I spent my career working with digital, now I’m jumping over to analogue for my midlife crisis. Coils... bugged the hell out of me because I just didn’t get them. After watching this video, I get it! Thank you for a very well explained and demonstrated video! 👍🏻
Yes mate, a no nonsense, straight to the point, clearly described presentation bursting with facts in a perfectly digestible format.... This is a gold standard introduction to inductors and their properties. Perfect.
Inductors have been quite a mystery for me this far. Your excellent demonstrations helped a lot in understanding them better. This was likely the best practical intro to them I've seen. Keep up the great work, thanks!
I recently started winding my own toroids for some low-power ham radio kits. It's worth mentioning that even on a high-end RF-rated toroid (e.g. type 43 ferrite) the proximity of turns can make a pretty big difference in the final inductance; if they're all bunched together, you get more inductance but lower efficiency, and if they're evenly spread out, the inductance is lower but the efficiency is higher. Not having a component tester, though, I had to come up with an alternate way to test inductances; the simplest way is to build a resonant circuit with a known-value (measured) capacitor and see what frequency it resonates at. With a decent oscilloscope, this should be a lot more accurate than a component tester.
One thing that you can also use for the winding of the inductor is "layered" enameled copper wire, it can handle more current at higher frequencies * layered enameled copper wire just means multiple enameled copper wires put side-by-side (aka in parallel) and then wrapped around the core; only electrically connected at the ends. Hope this helps!
Layers in an inductor are not paralleled wires. They are physical layers, one on top of another. This is important because the number of layers influences the AC losses in the winding due to proximity effect. Each layer _could_ be made of paralleled strands.
I've just started working on superconducting magnet coils as a technician. And asked the team leader about inductance, long story short your explanation is awesome.
Fantastic to see some real life practical examples of inductor usage. Inductors have always been a bit of a mystery to me. Love the analogy of a coiled spring.
You're very articulate...and make it nearly effortless for others grasp the content. I highly recommend your approach. You will make a great mathematics lecturer 👌
Don’t need to overkill catch diodes. When sizing catch diodes, remember that current doesn’t increase with fly back. The inductor does what is needed to keep the previous current flowing briefly, however much voltage it takes to do that. So if your 70mA relay coil is switched off, it will continue to pass that 70mA briefly. A 1N4148 catch diode will handle that easily! And with your power inductor at 1A, a IN4001 will do the job just fine.
Very nice video. The simple explanation of how an inductor works by using examples of things that are far and away more complex than a simple inductor seems counterintuitive.
I would like to re-iterate a previous comment. You are so easy to understand and don't leave anything out. Which a lot of Electro tech tutors have a tendency of doing.
Fantastic display , after 30 yrs learning and still playing with automotive electronics, in my field opening up and repairing modules are not preformed any more , But I still open and find that trying to solve basic faults , which I’m successful, and surprisingly high rate of repairs work , are simple as understanding basic principles, post like the one you have shown are a excellent learning and teaching Aid , well done !!!!! Your excellent skill and passion are shown through your well explained and simplified teaching, very happy to subscribe and view all your post, Sadly my world of repair is mostly software and this greatly confuses a Tech as simple software fault can imitate a hard Eletricial issue / fault with a clients concern is brought to a dealer ship , Thus , weeding out a software fault from a ‘ hard ‘ Eletrical issue can be trying , but it is just a elimination path I take , Your post show very importantly the understanding and it’s fantastic that you’ve taken the time to do so , Thankyou and looking forward to seeing more post , keep it up ! :)
Between the natural grown PCBs and the flyback "as a person" demonstration, you have earned my sub and like good sir. I don't often audibly laugh from youtube videos, let alone electronics related ones, but this one really got me. As a budding electronics enthusiast and (hopefully) future Electronics engineer, I hope to learn alot from this channel!
Thank you. Very informational video. I am a complete rookie in electronics and I am just beginning to find the fun of this hobby. Thank you for your Lesson.
Excellent explanation. I mainly deal with AC, but your clarification of DC circuits is massively helpful. Small point of contention though regarding definitions, an inductor I believe doesn't so much "resist" current so much as "impede" it. The definition and distinction I was taught is that resistance is work done that produces heat, whereas impedance doesn't. But then I guess no matter the length of copper wire you are using it will have some inherent resistance to it. Great video!
Beautifully explained. So electrically an indicator is like capacitor that has had its two parallel separate conductors shorted together at the end. And would become a capacitor again if "unshorted".
Love your presentation. I am glad that I am not the only one to notice the "black hole" in one's workshop that gobbles up all erratic kinetic objects never to be seen again. LOL. Like other commenters here, I have always been perplexed by inductors, but you make the concepts crystal clear. I guess the birds in NZ do not like PCB seeds which allows the PCBs to grow in the wild.
Before watching this video, I had a basic understand of inductance, coils, magnetic fields, etc., but now after watching this video, I not only feel I finally understand inductance, but how it's used and dealt with! Thank you!!
I had the same comment that someone else made. With inductors, you increase the voltage, not the current. The maximum current is what you pass through the inductor while connected to the supply. When disconnected, the current decays, based on the resistance in the flyback circuit. The rate (aka speed of the decay) is related to the inductance/resistance time constant. The higher the resistance, the higher the voltage (and faster the decay). But again the current never exceeds the what it was passing at the instant before being disconnected. Without a flyback diode - the resistance is infinite - or whatever the rest of the connected circuit is, as parts begin to break down. A related phenomenon is that the high voltage can actually cause a spark, as the collapsing magnetic field attempts to maintain the current. When one unplugs a high inductive load - such as an iron or toaster - from the household mains, you will likely see a spark - that is the flyback voltage trying to dissipate the current.
In RF parlance, especially in the amplifier arena, capacitors and inductors are labeled as tank blocking capacitors which pass RF current and block DC, while the plate chokes block RF current and pass DC, unless they're making up the tuned resonant tank circuit, where you want the cap to charge and discharge, and the inductor to ring, forming the flywheel effect in class B and C amplifiers. Another choke is used off the load capacitor to ground, which is for safety if the plate cap fails, connecting the HV to the tank. This, of course, blows the fuse before allowing HV into the antenna circuit. However, that choke's ringing causes HV to appear across the tuning and load cap's plates, and they have to be rated for that. In the plate power circuit of tube amps, the cap passes the anode's RF to the tank circuit while blocking HV DC, and the RF plate choke blocks the RF from entering the HV power supply. It's like using two types of check valves in a hydraulic circuit, and very similar to a diode's action.
Great video and information, thank you very much! FYI, I haven't sanded or burned the insulation from this kind of wire for many years now. Modern coated wire is made to solder through, at least on all the wire I've dealt with. Just hold the soldering iron and solder on it for a few seconds and it works like magic, instantly tinned.
Magnet wire insulated with a nylon/polyester blend can be soldered without stripping. Lots of magnet wire cannot and has to be mechanically stripped or striped in a "salt pot" stripper at very high temperature. One of my clients, which made large iron core transformers in house, used an oxyacetylene torch. If you set the flame to oxidizing (more oxygen than needed for the acetylene) and put the wire in the oxidizing part of the flame, the insulation is cleanly stripped. You can't do this with something like a propane torch. It will simply burn the insulation leaving a mess that still has to be removed mechanically, though more easily than unburned insulation. I used to buy magnet wire from a supplier to motor rewinding shops. They didn't stock the stuff with solder-through insulation because it isn't robust enough for industrial motors.
I built a 60 watt transistor stereo from Heath kit back in the day. I would bridge a 47 mf Disc capacitor across each speaker output To keep from hearing my neighbour talking on his CB radio through my speakers, It worked!
One important comment from an old winder: *Always* start winding the wire from the middle and wind both ends separately. This way you dont have to thread a long wire so many times. The total length of wire to thread is reduced by x4.
Looking at inductor's for antenna matching and came across this video. Very interesting especially about making them and the difference between the two with the same inductance. Tnx mate
How can i build something like that inductor tester? Am so much at the right place. This is the best ever tutorial after i wasted my two years on other channel to keep on feeling like quiting electronics.
This is the best video of concepts of inductor. I really undestand when you make analogy with spring. The diference aboult capacitor and inductor is very interresting. Thank You!
- probably already in the comments somewhere, but I'm not going to read over 600 comments to find out: The peak current at turn-off of an inductor can *_never_* exceed the current at the instant turn-off starts. This is a fundamental property of inductance. If a relay coil operates at, say 100 mA, the current at the instant of turn-off will be 100 mA and decline from there. For small relays a 1N4148 or 1N914 or similar diode is entirely satisfactory. If the coil current exceeds half an amp then you might go to something rated at 1 amp. I've used dual transistors in surface mount packages for driving relays. One transistor is used as the switch and the other is used as a diode (collector-base; the base-emitter diode has some better properties for some applications but small reverse breakdown voltage, typ. 6 or 7 volts for common types). This makes things very compact. ~~~ That HY-2 inductor core is a Micrometals Type 52 powdered iron material, or a counterfeit thereof.
I had to pause to comment, "oh my god," as you smashed LED, resistor and cap, and I'm an atheist. You are a Kiwi treasure. I salute you with subscription, sir.
I really enjoyed your flyback to a spring example! I need to find out the opposite of what you showed after that, however... I need to figure out how to best protect any other circuitry while, at the same time, getting the highest possible flyback voltage. It doesn't help that my limited amount of electronics background is close to 50 years old ~ with a LOT of "water under the bridge" during that time... (I'm having to go back & start over from scratch via youtube, etc.) Fortunately, I DO remember enough to have a healthy respect for HV & how to discharge scavenged flybacks, capacitors, & condensers without "knocking myself into the next county ~ if not the next life..." I'm wanting to set up at least 3, horizontal shaft, Briggs & Stratton 4 stroke motors with to run off of HV produced HHO on demand. These motors, in turn, would spin "smart drive" stator/rotor motors, rewired to be generators, with a bit of the output getting diverted to charge the flyback system for HV/LC... Any suggestions on how to protect the other circuitry withOUT reducing the flyback voltage???
A better analogy for the stored energy is the kinetic energy of a moving body, because inductors give inertia to electric current. Interruption of the circuit (creating a voltage spike) corresponds to collision of the moving body with an obstacle (exerting a high force for a short time). A compressed spring is an analogy for a charged capacitor. Movement created by the released spring corresponds to discharge current from a capacitor.
Those are the best mechanical analogs. Add a dashpot (shock absorber) as the mechanical analog for a resistor and you can visualize RLC circuits as masses, springs, and dashpots - or vice versa. One good example would be examining the response of a suspension sytem to a bump in the road. The tire/wheel would be the mass (inductor) connected to the spring (capacitor) and dashpot (resistor). The damped system can then be analyzed as an RLC circuit responding to a step input.
@@vicruzr wow😳 wonderful analogies. Please where can I get more of these analogies (any detailed basic e-book at all🙏 )for better understanding of circuits, bit by bit to complex level.
Automotive ignition systems use this principle to fire the spark plugs. In the old days they used mechanical points along with an ignition coil to open and close the circuit.
From the coil32 page......Another case is the inductor in the switching power supply. The commonly used ferrites have a relatively low value of saturation flux density (about 0.3 T), so in the power switching circuit the inductor is switched between the maximum value of the field when it almost gets a saturation and zero-field value, when it is demagnetized to a value of residual induction (curve [4]). As we can see the slope of the major axis of the ellipse 4 is much smaller than that of the ellipse 3. In other words, the magnetic permeability of the core in this mode is greatly reduced. The situation becomes worse if the choke core has DC bias (curve [5]). The major hysteresis loop of the real ferrite is more rectangular than on our schematic image and, in the end, the dynamic magnetic permeability of the power inductor on a ferrite ring falls to several units. As if there is no the ferrite! In the end, the inductive reactance of the inductor decreases, the current increases dramatically (which results in an even larger decrease in µ!), the key transistor heats up and burnout. The calculations of Coil32 for this choke give an absolutely wrong result. Because, we used to calculate the value of initial magnetic permeability, and in a real circuit, the permeability is two to three orders smaller. You will get the same situation if you will measure the relative permeability of the toroid by the trial winding. The solution is to use a ferrite core with the interrupted magnetic circuit. In the case of the ferrite ring, it is necessary to break it in half and then glue that two half with the non-magnetic gap. The major hysteresis loop of such a core becomes more sloping [2], the residual induction is much less [B'r], the effective magnetic permeability is also less than that of the core without a gap. However, the curve of magnetization [6] shows that the dynamic magnetic permeability of this inductor is much higher than that of similar, but with a core without a gap. It has permeability about 50..100. Coil32 also is unable to calculate this choke, since it does not take into account the non-magnetic gap. Another solution is the use of special rings for the power supply as powdered iron toroids (not ferrite). Such toroids can be found in pulse power supply units and motherboards of computers. The non-magnetic "gap" in such ring is distributed along its length. Conclusion. The Coil32 program calculates only low-current ferrite toroid coil working in low magnetic fields. For the power chokes calculation, it is necessary to use a completely different methodology.
Just a grammar tip to help polish the old image: Apostrophe S after a noun denotes possession. "Inductor's" implies there's something that belongs to said inductor. For plural, just drop the apostrophe. "Inductors". You also don't need to capitalize after the ampersand. Best of luck to you
I work on refrigeration systems. We put vfds on the condenser motors a while back. They were blowing up motors left and right. Aside from the motors not being rated for vfds at the time (over a decade ago) they added these electric filters on the outputs of the vfds. I'm no electronics guy, but are those filters we added essentially just inductors for taking out the spikes like you mention in this video on the buck converters? The output of vfds are dc that mimic ac as far as I understand. Which isn't much.
Excellent and extremely thorough presentation (technical content and instrument results) plus totally understandable physical speech and phraseology!!! Plus, plus, plus - no bloody annoying and distracting music!!! Previously subscribed to your site - cheers from Down Under.
I have that very same component tester. It doesn't work too bad. The LCD screen lost its seal on mine shortly after I bought it, but still works. Every once in awhile it will give some erratic readings. I bought mine and assembled it. I had to come up with my own case for it.
After inductance, the next most important property of inductors is it's saturation current. Basically when inductor reaches saturation current its inductances decreases to almost zero. This is the probable reason those inductors presented different results.
Oh yes, diodes work great! I had to use about 1500 of them on the electric valves in my pipe organ, each valve's coil was 40, 60 or 90 OHMs @ 12vdc. I had to use diodes to deal with flyback voltage potentially damaging delicate contacts, and to electrically isolate sets of valves connected to the same "66" terminal blocks so each set's valves could be operated separately from the other from the keyboard.
This is probably one of the better videos I have seen you make. Quick quick question I am building speaker crossovers and found Inductors are very expensive. I wanted to ask what type of Toroid would you suggest for this purpose. I am thinking I can save a lot of money if I just build my own inductors. I want to use iron core inductors for the large woofers rest could be air core but I guess I could use iron core for those too as I could use less wire. I will probably be using 18 awg (1 mm2) wire. Could I even use an iron bolt?
5:43: "Placing a diode backwards to the power source across the inductor/coil allows the flyback to flow back through the diode when power is disconnected from the inductor/coil." While the sentiment is correct, the description is not. Inductor voltage "flies back" as the result of a discontinuity of CURRENT, not "power." V = L*dI/dt, where dI/dt is theoretically infinite when the current suddenly is disconnected. Inductors will do all they can to prevent current discontinuity by the voltage suddenly flipping trying to find a place for the CURRENT to go to. That's what the diode does. No current can flow through the diode when it is biased off, but during this voltage flip, the diode is suddenly forward biased, giving the current a place to go. If you put a current probe on the diode, you would see current changing smoothly from its DC value, then ramp downward with a ramp shape that is I(t) = integral (Vdiode/L)*dt until the current goes to zero, and which point the inductor energy (1/2 * L*I^2) has been dissipated by the diode. You do a disservice to your viewers by interchanging current and power. They are completely different animals!
@Fred Garvin So how do you get a higher output voltage then? As far as I know it occurs when you cut the supply to the inductor, causing its field to collapse and it generates a back emf. The duty cycle is to regulate the output voltage and with higher switching frequencies you can get higher voltages from smaller inductors because faster current disruptions cause higher back emfs.
Ideas for other videos: I would like to better understand inductor saturation, and see if we could show that it eddie losses is why one worked better than the other. How to select low cost capacitors for high output induction heaters (high current applications). Using a microcontroller to monitor and control an induction heater, frequency matching and to protect the mosfets. How to test if mosfets are still good, and general trouble shooting of SM power supplies.
Wow you make this sound so easy but electronics is so hard for me to really grasp. I’m still really lost but you did make a lot of sense and this is such a great channel I subscribed and have been watching your videos nonstop. So if inductors have no effect on DC power is it a waste to put one after the capacitor in series with the output. I am going to rectify a welder from AC to DC. Some videos I see people putting an inductor last in the circuit and some people just do the rectifier and capacitor without an inductor. Basically if I understand you correctly if the circuit has been rectified to DC and then run through a capacitor then the inductor isn’t doing anything at the output. I hope this question makes sense because I’d like to hear your thoughts. Thanks
oh boy, where do i start... "inductors can't store energy when disconnected from power supply" - no, they can. Ideal inductor will store its energy indefinitely if it is shorted. Real inductors rarely achieve more than a second of useful storage time. This is unlike capacitors primarily because our insulators are much closer to ideal than our conductors. Like capacitor requires ideal insulator (zero leakage) to store energy indefinitely, inductor requires conductor with no resistance (superconductor) to store its energy indefinitely. spring analogy - see other comments... the analogy is acceptable, but there is a better analogy with mass hitting a brickwall. "if flyback were a person" - oh dear... diode peak current 220 amps "massive overkill" - it is indeed massive overkill. The peak current that will flow through the diode is equal (slightly less, actually) to the current that was flowing through the coil just before breaking the circuit. This is exactly the rule "inductor resists a change in current". It will slowly decay afterwards. There is no need to account for more. Heating may be of concern if the load is cycled on and off fast. "Inductors help smooth out voltage ripple caused by high switching frequency" yes they can, but their primary use in switchmode converters is very different. They are temporary energy storage that can be filled using one voltage (the input voltage) and drained at another voltage (usually but not always, the output voltage). They are at the very heart of the conversion process (with some exceptions). "these spikes are undesired voltage ripple" - no. These are conducted emissions (mostly caused by parasitic inductances, capacitances and transformers in your circuit), they are not called "voltage ripple". Voltage ripple is usually the changes in capacitor voltage that happen as the inductor enegry is dumped into it, and then capacitor is discharged by the load. The ripple usually looks like sawtooth with a bit of square wave, but it can take very weird and wonderful shapes due to complex behavior of capacitors and inductors, feedback problems, burst mode operation of some converters, and lots of other intricacies. On your pictures, true voltage ripple is clearly visible only under load (but you measure peak-to-peak value which is dominated by these conducted-emission spikes). "the buck converter got very hot" and you have not explained why. You have removed the fundamental piece of it, effectively shorting out the switching node of the ic. The IC is always in overload protection, and i'm actually surprised it didn't die right away. This is why it got hot. "" - you don't explain, why so. What properties of these materials are the reason for their intended application. I tell ya. It is the energy that can be stored in the core before core is saturated. Power applications require that energy storage. Signal filtering and transformer applications don't. You can actually make a pretty decent power inductor from a high-permeability core by introducing an air gap (effectively reducing its permeability; the energy is then actually mostly stored in the gap, not in the core). "1mm copper wire which is suitable for the current" - waaay too simplified. There are two current ratings for an inductor: the current at which its core saturates (where it mostly turns into a resistor), and the current at which it overheats. They are not equal. The saturation rating is insensitive to wire thickness. In practice, inductors are usually picked so that the peak current never exceeds saturation rating, and rms current never exceeds overheating rating, although there is more to it (core loss can cause additional heating). 1mm may be suitable or may be not, there is no simple answer. "you may have to use a larger toroid because the wire will not fit" - yes and no. The core must be able to hold the energy the converter requires. That's the minimum. Then you may indeed be unable to fit enough wire and that will indeed force you to pick a bigger core. "" - that's a very simplistic calculator that is not suitable for designing power inductors, because current rating is extremely important, and that calculator gives you no clue. Peculiarly, the calculator has wire thickness. The thickness mostly doesn't affect the inductance, so i wonder what is it there for. For estimating the needed length is my guess... ==final message== "inductors have no effect on dc power" - sorta true. "inductors only affect ac power" = same as above "ac power === ripple" - yes but not quite. Every ripple is "AC", but not every AC is ripple. "AC" in quotemarks because ripple superimposed on DC is usually not enough to make it truly alternating. "inductors don't affect voltage" - just nonsense. "inductor resists sudden changes in current flow" - true. "which in turn can smooth out unwanted voltage ripple" - true, but that's not their main use in switching converters.
Olá !!! amigo sabe me explicar por que a limalha de metal não grudou em toda a extensão da bobina ficou presa ( grudou ) apenas no canto esquerdo ??? em 2:24
Thanks keep it up i wish if you could explain in depth how many turns of an inductor or of a wire around a reed switch is needed to turn it on or if you could recommend a website or a calculator to do such task
I love that you don't do anything crazy with your voice and I could easily imagine a really boring lecture from someone who sounds the same, but everything about how entertaining and educational this is comes from what you are doing and not from sounding like you're on your thousandth cup of coffee for the day. Honestly laughed at the concept of black holes being a common, if unseen, component of your average workshop, but that is as valid an explanation as any for how easily things tend to go permanently missing!
That's why you always connect a diode across a relay coil, or solenoid etc. when switching it with a transistor other wise the flyback would soon destroy the transistor when it switched off.
The hammer demonstrates the flyback best. Swing the hammer with low force but when it hits and stops quickly it suddenly has torque greater than what you swung it with. When the current in an Inductor stops suddenly it creates a higher voltage.
The diode current rating only needs to slightly exceed the coil's dc current, as it is that coil current that will continue to flow (briefly) through the diode, when the current source is disconnected.
This is a very good tutorial on inductors mate. I only have one issue with it. I live in Australia, and I was recently hit by a flying little spring. And now I'm wondering about the truth of potential energy... 😕😁
THIS IS the best JLPCB advertisement among all JLPCB advertisements :)
You forgot the first C in JLCPCB.
Too Bad he didn't clip them to the the tree branches, too.
I first thot he'd get shocked by the electric barbed wire fence.
Whew, Lad!
Came to comments just to say this or see someone else saying this… and… well, I am not disappointed… first comment 🤘
@@user-mp3eq6ir5b same, I was like… is it going to zap him? I was confused why he was going out there dressed like that 😂
*MARKETING*
Man, you're a legend, wish I had professors half as interesting and clear in expression as you are.
th-cam.com/video/aY8ONv6_a7I/w-d-xo.html&feature=share
My courses were all math with a rare lab---too bad I did not have you Dr. Schematix!!! Hands on is the only way to learn.
He must’ve flunked English. There’s no apostrophe in the plural word “inductors”.
Pravda!
@@outerrealm It's OK, he is smart as hell when it comes to inductors.
I spent my career working with digital, now I’m jumping over to analogue for my midlife crisis. Coils... bugged the hell out of me because I just didn’t get them. After watching this video, I get it!
Thank you for a very well explained and demonstrated video! 👍🏻
I've watched so many inductor tutorial videos and I swear none of them were even close to being as informational as this one. Thank you.
Yes mate, a no nonsense, straight to the point, clearly described presentation bursting with facts in a perfectly digestible format....
This is a gold standard introduction to inductors and their properties.
Perfect.
Inductors have been quite a mystery for me this far. Your excellent demonstrations helped a lot in understanding them better. This was likely the best practical intro to them I've seen. Keep up the great work, thanks!
i still dont get what theyre used for tbh
@@PinkeySuavo Me neither.
I recently started winding my own toroids for some low-power ham radio kits. It's worth mentioning that even on a high-end RF-rated toroid (e.g. type 43 ferrite) the proximity of turns can make a pretty big difference in the final inductance; if they're all bunched together, you get more inductance but lower efficiency, and if they're evenly spread out, the inductance is lower but the efficiency is higher.
Not having a component tester, though, I had to come up with an alternate way to test inductances; the simplest way is to build a resonant circuit with a known-value (measured) capacitor and see what frequency it resonates at. With a decent oscilloscope, this should be a lot more accurate than a component tester.
I have done that.
The tolerance on the Capacitor and the accuracy of the frequency counter or Oscilloscope sets the tolerance of your final answer.
One thing that you can also use for the winding of the inductor is "layered" enameled copper wire, it can handle more current at higher frequencies
* layered enameled copper wire just means multiple enameled copper wires put side-by-side (aka in parallel) and then wrapped around the core; only electrically connected at the ends.
Hope this helps!
Layers in an inductor are not paralleled wires. They are physical layers, one on top of another. This is important because the number of layers influences the AC losses in the winding due to proximity effect. Each layer _could_ be made of paralleled strands.
Loved that "if flyback were a person" thing. I wish I had a physics teacher like you 🙏 🤓👨
I've just started working on superconducting magnet coils as a technician. And asked the team leader about inductance, long story short your explanation is awesome.
Nice theoretical and practical demonstration. In the same manner I would like to have a look at chokes!
Fantastic to see some real life practical examples of inductor usage. Inductors have always been a bit of a mystery to me. Love the analogy of a coiled spring.
the best inductor/inductance explanation since my days of electrical engineering at Tulane.
You're very articulate...and make it nearly effortless for others grasp the content. I highly recommend your approach. You will make a great mathematics lecturer 👌
Don’t need to overkill catch diodes. When sizing catch diodes, remember that current doesn’t increase with fly back. The inductor does what is needed to keep the previous current flowing briefly, however much voltage it takes to do that. So if your 70mA relay coil is switched off, it will continue to pass that 70mA briefly. A 1N4148 catch diode will handle that easily! And with your power inductor at 1A, a IN4001 will do the job just fine.
Very nice video. The simple explanation of how an inductor works by using examples of things that are far and away more complex than a simple inductor seems counterintuitive.
I would like to re-iterate a previous comment. You are so easy to understand and don't leave anything out. Which a lot of Electro tech tutors have a tendency of doing.
Fantastic display , after 30 yrs learning and still playing with automotive electronics, in my field opening up and repairing modules are not preformed any more ,
But I still open and find that trying to solve basic faults , which I’m successful, and surprisingly high rate of repairs work ,
are simple as understanding basic principles, post like the one you have shown are a excellent learning and teaching Aid , well done !!!!!
Your excellent skill and passion are shown through your well explained and simplified teaching, very happy to subscribe and view all your post,
Sadly my world of repair is mostly software and this greatly confuses a Tech as simple software fault can imitate a hard Eletricial issue / fault with a clients concern is brought to a dealer ship ,
Thus , weeding out a software fault from a ‘ hard ‘ Eletrical issue can be trying , but it is just a elimination path I take ,
Your post show very importantly the understanding and it’s fantastic that you’ve taken the time to do so , Thankyou and looking forward to seeing more post , keep it up ! :)
Between the natural grown PCBs and the flyback "as a person" demonstration, you have earned my sub and like good sir. I don't often audibly laugh from youtube videos, let alone electronics related ones, but this one really got me. As a budding electronics enthusiast and (hopefully) future Electronics engineer, I hope to learn alot from this channel!
These ads are actually great. Most TH-camrs make the ad spots boring af, but these are hilarious
Thank you. Very informational video. I am a complete rookie in electronics and I am just beginning to find the fun of this hobby. Thank you for your Lesson.
When people.say they don't trust youtube to find knowledge.
@@bringer-of-changeThis too is part of the Scam, to justify and exonerate the role of the Bogus, rigged Education system.
69likes🌚
Your video & Demonstration has relief me from some misunderstanding the nature of inductor. Thanks for the video.
Excellent explanation. I mainly deal with AC, but your clarification of DC circuits is massively helpful. Small point of contention though regarding definitions, an inductor I believe doesn't so much "resist" current so much as "impede" it. The definition and distinction I was taught is that resistance is work done that produces heat, whereas impedance doesn't. But then I guess no matter the length of copper wire you are using it will have some inherent resistance to it.
Great video!
impedance includes resistance. are you thinking of reactance?
@@dotanuki3371 Yes, both are included in the term impedance, but inductive reactance is not the same as resistance.
Beautifully explained.
So electrically an indicator is like capacitor that has had its two parallel separate conductors shorted together at the end.
And would become a capacitor again if "unshorted".
Love your presentation. I am glad that I am not the only one to notice the "black hole" in one's workshop that gobbles up all erratic kinetic objects never to be seen again. LOL. Like other commenters here, I have always been perplexed by inductors, but you make the concepts crystal clear. I guess the birds in NZ do not like PCB seeds which allows the PCBs to grow in the wild.
Before watching this video, I had a basic understand of inductance, coils, magnetic fields, etc., but now after watching this video, I not only feel I finally understand inductance, but how it's used and dealt with! Thank you!!
I had the same comment that someone else made. With inductors, you increase the voltage, not the current. The maximum current is what you pass through the inductor while connected to the supply. When disconnected, the current decays, based on the resistance in the flyback circuit. The rate (aka speed of the decay) is related to the inductance/resistance time constant. The higher the resistance, the higher the voltage (and faster the decay). But again the current never exceeds the what it was passing at the instant before being disconnected. Without a flyback diode - the resistance is infinite - or whatever the rest of the connected circuit is, as parts begin to break down. A related phenomenon is that the high voltage can actually cause a spark, as the collapsing magnetic field attempts to maintain the current. When one unplugs a high inductive load - such as an iron or toaster - from the household mains, you will likely see a spark - that is the flyback voltage trying to dissipate the current.
In RF parlance, especially in the amplifier arena, capacitors and inductors are labeled as tank blocking capacitors which pass RF current and block DC, while the plate chokes block RF current and pass DC, unless they're making up the tuned resonant tank circuit, where you want the cap to charge and discharge, and the inductor to ring, forming the flywheel effect in class B and C amplifiers. Another choke is used off the load capacitor to ground, which is for safety if the plate cap fails, connecting the HV to the tank. This, of course, blows the fuse before allowing HV into the antenna circuit.
However, that choke's ringing causes HV to appear across the tuning and load cap's plates, and they have to be rated for that.
In the plate power circuit of tube amps, the cap passes the anode's RF to the tank circuit while blocking HV DC, and the RF plate choke blocks the RF from entering the HV power supply. It's like using two types of check valves in a hydraulic circuit, and very similar to a diode's action.
Great video and information, thank you very much! FYI, I haven't sanded or burned the insulation from this kind of wire for many years now. Modern coated wire is made to solder through, at least on all the wire I've dealt with. Just hold the soldering iron and solder on it for a few seconds and it works like magic, instantly tinned.
Magnet wire insulated with a nylon/polyester blend can be soldered without stripping. Lots of magnet wire cannot and has to be mechanically stripped or striped in a "salt pot" stripper at very high temperature.
One of my clients, which made large iron core transformers in house, used an oxyacetylene torch. If you set the flame to oxidizing (more oxygen than needed for the acetylene) and put the wire in the oxidizing part of the flame, the insulation is cleanly stripped. You can't do this with something like a propane torch. It will simply burn the insulation leaving a mess that still has to be removed mechanically, though more easily than unburned insulation.
I used to buy magnet wire from a supplier to motor rewinding shops. They didn't stock the stuff with solder-through insulation because it isn't robust enough for industrial motors.
I built a 60 watt transistor stereo from Heath kit back in the day. I would bridge a 47 mf Disc capacitor across each speaker output To keep from hearing my neighbour talking on his CB radio through my speakers, It worked!
I am a starter mechatronic and stuff like this is really helpfull...not every proffessor explains stuff like this...love your content!
Excellent explanation of theory and good examples.
As someone who's fried a few boards early on in my days of home building CnCs, this a huge resource.
One important comment from an old winder: *Always* start winding the wire from the middle and wind both ends separately. This way you dont have to thread a long wire so many times. The total length of wire to thread is reduced by x4.
That flyback person demo is awesome. Well done video. Thanks!
Finally I got proper knowledge about inductor and it's used nice video 👏👏 thoroughly practical enjoyed your video Thanks 👍😍
Looking at inductor's for antenna matching and came across this video. Very interesting especially about making them and the difference between the two with the same inductance. Tnx mate
How can i build something like that inductor tester?
Am so much at the right place. This is the best ever tutorial after i wasted my two years on other channel to keep on feeling like quiting electronics.
Best possible explanation of inductors I have ever came across.
One of the best videos I have ever watched on youtube!
Thank you for sharing your knowledge so effectively xD
The PCBs growing in the forest like mushrooms were great
Glad you enjoyed it. I try to keep my sponsorship segments entertaining & fresh :)
Copied from Marco Reps :-(
@@gustinian Nah. Marco Reps can only harvest capacitors where he lives, PCB's don't grow in that climate
Wait you guys find components in your forests my forests only grow meth labs and tires
@@thomastruant8837 Indiana?
I studied this at university in New brunswick. The prof who taught the subject was very good explainer. so this video.
This is the best video of concepts of inductor. I really undestand when you make analogy with spring. The diference aboult capacitor and inductor is very interresting. Thank You!
- probably already in the comments somewhere, but I'm not going to read over 600 comments to find out:
The peak current at turn-off of an inductor can *_never_* exceed the current at the instant turn-off starts. This is a fundamental property of inductance. If a relay coil operates at, say 100 mA, the current at the instant of turn-off will be 100 mA and decline from there.
For small relays a 1N4148 or 1N914 or similar diode is entirely satisfactory. If the coil current exceeds half an amp then you might go to something rated at 1 amp. I've used dual transistors in surface mount packages for driving relays. One transistor is used as the switch and the other is used as a diode (collector-base; the base-emitter diode has some better properties for some applications but small reverse breakdown voltage, typ. 6 or 7 volts for common types). This makes things very compact.
~~~
That HY-2 inductor core is a Micrometals Type 52 powdered iron material, or a counterfeit thereof.
I had to pause to comment, "oh my god," as you smashed LED, resistor and cap, and I'm an atheist. You are a Kiwi treasure. I salute you with subscription, sir.
Best video about electromagnetics I've seen so far
you just killed me over here with the god dammed spring bouncing all over the place LOL good one.
THAT PCB INTRO WAS GENIUS!!!!
I really enjoyed your flyback to a spring example! I need to find out the opposite of what you showed after that, however... I need to figure out how to best protect any other circuitry while, at the same time, getting the highest possible flyback voltage. It doesn't help that my limited amount of electronics background is close to 50 years old ~ with a LOT of "water under the bridge" during that time... (I'm having to go back & start over from scratch via youtube, etc.) Fortunately, I DO remember enough to have a healthy respect for HV & how to discharge scavenged flybacks, capacitors, & condensers without "knocking myself into the next county ~ if not the next life..." I'm wanting to set up at least 3, horizontal shaft, Briggs & Stratton 4 stroke motors with to run off of HV produced HHO on demand. These motors, in turn, would spin "smart drive" stator/rotor motors, rewired to be generators, with a bit of the output getting diverted to charge the flyback system for HV/LC... Any suggestions on how to protect the other circuitry withOUT reducing the flyback voltage???
A better analogy for the stored energy is the kinetic energy of a moving body, because inductors give inertia to electric current. Interruption of the circuit (creating a voltage spike) corresponds to collision of the moving body with an obstacle (exerting a high force for a short time). A compressed spring is an analogy for a charged capacitor. Movement created by the released spring corresponds to discharge current from a capacitor.
Those are the best mechanical analogs. Add a dashpot (shock absorber) as the mechanical analog for a resistor and you can visualize RLC circuits as masses, springs, and dashpots - or vice versa. One good example would be examining the response of a suspension sytem to a bump in the road. The tire/wheel would be the mass (inductor) connected to the spring (capacitor) and dashpot (resistor). The damped system can then be analyzed as an RLC circuit responding to a step input.
@@vicruzr wow😳 wonderful analogies. Please where can I get more of these analogies (any detailed basic e-book at all🙏 )for better understanding of circuits, bit by bit to complex level.
This is the best video tutorial on Inductors I have seen thus far. Much appreciated, thanks.
Hello thanks very much for teaching I have learnt something new looking a head to more videos like this
Awesome ! I’m building a voltage current sensor for I2c bus 😅 .300 mA 😮 all going to be part of my oscilloscope / logic analyzer build
Teach me how to do that brother
Automotive ignition systems use this principle to fire the spark plugs. In the old days they used mechanical points along with an ignition coil to open and close the circuit.
From the coil32 page......Another case is the inductor in the switching power supply. The commonly used ferrites have a relatively low value of saturation flux density (about 0.3 T), so in the power switching circuit the inductor is switched between the maximum value of the field when it almost gets a saturation and zero-field value, when it is demagnetized to a value of residual induction (curve [4]). As we can see the slope of the major axis of the ellipse 4 is much smaller than that of the ellipse 3. In other words, the magnetic permeability of the core in this mode is greatly reduced. The situation becomes worse if the choke core has DC bias (curve [5]). The major hysteresis loop of the real ferrite is more rectangular than on our schematic image and, in the end, the dynamic magnetic permeability of the power inductor on a ferrite ring falls to several units. As if there is no the ferrite! In the end, the inductive reactance of the inductor decreases, the current increases dramatically (which results in an even larger decrease in µ!), the key transistor heats up and burnout. The calculations of Coil32 for this choke give an absolutely wrong result. Because, we used to calculate the value of initial magnetic permeability, and in a real circuit, the permeability is two to three orders smaller. You will get the same situation if you will measure the relative permeability of the toroid by the trial winding.
The solution is to use a ferrite core with the interrupted magnetic circuit. In the case of the ferrite ring, it is necessary to break it in half and then glue that two half with the non-magnetic gap. The major hysteresis loop of such a core becomes more sloping [2], the residual induction is much less [B'r], the effective magnetic permeability is also less than that of the core without a gap. However, the curve of magnetization [6] shows that the dynamic magnetic permeability of this inductor is much higher than that of similar, but with a core without a gap. It has permeability about 50..100. Coil32 also is unable to calculate this choke, since it does not take into account the non-magnetic gap. Another solution is the use of special rings for the power supply as powdered iron toroids (not ferrite). Such toroids can be found in pulse power supply units and motherboards of computers. The non-magnetic "gap" in such ring is distributed along its length.
Conclusion. The Coil32 program calculates only low-current ferrite toroid coil working in low magnetic fields. For the power chokes calculation, it is necessary to use a completely different methodology.
this is my first time watching your channel, and man, you didn't hold anything back with picking wild PCBs, that was fantastic!
Wasn't even searching for this topic but I'm glad I found it, super interesting 👌
Just a grammar tip to help polish the old image: Apostrophe S after a noun denotes possession. "Inductor's" implies there's something that belongs to said inductor. For plural, just drop the apostrophe. "Inductors". You also don't need to capitalize after the ampersand.
Best of luck to you
This is by far the best sponsor acknowledgement I have ever seen :D
Very informing!! I am in the process of learning more and indulging in projects involving inductors
Omg that spring reference changed everything for me! Subscribed mate 🤙🏻
But it's not like a spring in that the current in the inductor doesn't change direction when it collapses.
Sir you are a genius at explanation and teaching. Your video was so clearly done and while interesting. I applaud you. Well done.
I work on refrigeration systems. We put vfds on the condenser motors a while back. They were blowing up motors left and right. Aside from the motors not being rated for vfds at the time (over a decade ago) they added these electric filters on the outputs of the vfds. I'm no electronics guy, but are those filters we added essentially just inductors for taking out the spikes like you mention in this video on the buck converters? The output of vfds are dc that mimic ac as far as I understand. Which isn't much.
Excellent and extremely thorough presentation (technical content and instrument results) plus totally understandable physical speech and phraseology!!! Plus, plus, plus - no bloody annoying and distracting music!!! Previously subscribed to your site - cheers from Down Under.
That was such a clear and concise description and explanation as well as providing many useful pointers. Thanks.
Your examples of flyback at 5:15 and 5:30 are... absolutely perfect 😎❤👍
I have that very same component tester. It doesn't work too bad. The LCD screen lost its seal on mine shortly after I bought it, but still works. Every once in awhile it will give some erratic readings.
I bought mine and assembled it. I had to come up with my own case for it.
After inductance, the next most important property of inductors is it's saturation current.
Basically when inductor reaches saturation current its inductances decreases to almost zero.
This is the probable reason those inductors presented different results.
Does that mean its resistance drops as well? At the same time it reaches above saturation
Awesome... waiting for next inductor video that it can cause issue in circuit with practical and theoretical explanation...
*Finally, an inductor tutorial that makes sense* 👍👍👍👍👍
The best inductor video on TH-cam!!!
Nice video! I especially love the JLCPCB advertisement. I also love how you showed how flyback would be if it was a person.
It's PCB season here in Australia. I'll be heading to the hills to pick a few bags worth next weekend.
JLCPCB needs to pay this man more
There is sooo much more to designing inductors. This is just a taste.
This helped me with inductors more than any other video I've seen. Thank you!
Oh yes, diodes work great! I had to use about 1500 of them on the electric valves in my pipe organ, each valve's coil was 40, 60 or 90 OHMs @ 12vdc. I had to use diodes to deal with flyback voltage potentially damaging delicate contacts, and to electrically isolate sets of valves connected to the same "66" terminal blocks so each set's valves could be operated separately from the other from the keyboard.
This is probably one of the better videos I have seen you make. Quick quick question I am building speaker crossovers and found Inductors are very expensive. I wanted to ask what type of Toroid would you suggest for this purpose. I am thinking I can save a lot of money if I just build my own inductors. I want to use iron core inductors for the large woofers rest could be air core but I guess I could use iron core for those too as I could use less wire. I will probably be using 18 awg (1 mm2) wire. Could I even use an iron bolt?
Very nice explanation... I listened to this multiple times. Thanks a lot.
Awesome explanation. I had a suggestion, can you show us what exactly is "opposes sudden change in current practically"?
I wish I know all this at my university, it is so clear and visual thank u👍👍👍
5:43: "Placing a diode backwards to the power source across the inductor/coil allows the flyback to flow back through the diode when power is disconnected from the inductor/coil." While the sentiment is correct, the description is not. Inductor voltage "flies back" as the result of a discontinuity of CURRENT, not "power." V = L*dI/dt, where dI/dt is theoretically infinite when the current suddenly is disconnected. Inductors will do all they can to prevent current discontinuity by the voltage suddenly flipping trying to find a place for the CURRENT to go to. That's what the diode does. No current can flow through the diode when it is biased off, but during this voltage flip, the diode is suddenly forward biased, giving the current a place to go. If you put a current probe on the diode, you would see current changing smoothly from its DC value, then ramp downward with a ramp shape that is I(t) = integral (Vdiode/L)*dt until the current goes to zero, and which point the inductor energy (1/2 * L*I^2) has been dissipated by the diode. You do a disservice to your viewers by interchanging current and power. They are completely different animals!
That's one of the best demonstration of flyback ..
I always used a diode wired backwards across the relay coil terminals to prevent a voltage spike effecting the circuitry elsewhere in the project.
Interesting for sure. Nice to see the factual results with the scope, between the different inductors. Thumbs Up!
Inductors are useful for buck-boost converters too. They take advantage of the voltage spikes to produce higher outputs than the input voltage.
@Fred Garvin how come?
@Fred Garvin So how do you get a higher output voltage then? As far as I know it occurs when you cut the supply to the inductor, causing its field to collapse and it generates a back emf. The duty cycle is to regulate the output voltage and with higher switching frequencies you can get higher voltages from smaller inductors because faster current disruptions cause higher back emfs.
@Fred Garvin boost needs the back emf of the inductor that occurs when you disconnect the power and it tries to keep the current going.
EXCELLENT INFORMATION.
Very good Presentation.
Thanks A LOT.
Ideas for other videos:
I would like to better understand inductor saturation, and see if we could show that it eddie losses is why one worked better than the other.
How to select low cost capacitors for high output induction heaters (high current applications).
Using a microcontroller to monitor and control an induction heater, frequency matching and to protect the mosfets.
How to test if mosfets are still good, and general trouble shooting of SM power supplies.
Wow you make this sound so easy but electronics is so hard for me to really grasp. I’m still really lost but you did make a lot of sense and this is such a great channel I subscribed and have been watching your videos nonstop. So if inductors have no effect on DC power is it a waste to put one after the capacitor in series with the output. I am going to rectify a welder from AC to DC. Some videos I see people putting an inductor last in the circuit and some people just do the rectifier and capacitor without an inductor. Basically if I understand you correctly if the circuit has been rectified to DC and then run through a capacitor then the inductor isn’t doing anything at the output. I hope this question makes sense because I’d like to hear your thoughts. Thanks
Gotta love your Widlariser at 5:30. 👍
Watching this in 144p at the first scene where the 8bit musis plays while he gathers pcb boards from nature was certainly trippy
oh boy, where do i start...
"inductors can't store energy when disconnected from power supply" - no, they can. Ideal inductor will store its energy indefinitely if it is shorted. Real inductors rarely achieve more than a second of useful storage time. This is unlike capacitors primarily because our insulators are much closer to ideal than our conductors. Like capacitor requires ideal insulator (zero leakage) to store energy indefinitely, inductor requires conductor with no resistance (superconductor) to store its energy indefinitely.
spring analogy - see other comments... the analogy is acceptable, but there is a better analogy with mass hitting a brickwall.
"if flyback were a person" - oh dear...
diode peak current 220 amps "massive overkill" - it is indeed massive overkill. The peak current that will flow through the diode is equal (slightly less, actually) to the current that was flowing through the coil just before breaking the circuit. This is exactly the rule "inductor resists a change in current". It will slowly decay afterwards. There is no need to account for more. Heating may be of concern if the load is cycled on and off fast.
"Inductors help smooth out voltage ripple caused by high switching frequency" yes they can, but their primary use in switchmode converters is very different. They are temporary energy storage that can be filled using one voltage (the input voltage) and drained at another voltage (usually but not always, the output voltage). They are at the very heart of the conversion process (with some exceptions).
"these spikes are undesired voltage ripple" - no. These are conducted emissions (mostly caused by parasitic inductances, capacitances and transformers in your circuit), they are not called "voltage ripple". Voltage ripple is usually the changes in capacitor voltage that happen as the inductor enegry is dumped into it, and then capacitor is discharged by the load. The ripple usually looks like sawtooth with a bit of square wave, but it can take very weird and wonderful shapes due to complex behavior of capacitors and inductors, feedback problems, burst mode operation of some converters, and lots of other intricacies.
On your pictures, true voltage ripple is clearly visible only under load (but you measure peak-to-peak value which is dominated by these conducted-emission spikes).
"the buck converter got very hot" and you have not explained why. You have removed the fundamental piece of it, effectively shorting out the switching node of the ic. The IC is always in overload protection, and i'm actually surprised it didn't die right away. This is why it got hot.
"" - you don't explain, why so. What properties of these materials are the reason for their intended application.
I tell ya. It is the energy that can be stored in the core before core is saturated. Power applications require that energy storage. Signal filtering and transformer applications don't.
You can actually make a pretty decent power inductor from a high-permeability core by introducing an air gap (effectively reducing its permeability; the energy is then actually mostly stored in the gap, not in the core).
"1mm copper wire which is suitable for the current" - waaay too simplified. There are two current ratings for an inductor: the current at which its core saturates (where it mostly turns into a resistor), and the current at which it overheats. They are not equal. The saturation rating is insensitive to wire thickness. In practice, inductors are usually picked so that the peak current never exceeds saturation rating, and rms current never exceeds overheating rating, although there is more to it (core loss can cause additional heating). 1mm may be suitable or may be not, there is no simple answer.
"you may have to use a larger toroid because the wire will not fit" - yes and no. The core must be able to hold the energy the converter requires. That's the minimum. Then you may indeed be unable to fit enough wire and that will indeed force you to pick a bigger core.
"" - that's a very simplistic calculator that is not suitable for designing power inductors, because current rating is extremely important, and that calculator gives you no clue.
Peculiarly, the calculator has wire thickness. The thickness mostly doesn't affect the inductance, so i wonder what is it there for. For estimating the needed length is my guess...
==final message==
"inductors have no effect on dc power" - sorta true.
"inductors only affect ac power" = same as above
"ac power === ripple" - yes but not quite. Every ripple is "AC", but not every AC is ripple. "AC" in quotemarks because ripple superimposed on DC is usually not enough to make it truly alternating.
"inductors don't affect voltage" - just nonsense.
"inductor resists sudden changes in current flow" - true.
"which in turn can smooth out unwanted voltage ripple" - true, but that's not their main use in switching converters.
Very good also, but he got the point across with out going over a bunch of heads!
Olá !!! amigo sabe me explicar por que a limalha de metal não grudou em toda a extensão da bobina ficou presa ( grudou ) apenas no canto esquerdo ??? em 2:24
You saved the day.
Russians are smart!
Thanks keep it up i wish if you could explain in depth how many turns of an inductor or of a wire around a reed switch is needed to turn it on or if you could recommend a website or a calculator to do such task
I love that you don't do anything crazy with your voice and I could easily imagine a really boring lecture from someone who sounds the same, but everything about how entertaining and educational this is comes from what you are doing and not from sounding like you're on your thousandth cup of coffee for the day. Honestly laughed at the concept of black holes being a common, if unseen, component of your average workshop, but that is as valid an explanation as any for how easily things tend to go permanently missing!
That's why you always connect a diode across a relay coil, or solenoid etc. when switching it with a transistor other wise the flyback would soon destroy the transistor when it switched off.
The hammer demonstrates the flyback best.
Swing the hammer with low force but when it hits and stops quickly it suddenly has torque greater than what you swung it with. When the current in an Inductor stops suddenly it creates a higher voltage.
Best inductor video on TH-cam! Thanks!
The diode current rating only needs to slightly exceed the coil's dc current, as it is that coil current that will continue to flow (briefly) through the diode, when the current source is disconnected.
Thank you for concrete simple and clear teaching on inductor.
This is a very good tutorial on inductors mate. I only have one issue with it. I live in Australia, and I was recently hit by a flying little spring. And now I'm wondering about the truth of potential energy... 😕😁