that after listening to it probably a dozen or more times when editing it. Then again, maybe that's why I didn't notice it. At least the video is the correct one, I'd rather that then the other way around. Thanks for pointing it out.
My professor in the university has called this effect as a "to review with a fresh eye". The probability to find new error increase with break period duration. So, there are two options ... 1) take a long break to forget it and check it again 2) ask someone else to check it. ....
it is very typical phenomena in self checking
l=271 uH, f=820=khz
Brother, I need your help. Please help me. ۔
Its simple radio
Irish American, Dublin ?
Nope, Eastern Canadian, so some Irish influence for sure.
@@RimstarOrg @RimstarOrg Eastern Canada - you're on the right coast to catch the accent - directly across the sea! I'm interested in using your neural net back propagation code- I'm new to neural nets, but would I be right in thinking that this approach doesn't offer anything a LUT (look-up table) or perhaps a kernaugh map (for logic minimization) , doesn't provide? The system won't grow any more intelligent than the training data provided,
intelligence in this case just calling the appropriate/next element in a LUT.
The example I give can be done with a LUT instead but there are uses where it goes beyond that. Neural networks can do object recognition for example. The inputs would be an image of an object and the output would tell you what the object is. I guess that's sort of like a LUT but how do you do object recognition with a LUT? But in that case it still only recognizes objects that it's been trained on so in that way it's like a LUT. There are also neural networks that look at an image and output a descriptive caption for the image, neural networks that given a text description, output an image, neural networks that being trained on recipes can output novel recipes,... There are countless examples that go beyond LUTs.
@@RimstarOrg Thank you for the detailed reply. I didn't mean to question the value of your code or approach, I find it fascinating but I'm new to neural networks and see the provided neural network will only provide the same functionality as a LUT for object recognition - I think the key to using a neural network like this to provide intelligence would be for primitive tasks of things like edge detection, path-finding to build more complex and generic approaches , intelligence that can be used on non-trained data. Path-finding would be one where you could use a random seed, go through all possible iterations, score for the lowest possible time to solve, then feed that back in for the next path-finding excercise. Done over a large enough dataset - it should lead the net to arrive at some general rules for pathfinding. But I believe this would be a genetic algorithm and not a neural network. I can see how a genetic algorithm would accomplish your examples, but not a neural network- I struggle to see how a neural network is anything other than a LUT. I'll have to read up and fill my knowledge gap!
The info is very good,but delivered far too quickly. Please slow it down.
I keep seeing this design for a radio as a project, but it's not very practical as you can't seem to buy crystal earpiece easily. It's certainly not sOmething your average joe would have lying around. Amazon has them for $10 but that kind of defeats the purpose of a cheap radio made from household materials.
At this time in history the point isn't really to be able to build a cheap radio, but to learn how the simplest possible receiver works.
Anyway It never was quite as cheap as you might think because you need 50 feet or more of antenna.
I recon that instead of going into an earphone you could go into a simple amp circuit and then drive a speaker or earbuds if you wanted to. You could easily salvage parts from junk electronics, and THAT circuit is pretty easy to understand too.
If you did that you would know more about electronics than 99 44/100 percent of everyone you will ever meet.
And THAT is the point. I think.
third
first
Please bro call me