hello youtubers welcome to this nextsession about how to use a multimeter for beginners and in this session we'regoing to basically cover off how to measure current that the otherthings we are going to do we're going to go through the answer to the questionthat i posed on the first session i will then go through just explain someconcepts with that on soap because it does help with an understanding of ahand electricity works particularly ac and dc i'll then posed a new questionfor the next video that will review and then we'll get stuck into the actual howto measure count with a multimeter so for those of you may have startedthis video looking for a quick three or
five minutes solution on how to measurecurrent you're not going to find it here this video probably run into 20-30minutes there are loads of videos on youtube which kind of give a quicksimple packed answer to that this video is for those if you want to areally good understanding of some basic concepts on electricity and how to dothose make those measurements with a multimeter so let's get stuck into it i'll quicklygo through some of the answers now first of all thanks very much to those of youwho did respond to the question i'll just repeat the question again best pr iasked i say which would which was more
dangerous ac power or dc power and i just left itlike that but not out of further detail and a number of you came back and someof the answers were certainly failure off the mark and not correct that butthat doesn't matter just attempting to answer a question and getting a drunk isgreat there's nothing wrong with puttingsomething out there that you may think is right if you can learn from it if i wasworried about making mistakes and saying the wrong thing
i wouldn't even turn that camera on eachtime i want to do a video because i'm constantly making mistakes you don't bescared you don't you make some mistakes jump in answer the question don't worryand there was some good answers a lot relating to in particular it also depends on theamount of voltage and the amount of carrot involved which is very true and acombination of those two is ultimately which can what can be very dangerous and kill youboth on an 80 side and a dc side but the answer i was kind of looking for andi'll explain more about and if it sparks
debate that's fine but basically theanswer that todd harrison gave and i read out is isanswer it covers most of what i was hoping to hear but i will then gofurther and it kind of brings out a concept that we need to understandbetween ac and dc and it is i'm going to say dc is more dangerous to work withbecause once you touch something with dc your muscles will contract and staycontracted make it making it impossible for you or others to remove you from thepower with a see your muscles would be pulsing on and off giving your reflexesa chance to pull away or someone to
knock you off the power before it beforeeven more permanent damage is inflicted and that is very true i can attest tothe fact and this is something i learned when i asked studying my electronics andthe dangers of dc vs ac that's what dc does dc is constantly on it's not likeac which is going to recycle of being on and off and building up and coming onand off it's permanently on at that voltage andso in essence if you get a shot from dc your muscles contract if it's a a let'ssay a piece of wire or a contact that you're holding on to your musclescontract and potentially keep you there delivering a a lethal dose ofelectrocution
well as ac tends to actually throw youback and i can attest to that was about the week week and a half two weeks ago imanaged to get my shot give myself a shotgun on there - 20 and it threw me back and i said iset for wild that with a little bit of a shake-up but that's what and ac does toyou so that was the on sighs kind of lookingfor and dc is is dangerous in terms of far more aspects dc when it comes toelectrical components hide by dc at high current becomes very challenging and infact the components particularly even switchgear switches and breakers becomevery complicated because in essence you
and this is you weld with dc so theamount of power you getting when you've got direct current you can weld metalstogether with a couple of car batteries and some content you can actually worldthings together and switches after 10 amps it's amazing d switches below 10apps are ready to be cheap to buy you soon as you go about 10 x 15 and tostart approaching 20 amps the contact and break is inside a switch and whenthey slept together you potentially get and they can actually then well themselves together anywhere quickly i'mgoing to put a diagram together and we'll go through that and hopefullythat'll give you a better understanding
ok so let's get stuck into thatexplanation or the ac vs dc but before we do that again i just want to thank contest again forthe loan all this fluke multimeter for this tutorial and they kindly do like methis equipment if you follow any of my other videos you realize they actuallylet me some quite interesting equipment for particular for the solar side aswell which i certainly wouldn't be able to get my hands on if they weren't on board with this sothanks very much to them right so let's get in a little closer to this diagramwe don't want to get too advanced or too
technical but let's try to get a basicunderstanding for my little scribble diagrams here ok so we're going to take so sorry to theamericans we're going to kind of use a european / that south africa standardfor this one of an average around 250 volts so if you can imagine your your xaxis over here is time and the y-axis is the voltage now what happens with a see the voltagegoes up to a peak then comes down to zero then goes negative for a while andthen comes up to zero and it repeats the
cycle again and depending on where you are in theworld that either happens at 50 hertz or 60 hertz which is either 50 times asecond or it 60 times a second now this just to get an understandingfor an average or a comparison to say a a comparative equivalent to a dc voltagebut it's a naughty analogy to make but some people do but to get the averagevoltage of what you get in coming out of your mains out later what have you of230 the voltage voltage actually goes up to a peak of 325 volts and then comesback down and then goes down to negative 325 bolts
so you've actually got a peak-to-peakvoltage of 650 volts now what happens what what we that sowhat we doing what the useful voltage for powering your at you at yourappliances or whatever at home is the average under these two bits over hereunder these two cycles and that what we are here about the term on a multimetercordon rs rms multimeter that means root mean square and that's a calculation tounderstand the average of this area under here and that is 230 like ok so as you can see from that sobasically an ac voltage it's kind of like and one energy is like thinking ofand an old steam locomotive with the
pistons game back and forth it literally is shuttling back and forthin essence in that piece of wire doing its work by doing that as opposed to dcwhich is just playing straight for the whole time so if we go to the dc side let's say wehad an equivalent dc voltage of 230 volts dc it would look like this and ifyou had this on the sill escape that's what it would look like an oscilloscopeyou get a nice wave like that representing your your ac over time andeasier to just be a flat straight line like that actual 230 mark that is justconstantly on
it's not you you can tell that with anac voltage is a lot of time when it's way below that kind of even the 230 atpeaks at 325 then it's coming right back down again and then it hits zero thenegative side all that's negative it's not gonna hurt you but the negative sideobviously it's building building building it hits its peak and it comesback on and that set by as if you've ever touched a see it gives you that badbut its contents going on and coming off so it actually gives you a chance torelease or in fact kick you off if you get a shock whereas dc you just getting the full onto 30
all the time and it will grab you andclinch you on so that was kind of basically the answer i was trying to getto and more importantly the reason i wantedto kind of demonstrate this and it doesn't mean the other answers were werewrong that then in part they were right in what they're saying in terms of themakeup between current and voltage and what have you but i just want to stresshow dangerous dc in particular can be generally speaking we think of dc withlittle batteries and 12-volt car batches in the course of the twelve cop actuallyyou can put your fingers on the two terminals it's not going toshock you why isn't it going to shock
you perhaps there should be another questionbut it's not going to shock you because it just doesn't have there's enough current in a in a carbattery to do damage but the voltage is low ok and but dc black in particular oneapplication i can tell you where you can potentially get heidi sees in solarpanels linked together in series you can get you can get 300 400 500 600 voltsplus and their things become very dangerous if you had to the wiresbetween two solar panels which were
linked in series build with that i dcvoltage together and you had a bag a continuous circuit i you didn't break itsome way and you had count running and you pull that apart at 600 volts you hadbeen potentially for a lot of trouble because that it would mark it's likelightning it would off between those those two contacts so that's where youhave to be very careful with the high-voltage dc i se electronics andwhat-have-you different different stories at current levels and thevoltage levels are a lot lower so i want to pose another question forthe next video and that is basically when electricitywas first started being used mainstream
and there were power stations generatingelectricity and transmitting it to houses for lighting and what have you they initially started off with actuallytransmitting dc believe it or not and then laterswitched over to ac and i'm keen to understand if song can give anexplanation as to why ok so that is the next quiz question fornext week as i said take a stab at it if you runit doesn't matter but i'm post an answer and we'll discuss the answer in the nextvideo ok let's jump into what we're here forand that's to understand how to measure
current ok so before i want to go back to thediagram and give a little analogy again of understanding what current is what ithought just a quick look back at the this fluke one double seven when we do currentreadings we going to be jumping popping these banana plugs into two different intwo different connectors now the black still remain in the common as it doesfor all measurements but this time the red will go but either between the 10amp or your main and pitch which is generally the case almost multimetersthe tenant connector or your milliamp
connector and that can vary frommultimeter to multimeter and it can be as low as 200 milliamps it could be fivehundred six hundred milliamps as i said showed you earlier some multimeters justhave all demonstrated here on this week some only have three connection pointsand this is more for electricians they just have a connecting point for tomeasure and higher values they you can make millions but not down to theresolution that you can on let's say i'm ultimate like this the wisest thing always is to alwaysstart off in the higher setting down here and i would advise that if youdon't if you are an existing multimeter
which is infused i would recommendgetting one that's fused i'd also recommend getting one thatdefinitely has separate play plug connectors for your courage and it's notshared with the voltage and we'll cover that why a little bit just now but havingfused points for your milliamps and your answer is important as i said we starton the higher one when you realize your current level is safe you can then clickdown to the lower one but let's get in and have a look and anunderstanding about what current is so we're going to goback to this diagram i did in the first
video as i said just like a garden hosehas got water in it just like a piece of wire has electricity flowing in it there's two components which are fairlysimilar you have pressure pushing the water out and that we regard as asvoltage and i said it's like tapping in a little hole in the pipe and putting apressure gauge in there you can relatively speaking with a few caveatsactually take fairly safely take high voltage readings and because you're justtapping in through a little hole you just take a reading of your piece ofwire what have you and getting a pressure reading the voltage
however when it comes to current it's adifferent story for current just like let's say in a pipe this gauge over herecannot tell you the volume or amount of water flowing in this pipe and thatremember that is current in essence that's your other aspect current is thesame as it's the volume it's the amount of electricity or relating to thisdiagram it's the amount of water so to be able to understand how much is inthere you have to put let's say we had alittle pedal inside this flow of water you have to excuse my diagram justpretend it's a nice little pedal that's in this flow of water which will measurethe volume flowing past it
ok and therein lies the little challengethat we have to be aware of you have to place your measuring deviceinside the flow there is a caveat to that america andi'm gonna come back to that but for the most part for the basic side ofmeasuring current with a multimeter you need to place your multimeter in theflow of electricity so when we come back to our multimeter whenyou take your probes this time as opposed to say being on the outside ofyour circuit in essence and just taking a pressure reading these probes nowbecome part of the circuit the electricity that you're trying tomeasure is going to flow through your
one probe and out of the other throughthe probe through your multimeter and out the other and that's where measuring parent can bea challenge because your multimeter has to be able to handle that flow ofcurrent and current can potentially generate heat can melt things if it'stoo high and that's why by default most multimeters are not gonna lie tomeasure up to 10 amps some can rely to measure 2 15 or even 20 amps but onlyfor a very short period of time there's not many multimeters that allowyou to measure higher than that the caveat to that is you can measurecurrent in a safer way and that is
something you can do it with a currenttap so as i said you can do it with thecurrent app or you can do it with a special multimeter that has a clamp andthis clamp basically can read current induced field the magnetic field arounda conductor to measure safely without breaking a circuit high currents butwe're not that there that is something that we will cover ina more advanced series i just want to put it out there thatthere are other ways they are you can even use a current shunt and that issomething else will cover off when we moved to the kind of advanced series ofvideos on this topic
ok so let's get stuck in we're going toget something to measure and i'll explain again how are connectingeverything up and how that current is actually flying through your multimeter ok so i've got all the components thatwe're going to use for this little too and i thought i just quickly show youwhat we've got to go to an essence i car headlight lamp here we've got themultimeter we've got the probes and we've got some attachable crocodileclips now someone made very good fair comment in the previous video and we'restating that if you remember i used those little crocodile clips to clickconnect to that led when i was a
measuring the voltage across not heavyand they said that perhaps that wasn't there could be some safety issues ofthat now they were did right in that application though not the measuringvoltage you can get away with using a some crocodile clips and thinner wirebut at the end of the day it's good practice to always try and be safe andthe safest thing to do to have crocodile clips on your probes is to get ones thatattach directly to your program like the ones i have here because they can handlemore current but i'll demonstrate that now then the other thing i want to showyou so i've got my variable power supply care which is what we're going to use topower the headlight
i've already got it set at just over 13volts and the maximum i've got it set to i can vary the current that it's goingto put out i've got to set 2 3 amps and i can tellyou now this car lamp would actually draw far more than three amps if my power supply could put that outbut it's enough to get it started so we'll hook it all up and see how thatworks ok so first of all the first thing weneed to check we've got our multimeter as i saidhopefully you've got a multimeter which has separate inputs for measuringcurrent it's far safer that way
potentially they have shared inputs areon voltage on your voltage input that if you make the wrong selection whileyou've got things cabled app you can cause a short and blow things so in the for now as we can see we'vegot our black in the common we starting off with our red connector in the tempconnection ok not in the milliamp becausepotentially we don't know what kind of going to measure i know ahead of time we know what we'regoing to probably see but potentially if you don't know
always start in the bigger one ok then what we're goingto do i'm going to clip on these crocodile clips onto the probes makesure that nice and firmly connected ok then what we're going to do we gain i'm going to connect as rule of thumb onwhat i do is basically your life live feed coming from your source voltagegoes to your life or your positive on your multimeter okay then in essence and this is where it gets alittle bit confusing your black probe on
your multimeter isn't acting as anegative this time you feeding you this is one line of the circuit the positiveline of the circuit i don't show you in a diagram but thisis a positive light positive line of the circuit which comes around through yourmultimeter it still positive it comes out here so this needs to go to thepositive connection of the load that you're trying to feed electricity to oryour dc voltage - so that's clipped on there like that and then i can directlytake the negative instance is is this side this is the negative side of thepower supply it gets connected like that what we want to make sure is that thewires are all apart and we're not going
to get a short so i've got them laid outlike this let's make sure they're not going to touch they look i'll even pull these wiresapart to make sure not so that looks safe so what i'm going to do next is we needto select the correct setting on the so we move around the dark we go past or the voltage selections we've got homes you gotcontinuity then we've got milliamps
now remember i said we're not measuringmilliamps we've gone to the biggest setting amps we put it on two amps andon this flukes other as i said the thing you do need to note in particular onthis fluke one double seven it defaults to ac ok we're not measuringa see you get up and incorrect reading so we need to select this kind of secondfunction back button over here the orange one and that then takes us to dcas your night on the display there ok so we're all set up let's pull thisup so that you can see what happens when i switch on the power supply i'm switching it on now i don't know ifyou can hear that there's a nice become
that comes next is drawing so much cantand you can see the light has come on and what are we reading 3.0 30 amps that's a fair amount of current it's not a huge amount but it's still afair amount had i garden use this four hundredmilliamp connection first i blown the fuse it on thismultimeter will it wouldn't have caused any damage but it certainly would havebeen inconvenient you your potential not going to have spare ceramic fast falloff fast blow fuses lying around you're well-equipped if you do so thenyou're gonna have to go off to the
hardware store and go get the correctviews don't be tempted if you do that byaccident by trying to short out the fuse or put an incorrect fuse or potentiallydamage your valuable multimeter so there we go let's get a diagram so wecan just see what we've done here ok so i've got the simple diagram hereand what i'm going to do is i'm work first block the sacks on to demonstratein essence what we did the other day when we did the voltage measurement wehad our we had a battery and i said althoughit's commonly i just had a single 1.2 volt sell commonly called as a batterythat is in fact a self that is just one
cell that many cells together form abattery and we had the power supply feeding a load in this case it's thelight and here we then we had our multimeter digital multimeter we have the common which in that case inessence deep x is your negative because it we work with dc and we had a positive oneither side to measure the voltage now what happens you get your choice ofwhether to power supply or a battery feeding your load all of your currentelectricity is basically flowing through your load and around like that that yourcontinuous circuit flying around like
your digital multimeter when you scottget it's got it said two bolts has a very high resistance so it doesn't allowmuch current to flow through itself it is minuscule and that is how rememberit's like that little patient pressure gauge and put in a pipe it's just tapping in to measure thepressure okay so it's not in essence reallyforming part of the circuit at all now what we're doing today and how wehad things connected up is a different story altogether we've got the power supply and as i saidwe had the positive connected to that
positive red probe of the multimeter andthen we had the black sometimes referred to as negative you if we measuring dcbut in essence it's the common but that common in essence is feeding thepositive feed out to our low to our light and it goes then through the lightand back to the past plan but as you can see your digital multimeter forms partof that circuit all that current which you are trying to measure which isflying through your light source has to flow through your multimeter yourmultimeter here in essence has a very low resistance to that flow ofelectricity now we're going to learn aboutresistance and continuity probably in
the next video but that's the important thing to notewhen measuring current if you don't have if you don't do something more advancedlike having a carrots tap or current clamp or i sent the common way formeasuring character is like we have it set up now and you have all your currentgoing through your multimeter so that's the circuit ok and as younoted we are we are measuring about three amps so now we're going to justmeasure something a little smaller to show how can small measure a smallercurrent or and page before we get to measuring that that smaller currentthere's something i actually want to let
which i picked up all doing thisdemonstration i'm switch on the power supply again there you go the light comes on thiswire which i'm using from my variable power supply is actually quite cheap whythat i picked up at my electronics shop it doesn't have any rating on it andneither on on the packing packing that it came in did it have a rating i mainly use this to power small dcelectronics but i can tell you right now even with just three amps throwingflowing through it i can feel this why i starting to heatup in my hand
it's got nothing to do with this lightsource of the heat that a little bit of heat that's coming off here this wire is starting to heat up as wespeak and that is something very critical youhave to note about current is that thin wire can potentially handle quite a highvoltage but when it comes to current it's a very different story altogetherthat higher volume that high flow of electricity once bigger wire and that'ssomething we will we will address again in later videos i say
this if you feel why heating up like iwish the temperature is literally getting very warm that is potentially going to cause afire if it is left in that kind of state it also means you have losses you don'thave you lose a lot of your your your energy and power that you try to supplya source load with ok let's move on ok so now we're going to do ameasurement of the current which is used by the current or that m page which isused by this little eddie grade led so i'm going to connect it up and againremember we've still got the multimeter connected in exactly the same way eventhough we know this is not going to use
match we're going to err on the side of safetywe've got it connected to the temp connected here we've got the powersupply coming into the red lead to positive which feeds through so remember this is acting as thepositive and then this negative back to the power supply and on the led youprobably won't see it on the camera but if you're going to try this for yourselfthat led you can there are little metal pieces which goyou can see the bigger one is actually the negative and a smaller one is thepositive so that's the way i'm
connecting it app over here i'm going toset that down there i'm going to set my power supply below 1volt because it won't take much light up this led we've got our multimeter onready and remember if you on the one double seven if you happen to change anyof the settings it's going to default back to ac remember to use a secondary function keyhere to go to dc which is noted as you can see here on the multimeter it's gotin orange the dc symbol above the ac symbol whichis the default which is the default ok so i'm switching on the power supply
let's have a look and see that at whatlevel that led is going to come on let me know if you can see that there you go i've got it happened about 2 volts andyou can see it's at 0.00 8 amps so it's not a very fine reading but we now knowthat it's below the temps so we can safely state right all thisisn't going to give us enough resolution and when i use the term resolution ifyou want to understand the terms accuracy and resolution you can i've got a good video which i'll add alink to on this one now so you can go and view which explains all about aresolution and accuracy but the
resolution here and it's perhaps notenough for us to understand exactly what this is using so now we can go andchange things out that i'm going to switch off the power supply i'm going to simply change the redconnection . to the 400 million amp ok as you saw four hundred milliamp itwasn't near 400 milliamps on the we can now go to the milliamp setting onthis fluke one double seven so i switched it over again note it defaultsto ac we push the orange battle to give us a secondary function which as you cansee on here hopefully the light's not obscuring ittoo much i tell you what i'm working for
a quick you just say you can see that as you cansee the secondary functions on the current readings here are the dc one's astraight line with the dash is underneath and that's reached byobviously pushing that button over there and as you can see we've got now got dc ok so let's come back and have a look i'm not going to switchon the power supply again what's the led led comes on well now we get a reading that's alittle more easy to read a little more
accurate and we got better resolutionbecause now we you can see over here showing small m big a milli amps ok so millions 10 to the minus 36 . 1618 so not many milliamps flying in here but there you go we're forming part of that circuit andthat's how we can read current or the volume of electricity being used by thisled and that's quite important fact because later down the line when we cometo do some more advanced measurements like power consumption you do need to make no voltage but themore important fact
besides voltage is the current which isbeing used the amount of electricity because that can help you understandwhat size battery you need what site so the panel you need all howmuch power your house is using or particular plants so that's when things really do getinteresting and again we will cover that off when i start the more advancedseries on doing measurements with a so there you go how what i'll do justfun i'm going to drop the voltage a little bit so we can see how the readinggoes down on the multimeter this is obviously set to auto range atthe moment so it will pick up the right
range on the fluke one double sevenyou've got this range button where you can go and manually select a range so now it's only showing us . one of themilliamp you can go and slip different ranges for your own preference and ifyou hold it down for about two seconds it goes back to auto which is the fareasier motu you to use it in the ark times when you want to go tomanual range when you want to see a particular rate resolution or or readingthen that's where it can be very useful but again here we go just switch put up the the voltage andit's now using 14.3 6 milliamps
and so we have some fun and games tillactually i blow this again camera increase the amount of current that mypath supply will give up we're at 2.2 . 51 bolts at the moment and as we increase the pressure allowingthe led to use more and more current so what are we up to 50 going towards 60would be nice as your voltage that's going to go out to say tell you what i'mquickly going to stop here and get another fluke multimeter and we'llmeasure the voltage at the same time just a bit of fun ok so what have i donehere for for a little bit of fun with the sir
demonstration and as per the diagram ofactually got things connected up as they are here in this diagram that i showedyou earlier we've got our fluke one double sevenconnected up so that it's in the path of the circuit it's part of the circuit tomeasure current amount the volume of electricity flying through our lightwhich source which is an led this time and then this digital multimeter overhere is a fluke 115 which is connected up so that it can measure the voltage ok so in this case you'll see i am usingthese nasty little crocodile clips and these thin wise but remember for voltageyou can get away with doing that
it's not best practice but you can dothat because you haven't got a lot of current flowing through these so herethey are positive negative positive lead is on the positive side of the led overhere negative sign negative is over there positive is over here on this multimeter i flick through to the voltage dcvoltage black in the common rail diesel on the vault side and i'm going toswitch on the power source again so i keep an eye on the led let's see whenthe led does liked up you'll see that the voltage they regard i can see youcan just see it
come on their water we act about 2.2bots so now you seeing basically exactly what my variable power supply is puttingout i'm going to step the voltage up untilwe blow the led let's see what happens let's note the milliamp readings will begetting up to 2.7 how much current and voltage can it take 60 yard when it cani smell something 3.2 let's step it up a bit quickly80-odd milliamps almost a hand i can see it changing color at four volts you feelit i can see it changing color so i knowthings are going to change soon it's still there 12 any three my point 5volts heavens it's taking a bit of
punishment this is gone up into another range wherethey were going to overload six fault 7 volts hundred and thirty-six saw aflicker now just not what's going to happen hereon the side i leds dying bang there we go so there's another use i'vestill got the power supply sit on the settings where blue so roughly around mynod volts and as you can see we've actually blown a circuit inside this ledwhich is allowing it to pass electricity so we still have pressure obviously butthe circuit is is now broken so it's
holding the pressure but the volume ofelectricity that was flying through there and i forget it was a hundred andsomething odds milliamp has now stopped because the circuit is broken anyway that there was a fun littledemonstration ideally hope you did learn somethingfrom it if you do have any questions or what have you then certainly do personand again i ask more senior and wiser viewers who watch this if you havepicked up any mistakes then do let me know so i can annotate and make thecorrections and thanks very much for watching
as i said please do post any answers tothe quiz question and we'll cover that off in the next video and you think someone else might mightgain value from this video then certainly please do share it on yourtwitter or facebook it certainly helps me and give it thethumbs up if it was gave you any value at all thanks for watching and we'll catch yousoon