How to use a multimeter like a pro! The Ultimate guide

do multimeters stress you out because they look complicated and hard to use with their giant user manuals dials settings buttons Terminals and leads and there's so many different versions too how can anyone understand this well they're actually quite easy and I'm going to show you how in this video you can even download my multimeter PDF book 2 and support the channel links down below for that along with links to our sponsor PCB way who offer everything from circuit boards 3D printing CNC Machining injection molding and even sheet metal fabrication do check them out links down below there are a lot of different multimeter designs but basically we just have the analog and the digital versions analog multimeters use a dial which is horrible to use and difficult to read and they usually just have a few basic functions hardly anyone uses these anymore I can't stand them and I'm not going to cover them in this video instead we're going to use digital multimeters which have digital displays these are precise very easy to use and usually have a lot more functions we have two main types of digital multimeter there's the manual range and the auto range with Auto Range we just select the function and the multimeter will tell us the answer but with the manual range version we have to select the correct range to get the correct answer we will see how that works a little later in the video but Auto Range are the easiest and the fastest to use however they are typically more expensive I'll leave my multimeter recommendations in the video description for you however all multimeters have the same basic functions of reading voltage current and resistance different multimeters will have more advanced functions than things such as capacitors transistors diodes temperature Etc we will cover all of these but let's get started with DC voltage what do you use your multimeter for or what tips do you have let me know in the comment section down below DC voltage is represented by this symbol we find this type of electricity with batteries solar panels and almost all of our electronic devices with DC or direct current electrons flow in One Direction think of it like the flow of water in a river that's why our oscilloscope shows a straight line when we connect it to a battery and that's why we use this symbol we place the red lead into the V terminal and the black lead into the com terminal then we connect the red probe to the positive and the black probe to the negative terminal of the battery on the Auto Range multimeter we just select the DC voltage setting and it will instantly tell us the answer if you see a negative number you just need to swap the leads over here I'm testing a simple voltage divider circuit we can see a reading of 0. 031 volts which is 31 millivolts we can switch to the minivault setting for more Precision this particular device defaults to aec millivolts and it indicates that we need to press the yellow button to switch to DC millivolts with the manual range version we have to select the correct scale that's quite easy we just select the next number up for example this battery is rated 12 volts that's higher than the 2 but less than 20. and so we used the 20 scale this battery is rated 1.

5 volts that's less than 2 so we use the 2 scale but what if we don't know the voltage how do we choose the correct scale well that's easy we just start from the highest value and turn the dial until it changes to o1 that means we have gone too far so we turn it back to the next position and that will give us the answer we can also measure voltages in a circuit for example here I have a basic prototype board with some resistors and an LED I can read the total voltage of The Circuit by measuring across the positive and the negative I can also check the voltage at any point in the circuit by connecting across individual components we can check the voltage drop of that component although it must be powered in order to do this remember we can only measure the difference in voltages between two different points if we try to measure the same point we won't read any voltage because there is no difference the electrical sockets in our homes provide AC or alternating current this is different than DC electricity which we get from a battery with AC the current alternates Direction flowing forwards and backwards think of it like the tide of the sea so our oscilloscope will show a sine wave for AC which is why we use this symbol this is a much higher voltage than a battery electricity is dangerous and can be fatal you should be qualified and competent to carry out any electrical work you can buy socket testers which will test the wiring of your sockets some will even show you the voltage these are much safer I highly recommend that you use these devices instead for ac voltage measurements ensure that the red lead is in the v terminal and the black lead is in the com terminal on the Auto Range type we simply select the ac voltage symbol keep your fingers away from the tips as these will become electrified if you touch this electricity can flow through you and shock you ensure the insulation on your cables is in perfect condition never use or try to repair a damaged cable just buy a new one always connect the black wire to the neutral first because if you connect the red wire to an active terminal first the black wire will instantly become electrified do not use in wet conditions wear rubber boots to insulate yourself and do not touch grounded surfaces while taking measurements for North American circuits I recommend you flip the breaker first we often find a safety screen over the terminal of the socket so we place the black probe into the large slot and the red probe into the small slot and then we push until the safety screen opens when it is safe to do so you may flip the breaker again and the meter will then read the value the British circuits turned the switch off first we also have a safety screen on these type so place the red probe into the Earth terminal and push down to disable this then we place the black lead into the neutral terminal and the red lead into the live terminal when safe to do so flip the switch and the meter will then read the value for Australian circuits turn the switch off first and then push the black probe into the neutral terminal and then the red probe into the active terminal when safe to do so flip the switch and the meter will then read the value for European circuits I would recommend that you first flip the breaker we need to place the probes into the terminals and then apply a light pressure and tilt the leads to lift the safety screen and then we can insert the terminals when safe to do so we may then flip the breaker again we can reverse the probes and still measure the voltage also with this system for manual range devices we follow the same connection and safety procedures as the Auto Range tutorials but on our meter we select the next value up from the voltage we are expecting to read for example on a 120 volt connection we select the 200 setting on a 230 volt connection we select the 700 setting if you are not sure of the voltage start with the highest value first and turn the dial until the correct value is displayed do not exceed the maximum voltage of your meter if the meter shows a 1 the reading is out of range and you will need to turn the dial to a higher setting you can buy either an average RMS or a true RMS multimeter I'd highly recommend that you buy a true RMS type as this is more accurate electrical equipment can distort the waveform only true RMS meters will accurately be able to measure this don't forget to check out PCB way for all of your 3D printing CNC Machining injection molding and even sheet metal fabrication needs I have a link for you in the video description down below resistance is represented by this symbol and it uses the unit of ohms it's a measurement of how easily electrons or electricity can flow through something for example electrons can flow very easily through this wire which is why we use copper wires however it's much harder for it to flow through this resistor and it's very very difficult to flow through rubber which is why we use rubber insulation on the wires to protect us from the electricity in the copper wire to measure resistance we need to place our black lead into the com terminal and the red lead into the terminal with the ohm symbol with the Auto Range device simply turn the dial to the resistance setting and then connect your leads across the component it doesn't matter which side you connect it the device will Now display the results we can test items like speakers resistors wires potentiometer Etc but pay attention to the letters on screen this one shows just ohms this one shows K ohms meaning thousand ohms this one shows M ohms meaning Mega or million ohms with the manual range we need to select the correct setting remember we use the next number up for example this resistor is rated at 3 K ohm that's more than 2K so we go to the next value up which is the 20K and then we can see the result this multimeter has a maximum setting of 2m so if I try to read this 5. 6 M resistor it will just show a one because it's unable to measure values this large do be aware that the resistance also changes with temperature resistors also have a tolerance this one shows three kilo ohms plus or minus one percent so it could be anywhere from 3030 ohms to 2970 ohms but when we measure it it's 3014 ohms so this is within the stated tolerance other resistors like this one have a five percent tolerance however this resistor is around 2 Mega ohms but when we add it to this simple circuit we get a reading of around two kilo ohms that's because it's now in parallel and resistance divides so do not try to test components on a circuit board without isolating them first current is a measurement of how many electrons are flowing through a particular point in a wire direct current means electrons flow in Just One Direction we typically find this in battery operated equipment it is measured in amps or amperes this uses the symbol a the dashed line just represents direct current we must place the multimeter in series with the circuit and we can do this either for the total circuit current or the branches of the circuit do not connect the meter in parallel with the load this can cause a large current to flow through your meter and it will damage it your meter will either have three or four terminals one of them will likely show ma for milliamps it should also State a number to indicate the maximum milliamp current that it can measure through this terminal this one for example States a maximum of 400 milliamps if we know the circuit that we're testing is below this we can place the red lead into this terminal otherwise we must use the a terminal this is usually stated as 10A meaning a maximum of 10 amps the time indicates for how long it can be connected for for example 10 amps but 10 seconds per 15 minutes now select the direct current setting place your red probe into the 10A terminal and the black lead into the com terminal connect the black probe to the load side and the red probe to the supply side and then ensure that the multimeter is in series with the circuit once the circuit is powered we will then get the result with the manual range we need to select the correct setting we already know that this circuit is around 15 milliamps so we use the milliamp terminal and then choose the next highest value which in this case is 20 milliamps we can then see the result if we do not know the current then we start by using the 10A terminal we select the highest setting and we work our way down although here it shows it's just 0. 25 amps alternating current means the electrons in the electrical system are constantly flowing backwards and forwards we find this in our home's electrical system it is measured in amps or amperes this is represented by the letter A with a sine wave remember electricity is dangerous and can be fatal you should be qualified and competent to carry out any electrical work if you just need to measure AC current through a wire I would highly recommend that you instead use a clamp meter this is much safer simply clamp around one wire and select the alternating current option if you clamp the active and neutral wires together the current will cancel each other out and you will not get an accurate reading if you need to measure the current of a device then just buy an energy monitor plug instead unplug your device into this it will safely show you the current voltage and power if you absolutely must use a Multimeter then we have to connect the device in series with the circuit the device has a very low internal resistance so connecting in parallel will expose the meter to the full voltage of the circuit and this will instantly cause an enormous flow of current through your meter and it will destroy it so be very careful the probes will also become electrified along with any conductive surface they come into contact with again be careful first check that your meter has an AC current setting if it doesn't then do not attempt to use it for this purpose next check the terminal identification some will have a dedicated terminal for measuring milliamps and it will state the maximum current that it can handle if you know that your circuit will exceed this or you do not know the maximum current then we need to use the terminal marked with an a typically this will be labeled 10A indicating a maximum of 10 amps can be connected it usually tells you for how long for example a maximum of 10mm times for 10 seconds and you must then disconnect it for 15 minutes to cool down if you measure a lower current you might be able to extend this time please check the manufacturer's guide for this most meters will come with a fuse to protect the device this heats up and breaks the circuit if you exceed 10 amps you can check the fuse by connecting the red lead to the V terminal and placing the probe into the fuse terminal and then we select the resistance setting if it displays a value of less than 0.

5 it should be okay if it states o l then it is broken you can remove the back cover to replace the fuse to use the multimeter place your red probe into the 10A terminal and the black lead into the com terminal and then select the alternating current setting ensure the power is disconnected from the circuit connect the black probe to the load side and the red probe to the supply side ensuring your meter is now in series with the circuit check the area and ensure it is safe to turn the power back on you will then see the results if you have a manual range meter start with the highest setting this is usually 10 amps it will then display the results we use the continuity function to test if two points in a circuit are connected if so it means electricity can flow simply connect your black lead into the com terminal and the red lead into the terminal with a continuity symbol if it doesn't show this that it has the function then we can use the V terminal the screen will default to ol meaning open loop tap the leads together to test the meter you should hear a continuous tone it will also display the resistance usually in wires this is around zero ohms or very close we can use this setting to test a break in the circuit or a wire we can test that switches operate correctly and we can check if fuses are also working correctly we can test cables over very long distances by connecting one end together and testing the other end it's important to know that we can get false readings though if we try to test between these two points which are clearly broken the meter has found an alternative route and so it will indicate continuity you must consider this an isolate where possible continuity tests do not work with high resistance circuits for example this wire is fine this low value resistor is also fine but this high value resistor is too much and the meter indicates that there isn't continuity even though there is frequency uses this symbol this refers to how many times the pattern of an electrical signal repeats per second for example homes in North America use 60 hertz and homes in Europe use 50 hertz this just means that the AC sine wave repeats 60 or 50 times per second but we measure this in the unit of Hertz this is all to do with the speed of the electrical generator look remember electricity is dangerous and can be fatal you should be qualified and competent to carry out any electrical work to read frequency we insert the red lead into the V terminal and the black lead into the com terminal then select the frequency function on the meter ensure your leads equipment and working area is safe and I recommend turning the power off first do not touch the probe ends wear rubber boots to insulate yourself and stay away from any grounded surfaces then Connect into the electrical system and when it is safe to do so turn the power on the meter will now show the frequency and the value will change depending on where you are in the world turn the power off before disconnecting this particular meter defaults to ac voltage and indicates we need to press the yellow button to take a frequency reading diodes look something like this they only allow current to flow in One Direction we use this symbol to represent them in engineering drawings to test them turn the dial to the diode setting connect the red lead to the diode terminal and the black lead to the com terminal if we connect the leads like this we should read ol because the diode has blocked the meter from taking a reading when we reverse the leads a value should appear typically between 0. 5 and 0. 8 if ol displays on both orientations or a reading of around 0.

4 appears in both directions then the diode is faulty and needs replacing we can also check diodes with the resistance function we should see a value of between one kilo ohm to 10 mega ohms and reversing the connections we should just see ol LEDs are also diodes they just emit light we can use the diode function to test these also the LED should produce ATM light LEDs only light in One Direction and block the current in the reverse Direction high voltage LEDs will not show a value capacitors store and discharge electrons within the circuit they are represented with these symbols on the side of electrolytic capacitors it should State the rated capacity the maximum voltage and also the negative terminal some types do not display this we would need to therefore find the manufacturer's data sheet capacitors can store high voltages for a very long time after they've been disconnected do not touch the leads as it will discharge through you we can test the voltage of the capacitor by selecting the DC voltage setting place the black wire into the com terminal and the red wire into the V terminal then carefully connect the probes to the capacitor with the black probe touching the negative terminal of a polarized capacitor not all capacitors are polarized the meter will Now display the stored voltage if we see a reading of several volts or more like this one then we should place an appropriately sized resistor across the terminals this is a small capacitor so I will just use a 2 kilo ohm 0. 25 watt resistor and then we can see the stored energy is safely discharged now select the capacitor setting this particular model defaults to diodes and indicates that we need to press the yellow button to switch to the capacitor setting the black lead remains in the com terminal and the red lead in the capacitor symbol terminal connect the black probe to the negative side if polarized and connect the red probe to the positive side it will then display the result with non-polarized types we can use the probes on either side the result will probably not match the rated value you can see here that this one is slightly higher and this one is slightly lower so we need to consider if they are appropriately sized for our circuit and we can exchange them if needed transistors look like this and they are basically a type of electronic switch they are represented by these symbols although we use the hfe setting on a multimeter to test them we locate the identification number on the front and then we find the data sheet for that it will tell us here if this is an npn or a PNP type it will tell us which leg is the base emitter and collector and also the hfe value which is the current gain next you will need to locate the transistor test area on the meter sometimes we need an adapter like this one we then select the hfe setting we then align the transistor with the type for example this is an npn type so I use the npn side and then we insert the legs into the correct terminals the meter then displays the result this one is within range so it's good to use if the meter shows a value outside of this range or it displays just a one then the transistor is faulty if you do not have an inbuilt transistor tester then we can use the diode setting insert the red lead into the terminal with the diode symbol and the black lead into the com terminal then insert your transistor into a test board we already know that this one is an npn type so we place the red lead on the base bin and we will then see a reading of around 0. 6 to 0.

7 when we connect to either the emitter or The Collector it should not give a reading if we test across the emitter and collector or if we place the black Probe on the base and then test the emitter or collector this one is a PNP type so we need to place the black Probe on the base pin when we place the red Probe on the emitter or collector we should see a reading of between 0. 6 and 0. 7 we should not see a reading if we test across the emitter and collector or if we place the red lead on the base pin and test the emitter or collector this is the symbol for temperature reading although not all multimeters have this it's very simple to use this feature we just find our temperature probe which typically looks like this with the thermocouple at one end and the connectors are the opposite end ensure that the connectors are inserted with the correct polarity place the black lead into the com terminal and the red lead into the terminal marked with the temperature symbol although this one just says input but we can still use this terminal then select the temperature setting on the meter it will then display the result this one defaults to Celsius but we can change the fahrenheit just by pressing the button these probes are used for air temperature or surface temperature only do not use them in water we need to test a battery in two ways first place the red lead into the V terminal and the black lead into the com terminal then select the DC voltage setting we connect the red probe to the positive terminal and the black probe to the negative then we see the voltage results this battery is rated at 1.

5 volts but when we test it we see 1. 593 volts that's because this is brand new and fully charged this battery reads 1. 07 volts so the battery is dead to fully test the battery we need to take a resistor of around 100 ohms and connect this across the probes then we connect the pros to the battery terminals the current will flow through the resistor the voltage should only drop slightly this battery is rated at 1.

5 volts and under a load it reads 1. 547 volts so this battery is good however this battery is also rated at 1. 5 volts but when I test it with a resistor the voltage drops to 0.

86 volts so this battery is not good and needs replacing check out one of the videos on screen now to continue learning about Electronics engineering and I'll catch you there for the next lesson don't forget to follow us on Facebook Twitter LinkedIn Tick Tock Instagram and the engineeringmindset.