Multimeters - The Complete Guide

today in the workshop we're looking at multimeters we'll see how to choose a multimeter and how to use it to perform some useful tests we'll also compare meters to see if the expensive ones are really worth the extra money we're getting some accurate readings today so welcome to the [Music] [Applause] workshop well hello and welcome to the workshop and today we are going to go onto the workbench and work with the most essential piece of test equipment that there is the multimeter the multimeter is literally the Swiss army knife of test equipment it can do

a bit of everything and it is so useful when you are troubleshooting and creating electronic circuits you can use multimeters to troubleshoot your wiring you can use it to test the components within your circuit you can also use it to make adjustments to voltages and currents multimeters can also be very useful around your home so it's something everybody should really own now if you're in the market for a multimeter you've probably noticed the price range is very extreme you can get multimeters for $25 you can get them for $2500 and obviously there are a number

of features included with the more expensive multimeters that you won't find in the cheaper ones but do you really need them and are the least expensive multimeters as accurate as the more expensive ones is it worth spending the extra money to get a name brand multimeter we're going to figure that out today what we're going to do is we're going to look at the multimeter we're going to examine all of the features of a multimeter and I'll show you how to use them so if you've got a new meter and don't know how to use

it you're going to want to follow along for that we're also going to put them to the test we're going to test inexpensive ones against expensive ones and see how accurate they are so sit back and let's learn a little bit more about the multimeter in its basic form a multimeter is an instrument that can measure voltage current and resistance a modern multimeter however can measure several more parameters making it an essential instrument for your test bench multimeters can fall into two different categories digital multimeters which are by far the most common these days and

analog multimeters which are no longer really used much within the digital multimeters we can also divide these into two categories manual arranging multimeters which require you to select arrange your measuring and auto ranging multimeters which select a range for you while all multimeters are different there are many common components between them all multimeters will have some form of a function selector to allow you to select the measurement function you wish to perform multimeters will have input Jacks these are banana Jacks that allow you to connect test leads to the meter the multimeter will have a

digital display this will display the measurement reading as well as other information and there will be buttons for additional settings and selections another essential component of every multimeter or the test leads that connect to it virtually every multimeter uses banana plugs for its test leads so you can exchange leads between different brands of meters to measure voltage and resistance on multimeters you generally connect your leads between the Comm and the V lead to measure current you'll need to make a different connection usually to a 10A or ma connection as well as the Comm lead today

we're going to learn how to use a Multimeter we'll learn how to select the multimeter and we'll perform some accuracy tests on a number of different multimeters we'll learn how to read multimeter specifications we'll look at a few multimeter accessories and of course we'll cover that all-important multimeter safety so if you find multimeters to be confusing we're going to take the confusion away today so let's go and start working with some multimeters and here we have a collection of multimeters and a wide variety of features and prices now we'll start off with this one here

this is the oldest multimeter I have uh technically this was probably the first piece of test equipment that I brought in into the Drone bot workshop and it even played a part in helping wire up the workshop now this is a manual ranging multimeter in other words when you're selecting resistance or voltage you have to select the range that you're in now that can sometimes be inconvenient if you don't know approximately what range to go for you have to start at the highest one and work your way down but it also has advantages over autor

ranging ones in that if you're measuring a fluctuating voltage the numbers and everything will stay the same the decimal point whereas on an auto ranging multimeter it'll quite often jump into a different range with a different decimal point and you'll get it very difficult to read reading so there is still use for a manual range multimeter otherwise this is a basic multimeter and it measures all the basic functions uh resistance uh voltage current it also measures capacitance and it measures frequency as well now over here we've got an auto ranging multimeter and this has a

number of different features on it it'll measure all the things I just mentioned uh before it'll measure temperature Etc uh the auto ranging this means you flip it into what you want you want to measure voltage you want to measure current Etc you put it into there and it'll be up on the screen for you without you having to determine a range and that's kind of nice uh this is a pretty nice meter actually make a lot of use of it now over here we've got a meter that you can see is a bit different

and uh this is because it's got an inductive C current sensor on it here and so this is for non- contct current sensing and I'll be showing you how we do non- contct current sensing in a little bit now uh this is the newest meter that I've got here in the workshop in fact just a few days old and this is one of these automatic it does everything you don't even have to tell it whether you're measuring voltage or current or resistance it can figure it out although you can manually set that but this is

also a two channel oscilloscope and a signal generator so it's really basically an entire Workshop in one package and as I said I just picked this up and so I'm just starting to play with it uh I just couldn't resist it I kind of have shiny object syndrome speaking of shiny object syndrome I did pick this up I would not recommend it to anyone now there are more expensive versions of this type of device but this is a meter that's made for SMD stuff you can essentially get around the contacts on the board and then

read it on here here or that's the theory it isn't a particularly good implementation this one and we won't be looking at it again plus I have a better solution for doing that than using a meter like this now back to the meters uh this is a benchtop uh multimeter and I love having a benchtop multimeter this is AC powered it's not battery powered but having a meter on your bench all the time can really be very very handy so if you got a permanent workbench situation you might want to look at something like this

and finally this is the flagship of my meters it's the only name brand one I have it's a fluke and uh for those of you who've been in electronics for a while you'll know that flukes are pretty well an industry standard back when I was a technician in the 1980s every time you were assigned to toolkit it always had a fluke multimeter and it's a very versatile meter this is one of the lower pric flukes nonetheless it's the most expensive meter of all of these meters here so one thing we're going to do today is

determine whether that extra expense was warranted when we check the accuracy of these things but at any rate you can see there's a wide variety of multimeters to choose from now let's go and take a look at a few accessories that we can add to these multimeters so I have a number of multimeter accessories for you over here now uh most of these were bought after market and accessories for one multimeter will fit the other one because accessories really are things that have to do with the probes and the probes on multimeters all use the

same standard banana plugs and banana Jacks so they're very easy to Interchange things now one accessory that probably came with your meter is this and this is a thermal probe and this is what you use to measure temperature on the multimeter so you would just plug this in in place of the regular probe and use the end over here to measure temperature with uh you can also get different probes for your meters these probes have interchangeable tips and right now what I've got on them are insulation piercing tips they're very sharp needle like tips that

can actually Pierce through wire insulation so you can take measurements without having to remove the wire they have another use as well and I'll show you that in a moment another tip you can get is one that replaces that really ELO uh SMD measurement thing I showed you this is just basically the same thing on a set of leads and you can use that to measure like uh things that are on a circuit board it's very very handy actually and most of these have to do as I said with banana plugs and banana Jacks and

so Banana cables are actually an accessory them themselves and you can get things to adapt them and that's what I have over here so you can get all these different ends that you can put on and they just snap on to the banana end over here I've got one that makes it into a lug and here's another one that makes it into an alligator clip the wrong color but that's what it is and I've also got these ones that turn them into the needles sized ones and these are very very handy as I said for

something else and that's something else is to use with sess breadboards these needles will fit perfectly into the leads on a sess breadboard so if you're taking measurements on a breadboard these are very handy to have either as an accessory for a banana or just basically on the end of some leavs like I have over here another handy thing are these ones and these have a little clip on the end of them and they let you clip onto wire I don't know if you can see the clip it's very very tiny but if I take

something like a resistor here for example I can grab onto it it's a grabber and so it lets you grab onto a lead and that's really really handy when you're trying to measure something and measure right onto a lead when something's in circuit another style of banana cable that I really like are these ones and what I like about these is that the ends of these cables are have also a banana socket on them so you can just um daisy chain these things can stagger them like that and that's great when you have like a

common ground connection or something and you're trying to hook more than one meter up so you can get a lot of different accessories for your multimeter and it'll really expand the things that you can do with it okay now that we've taken a look at a bunch of multimeters it's time to actually start working with them so what we're going to do is we're going to take out our meters and we're going to go through all of the basic functions of a multimeter we'll be covering the following basic functions resistance which also includes continuity and

a diod check DC voltage and current ac voltage and current frequency capacitance and temperature we're going to begin by making a resistance measurement in order to do this we need to place the meter's function selector in the ohm or resistance position we'll place the leads into the Comm and the VJ on the meter measuring a resist is quite simple we'll connect our red test lead to the V Jack and connect that to one side of the resistor we'll plug our black test lead into the C Jack and connect it to the other side of the

resistor when measuring a resistor lead polarity is not important because resistors aren't polarized if you're going to test a resistor on a circuit board make certain that you remove the power first you may also need to remove one leg of the resistor to get an accurate reading as the rest of the circuit can affect the resistor reading another function in resistance mode is the continuity function when the continuity function is activated the meter will emit a sound when it encounters a low resistance this is great for troubleshooting purposes most meters also have a diode test

function this will display the voltage drop across the diode when you hook it up in the correct direction when you hook it up in the other direction you won't get anything so now let's go use the resistance function on our multi meter now we're going to start off with a couple of very basic multimeter functions and I'm using the Fluke meter to demonstrate this just because it's got a very simple control on the front just one dial and not a lot of writing on it so you can see what it's doing but of course you

could use any of these multimeters for these demonstrations now we're going to start off by measuring resistance we're also going to check continuity and we're also going to check a diode and they're all in the same function here in the meter as they are in many meters and so when I put it on to here it's on Resistance mode you can see it says Auto down here so it's Auto ranging right now and it's gone up to Mega ohms because of course my two probes are not connected right now so naturally uh they don't have

any resistance now I have a resistor across the board over here and so we'll disconnect to it using these probes and we get a reading of 4.72 and this is a 4.7k resistor now it's a 4.71 so that's within tolerance and so that's a very simple thing to measure resistance now we'll take that out and we'll move on to the next thing here and this is continuity you can see in the corner of the meter it's got a little thing that indicates it's going to make a sound and basically it's measuring a resistance but it's

also going to give me a sound every time that I have pretty well down near zero ohms and that's a a wonderful feature for when you're trying to troubleshoot some wiring you don't have actually look at the meter you can just hear the sound now we're going to move up over here and you can see the little diode symbol in the corner we're in diode test mode and of course a diode can let current go in One Direction but not the other so we'll go across this diode here and we don't get anything on the

meter now we'll reverse the polarity and we get a reading 555 and that's the voltage drop across the diode so the diode is working it only conducts in One Direction and it also is giving us a reading and I've also got another type of diode here a light emitting Di and if I go across the LED in One Direction we get absolutely nothing it is a diode let's reverse the polarity there and you can see I get a reading 1785 and that's the uh voltage drop across the LED and if you look at the Led

it's also on right now so this is indeed a great way to test an LED so here we've already started off with a meter and we've been able to measure resistance we've been able to measure continuity and we've also been able to check both diodes and LEDs so I'd say it's a pretty good start to show you how versatile that this instrument actually is the next parameters that we're going to measure are voltage and current and we're going to start by measuring DC voltage in order to measure DC voltage you'll need to place your meter

in either the Volt or DC volt position if your meter only has a volt position you'll need to select your auto sense DC make certain that you observe the maximum ratings for DC voltage and don't exceed them at any point you'll place your two test leads in the Comm and the V Jacks to measure voltage now here's how we'd measure the voltage on a battery we would connect the red test lead to the V Jack and connect that to the positive lead of the battery our black test lead would be connected to the com Jack

and that would connect to the battery's negative terminal when checking DC voltage you need to observe the lead polarity otherwise you'll get a reversed reading remember that your meter has a very high impedance and provides virtually no load this means that when testing batteries you're not going to get a very accurate reading some meters have a battery test function which provides a load the next parameter we're going to measure is DC current you'll need to place your meter into the a or ma position you may also need to selector Auto sense DC once again make

certain to observe the maximum current rating you'll place your leads in the Comm and into the ma or a jaxs on your meter now here's how we'd measure the current that this transistor radio is drawing from a 9V battery in order to measure current we need to break the connection we can then connect the Comm lead to one side of the broken connection and complete the connection with the 10A or ma lead now when it comes to measuring AC we need to remember that there are different ways of expressing ac voltage one method is Peak

to Peak this is the difference between the maximum positive and negative Peak in the waveform the most common method of expressing ac voltage is root mean square or RMS this the equivalent DC voltage that would produce the same heating effect in a resistor most meters use RMS and many of them use true RMS true RMS provides an accurate reading even when the waveform is not a sine wave some Advanced meters allow selection between Peak to Peak and RMS we're going to start by measuring ac voltage we'll need to place the meter in The Volt or

AC volt position on some meters you'll need to select your auto sense AC as always we'll observe the maximum voltage rating and as we did with DC voltage we'll place our leads in the Comm and the V Jacks now here's how we'd measure the output of this Transformer we'd connect the red lead to the V Jack and connect it to one side of the Transformer output the black lead will be connected to the com Jack and will be connected to the other side of the Transformer's output since we're measuring AC the lead polarity is not

important on some meters you'll also display the AC frequency when you measure AC and the last parameter that we're going to measure is AC current and we're going to do a direct connection as opposed to the non- contact methods that I'll show you a bit later for this we'll need to place the meter in the a or the n ma position and you'll need to select or Auto sense AC if your meter requires this once again we will observe our maximum current rating and as we did with DC current we'll put our leads in the

Comm and either the ma or Ajax depending on how much current we're trying to measure now here's how we would measure the current on the light bulb connected to the output of the Transformer as with DC current we need to break the connection we'll connect our Comm lead to one side of the brake and our 10 a or ma lead to the other side as this is AC the polarity of the leads is not important we're going to test our voltage and current measurement functions using this circuit this is a pretty simple circuit which drives

an LED from an AC input it uses a 6vt AC Transformer a bridge rectifier to convert the AC to DC a 6 180 microfarad capacitor to smooth out the DC and it uses an LED and the LED has a 100 ohm resistor and a 1K potentiometer as its dropping resistor you can adjust the pot to adjust the amount of current through the LED we're going to use five different measurement points on this circuit measurement point one is across the ac voltage so this will measure the ac voltage output of our Transformer measurement two will meure

measure the AC current consumed by our circuit measurement 3 will measure the DC current going to the LED we can adjust this current with the 1K potentiometer measurement 4 will measure the DC voltage output from the bridge rectifier and measurement five will measure the voltage drop across the LED now when properly operated the LED should have a current of 20 milliamps and a voltage drop of 2 volts so let's go wire this up and check it out with our meters now throughout this video I've been trying to make the case for having multiple multimeters and

I think this is the ultimate example over here obviously you could do all of this with one multimeter but each of these meters is measuring one of the parameters in the circuit that we've just seen now the first meter is measuring the ac voltage that is coming right off of the Transformer and uh you can see it's about 7 and 1/2 volts this multimeter is measuring the current that we're drawing and we're currently pulling about 232 AC milliamp from this so we're not taking very much current at all this next one is also measuring current

this is the current that the LED is drawing and this is what we can set with the potentiometer and if you recall the specifications on the LED are that the optimum are 20 milliamps of current and it'll have a 2vt volt drop across it and over here is the voltage drop across the LED and as you can see it's 2. 059 so it is indeed quite close to specification and this is the DC voltage that we're getting on the output now we can do some interesting things here for one thing we can see how much

that the output is affecting the DC voltage how much the load of the LED is affecting it by just removing the LED from the circuit for a moment obviously these Dro to nothing you'll note that the current over here in milliamps is practically nothing as well and this voltage has dropped has jumped almost all the way up to 10 Vols and so if I put the LED back on we'll see that everything resets itself and uh we can also adjust the amount of current that we're getting so say that we wanted to draw a little

bit less current from our LED we could set the Pod up over here and the LED is going to dim a little bit but we can actually get it down to about half the current and we can still see the LED and as you can see the power supply voltage has risen as well and we are still dropping about 2 volts across the LED so you can do a lot of interesting experiments when you have multiple multimeters but what I'm really trying to illustrate here is both the different settings that you can use for the

meters to measure all the different parameters and also if you look at the breadboard the different ways that I have attached it with the probes uh with the bananas over here with the clips across the led the ways that you can get at your circuit when using a multimeter and that I think is the key point of this rather extravagant demonstration some multimeters have non-c cont sensing functions these allow you to sense alternating current without directly contacting it and it comes in a couple of different forms there are the current sensing clamp meters these allow

you to sense current flowing in wires without directly contacting the wire there's also the ncv live function on some multimeters the ncv or non- cont voltage sensor and determine if a wire is live without coming into direct contact with it now in this demonstration we're going to use the clamping meter to do an inductive current test and this is a great thing to be able to do because measuring AC current especially High AC current can be somewhat dangerous so not having to actually get in contact with the wires is a good thing and so what

I'm going to do is put this into the current mode and they've got two of them a high current mode up to 1,000 amps and a lower current one that says 60 or 600 amps you get two ranges over here and these currents are normally for Fairly High currents you're not going to be measuring milliamps or anything with them I'm going to put the function onto AC mode over here so it's on AC now now I'll show you how this works I've got a soldering gun and it's plugged in uh to this assembly over here

which is this an AC plug that's also got its three wires split out here and you'll see why in a moment now first I'm going to put the meter around here I'm going to put this on and I don't get anything at all on the meter if you can see that but that's because that's not how it works I'm going to put it just around the hot lead which is this one over here and turn it on and there you go I've got about 1.17 1.15 um amp of current which for a 150 wat uh

soldering gun at 120 volts is probably about correct and you can also measure this down on the um neutral side as well it'll measure over there as well but of course it will not measure on the ground you can't expect anything there and naturally you don't get it so inductive Uh current sensing is a very handy thing to be able to do it's a very safe thing to be able to do just remember you need to be sensing one of the wires if you try to do both of the wires they'll cancel each other out

and you won't get any reading at all now these two multimeters have a feature called ncv or non- cont voltage sensing and that can be a very handy feature to look for in a multimeter if you're an electrician or if you do a lot of electrical work what ncv lets you do is sense the presence of voltage without actually having to have any contact now it doesn't measure the voltage it just gives you a rough idea of the level of it and whether it is there or not and so it's great for finding out if

an AC outlet is live or not now in both of these meters it works the same thing you put it into ncv mode and then it goes and senses a voltage I'll try it with this one here now right now I've got it in ncv mode and I'm placing against the power bar that currently is off and I'm not getting any reading if I turn it on I'll get a reading and it says low over here because it doesn't see that high but if I move it to this one it sees high so this one

is actually sensitive enough to see the high lead and the neutral lead of the power which is pretty cool and so it lets me know that there's power here or that there's power not there and prevents me from having to actually measure it now if you are determining this so that you can work on the AC line you would definitely want to measure the voltage just to double check but it's a great way to know whether an AC outlet is active or not and it's a cool feature to have in a multimeter if that's something

that you need most multimeters have a function for checking capacitance you'll find a cap or capacitor symbol or microfarad position on your selector switch to measure capacitance you'll place your leads in the Comm and the V Jacks measuring a capacitor is pretty simple you'll take the red lead connect it to the V Jack and connect it to the positive side of the capacitor if it's polarized otherwise just connected to any side the Comm lead will be connected to the negative or other side of the capacitor make certain that you check polarity when you're using a

polarized capacitor it's a good idea to discharge large capacitors before measuring or your reading accuracy may be affected never measure capacitance in a live circuit always remove the power before measuring a capacitor I'm going to use the benchtop multimeter to test capacitance and I've gone to my parts drawers and taken a couple of drawers of capacitors out test with now these are supposed to be 1 microfarad capacitors we'll start with that now I've set the meter into its capacitance position which in this case is just as simple as pressing this and I'm using these short

test leads and it's actually a good idea to try to use short test leads when you're testing capacitance because the capacitance of the test leads themselves will come into play although when you're working with a value like one microfarad that's pretty negligible when you're down at some very low values of capacitance though that is an issue now this is a polarized capacitor and so I'm going to need to observe polarity and on these the longer lead is the positive and the lead that's marked off is the negative so we'll connect our positive here and our

negative here and we'll watch the meter and notice it says overload what it's doing right now is it's measuring the capacitance it takes a while to measure capacitance it's not instantaneous because what it does is it charges up the capacitor and then it discharges it and it measures the amount of time it takes and that's how it calculates capacitance and this is just a little below 1 microfarad according to this I'll take another one from the same drawer because Tolerance on capacitors is actually pretty awful okay this one let's see how it does again we

have to wait for a reading with a larger capacitor and it's almost a microair as well now let's go to this one here and I've got two values on here the back value is 470 Nars now these are not polarized so it doesn't matter what lead connects to what side so we'll connect the 470 and I get 435 Nars and we could try another one as well and this is actually great if you're working on some kind of radio or audio circuitry where you're trying to match capacitors you can get a few to your drawer

that matched perfectly this is 4378 so it's very easy to measure capacitance as to how accurate the readings are I'm not exactly certain but uh this meter has a fairly wide range you'll find a lot of meters though don't have a wide range of capacitance and there are better methods of testing capacitors uh meters that are dedicated for that nonetheless just for testing capacitors on circuit boards or for matching up capacitors having Capac capacitance testing is a very handy thing in a multimeter the next parameter that we're going to measure is frequency not all multimeters

have a frequency measurement function but if yours does place your selector switch into the frequency position you'll need your leads in the Comm and the V Jacks measuring frequency is pretty simple you'll place your red test lead in The V Jack and connect it to the hot or active lead on your frequency or audio Source the CM lead will be connected to the ground side of your frequency Source you should note that some meters have a pretty limited frequency range as they're not really dedicated frequency counters now what I'm displaying to you here is my

manual ranging multimeter and specifically you can see it's pointing at the frequency measurement and it says 20 khz and that's because that's the maximum frequency that you can measure with this multimeter and that's not uncommon all the multimeters I have over here with the exception of one of them really can't measure very high frequencies this is the exception my desktop multimeter is actually measuring 20 mahz right now it's being fed a a signal assign wave of 20 MHz it's giving me the duty cycle of the sine wave as well and so that's pretty good performance

although it doesn't compare to a full-fledged frequency counter my counter can go to 2.4 GHz and this tops out at about 20 MHz otherwise this meter isn't too bad it tops out at about a megahertz and this one here goes to I believe about 80 KZ before it stops and the thing is frequency counting isn't something you really buy a multimeter 4 in fact it never used to be included in multimeters but in recent years they started to add it because being a digital circuit is not that difficult to do so uh you could use

the frequency counter in a multimeter to verify line voltage frequencies of course 50 HZ 60 HZ maybe 400 HZ they're great for that and for audio work they're okay uh they don't have that many digits this one here again displays the most digits five the other ones are pretty well four digits but uh for most work they'll be fine certainly not for radio work or anything where you're doing timing accuracy but for general purpose when you do need to know a low frequency an audio frequency perhaps a music frequency for tuning a instrument they would

be fine for that but otherwise I wouldn't go shopping for a multimeter if you're really looking for a frequency counter many multimeters have a function to measure temperature if yours does place your meter selector switch in the temperature position in order to measure temperature you're going to need a thermocouple sensor and there was probably one included with your multimeter on some multimeters there's also an internal temperature sensor just to measure me the ambient temperature if you have a thermocouple sensor plug it into the Comm and the V Jacks measuring temperature is pretty simple all you

need to do is plug your thermocouple into the Comm and the V Jacks and place the thermocouple end on the device whose temperature you wish to measure you'll find that thermal couples respond very quickly and will give you a very accurate temperature measurement now I've got my thermal couple hooked up to my plant meter and this is the thermocouple you can see the end over here is the actual thermocouple sensor and you can see that it's reading the ambient room temperature right now it's a little bit warm inside here 25.4 it also gives a reading

in Fahrenheit above there now here we have a Raspberry Pi and it's been running for about maybe 15 minutes now this Raspberry Pi doesn't have a micro SD card in it and there's nothing as you can see connected to it other than the power supply so it's not doing anything nonetheless it's starting to heat up so I'm going to take a reading of the chip over here on the pie just by touching that and you can see it goes up instantly therms respond very very quickly and it's about 51° C or 125° F to 52°

C rather hot little piece of pie over here and I'll remove the thermister from it and you can see the temperature rapidly Falls as I say these things are very quick to respond and so these are really great for troubleshooting on boards where you think you might have a component overheating because you can narrow it down to the exact one with this very fine tip of the thermister so measuring temperature is actually a very handy function in a multimeter shopping for a multimeter can sometimes be a bit confusing there are so many features in multimeters

there also are specifications some of which make sense some of which don't make a lot of sense how do you choose the correct meter well the good news is you really can't make a bad choice multimeters these days are great even the most inexpensive multimeter is an Ideal tool for your workbench so you really can't go wrong but of course you want to get the most value for your money so what we're going to do right now is show you how to read the specifications of a multimeter and then I'll show you a few Advanced

features that some of my meters have that you might want to have on your multimeter a good multimeter will come with a very long list of specifications and you can break those down into the following categories accuracy resolution input sensitivity input impedance the input ranges sampling and display rates and safety ratings and features accuracy defines how close a measurement is to its actual value it's expressed as a percentage of the reading an accuracy measurement also includes additional counts you'll find accuracy listed for each function on the multimeter resolution is defined as the smallest change that

the meter can display this is related to the number of digits on the multimeter a 3 and A2 digigit multimeter has a maximum display of 1 1999 the one being considered the half digigit this can also be expressed as counts we Define sensitivity as the smallest detectable input change for a given measurement function and range so there will be several sensitivity measurements in a multimeter spec sheet the unit used depends upon function a multimeter impedance is the resistance that it presents to the Circuit as it's measuring it you want as high an impedance as possible

in order to avoid loading the circuit down impedance is expressed in Megs the range or the minimum and maximum values that the meter can measure for each function manual range multimeters will have a series of ranges specified you'll find separate range specifications for both AC and DC functions the term sampling can actually be used for two different things on a multimeter it can can refer to the analog to digital converter sampling rate that converter sampling rate is always specified with a bandwidth sampling can also refer to the display refresh rate how many times is the

display changed per second one of the primary safety features in a multimeter is a fused input or inputs these are usually found on the current inputs multimeters are also rated with a category or cat rating common cat ratings for multimeters are cat 2 cat 3 and Cat 4 there are also other features that you may look for when looking at a multimeter true RMS allows more accurate readings when the signal is not aign wave a backlit display can make the meter easier to view in low light Auto ranging is a convenient feature that's easier to

use than manual ranging a data hold feature will freeze the display way so that you can look at it when it's more convenient some multimeters have a USB interface that can be used with PC software or a spreadsheet many multimeters also have a bar graph display that makes it easier to visualize fluctuating signals now let's take a look at a few of my multimeters now specifications are of course very important when you're selecting a multimeter but it's not the only thing I've got all the multimeters that we're working with today out and each of them

is rather unique they all perform the same basic functions but they all are unique in their own special little way now this is probably the most unique one of course the clamp meter and one thing aside from the clamp that makes it unique is it only has two input Jacks the other ones all have four of them and that's because this one doesn't measure current directly it relies upon the clamp it relies upon inductive measurement for that this is really more of a multimeter that would be assigned to someone like an electrician rather than an

Electronics so uh if you do a lot of wiring around the house Etc or if you do industrial wiring then this is the kind of meter you probably want to get if you do have a permanent workbench setup I would highly recommend getting a desktop or a bent top excuse me multimeter uh the fact you'll never need to replace the batteries is a cool thing but it's always nice just to have one on your bench now I actually had to modify this one it didn't tilt up enough and so I added a couple of extra

feet onto it here but other than that it's been a great thing to have now there are other unique features in all of these meters one that two of these share my oldest one in this one that I really like I'll demonstrate for you over here now I'm just going to turn it on to a function right now that's molts after it boots up note over here the way that it's flashing it's telling me that's where the test leads go and so if I go into a current function it's telling me the test lead leads

need to be changed over here and that's a very handy thing to have because if you are for example measuring current and then go back to measure voltage you need to remember to change those leads over to the correct position otherwise you'll learn how to replace the fuse inside your multimeter when you short out the voltage so very handy to have this little meter here my oldest one also has a similar feature on it uh the fluke multimeter uh one thing I like about it those two things I like about it for first of all

it is quite simplistic to dial it's not as busy as everything here so this is great for an educational setup or where you're dispensing multimeters out to a crew of people which is probably why I always got them in my electronics kit when I was an Electronics technician they're very simple to use it's very obvious how they're used they're also extremely durable this multimeter weighs more than any of these meters here including the benchtop one it's obviously got something inside it that's very solid and that's one thing they are they're rugged and they're reliable so

if you're out in the field or if you're using multimeters in an educational setup this is the kind of meter I'd go for if I could only choose one that would be a difficult choice but I'd say this one does encompass uh most of what you need and the price is certainly right it's about $ 3540 for one of these and don't get hung up on the brand name by the way when you're looking for user manuals for example this one over here I couldn't find it under this manufacturer's name but I found it under

this manufacturer's name look for the part number because they're all basically using uh the same parts and putting together meters and you'll notice that when you're shopping for them you can often see the same meter advertised by different manufacturers but that's a great thing that just brings down the price and does keep the quality up and finally this allinone thing might be a great thing to have as a second meter I would get this as a first meter and then deci on either something like this or maybe a bench multim meter but um you know

everyone's unique and your selection might be different you'll notice though I'm pushing the fact that you probably need two multimeters you'll find there's a lot of situations where you're measuring voltage and current simultaneously and that's great to have but uh the good news is you can't really make any wrong choices when you're out selecting a multimeter they all will give you a lot of value and uh they all have a lot of features that you can use on your workbench now I'd like to demonstrate a feature that I find very useful in a multimeter and

one of these meters has it and one of them doesn't now to demonstrate this I've simply got a potentiometer this is just a 100K pot and it's wired up to a couple of test leads I'm going to put them into the fluke which is measuring resistance which is what you'd expect to measure from a potentiometer and it does indeed measure my resistance and I'm moving it up and down a little bit now what I'm doing is I'm simulating a fluctuating reading and as you look at the numbers they're really all over the place it's a

little hard to gain any information from that now I'm going to move this to the other multimeter and do basically the same thing so we get a reading and I'm moving it up and down but one thing you might notice about this display that the other display doesn't have is at the bottom I've got myself a bar graph and the bar graph is very handy when you have a fluctuating reading now I'm using resistance but it also will work with voltage and current and I find that to be a very great feature to have so

when you are looking for a multimeter you might want to consider getting one that does have a bar graph display as well and so now we come to that moment that you've all been waiting for the great multimeter Showdown as you've noticed I have a variety of multimeters and they span range of prices and they have a number of different features but at the end of the day the thing that matters the most is do they give accurate readings so I've got some calibrated test sources we're going to check out all of our multimeters we're

going to see how the cheap ones Faire against the more expensive ones in our great multimeter Showdown and so we're going to begin our Showdown with a resistance test and what I've got here is five multimet that are all testing Precision resistors and they're testing a 1K 1% tolerance Precision resistor so this resistor should have a value of anywhere between 999 and 1,01 ohms and I think you can see that all of these meters are pretty well within that range this one is a little bit over but I also want you to consider the test

leads that I have here these test leads are going to be adding some resistance as well and of course on any of the resistance tests that needs to be factored in so let's say that everything here is pretty capable of measuring the 1K Precision resistor now let's go and try a few other values and so for the second of our resistance tests I'm using a 10K Precision resistor and so this is a 10K 1% tolerance Precision resistor and so it should have a value within 10 ohms of that value and I think you can see

everything here is pretty well within there these two are a little bit out but not by very much I I think you could pretty well say that everything here is capable of measuring 10K I have to say I've been pretty impressed by this little clamp meter because it's been bang on for both of our tests and once again it is and this one of course is measuring down to an extra digit of precision so we're going to do one final resistance test this time with a bit of an oddball value resistor and so for our

final resistance tests I have a value which may seem a bit odd but it's actually very popular when used with digital to analog converters and the value of my Precision resistor is 499 KMS and as you can see everything here is reading pretty close to 499k within the .1% tolerance of this resistor so I would have to say that all of these multimeters are quite capable of accurately measuring resistance I wouldn't really give any one of them a particular advantage on it perhaps I would assign an extra point to the bench multimeter because it has

an extra digit of precision but I think all of these are capable of measuring resistance quite well now our next Showdown is to test accuracy for DC voltage measurement and in order to do this I've used a module from Ada fruit this module is a voltage reference module and it's made for analog to digital and digital to analog converters it takes an input of 5 to 12 Vols and produces two outputs one at 2 .48 Vol and the other one at 4.96 Vols now those may seem like odd voltages until you look at those numbers

a bit more carefully then you'll realize how useful those would be for something like an analog to digital converter and so I've got that wired on a sillus breadboard powered up by a 9vt battery so we've got a nice power supply that doesn't have any Ripple or noise in it and I've got the two outputs wired up here I've got the 4.09 6 output over here and the 2.48 volt output over here and what we're going to do is we're going to feed that into the meters individually and see how accurate they are now as

you can see I'm already using my benchtop multimeter and feeding the 2.48 into it and it is very accurate 2.483 volt DC and so we can move this here to get the 4.96 and I get 4.95 which is close but not exactly 4.96 but all and all not too bad now let's take another meter and give it an equivalent measurement so we'll plug into this meter and this is the 4.96 if you recall and can you see that 4.94 that's pretty darn close okay okay let's see what the other voltage is and that's supposed to

be 2.48 is 2.49 2.05 I'd say this meter is actually reading very accurately quite impressive actually okay let's go over to the fluke now this of course is our most expensive meter and right now we're feeding 2.48 and 2.05 54 it's close not exact but it's pretty close and the 4.96 is actually 4103 so uh off by a little bit not too much but a bit and remember that is the most expensive meter I've got here now let's turn this thing on and put it into multimeter mode and my 4.96 is reading 4.95 that's pretty

good now let's see what happens with the other voltage here my 2.48 is 2.51 so this meter is also very very close and finally the last one is this and we'll feed into here and 2.52 where it should be 2.48 very close and 4.99 instead of 4.96 so also very close so all of these meters were very close uh this one in particular was uh quite accurate uh as was this one for the uh 2.48 volt it was very accurate uh the fluke actually was probably the least accurate which is surprising since it's the most

expensive multimeter over here and uh you could repeat this test uh with different voltages as well Ada fruit only sells this module but Texas Instruments actually sells the chips on this and they make them up to 10 volts and they're Precision down to 0.1% so if you need a Precision reference it's a good thing to use as well and so there you go all of our multimeters are quite accurate for measuring voltage now the next test we're going to do is capacitance and it's actually a pretty difficult test to do not that it's difficult to

measure capacitance on any of these meters it's quite simple to do that but what's difficult is to get an accurate reference capacitor they do sell Mic capacitors which are very high tolerance but they're extremely expensive it would be over $100 per Capac Itor to get a reference capacitor that's within the range of all these multimeters because the cost goes up as the value goes up and most mic capacitors are very low value so I didn't think it was worth spending $100 for one capacitor that I would use just once to test a bunch of meters

many of which were worth less than the capacitor itself so what I've done is I brought another meter into the picture this is what's called an LCR tester and it's a very inexpensive manual ranging one you can get much better ones in these and while it's not necessarily more accurate than the capacitance testing function in these multimeters it does have a number of advantages the main one being the range that it has and it can go down into the uh POF farad range whereas most of these meters here can go into the nanofarad range at

best so for low value capacitors something like this is really handy another thing it has which I like quite a bit is that you could insert the capacitor directly into here and being an LCR tester it also tests inductance and resistance as well so it's good for that and another great feature is this zero adjustment here this lets you uh compensate for the capacitance in the leads by zeroing the display so it's pretty handy so what I have here is a 10 microfarad capacitor that's I think pretty close to 10 microfarads we're going to start

it off on this meter and then see how the other meters fair and this one reads 9.96 and it actually reads pretty fast compared to the other meters for capacitance now I'm going to go to the bench top multimeter first and we'll plug in our leads and of course this takes a little time it's charging and discharging to make a reading and this is 10 microfarads and it reads 9.90 microfarads pretty close close to what that one read as well now let's give the fluke a try and we'll just bring it where we can see

it somewhere 10.08 microfarads it reads a little bit higher than the other ones but otherwise certainly within the ballpark and our fancy osilloscope all in one meter 10.44 it also reads a bit high but uh a gain within tolerance let's go to the clamp meter and we'll put it where we can see it 10.25 it also reads a bit higher than what the LCR reads and last but not least this metor here and what are we going to get here 10.2 three so it kind of jives with this one here so they're all within the

same ballpark and really when you're testing capacitors it's quite often not the exact value you want you just want to find out if the capacitor is working or not or you're trying to match up capacitors for audio circuitry and for those purposes any of these meters would work fine if you need something to measure a wider range of capacitors though you might consider something like this LCR tester and you'd also have the ability to measure inductors as well and so that about wraps up our look at multimeters for today I hope you enjoyed it I

hope you learned something and I hope it it'll help you choose your next multimeter and remember the best accessory for a multimeter is another multimeter you'll really find it versatile to have more than one of these devices on your workbench now if you want a bit more information about multimeters there's an article that accompanies this video on the dronebot workshop.com website and you'll find the link to that article in the description right below this video while you're on the website if you haven't yet please consider signing up for my newsletter it is not a sales

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