Tech Tuesday: Capacitors explained

[Music] g'day and welcome back to RC model reviews another tick Tuesday for the sixth November 2018 and today I'm talking about capacitors now I said I was going to talk about accelerometers but I've decided to leave that till next week because then we do something different you know changes as good as a holiday let's have a holiday let's change it to talk about something that's really quite simple it is what we call a passive component and they're one of the building blocks of all the electronic devices that we have in the Hobby capacitors are an essential building block the basic the basic passives are capacitors resistors and inductors and they're called passives because they just lie around doing nothing they don't have any active elements as to say they are would you say they don't amplify anything they simply change the way the electricity flows but they don't change it in an active way they passively change it that didn't explain to them thing that never mind let's move on capacitors and this is this circuit diagram for a compare the elta symbol for a capacitor in a circuit diagram and it tells us a lot about capacitors actually because what the capacitors are really is just two plates of conductive materials separated by an insulator that insulator can be here it can be plastic it can be a liquid it just it can be an oxide of metal it'll be anything that doesn't conduct electricity which is basically what an insulator is isn't it so that's what a capacitor is capacitors are measured there's two values for a capacitor one is the voltage rating because as you can see if this is a good insulator and here you put voltage on one side and the other voltage you know like positive on here and negative on there if you put enough voltage then a spark will jump through here or even with a plastic insulator the plastic will break down and you'll get electricity jumping between the plates and that's when they file it can produce a short-circuit so you need to write the voltage that maximum voltage capacitor can handle if you use a voltage capacitor with two lower voltage rating then the insulating layer will break down and sometimes magic smoke will come out so the voltage rating is probably you know in terms of longevity that's a really important thing now the other rating is the capacity of the capacitor but go capacitors because they have a capacity and that's measured in farad's that's the unit of measurement but a farad is a huge amount of capacity so normally we talk about them and things like micro farad's nano farad's or pico farads so there are all tiny fractions of a farad obviously if you look up those there's prefixes you work at what they are you know micro is one millionth nano is one billionth and pico is 1,000 billion for whatever so yes so we're dealing with very small amounts now when I say farad's you know don't you dear Ferris would say she sometimes you do because there's a thing called a super cap which is really really really just check my notes really high capacity capacitor and sometimes they're measured in farad's I'll talk about those a bit more in a moment but here we go there's a competitor there's the symbol and how do they work well I'll just show you basically they are like a reservoir of electricity you can temporarily store electricity capacitor and then pull it out again it's one of the most common uses for a capacitor that because the reservoir of electricity no not like a battery though because batteries don't store electrons they store chemical energy they convert the flow of electricity into a chemical energy that can then be reversed in therefore the electrons come back out again making electrical circuit so these have no chemical actions are stalkers are completely passive there's no chemical reactions it's just a buildup of electrons on one plate and a lack of electrons on the other place so if we were to connect this up to a battery let's say we had a battery here it had a positive terminal a negative terminal and we ran a wire from the positive to there and from the negative to there what would happen here is actually really interesting opposites attract that's why ugly women like me okay but opposites attract so what happens here is on the positive terminal here that will actually attract but normally speaking you've got electrons on both sides of these plates right just a few electrons if you can eat up to a battery the electrons on this plate are attracted to the positive terminal so you end up losing electrons from this plate and and because of the way things are going electricity flows in a circuit so you have electrons traveling up this way and you have extra electrons arriving on that plate so you have a capacitor is charged with electrons less toward the plates control it hold the electrons no chemical stuff it's just raw electrons stored inside your capacitor and that has a number of benefits over a battery obviously because chemical reactions break down over time you know chemistry's the for example it's take a lead acid battery the acid goes you know get contaminated the lead forms sulfates and then breaks down forms a layer on the bottom which shorts out the place so many think bad things can happen with batteries but with a capacitor there's nothing chemical happening so they would in theory last a long long long long long time they don't always they'll get on to that later on but up also because you're not having to wait for a chemical reaction to take place you know when you charge your life or you charge it at 1 C and it takes an hour it takes over an hour to actually charge that battery because you can't charge it too fast if you tried to charge it 100 C it explode because the electrons would rush in the chemical reaction would take place but then it protects place so quickly that gas is liberated that the electrolyte and the battery boils and then the guests pressurize it and then boom you're going to be explosion with capacitor none of that carry on it'll accept electrons as as as quickly as you like the limit being basically the wires that connect in the plates if they just pass too much can't they'll get hot and melt it's really the basic limit so you can charge capacitors really quickly and you can discharge them really quickly which brings us to this thing is what's that it's called effectively series resistant now as I mentioned the only limiting factor in charging your capacitor is how much current the wires and the plates can handle before they become fuses and melt and because everything that conducts electricity apart from superconductors and we're not going there has a resistance so in theory if we were to draw this there's actually what we call a parasitic resistance in the capacitor if this is a capacitor there's a resistor in there and it's actually just the resistance of the wires and the plates and what happens is that resistance can reduce the efficiency of the capacitor to take large amounts of current and deliver large amounts of current so we want to do that we want to be able to charge it and discharge it very quickly and have it handled very high flows of current in and out we need a capacitor which has a low effective series resistance it's this thing in here and that enables it to work far more efficiently and high-current high flow situations and one of those is let me show you when you'd use a high ESR capacitor actually I mean a low ear side capacitor capacitor capacitor with a low effective series resistance one that looks able to handle lots of current here is a typical setup when you might want to use a capacitor this is a battery lipo there's an ESC there's your motor yes pretty standard stuff isn't it now his as well as powering the ESC in the motor the battery may be providing voltage to a video transmitter and a camera let's put an aerial on the video transmitter before it burns out okay and bad things can happen here this is if you were around in the early days of many quads and things you'll know that it was really common to get really bad lines on the video when you had your motors when you're out of something the video to old crap either be lines all the way through the reason for that is that inside the ESC there are little tiny solar states which is called Fitz which we'll cover in a future video which are basically turning off and on the current going to the windings around the around the motor there on the stator of the motor so those voltage those currents are being switched very quickly and that means the load on the battery through the ESC is varying quite significantly as one core gets turned on there's more current drawn and then it gets turned off and another one gets turned on and with batteries as we probably already know when you put a load on the battery the voltage drops its natural it's just because again there's a parasitic resistor inside the battery you know and there's the internal resistance of the battery and when you put a load on it some of the voltage gets dropped across the internal resistance it's not a real resistor so a theoretical one but that voltage disappears across there so if we would have put an oscilloscope here let's have a look it's getting oscilloscope I should actually do this on the bench shouldn't I okay and here is the oscilloscope it's put a knob on it you can't have a Silla Scopes without knobs if you to run some leads that one on to veer and went on to this are you gonna measure the voltage across your battery and going into your video transmitter now when you give this thing some hoobs open up the throttle broom and the motor starts spinning a TPS he's switching the voltages or the currents really really quickly the voltage looks normally we'd have like a 12 volts sets of three so packed 12 volts straight line so over time that voltage doesn't change when you actually start putting a whole lot of load on it and start running the motor as the voltage switches off and on you get you get a buggered felt pin let's find one that works shall we you get voltage that goes like this you see that's going up and down because every time a magnet electromagnets switched on through the ESC pulls the voltage down when it's switched off the voltage goes up next one gets switched on so it goes down up and down dumps over get Alice this wave your way for wavy lines the achar noise on the voltage right of course by the ESC and Nick feeds through into the video transmitter in the Cameron you get lines all of your picture but you can fix that to a huge degree because you take your good old friendly capacitor put it on there and what happens then well when the voltage drops temporarily here because the the battery is having extra current drawn well let's say you've got it turned on right and this charges up so this charges up to 12 volts capacitors all charged up across the battery suddenly the motor the ESC draws a lot of current to drive the motor and the battery can't provide enough current it can't on its own because could that resistance so the voltage starts to drop in the battery well this also provides current out here to meet the need so it's like a backup battery but it's a very very fast battery and it can provide very very high massive current for a very short period of time if we look at the noise that's exactly what we need because we have little dips but they're very short drops in voltage as things are switching so if the capacitor can fill in those gaps you end up with the capacitor handling all these gaps here I hope I'm good enough resolution on the cameras of it so it basically takes you back to a smooth line and all the noise disappear so this is a good way to think about this I'll show you another analogy it's a brilliant analogy I'm good at those this is how capacitor works in that situation here's a car engine there's the radiator and there's the little plastic tank that you have which takes the overflow from the radiator it's like the I don't what you call it but it's the overflow tank anyway this is the engineer at my Bugatti Veyron it's a w twin engine I think but it could be any engine water called so what happens is here when you when the system is sitting there cold everything's fine now you start up the motor the engine start the engine up it gets hot and so therefore the water in the cooling system expands expands epic zone a finite space for it to be and so what happens is it's designed so that as the water expands the excess flows through a tube into a little plastic bottles so starting off and this tube goes right down to the bottom starting off you might have this much water in the bottle once the engine is warmed up you can have this much because the water's expanded inside the cooling system right so that's fine so the excess water goes into that bottle it's like charging up our capacitor from the battery the basically the the cooling system is charged up that bottle now what happens is when you turn the motor off turn the engine off everything starts to cool down and again the water shrinks but it's in a fixed thing so what happens is as the water and the radiator and the block of the engine gets smaller it starts sucking the excess water back out of that overflow bottle into the radiator Sarah don't you end up with the radiator you know being short of water and that's what the capacitor does when the voltage from our battery drops because there's a huge load from the motor the capacitor provides the extra voltage extra power needed to fill in the gap so make sure that we never run dry it provides fills in the gaps fills in the bumps on the noise I might show you I'm trying to do an experiment on the beach if I do here it is and here we are at the bench now what I've got here let me show you what I've set up here I've got my oscilloscope and I've got a power supply over here which is doing 10 volts so this signal there if I wind the voltage up and down you'll see that line goes up and down that is our DC and if I turn this off completely you'll see it goes right down to the bottom once the voltage has ballooned away there we go so that's zero volts that's 10 volts right 19.8 to the map doesn't matter but that's the DC that's our battery let's say our battery is putting this voltage out now suddenly our motor starts going so it's starting to draw all sorts of current from the battery so we'll get and I'll turn this on you'll see what happens in a moment now I've got to sit it hang on let's go over I'll shall sit up the here we go here is the noise that appears on the top of our DC so it still it's not AC because zero volts is down here so it's just a noise on top of the DC this is the noise generated we've simulated it that ESC would generate and that would make lines all over a fpv gear make it look really crap so how do we fix it how do we fix it well duh mr. capacitor mr. capacitor comes to the party I'm going to put this capacitor across the battery and let's see what it does to that noise component up there so put it on here and on there look it's effectively almost removed it take it off put the capacitor but the capacitor on noise goes away take capacitor off noise comes back so this is effectively filling in the highs and lows by absorbing the high electricity and feeding it back out when the voltage drops down so that's how we remove noise using a capacitor and you've seen it yourself it must be true it was on the oscilloscope now here's another really cool thing about capacitors in another place that used very often and that is separating AC from DC now DC's direct current that's just like a battery and the Vox just current one voltage and it just goes round the circle or wherever through the circuitry it's just a direct current doesn't it doesn't change polarity stays the same polarity alternating current however it goes because of course we have AC in our houses if you're in America you've got a hundred and ten volts AC if you're in Europe and Australia and New Zealand you pay more so you get two hundred and twenty volts ac and that means that the voltage just changes up and down what I've drawn here is a picture of this quite normal here's say 12 volts and we've got a wiggly line so this particular this is their oscilloscope of course this is voltage this is time so on this signal here we've got an AC waveform superimposed on a DC voltage because the actual voltage never goes below zero but it does go up and down so you might say we only want the AC component let's say we're coupling a video camera to a video transmitter somewhere in there you might find that you want to change it from being like this - just being pure AC that's what you do is you do this if we put this is the waveform that we'd see here so it's got DC coming Edea there's 12 volts on here and it's got that signal on the top you just want the AC out here you put a capacitor in there if we drew this graph again 12 volts zero then what you'd get is this you've still got that wiggly line but it's down at zero volts it's taking out the DC because capacitors block DC competitors do not allow direct current to flow I'll show you with the meter on the bench if we put a meter on or put a capacitor in the circuit nothing happens no current flows if it's DC nothing happens at all because the DC can't travel because remember capacitor has two plates with an inch later in between so the current can flow through the insulator simple as that this how we can extract a AC signal from a situation where it has a DC component and getting a bit complex here but basically that happens a lot in signal processing receivers and audio amplifiers stuff like that video stuff we need to you know I select those two components so let's take a look at the different types of capacitors the way they are made and as they basically all of them are two plates with an insulator in between but the way to physically weigh their work the way they're physically made vary significantly and a size and everything vary significantly because if obviously if you've got a capacitor that's designed to handle very high voltages the insulator must be quite thick and therefore it's going to be a bulkier capacitor if you only have to deal with like six volts you can make things later so super super thin that you can make the capacitor really really small so there are a number of the most common capacitors we use in the Hobby today or the manufacturers use are what we call ceramic ceramic capacitors their little square block things they mount the surface mount components they fit on a circuit board I'll put a picture of one up here hopefully and it just looks like a little rectangle little block with little silver ends and but if we were to look at it cross section it so here's our ceramic capacitor as a silver in there and a silver in there and it goes onto a circuit board normally the circuit board is like that and you'll see the solder there and solder there they said they fit now inside here very very clever what they've got is from each end there are little plates come out like this and they like they go like fingers and link up together so like this if you imagine yeah like that and so therefore you can see the whole plate thing you've got a plate you're going to inch later plate and chelate a plate inch later so because they are dealing with you the fairly low voltages generally less than 25 volts the the insulator the ceramic that insulates has met those plates is very very very thin and that means the whole capacitor can be really small another benefit is it'll work either way around you you can dust matter with your positive on this end and negative on there or whether you do the reverse and have negative on there and positive on there they don't care about polarity they're just independent and so these are very common very popular they're quite quite tough but they can be broken with sudden shock because ceramic is a bit brittle sometimes so but they are that the the backbone of modern electronics and you get them from from a few hundred Pico farad's up to several micro farad's so they cover a wide range and generally the more farad more micro farad's you've got the bigger they are so some of quite big some are quite small that's ceramic so they're just a component you'll find on a circuit board now the other type that you'll find very very commonly there's something called an electrolytic and I'll draw a picture of one here well I'm very crappy at drawing and they just got like a little cairn I got two wire legs in at the bottom that's the normal it's what they call a through-hole version and they're very interesting because they're different to ceramic they're dumb to ceramic because first of all they have a polarity you can only use them one way around if you put an around the other way bad things happen but electronics are very cheap to make and they can have quite high capacities so that's why you commonly find them when you're looking at values of plus a hundred fifty micro farad's will beget generally you'll find an electrolytic capacitor and the way they're built is stunningly clever if you were to look inside here you'll find that mr. Stuart cross-section from the top here's the can if we took cut the coat of top off the can you would find that there was a spiral of metal foil like that and another spiral of metal foil like that if I can get it right so so there's two layers of metal foil there round into a spiral and then there is a liquid in there was liquid what's the liquid for the liquid is part of the whole construction and we'll show you in a simplified form how this all works right here is one plate of our electrolytic capacitor part of that spiral and here is the other one because these go off this will go off to my plus and this will go off to - and obviously you've got the can in there so we just assume that this is a thing and there is a liquid in here so what happens is these are aluminium usually aluminium there can be other embezzles but aluminium is the most common you can have tantalum and nothing there's no VM as well but Elementium electronics are most common and what happens is when a current is passed a forming current is passed through this capacitor you get anodizing takes place anodizing is a really cool thing too it converts aluminium into aluminium oxide and aluminium conducts electricity really well aluminum oxide doesn't conduct it also when you do this if you pass a current through here a very very very very thin layer of oxide different coloured pin yeah see if this one a week very very different thin layer of oxide as thin as my pin here forms around this electrode and it becomes in this you later suddenly the electricity can't flow anymore and of course it's a perfect capacitor because the capacitance of a capacitor is determined by two things the area of those plates and how close they are together so the bigger the plates the more capacity and the closer you can get them together without them touching an electricity flowing then the higher the capacity you get so what they do here is by using a oxide it's only a few atoms thick few molecules thick on the surface of the thing and also remember because this electrolyte here is a conductor conducts electricity effectively you've got the the negative within a few atoms of the positive plate and so you get massive massive amounts of capacity in a really small space so that's why we use electronics and enables us to make really really high capacity capacitors in a fairly small space that's the secret so they are very very common where you need a lot of capacity now obviously because that's such a very thin film of oxide the voltage rating is very very critical exceed the voltage rating then that film will break down and bad things will happen because effectively you've shorted out your capacitor because the electrolyte will still have the negative and this will be positive with nothing separating them so the current will flow and boom because these things go bang - I trust me if you get if you get a failure inside electrolytic capacitor they explode and for that reason if you look at the top on try and overlay a picture this is the top again you'll find that there's some little grooves little things cut on the top of the can that's because it provides safe venting if something does go wrong and this shorts out and this liquid this electrolyte starts boiling because of all the electrical energy flowing through it then these little grooves they will split on the top of the camel open up rather than the whole thing exploding and creating your danger that's the theory it'll just split you can often tell if an electrolytic capacitor is faulty because instead of having a perfectly flat top let me show you what you know so like this instead of having a perfectly flat top they dome up they start doming up because what's happened is that the liquid in here has turned - guess that's pressurized it and if you see that there capacitors bugger - even if it's working now to be stuffed in a very short period of time so you replace it so electrolytic capacitors they are fantastic but they do have a finite lifetime because where the wires come in there's usually a rubber seal down here and and stuff gets past the rubber seals and over time the electron the electrolyte gets breaks down and gets contaminated and so they don't last forever they're not like the ceramic cats which in theory will last forever electrolytic not so good and there is another form electrolytic capacitor called a tantalum which is quite common in our little stuff it's usually a little orange rectangle and I'll show you some of those on the bench and they are also very high capacity for a very small space in fact higher capacity than the aluminum ones because the tantalum oxide film is even thinner than the aluminium oxide film but they also are very prone to failure put too much voltage on them they turn black and smoke and flames come roaring out whew great fun and you might notice that if you've ever connected a battery around the wrong way to a receiver probably the smoke was caused by the tantalum capacitors that are sitting across the battery input to smooth out the noise that might come from your ESC or error as we mentioned earlier is simple now there is another type of capacitor called plastic film capacitors sometimes called a mylar capacitor sometimes called a polyester capacitor that's describing the type of plastic film that separates the place I've drawn the thing yeah I mean here we go there's one plate usually that's a foil it's kind of a usually an aluminium foil so you get a foil plate in a foil plate in a plastic sheet separating them and then they wind them all up screw them up into a little ball and then they're small enough to use on a circuit board I've actually made one I made one myself out of kitchen foil and kitchen film and let's go to the bench and I'll show you will measured it has capacity I'll show you another really interesting thing associated with these capacitors and how it goes back to the video I did last week about MEMS devices let's go to the bench and look at there now and here is my homemade capacitor I promised you here we go look what I've got here is two by two sheets of aluminium foil or aluminum foil if you live in the USA just kitchen foil and some plastic which is separating those sheets so we have two plates and an insulator the insulator is just as kitchen film this cling film separating the two sheets and yeah I've got my multimeter and most reasonable multimeters have a capacitance case it's that little capacitor symbol so you know that sort of us and it's going to there and we'll measure my capacitor right now because we've got wires close to get them got a capacitor there's what we call residual parasitic capacitance and this we need to get rid of that I press this button here and it will zero will it come on they regard didn't press it hard enough zero so now I'm going to measure my capacitor by putting one probe on there and one probe on there and it should tell me that whoa we've got 17 nano farad's in our capacitor there you go so that's a 17 nano farad capacitor there not a very good one but it's there now I'm gonna show you something else remember last week I talked about the MEMS devices and how they used like they had a capacitor on there which varied in value because the plates came closer and further apart due to the Coriolis effect now I'm going to show you how that works so let's measure a capacitor drink it my probes on here evenly okay there we go we've got six deep roughly roughly 17 to 18 oh it's going up a bit cuz I'm pressing hard I won't press so hard here seventeen nano farad you watch what happens when I press on my capacitor whoa shut up to 40 3:45 time handoff goes back down to 17 or 18 Chris again now why is that capacity changing well it's changing because I'm pushing the plates closer together cuz there's air between the plates now this is just it's not tightly wound so when I press the arrow and push the plates closer together it's still separated by the plastic film the D electric capacitance goes up and it's how that MEMS device works as the two parts of the MEMS device get closer together the capacity goes up and when they go further apart capacity falls down so that's how they measure it no electrical conduction or connection required it's just a capacitance thing so you could build your own capacitive touch bed that's how you roughly how your capacitive touch screen works on your cell phone - there you go isn't that simple figure and make your own capacitor yeah I'll show you something here which is gonna surprise you it's gonna shock you now that's my roughly 15 or 18 nano farad capacitor but remember I took the best ceramic capacitors and how effective they are and how small let's have a look here's a 15 nano farad let me just pull in a bit so you can see okay there they are here's my finger as a size comparison here are the meter probes as a size comparison that has got the same those little each one of those individual components is the same capacity as my honking great handmade 17 or 18 nano farad capacitor here so you can see that how do they get so much capacity in a small device well obviously the plates much smaller than these plates but there's so much closer together that you get a high capacity of matching capacity so if I put this in a vise and scrunched it really tightly I'd probably get I may even get a couple of hundred nano ferret's of capacity out of that homemade capacitor but by doing it with a ceramic substrate very very thin very very small spacings they can give that of a tiny tiny little device like that and finally another place we use resistors sometimes is in determining timings oscillators and things because one of the interesting things about a capacitor is that as I mentioned they will charge really quickly but if you put a resistor in series with the capacitor it'll limit the rate at which it charges because obviously the the current is reduced by having to pass through a resistor so instead of just charging it up instantly it takes a while to charge up and that I'm it takes is something called the RC constant or the RCS or resistance times the capacitance and that enables us to do things like calculating build circuits that will trigger a certain thing to happen at a certain time now if we look at here's our oscilloscope connect it across that capacitor with the resistance in there what happens is we get something that looks like this as you can see it takes time as they slowly the capacitor charged up this is the voltage this is time so the capacitor doesn't just suddenly charge right up it takes time to charge up so if you have something here let's say we have a threshold here at this point here if we decide that that's going to turn on a transistor or something then that's the time that it takes to do it if we double the capacitance or if we have the capacitance then obviously that would charge more quickly and the thing would go there if we change the resistance value so we can use a combination of capacitors and resistors to develop time periods and use those time periods to switch stuff off and on not so common these days in the world of digital but back in the analog days it was a very very common way to create a timer or something like that just charge capacitor and wait till it gets to a certain voltage when it hits that voltage something happens Bing and you can vary this resistance if you make this a variable resistor you can then tweak a knob to change the time frame darkroom timers a lot of people to make darkroom time is way back in the old days as simple as that you know when you used to use film and cameras you need to have a certain amount of time before you took there the film at or the exposure out of this tank and put another one same thing there you just tweak a little knob and it would take a certain amount of time to charge the capacitor okay that's quite simple yeah that's capacitors basically one application the final application that you'll find for these things is in the hobby is as an alternative to a battery now if you go out shopping for Christmas presents as you you'll probably find little airplanes electric planes that you can charge up they take 20 seconds to charge or you know listen a minute to charge may fly for 20 seconds or so and a lot of people I saw talking to guide the other day who said you they must have a good battery and them I said no they've actually got a capacitor they've got a super cap in them it's a capacitor with so much capacity that it will hold enough power to drive the little tiny motor for 20 seconds you know and that's a lot of power you know going back a few years we do have super caps you have to you battery but that's an example of using a capacitor in place of a battery another example of that is a growing number of electronic devices which have memory that must be kept active when you change the batteries or something they used to use a little coin cell and the little coin cells only last three years after three years when you went to change the batteries all the memory was forgotten and sometimes it was just a good example as prep see all junior radio is they had a battery to back up the the model memory in the old jr. nine 303's and things like that nice we have to configure anyway those old radios had a coin cell on them and after five years the coin cell battery would often go flat and then when you if you did the radio go flat you'd get a error and you have to take it to the dealer and you have to fix it because you couldn't fix it yourself but that sort of thing these days has they instead of using coin cells they often use super caps which will keep something alive long enough to enable you to change your battery or something even some GPS receivers now have super caps so that if you're using it turning it off around during the day you will remember it's Almanac from one operation to another some of them still use a little tiny lithium battery but a lot of them are switching to super caps because lithium batteries don't last forever super caps virtually do so it's just another use for capacitors in the hobby so let's see if we can identify some of these capacitor types on common parts of the Hobby common components this is a flight controller board and these little orange things here and here and there and there that tantalum capacitors they're a type of electronic they use the tantalum metal instead of aluminium and a tantalum oxide and I think there's some on the other side as well and these ones here are obviously used as smoothing capacitors there's reservoirs of capacitors as we've talked about with the in the demonstration we did with the oscilloscope so those are tantalum I don't there's a couple of ceramics but I'd say yeah there's a couple of ceramics I think and there's a templum tantalum is used because it's got a lot more capacity than the ceramic and the ceramic is used because ceramics actually have a lower ESR that they they can they work better at high frequencies ceramics we good at high frequencies so we've got a power regulator I like this is a pair regulator you have some tantalum switch fill in the big gap so the low frequency noise is handled by the tantalum but the very high frequency noise these don't absorb it very well so they used the ceramics which handle high frequencies really well so you not only get rid of any low-frequency noise but also high-frequency noise so these will be in parallel across that to get the best of both worlds so to speak and here's a foreign one he is seeing on this we can see a range of various ceramic capacitors but these ones down here obviously you can see these are probably all in parallel to provide extra capacity because if you put too 10 micro farad capacitors in parallel you get 20 micro farad's they just double up it's like when you put batteries in in parallel you increase the current capacity will increase the capacity of a capacitor when you parallel it up with one of the same size so yeah that's sometimes es C's have a lot of capacitors to smooth out the noise especially the older one so I'll see if I can find an older style you see show you what I mean and here is a blast from the past this isn't listen to pull out a bit here on this so you can see this is marled iMix p230 with six inch arms and props and the es is used back in the old days you can see on these old what are they brand there but you can see on these old ears he's got two honking great electrolytic capacitors here across the battery input voltage to try and get rid of the noise that these things create mess of great electrolytic s-- but old school these days you'd probably use some really good ceramics to do that but do you sometimes you still get electrolytic so it'll do the job I know for example here's a Dell RC forum one and let me just pull out a bit so I can show you this is a forum one ESC and they come they actually provide an electrolytic in the package here here we go if I can give it out you go come on here's a low ESR electronic and we pullin of it because it's all a bit far away I pull it too far hang on it's a low ESR electrolytic that you can pop across the ESC to get rid of any noise that's created by it and it's part of the lot of what you get in the box basically with that forum on speed controller and here's a video transmitter it's a foxy at 200 milli watt video transmitter and you'll notice there's a lot of capacitors here all in parallel ceramic capacitors here again in parallel and I notice on this one there is a place here for a component that hasn't been used that's probably where they would put a tantalum capacitor but they probably found they didn't need it with all these ceramics so they just lift it off saves the scent here and the when you're making thousands of these it adds up to a bit of dollars in the long run so yeah these are just for power smoothie until here's the power supply this is what drops the voltage down from the input voltage which in this case can be I don't know what it is it's DC up to 24 volts that'll drop it down to the 5 volts or so that the circuit uses and having done that it drops it down by chopping it up and once you've chopped it up into little pulses you've got to fill in all the gaps so they put these capacitors here to smooth out the very very noisy output of this switched mode regulator so they're just acting again as reservoir caps and I've used ceramics because ceramics are very good this is a very high frequency switch mode power supply may even be as high as a few hundred kilohertz and the ceramics work really well at high frequencies so they probably didn't need this tantalum but if they've just used the tantalum probably wouldn't work so well because the high frequencies would have still been passing through them because these tent limbs not very good with very high frequencies ceramics ah so there you go there's another more capacitors and an everyday device and finally here's a foreign one your 4 button charges sorry here's a four button charger button button button I've taken it out of the box so you can see cuz I'm repairing it and you'll notice look at the size of that electrolytic capacitor it's a huge electrolytic capacitor there and there's those little score marks on the top huge electrolytic capacitor because this is handling quite large currents you know you'll charge up to 6 or 7 amps or something so you need to put a lot of capacitance across that in order to get the noise taken out we've got a little somewhere in here there'll be a switch mode regulator that we snipping the voltage up to be a boost back regulator and they'll have a really noisy upper so what you do is you put a big capacitor on it to smooth out all the noise to fill in all the gaps on the noise another capacitor over here first something for a probably the regulator for the digital circuitry so yeah that's what you get on there not much else in the world capacitors is a few ceramics probably hidden in there somewhere but yeah there's a use for your electrolytic so it's it for another dick Tuesday I hope I have been boozled you too much and I apologize to people who say it's not quite right because I always take a liberties to make things easier try and explain the concepts to you in a simple way so it's capacitors essential building block we may do some experiments on the bench when I've done I'll also do have done if I've done resistors I think I did Ohm's law but I may go looking a bit more at resistors have I haven't done it and we're looking in duck is because when you start putting these things together you can do some really cool stuff and of course semiconductors transistors fits that sort of thing that's a really important issue as well and you don't have to know how to use them but it really helps to know how they work and what makes them work so that you can understand better if something goes wrong or if why they're even there at all so that's it thank you for watching questions comes in the usual place I'm sorry this was a bit lighter than usual because I did this video two days ago and I forgot to turn on my microphone is it working now hello hello it is good yes so frustrating when that happens trust me anyway so I've had to do it again so this is actually tick Tuesday so for the 6th of November 2018 on the 8th we're could enter yourself take Thursday you guys is it thank you for watching gotta go things to do bye for now okay now I'm gonna show you about the way that we can extract the AC if this was a signal on top of a DC because remember zero volts is way down there how do we just get that AC how do we block the DC well I'm going to use a capacitor here in series with my oscilloscope probe and that will effectively stop the DC but it'll lit the AC come through so let's just disconnect that for a moment put that onto there and I touch this onto here and there it is there's that signal still but there's no voltage on it it's just the AC part of that because I've got a capacitor in series with that thing has blocked the DC current the DC counts disappeared but the signal is still there just as I mentioned on the whiteboard must be true you saw it on the oscilloscope yeah I just got it resting on okay cookies

Channel: RCModelReviews

Views: 122,803

Keywords: Electronics, basics, RC planes, model aircraft, FPV, first person view

Id: sm_iADwdqnI

Length: 39min 34sec (2374 seconds)

Published: Wed Nov 07 2018