Updated on: December 11, 2018
This guide will certainly show you exactly how to use a digital multimeter (DMM), a vital tool that you can utilize to detect circuits, discover other individuals’s digital styles, and also even on a car fuse. Hence the ‘multi’-‘meter’ or numerous dimension name.
One of the most standard things we measure are voltage as well as current. A multimeter is likewise excellent for some basic peace of mind checks and troubleshooting. Is your circuit not working? Does the switch work? Put a meter on it! The multimeter is your very first support when repairing a system. In this tutorial we will certainly cover measuring voltage, current, resistance as well as continuity.
Every fixer should know their method around a multimeter, which has just north of a zillion uses for testing electronic parts and circuits.
In this tutorial we’re going to reveal you how to use a multimeter. This tutorial is mainly resolved for beginners who are beginning out in electronics and also have no suggestion exactly how to utilize a multimeter and how it can be helpful. We’ll explore the most common features on a multimeter and exactly how to measure current, voltage, resistance and also just how to inspect continuity.
What is a multimeter and why do you require one?
A multimeter is a measurement device definitely needed in electronic devices. It integrates three crucial attributes: a voltmeter, ohmeter, and ammeter, and in some situations continuity.
The tool allows you to comprehend what is taking place in your circuits. Whenever something in your circuit isn’t functioning, it will certainly help you fixing. Here’s some scenarios in electronics projects that you’ll locate the multimeter helpful:
- is the button on?
- is this cable performing the electrical energy or is it broken?
- how much current is streaming through this led?
- just how much power do you have left on your batteries?
What can multimeters measure?
Nearly all multimeters can measure voltage, current, as well as resistance.
Various multimeters have a continuity check, resulting in a loud beep if two points are electrically connected. This is handy if, for instance, you are constructing a circuit and also linking wires or soldering; the beep indicates every little thing is linked as well as absolutely nothing has come loose. You can additionally utilize it to see to it two points are not connected, to aid stop short circuits.
Certain multimeters additionally have a diode check feature. A diode resembles a one-way shutoff that just allows power circulation in one direction. The exact feature of the diode check can differ from one type to another. If you’re working with a diode as well as can not tell which means it enters the circuit, or if you’re not certain the diode is functioning appropriately, the check function can be fairly handy. If your DMM has a diode check function, reviewed the guidebook to discover precisely just how it functions.
Advanced models could have other features, such as the ability to measure as well as identify various other electric elements, like transistors or capacitors. Because not all other multimeters have these attributes, we will not cover them in this tutorial. You can review your multimeter’s guidebook if you require to use these features.
What Do Every One Of the Symbols Mean?
There’s a lot going on when you look at the selection knob, however if you’re only going to be doing some basic stuff, you will not also make use of half of all the settings. In any case, right here’s a review of what each symbol indicates:
Direct Current Voltage (DCV):quite often it will be represented with a V– rather. This setup is utilized to measure straight current (DC) voltage in points like batteries.
Alternating Current Voltage (ACV): Sometimes it will be signified with a V ~ instead. This setup is made use of to measure the voltage from alternating current sources, which is virtually anything that links into an electrical outlet, as well as the power originating from the outlet itself.
Resistance (Ω): This gauges just how much resistance there remains in the circuit. The reduced the number, the less complicated it is for the current to stream with, and also the other way around.
Continuity: Usually signified by a wave or diode sign. This merely evaluates whether a circuit is full by sending a very percentage of current via the circuit as well as seeing if it makes it out the other end. If not, after that there’s something along the circuit that’s causing a trouble– discover it!
Direct Current Amperage (DCA): Similar to DCV, yet as opposed to providing you a voltage reading, it will certainly inform you the amperage.
Direct Current Gain (hFE): This setting is to test transistors and also their DC gain, but it’s mainly useless, since a lot of electrical contractors as well as hobbyists will utilize the continuity check instead.
Your multimeter might also have a devoted setting for evaluating the amperage of AA, AAA, and 9V batteries. This setup is normally represented with the battery icon.
Once more, you most likely will not even make use of half of the settings revealed, so don’t get bewildered if you just understand what a few of them do.
Just how to Use a Multimeter
For beginners, let’s review a few of the various components of a multimeter. At the extremely standard degree you have the device itself, together with two probes, which are the black and also red cords that have plugs on one end as well as steel pointers on the other.
The tool itself has a display at the top, which gives you your readout, and there’s a large selection knob that you can rotate around to select a specific setting. Each setup may additionally have different number worths, which exist to measure various toughness of voltages, resistances, and also amps. So if you have your multimeter set to 20 in the DCV section, it will certainly measure voltages up to 20 volts.
Your DMM will certainly likewise have two or three ports for plugging in the probes:
- the COM port stands for “Common”, and also the black probe will constantly connect into this port.
- VΩmA port (in some cases signified as mAVΩ) is just an acronym for voltage, resistance, as well as current (in milliamps). This is where the red probe will link into if you’re measuring voltage, resistance, continuity, and also current less than 200mA.
- the 10ADC port (often represented as simply 10A) is utilized whenever you’re measuring current that’s greater than 200mA. If you’re not exactly sure of the current draw, begin with this port. On the various other hand, you would not utilize this port in all if you’re measuring anything apart from current.
Warning: Make sure that if you’re measuring anything with a current higher than 200mA, you connect the red probe into the 10A port, as opposed to the 200mA port. Or else you could blow the fuse that’s within the multimeter. In addition, measuring anything over 10 amps can blow a fuse or destroy the multimeter also.
Your measurement tool might have totally different ports for measuring amps, while the other port is specifically simply for voltage, resistance, and also continuity, yet a lot of more affordable multimeters will share ports.
Anyway, let’s begin actually utilizing a multimeter. We’ll be measuring the voltage of a AA battery, the current draw of a wall clock, and also the continuity of a straightforward cord as some instances to obtain you started as well as acquainted with using a multimeter.
Parts of Multimeters
Multimeters have four components:
- Display: this is exactly where the measurements are presented
- Selection Knob: this chooses what you intend to measure
- Ports: this is where you plug in the probes
- Probes: a multimeter features 2 probes. Typically, one is red and also the various other is black.
- “COM” or “–” port is where the black probe needs to be connected. The COM probe is conventionally black.
- 10A is utilized when measuring large currents, better than 200mA.
- µAmA is made use of to measure current.
- VΩ permits you to measure voltage as well as resistance and also examination continuity.
COM mean usual and is usually linked to Ground or ‘-‘ of a circuit.The COM probe is conventionally black however there is no distinction between the red probe and black probe apart from color.
10A is the unique port made use of when measuring large currents (higher than 200mA).
The selection knob permits the customer to set the tool to check out different points such as milliamps (mA) of current, voltage (V) as well as resistance (Ω).
Two probes are connected into two of the ports on the front of the system. The probes have a banana type adapter on the end that connects into the multimeter. Any kind of probe with a banana plug will certainly function with this meter. This allows for various kinds of probes to be utilized.
There are various kinds of probes readily available. Right here are a few of our faves:
- Banana to Alligator Clips: These are terrific wires for attaching to large wires or pins on a breadboard. Great for carrying out longer term tests where you do not have to need to hold the probes in position while you control a circuit.
- Banana to IC Hook: IC hooks function well on smaller sized ICs as well as legs of ICs.
- Banana to Tweezers: Tweezers come in handy if you are needing to evaluate SMD components.
- Banana to Test Probes: If you ever damage a probe, they are affordable to replace!
To begin, let’s measure voltage on a AA battery: Plug the black probe right into COM and the red probe into mAVΩ. Establish to “2V” in the DC (direct current) variety. Mostly all mobile electronics use straight current), not alternating current. Attach the black probe to the battery’s ground or ‘-‘ and the red probe to power or ‘+’. Squeeze the probes with a little stress versus the favorable as well as unfavorable terminals of the AA battery. If you’ve got a fresh battery, you need to see around 1.5 V on the screen (this battery is brand name brand-new, so its voltage is somewhat more than 1.5 V).
You may measure DC voltage or AC voltage. The V with a straight line suggests DC voltage. The V with the bumpy line implies AC voltage.
- Set the mode to V with a bumpy line if you’re measuring AC voltage or to the V with a straight line if you’re measuring DC voltage.
- See to it the red probe is connected to the port with a V alongside it.
- Connect the red probe to the positive side of your component, which is where the current is coming from.
- Connect the COM probe to the other side of your component.
- Read the worth on the display screen.
Suggestion: to measure voltage you need to attach your multimeter in parallel with the component you wish to measure the voltage. Placing the multimeter in parallel is placing each probe along the leads of the component you desire to measure the voltage.
Measuring a battery’s voltage
In this example we’re going to measure the voltage of a 1.5 V battery. You understand that you’ll have roughly 1.5 V. So, you should select a variety with the selection knob that can review the 1.5 V. So you ought to select 2V in the instance of this multimeter. If you take an autorange one, you don’t need to fret about the range you need to select.
Start by turning on it, connecting the probes into their respective ports and also then setting the selection knob to the highest number value in the DCV section, which in my situation is 500 volts. If you do not recognize at the very least the voltage variety of the important things you’re measuring, it’s constantly an excellent idea to start with the highest possible value initially and after that function your way down till you get an exact reading.
In this case, we know the AA battery has an extremely low voltage, yet we’ll begin at 200 volts just for the sake of example. Next off, put the black probe on the negative end of the battery and the red probe on the positive end. Have a look at the reading on the display. Considering that we have the multimeter set to a high 200 volts, it reveals “1.6” on the display, suggesting 1.6 volts.
Nevertheless, I want an even more precise reading, so I’ll move the selection knob reduced to 20 volts. Below, you can see that we have an even more accurate reading that hovers in between 1.60 and also 1.61 volts. If you were to ever before establish the selection knob to a number worth less than the voltage of the thing you’re examining, the multimeter would simply check out “1”, symbolizing that it’s overwhelmed. So if I were to establish the knob to 200 millivolts (0.2 volts), the 1.6 volts of the AA battery is too much for the multimeter to handle at that setting.
All the same, you might be asking why you would certainly require to test the voltage of something to begin with. Well, in this case with the AA battery, we’re checking to see if it has any kind of juice left. At 1.6 volts, that’s a fully-loaded battery. Nevertheless, if it were to review 1.2 volts, it’s close to being unusable.
In a more practical circumstance, you might do this kind of measuring on a car battery to see if it may be passing away or if the alternator (which is what charges the battery) is spoiling. A reading in between 12.4-12.7 volts suggests that the battery is in good shape. Anything reduced and that’s evidence of a passing away battery. Moreover, start your automobile up and rev it up a little bit. If the voltage doesn’t raise to around 14 volts or so, then it’s most likely that the generator is having issues.
What happens if you select a voltage setting that is as well reduced for the voltage you’re trying to measure? Absolutely nothing bad. The meter will merely present a 1. This is the meter trying to tell you that it is overloaded or out-of-range. Whatever you’re trying to read is way too much for that specific setup. Try changing the multimeter knob to a the following greatest setting.
As to why does the meter knob read 20V and also not 10V? If you’re looking to measure a voltage less than 20V, you turn to the 20V setting. This will certainly allow you to read from 2.00 to 19.99. The first figure on many multimeters is only able to show a ‘1’ so the ranges are limited to 19.99 as opposed to 99.99. Thus the 20V max variety instead of 99V max variety.
Plug the red probe right into the best port as well as turn the selection knob to the resistance area. After that, connect the probes to the resistor leads. The means you connect the leads does not matter, the outcome coincides.
Normal resistors have shade codes on them. If you don’t understand what they suggest, that’s ok! There are lots of online calculators that are easy to make use of. However, if you ever locate on your own without internet access, a multimeter is really handy at measuring resistance.
Pick an arbitrary resistor as well as established the multimeter to the 20kΩ setup. After that hold the probes versus the resistor legs with the same amount of stress you when pressing a trick on a keyboard.
The meter will certainly read among 3 points, 0.00, 1, or the actual resistor value.
In this case, the meter reads 0.97, meaning this resistor has a worth of 970Ω, or regarding 1kΩ (remember you remain in the 20kΩ or 20,000 Ohm setting so you require to relocate the decimal 3 areas to the right or 970 Ohms).
If the multimeter reviews 1 or presents OL, it’s overloaded. You will certainly require to try a greater mode such as 200kΩ setting or 2MΩ (megaohm) mode. There is no damage if this occur, it simply indicates the range knob requires to be changed.
In case the multimeter reads 0.00 or almost absolutely no, after that you require to reduce the setting to 2kΩ or 200Ω.
Keep in mind that many resistors have a 5% resistance. This suggests that the color codes might show 10,000 Ohms (10kΩ), however due to the fact that of inconsistencies in the manufacturing process a 10kΩ resistor can be as low as 9.5 kΩ or as high as 10.5 kΩ. Don’t worry, it’ll function simply fine as a pull-up or basic resistor.
Generally of thumb, it’s rare to see a resistor less than 1 Ohm. Keep in mind that measuring resistance is not ideal. Temperature can affect the reading a great deal. Likewise, measuring resistance of a device while it is physically installed in a circuit can be really challenging. The surrounding parts on a circuit board can greatly affect the analysis.
The mockup typically appears like with a standard clock running of a AA battery. On the silver lining, the cable going from the battery to the clock is separated. We just place our two probes in between that break to finish the circuit once more (with the red probe attached to the power resource), just this time around our multimeter will certainly read out the amps that the clock is pulling, which in this instance is around 0.08 mA.
While many multimeters can likewise measure rotating current (AC), it’s not really an excellent idea (specifically if its real-time power), given that AC can be dangerous if you wind up slipping up. If you require to see whether an electrical outlet is functioning, make use of a non-contact tester instead.
To measure current you require to birth in mind that elements in series share a current. So, you require to link your multimeter in series with your circuit.
IDEA: to put the multimeter in collection, you require to place the red probe on the lead of a component and also the black probe on the following component lead. The multimeter acts as if it was a cord in your circuit. If you separate the multimeter, your circuit won’t function.
Before measuring the current, make sure that you’ve plugged in the red probe in the appropriate port, in this case µAmA. In the example below, the exact same circuit of the previous instance is made use of. The multimeter belongs to the circuit.
If there is extremely low resistance between two points, which is much less than a few ohms, the two points are electrically attached and also you’ll listen to a continuous sound. If the audio isn’t constant or if you do not listen to any noise whatsoever, it implies that what you’re testing has a malfunctioning link or isn’t linked in any way.
WARNING: To be able to check continuity you need to shut off the system! Switch off the power supply.
Touch both probes with each other and, as they are attached, you’ll hear a continuous sound.To examination the continuity of a cord, you just need to connect each probe to the cable pointers.
Continuity is a terrific way to check if 2 SMD pins are touching. If your eyes can’t see it, the multimeter is usually a wonderful 2nd testing resource. When a system is not functioning, continuity is one more point to assist fix the system.
- Establish your multimeter to the continuity setup using the selection knob.
- The readout on the display will immediately check out “1”, which implies that there isn’t any kind of continuity. This would be correct since we haven’t linked the probes to anything yet.
- Next off, ensure the circuit is unplugged as well as has no power. After that attach one probe to one end of the wire and also the various other probe to the other end– no matter which probe takes place which end. If there is a full circuit, your multimeter will certainly either beep, show a “0”, or something aside from a “1”. If it still shows a “1”, after that there’s a problem as well as your circuit isn’t full.
- You can additionally test that the continuity feature works on your multimeter by touching both probes to each other. This finishes the circuit and your multimeter need to let you know that.
A continuity examination tells us whether 2 points are electrically attached: if something is constant, an electrical current can move freely from one end to the various other.
If there’s no continuity, it means there is a break somewhere in the circuit. This might show anything from a blown fuse or negative solder joint to an incorrectly wired circuit.
Altering the Fuse
Among one of the most common mistakes with a brand-new multimeter is to measure current on a bread board by probing from VCC to GND. This will right away brief power to ground with the multimeter creating the bread board power supply to brownish out. As the current hurries via the multimeter, the internal fuse will warm up and after that stress out as 200mA flows via it. It will occur in a split second and also without any kind of genuine distinct or physical indication that something is wrong.
Remember that measuring current is carried out in collection (interrupt the VCC line to the breadboard or microcontroller to measure current). If you try to measure the current with a blown fuse, you’ll probably discover that the meter checks out ‘0.00’ and also that the system doesn’t activate like it must when you connect the multimeter. This is due to the fact that the inner fuse is damaged as well as acts as a damaged cable or open.
To alter the fuse, discover your handy dandy mini screw chauffeur, as well as start securing screws. The components and also PCB traces inside the multimeter are made to take various amounts of current. You will damage and perhaps ruin your multimeter if you accidentally push 5A via the 200mA port.
There are times where you require to measure high current devices like an electric motor or heating element. Do you see both areas to place the red probe on the front of the multimeter? 10A left wing and mAVΩ on the right? If you attempt to measure greater than 200mA on the mAVΩ port you risk of blowing the fuse. Yet if you utilize the 10A port to measure current, you run a much reduced threat of blowing the fuse. The compromise is level of sensitivity. As we spoke about above, by using the 10A port as well as handle setup, you will only be able to check out to 0.01 A or 10mA. The majority of systems make use of greater than 10mA so the 10A setting and also port works well sufficient. If you’re trying to measure extremely reduced power (micro or nano amps) the 200mA port with the 2mA, 200uA, or 20uA could be what you need.
You’re now all set to use your digital multimeter to begin measuring the world around you. Do not hesitate to begin using it to address many concerns. A digital multimeter will answer many concerns regarding electronics.
A multimeter is a necessary device in any kind of electronic devices lab. In this overview, we’ve shown you How To Use a Multimeter. You’ve discovered exactly how to measure voltage, current as well as resistance, and exactly how to examine continuity.