How INDUCTOR's work & How to make your own

in this video I'll teach you about the basics of inductors and inductance then we'll look at designing our own inductors from scratch I'll also demonstrate the destructive voltage spikes inductors can cause so you know how to avoid blowing up your circuits [Music] [Music] fortunately for me I live in a part of the world where PCBs grow in the wild but you might not be so fortunate but that's okay because this video sponsor is jlc PCB and they've got you covered jlc PCB is one of the largest PCB manufacturers in the world personally I've always been impressed with the quality and affordability they offer jlc PCB now offer SMT assembly service allowing their customers to receive complete ready to use circuit boards right out of the box without the need to solder fiddly surface mount components with a multitude of design options fast production time and with five PCBs costing less than a cup of coffee give jlc PCB your next PCB project did you know when current passes through a wire it produces a magnetic field that wraps around the wire in most instances this magnetic field is very weak and goes largely unnoticed now we all know that magnets and magnetic fields are particularly attracted to ferrous metals like this iron bolt I use the foil to produce some fine iron filings due to their small size they should be attracted to even relatively weak magnetic fields after connecting this light bulb to my power supply there is about five amps of current passing through the wire however I can't see any filings been attracted to the wire seems the magnetic field is just too weak here hmm well let's make a coil then by making a coil of wire the magnetic field intensity increases with every turn of wire after winding a couple hundred turns let's connect the coil to my power supply and try again and would you look at that the iron filings are being picked up by the magnetic field around the coil and if I switch off the power the filings drop away as the magnetic field collapses this magnetic field is what makes an inductor so useful you could think of the magnetic field around an inductor as a of energy storage and doctors come in many forms actors and sizes but fundamentally they are all similar essentially an inductor is made from enameled copper wire wrapped around a ferrite or iron core but how does inductors store and release energy from the magnetic fields they generate well that's a good question when we think about energy storage you might think of something like a capacitor or battery for example capacitors can be charged up and even when disconnected from their power source capacitors can hold their charge long after inductors can't store energy when disconnected from a power supply but they do something else pretty interesting when disconnected and inductor rapidly dumps all of its energy into one big voltage spike that lasts for only a fraction of a second to demonstrate this I'll connect my scope probe across the Seductor then connect my power supply across the inductor as well my power supply is set to output one amp of current okay so at this point we have one amp of current flowing through the inductor now watch what happens when I disconnect the inductor from my power supply the scope captures a snapshot of what just happened the moment I disconnected the power this voltage spike was a mess of 452 volts this voltage spike is called flyback but how does fly back occur well inductors connect similar to a spring let me explain if I compress the spring I'm storing potential energy in the spring then when I release it the spring releases all of its stored energy in a single burst flowing across the workshop into a black hole never to be seen or heard of again when inductor has current flowing through it it's storing potential energy in the form of a magnetic field similar to that of compressing a spring then when I disconnect the power the energy stored in the magnetic field around the inductor rapidly converts back into electrical energy that results in a huge voltage spike aka flyback similar to that of releasing a compressed spring flyback isn't just limited to inductors relays and motors are also inductive loads and can cause fly back just like inductors can let's see the fly back produced from this 5 volt relay it's so tiny and cute there's no way this could produce a mess of voltage spike I mean come on okay well scratch that den this tiny relay produced a mess of 356 volt voltage spike all from being powered from a mere 5 volts with 70 milliamps of current flowing through its coil and I'm sure you can imagine how destructive these high voltage spikes can cause to other electronic components if they share a connection with the relays coil basically a flyback were a person it would look something like this [Music] [Music] preventing flyback is fairly simple placing a diode backwards to the power source across the inductor / coil allows the flyback to flow through the diode when power is disconnected from the inductor or coil to demonstrate this I'll use this SB 5 for zero Schottky diode which can handle a peak surge current of 220 amps which might sound like a mess of overkill but in reality the flyback from an inductor the size could easily get close to or even exceed this figure under certain conditions I'll solder the diode across my inductor then connect it to my scope and power supply and repeat the test with the addition of the diode the flyback voltage spike is significantly reduced down to a mere 1 point 7 6 volts compared to before at 452 volts without the diode the same principle can be applied to the relay choosing an appropriately sized diode capable of handling high surge currents as necessary and many applications however in the case of my relay here a common one in for double a one diode should be able to handle the fly back from this relay without an issue this time the fly back from the relay was a mere 560 millivolts compared to 356 volts without the diode so now you know how to deal with fly back from inductors and inductive loads moving on what applications are most suited for inductors well in the case of buck converters or switch mode power supplies inductors are used to help smooth out voltage ripple caused by the high switching frequency voltage ripple is never a good thing besides inductors large electrolytic capacitors are used to smooth out the unwanted ripple on the output I'm connecting this buck converter up to my scope so we can take a look at the voltage ripple on its output the yellow flat line across the screen is the 8 volts DC output from buck converter and these voltage spikes you can see here is the undesirable voltage ripple on the output the voltage ripple measures around 72 millivolts peak to peak which for the price I paid for the buck converter is actually pretty good before we move on to making iron inductors first I want to make my own buck converter based on the excel four zero one six buck I see I ordered some PCBs from who other than jlc PCB and gathered the required components and soldered everything in place except the inductor if you'd like to build one for yourself check out the link in the video's description to understand how important the inductor is in a buck converter circuit I've soldered in a wire jumper where the inductor would normally be connected effectively deleting lis inductor from the circuit after connecting my scope to the buck converters output and powering it from my power supply we can see just how awful the voltage ripple is on the output at over eight volts peak-to-peak the voltage is also all over the place and completely unfit for purpose to make matters worse even though the test was limited to a few seconds the buck IC is getting very hot time to unsold the wire jumper and replace it with an appropriately sized inductor after reconnecting my scope and power supply to the buck converter we can see this time around we've got a pretty clean output with only 160 millivolts of ripple comparing the two tests side-by-side you should be able to appreciate just how important an inductor is in a buck converter circuit alright now we've got a platform for testing let's move on to making a couple different inductors to test first off we need to choose a toroid ring besides different sizes toy roids come in a wide variety of material options choosing what material is right for your application can be the difference between success and failure the black towards I have here are made from l8 ferrite and a more suited towards noise suppression applications while the green / blue towards our hy 2 material made from powdered iron and are more suited for power and ducktor applications such as in buck converters both types of toroid ZAR very attracted to magnets the only other thing we'll need is an emerald copper wire I'm using one millimeter thick copper wire which is suitable for the current I'll be drawing from my buck converter using a thicker wire than required will mean you may have to use a larger tyroid wasting valuable real estate in your projects while on the other hand using a wire that's too thin may lead to overheating so choose your wire gauge carefully there is a really useful inductor calculator on coil 32 net it makes calculating the number of turns of wire really simple first I'll enter the inductance I require which for my application is 47 micro Henry that is the recommended inductance according to the manufacturer of the buck I see I'm using next I'll measure my toroid ring using a pair of calipers to measure the outside inside as well as the height of the ring after entering all my measurements we come down to magnetic permeability the magnetic permeability will depend on what material your tyroid is made from and the magnetic permeability should be provided by the manufacturer in my case the magnetic permeability for my hy 2 toroid is 75 lastly we enter the wire diameter which in my example is 1 millimeter and then press calculate so this is how many terms of wire are required around the toroid and this is the overall lengths of wire required I measured out and cut a length of wire slightly longer than calculated to allow an error margin and then started to wind the wire around the toroid take your time here and try to keep each turn of wire neat and tidy as you can see I was very close to running out of room on this toroid I just managed to squeeze in the right amount of tens now let's do the same for my l8 tyroid bring the major difference between my two toroid x' is the magnetic permeability this time it's 900 ultimately this means less turns are quiet compared to the hy to tyroid after cutting the wire to length and wrapping it around the thyroid I used sandpaper to remove the enamel insulation from the wire in theory these tutorials have identical inductance yeah as you can see one has much more why than the other so it'll be interesting to see how these two inductors perform against one another before we put them to the test I wanted to verify I did everything correctly by measuring their inductance with my component tester now full disclosure this tester isn't super accurate nor does it offer fine resolution for measuring inductance but all I want to know is if I'm pitching in the right ballpark first I used a commercially made 47 micro Henry inductor to verify my testers accuracy or perhaps lack thereof and it measures in at point zero five millihenry which converted is 50 micro Henry hmm not bad okay now let's test my la conductor and it measures an at point zero five milli Henry as well and lastly my H Roy two inductor also measures an at point zero five Miller Henry so all three of these inductors have approximately the same inductance now we can move on to testing them let's start with the hy two inductor I'll connect my buck converter to my power supply which is supplying 22 volts I'll use my multimeter to measure the output of the buck converter and adjust the output to 6 volts DC with that done I connected my scope probe to the output so we can take a closer look at how much ripple is on the output with no load on the output the ripple was 280 millivolts ok let's use this 12 volt 50 watt halogen bulb as a load Heligan bulb is an ideal load for this type of testing scenario because the bulb is a resistive load with next to zero inductance that is very important because we won't be introducing any unwanted noise into the equation with the addition of the halogen bulb drawing current the voltage ripple is increased to almost 600 millivolts finally I'll raise the output voltage to 10 volts and reconnect the halogen bulb due to the increase in voltage from 6 to 10 volts the bulb will be drawing more current this time the ripple was slightly lower than before at just under 500 millivolts I then swapped out to hy - for the l8 inductor and repeated the same test just like before six volts no load six volts worst load then finally 10 volts worth load and here are all the test results comparing the h way to and l8 inductors side-by-side with no load the l8 inductor reduced the riffle by more than half compared to its counterpart however under load that hy too started to show its strength by keeping the ripple below 500 millivolts compared to the l8 inductor which suffered greatly under load I also wanted to briefly mention the buck converter I built in this video had rather high voltage ripple on its output in a future video I'll explain how inductance can cause issues in your circuits and how adding decoupling capacitors can improve the performance of your circuits with the addition of two capacitors I was able to reduce the ripple down to a mere 26 millivolts and the PCB Gerber files available for download have been updated to include the additional capacitors the takeaway from us exercise today is there is no one-size-fits-all solution so do your research before buying inductors or start making your own most manufacturers provide detailed data sheets explaining what applications their inductors are most suited for and if there's only two things you learned from this whole video it should be that inductors basically have no effect on DC power inductors only affect AC power or in other words brittle and inductors don't affect voltage rather an inductor resists sudden changes in current flow which in turn can help smooth out unwanted voltage ripple so if you found this video useful please give it a like it would be much appreciated it helps out mercifully and if you have any questions or suggestions for future videos leave them down in the comment section below thank you very much to my supporters on patreon you guys Rock you helped make content like this video possible and I will see you all in the next video bye for now

Channel: Schematix

Views: 379,311

Keywords: inductors, inductor, flyback, surge, voltage, spike, how, to, make, calculate, tutorial, toroid, ferrite, bead, ring, schematix

Id: d-E12DlzGGc

Length: 15min 54sec (954 seconds)

Published: Thu Feb 13 2020