How to Use a Multimeter to See If Power Is Off

Updated on: February 15, 2019

The Intro

This guide will certainly show you just how to use a digital multimeter (DMM), an important device that you can use to detect circuits, learn about other people’s digital designs, as well as also see if power is off. Thus the ‘multi’-‘meter’ or multiple measurement name.

The most standard things we measure are voltage and current. A multimeter is also fantastic for some basic sanity checks and also troubleshooting. Is your circuit not functioning? Does the switch work? Place a meter on it! The multimeter is your very first defence when repairing a system. In this tutorial we will cover measuring voltage, current, resistance as well as continuity.

Every fixer must recognize their method around a multimeter, which has just north of a zillion uses for screening electronic components and also circuits.

In this tutorial we’re mostly likely to reveal you how to use a multimeter. This tutorial is mostly attended to for newbies who are starting in electronics as well as have no suggestion exactly how to use a multimeter and exactly how it can be valuable. We’ll discover one of the most common features on a multimeter as well as exactly how to measure current, voltage, resistance as well as just how to inspect continuity.

What is a multimeter and also why do you require one?

A multimeter is a measurement device definitely essential in electronic devices. It integrates three vital functions: a voltmeter, ohmeter, and also ammeter, and in many cases continuity.

The tool allows you to comprehend what is going on in your circuits. Whenever something in your circuit isn’t functioning, it will certainly aid you fixing. Right here’s some situations in electronic devices tasks that you’ll find the multimeter helpful:

  • is the button activate?
  • is this wire carrying out the electrical power or is it broken?
  • just how much current is flowing through this led?
  • just how much power do you have left on your batteries?

What should multimeters measure?

Mostly all multimeters can measure voltage, current, as well as resistance.

A bunch of multimeters have a continuity check, causing a loud beep if 2 things are electrically attached. This is handy if, for example, you are constructing a circuit and also connecting wires or soldering; the beep suggests every little thing is attached and absolutely nothing has come loose. You can also utilize it to see to it two points are not attached, to aid prevent short circuits.

A few multimeters also have a diode check function. A diode resembles a one-way valve that just lets electricity circulation in one direction. The precise feature of the diode check can vary from one type to another. If you’re dealing with a diode and also can’t tell which method it goes in the circuit, or if you’re unsure the diode is functioning correctly, the check feature can be quite handy. If your DMM has a diode check feature, checked out the manual to figure out precisely how it works.

Advanced models could have other features, such as the capability to measure as well as determine various other electrical elements, like transistors or capacitors. Given that not nearly all multimeters have these attributes, we will certainly not cover them in this tutorial. You can read your multimeter’s handbook if you need to utilize these functions.

What Do Every One Of the Symbols Mean?

There’s a whole lot going on when you take a look at the selection knob, yet if you’re just mosting likely to be doing some standard things, you will not even utilize half of all the setups. All the same, below’s a run-through of what each sign implies:

Direct Current Voltage (DCV):every now and then it will be represented with a V– instead. This setting is utilized to measure straight current (DC) voltage crazes like batteries.
Alternating Current Voltage (ACV): Sometimes it will certainly be represented with a V ~ instead. This setup is utilized to measure the voltage from alternating current resources, which is pretty much anything that connects right into an outlet, in addition to the power coming from the outlet itself.
Resistance (Ω): This measures exactly how much resistance there is in the circuit. The lower the number, the less complicated it is for the current to stream through, and also vice versa.
Continuity: Usually represented by a wave or diode sign. This just examines whether a circuit is complete by sending out a very small amount of current with the circuit and seeing if it makes it out the various other end. Otherwise, after that there’s something along the circuit that’s triggering a problem– find it!
Direct Current Amperage (DCA): Similar to DCV, yet as opposed to providing you a voltage reading, it will certainly tell you the amperage.
Direct Current Gain (hFE): This setting is to examine transistors and their DC gain, however it’s mainly pointless, because the majority of electrical experts and hobbyists will use the continuity check instead.

Your multimeter might also have a committed setup for testing the amperage of AA, AAA, and also 9V batteries. This setup is normally signified with the battery sign.

Again, you most likely won’t also utilize fifty percent of the setups revealed, so don’t obtain bewildered if you only recognize what a few of them do.

Just how to Use a Multimeter

For beginners, let’s discuss several of the different components of a multimeter. At the extremely basic level you have the tool itself, in addition to 2 probes, which are the black and also red cords that have plugs on one end and steel ideas on the other.

The tool itself has a display screen at the top, which offers you your readout, as well as there’s a huge selection knob that you can spin around to pick a details setup. Each setting might likewise have various number values, which are there to measure various toughness of voltages, resistances, and also amps. So if you have your multimeter set to 20 in the DCV area, it will certainly measure voltages as much as 20 volts.

Your DMM will certainly likewise feature two or 3 ports for plugging in the probes:

  • COM port stands for “Common”, and the black probe will certainly always connect into this port.
  • the VΩmA port (sometimes represented as mAVΩ) is simply an acronym for voltage, resistance, and 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 denoted as simply 10A) is utilized whenever you’re measuring current that’s greater than 200mA. If you’re not certain of the current draw, begin with this port. On the other hand, you would certainly not use this port whatsoever if you’re measuring anything apart from current.

Warning: Make sure that if you’re measuring anything with a current more than 200mA, you connect the red probe into the 10A port, instead of the 200mA port. Or else you could blow the fuse that’s within the multimeter. Furthermore, measuring anything over 10 amps could blow a fuse or destroy the multimeter as well.

Your measurement tool may have entirely different ports for measuring amps, while the other port is particularly just for voltage, resistance, and continuity, however most more affordable multimeters will certainly share ports.

Anyway, let’s start in fact utilizing a multimeter. We’ll be measuring the voltage of a AA battery, the current draw of a wall surface clock, and the continuity of a simple wire as some instances to obtain you started as well as knowledgeable about using a multimeter.

Parts of Multimeters

Multimeters have 4 components:

  • Display: this is just where the measurements are shown
  • Selection Knob: this chooses what you intend to measure
  • Ports: this is where you connect in the probes
  • Probes: a multimeter comes with two probes. Usually, one is red as well as the various other is black.
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Ports

  • “COM” or “–” port is where the black probe ought to be connected. The COM probe is traditionally black.
  • 10A is used when measuring huge currents, above 200mA.
  • µAmA is made use of to measure current.
  • enables you to measure voltage and resistance and also examination continuity.

COM

COM represent typical and is usually attached to Ground or ‘-‘ of a circuit.The COM probe is conventionally black yet there is no distinction between the red probe and also black probe apart from shade.

10A

10A is the unique port made use of when measuring large currents (more than 200mA).

Selection Knob

The selection knob permits the customer to establish the tool to check out different things such as milliamps (mA) of current, voltage (V) as well as resistance (Ω).

Probes

Two probes are linked into 2 of the ports on the front of the unit. The probes have a banana type port on the end that links into the multimeter. Any type of probe with a banana plug will certainly collaborate with this meter. This permits various sorts of probes to be used.

Probe Types

There are lots of different sorts of probes readily available. Below are a few of our faves:

  • Banana to Alligator Clips: These are terrific wires for connecting to large cords or pins on a breadboard. Great for executing longer term examinations where you do not need to have to hold the probes in area while you manipulate a circuit.
  • Banana to IC Hook: IC hooks work well on smaller ICs and legs of ICs.
  • Banana to Tweezers: Tweezers are helpful if you are needing to check SMD elements.
  • Banana to Test Probes: If you ever damage a probe, they are economical to replace!

Measuring Voltage

To begin, allow’s measure voltage on a AA battery: Plug the black probe into COM and the red probe right into mAVΩ. Set to “2V” in the DC (direct current) array. Nearly all mobile electronic devices utilize direct current), not alternating current. Connect the black probe to the battery’s ground or ‘-‘ and also the red probe to power or ‘+’. Squeeze the probes with a little stress versus the favorable and adverse terminals of the AA battery. If you’ve obtained a fresh battery, you must see around 1.5 V on the display (this battery is all new, so its voltage is somewhat more than 1.5 V).

You can certainly measure DC voltage or AC voltage. The V with a straight line implies DC voltage. The V with the wavy line implies AC voltage.

Measuring voltage

  1. Set the mode to V with a curly line if you’re measuring AC voltage or to the V with a straight line if you’re measuring DC voltage.
  2. Ensure the red probe is linked to the port with a V following to it.
  3. Attach the red probe to the silver lining of your component, which is where the current is coming from.
  4. Link the COM probe to the opposite side of your component.
  5. Read the worth on the display.

Pointer: to measure voltage you have to link your multimeter in parallel with the component you want to measure the voltage. Positioning the multimeter in parallel is putting each probe along the leads of the component you intend 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 know that you’ll have approximately 1.5 V. So, you must choose a variety with the selection knob that can read the 1.5 V. So you ought to choose 2V in the instance of this multimeter. If you obtain an autorange one, you do not have to stress over the range you need to pick.

Begin by activating it, plugging the probes into their particular ports and after that setting the selection knob to the greatest number value in the DCV area, which in my case is 500 volts. If you don’t understand a minimum of the voltage array of the important things you’re measuring, it’s constantly an excellent idea to start with the highest worth initially and afterwards function your means down up until you get an accurate analysis.

In this instance, we understand the AA battery has a really low voltage, yet we’ll begin at 200 volts simply for the purpose of example. Next off, position the black probe on the negative end of the battery and also the red probe on the positive end. Take a look at the analysis on the display. Considering that we have the multimeter collection to a high 200 volts, it shows “1.6” on the display, suggesting 1.6 volts.

Nevertheless, I desire an even more precise analysis, so I’ll move the selection knob reduced down to 20 volts. Here, you can see that we have an even more exact analysis that floats in between 1.60 as well as 1.61 volts. If you were to ever establish the selection knob to a number worth less than the voltage of things you’re evaluating, the multimeter would simply read “1”, symbolizing that it’s overwhelmed. So if I were to establish the handle to 200 millivolts (0.2 volts), the 1.6 volts of the AA battery is excessive for the multimeter to manage at that setting.

In any type of case, you may be asking why you would certainly require to check the voltage of something to begin with. Well, in this situation with the AA battery, we’re examining to see if it has any type 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 pointless.
In a more practical situation, you can do this kind of measuring on a cars and truck battery to see if it could be dying or if the alternator (which is what bills the battery) is going poor. A reading between 12.4-12.7 volts indicates that the battery is in good condition. Anything lower and also that’s evidence of a passing away battery. Furthermore, start your car up as well as rev it up a bit. If the voltage doesn’t boost to about 14 volts or two, then it’s likely that the alternator is having problems.

Overload

What occurs if you choose a voltage setup that is also low for the voltage you’re trying to measure? Nothing poor. The meter will merely show a 1. This is the meter attempting to tell you that it is overloaded or out-of-range. Whatever you’re trying to read is excessive for that certain setting. Try transforming the multimeter handle to a the following greatest setup.

Selection Knob

Exactly why does the meter knob checked out 20V as well as not 10V? If you’re aiming to measure a voltage much less than 20V, you resort to the 20V setup. This will enable you to check out from 2.00 to 19.99. The very first figure on numerous multimeters is just able to display a ‘1’ so the ranges are restricted to 19.99 as opposed to 99.99. For this reason the 20V max range as opposed to 99V max array.

Measuring Resistance

Plug the red probe right into the best port and turn the selection knob to the resistance section. After that, connect the probes to the resistor leads. The way you connect the leads does not matter, the outcome is the very same.

Normal resistors have color codes on them. If you don’t understand what they indicate, that’s ok! There are lots of on the internet calculators that are simple to utilize. Nevertheless, if you ever locate on your own without internet gain access to, a multimeter is extremely convenient at measuring resistance.

Choose a random resistor and established the multimeter to the 20kΩ setup. After that hold the probes versus the resistor legs with the same quantity of stress you when pressing a trick on a key-board.

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The meter will check out among three points, 0.00, 1, or the actual resistor worth.

In this instance, the meter reads 0.97, implying this resistor has a value of 970Ω, or regarding 1kΩ (remember you are in the 20kΩ or 20,000 Ohm mode so you need to relocate the decimal 3 locations to the right or 970 Ohms).

If the multimeter checks out 1 or displays OL, it’s overwhelmed. You will need to try a higher setting such as 200kΩ mode or 2MΩ (megaohm) mode. There is no damage if this take place, it merely implies the variety handle needs to be changed.

Should the multimeter reviews 0.00 or virtually no, then you need to lower the mode to 2kΩ or 200Ω.

Keep in mind that lots of resistors have a 5% resistance. This implies that the color codes might indicate 10,000 Ohms (10kΩ), yet due to the fact that of disparities in the manufacturing procedure a 10kΩ resistor can be as low as 9.5 kΩ or as high as 10.5 kΩ. Don’t fret, it’ll work just great as a pull-up or basic resistor.

As a regulation of thumb, it’s uncommon to see a resistor much less than 1 Ohm. Bear in mind that measuring resistance is not excellent. Temperature level can influence the reading a whole lot. Also, measuring resistance of a tool while it is physically mounted in a circuit can be extremely complicated. The surrounding parts on a motherboard can significantly influence the analysis.

The mockup typically appears like with a basic clock running off of a AA battery. On the favorable side, the cable going from the battery to the clock is separated. We just place our 2 probes in between that break to complete the circuit once more (with the red probe attached to the power source), only this moment our multimeter will certainly review out the amps that the clock is drawing, which in this instance is around 0.08 mA.

While the majority of multimeters can likewise measure alternating current (AC), it’s not truly an excellent suggestion (particularly if its real-time power), because AC can be unsafe if you finish up slipping up. If you require to see whether or not an outlet is working, use a non-contact tester rather.

To measure current you require to keep in mind that elements in collection share a current. So, you need to attach your multimeter in collection with your circuit.

IDEA: to put the multimeter in series, you require to put the red probe on the lead of a component as well as the black probe on the next component lead. The multimeter acts as if it was a cable in your circuit. If you detach the multimeter, your circuit will not function.

Prior to measuring the current, make sure that you’ve connected at a loss probe in the ideal port, in this situation µAmA. In the instance listed below, the exact same circuit of the previous example is utilized. The multimeter becomes part of the circuit.

Check Continuity

If there is very low resistance in between 2 factors, which is much less than a few ohms, the two factors are electrically attached and also you’ll hear a continuous audio. If the noise isn’t constant or if you do not listen to any noise in any way, it indicates that what you’re testing has a damaged connection or isn’t linked at all.

WARNING: To examine continuity you must turn off the system! Shut off the power supply!

Touch the 2 probes together and also, as they are connected, you’ll hear a continual sound.To examination the continuity of a cord, you just need to attach each probe to the cord pointers.

Continuity is a great means to test if 2 SMD pins are touching. If your eyes can not see it, the multimeter is typically a terrific 2nd testing resource. When a system is not functioning, continuity is one even more thing to help troubleshoot the system.

  • Establish your multimeter to the continuity setting making use of the selection knob.
  • The readout on the display will quickly check out “1”, which implies that there isn’t any type of continuity. This would certainly be correct since we have not attached the probes to anything yet.
  • Next, ensure the circuit is unplugged as well as has no power. After that link one probe to one end of the cord and also the various other probe to the various other end– it matters not which probe takes place which end. If there is a full circuit, your multimeter will certainly either beep, show a “0”, or something other than a “1”. If it still shows a “1”, after that there’s an issue and also your circuit isn’t complete.
  • You can likewise examine that the continuity feature services your multimeter by touching both probes to each other. This finishes the circuit as well as your multimeter must allow you recognize that.

A continuity test informs us whether two things are electrically linked: if something is constant, an electric current can move openly from one end to the various other.

If there’s no continuity, it means there is a break someplace in the circuit. This might suggest anything from a blown fuse or bad solder joint to an improperly wired circuit.

Changing the Fuse

One of the most typical mistakes with a brand-new multimeter is to measure current on a bread board by penetrating from VCC to GND. This will promptly short power to ground through the multimeter causing the bread board power supply to brownish out. As the current rushes through the multimeter, the interior fuse will heat up as well as after that stress out as 200mA flows through it. It will certainly happen in a fraction of a second as well as without any type of real distinct or physical indicator that something is wrong.

Remember that measuring current is performed in series (disturb the VCC line to the breadboard or microcontroller to measure current). If you attempt to measure the current with a blown fuse, you’ll possibly discover that the meter reads ‘0.00’ which the system does not turn on like it ought to when you connect the multimeter. This is due to the fact that the interior fuse is damaged as well as functions as a damaged wire or open.

To change the fuse, locate your handy dandy mini screw driver, and also begin obtaining screws. The elements as well as PCB traces inside the multimeter are developed to take different amounts of current. You will harm and also perhaps destroy your multimeter if you inadvertently push 5A via the 200mA port.

There are times where you require to measure high current gadgets like a motor or heating aspect. Do you see the two locations to put the red probe on the front of the multimeter? 10A on the left and also mAVΩ on the right? If you attempt to measure greater than 200mA on the mAVΩ port you risk of blowing the fuse. However if you use the 10A port to measure current, you run a much reduced risk of blowing the fuse. The trade-off is sensitivity. As we spoke about above, by utilizing the 10A port and also handle setting, you will just have the ability to check out to 0.01 A or 10mA. The majority of systems utilize greater than 10mA so the 10A setup and also port functions well enough. If you’re trying to measure extremely low power (micro or nano amps) the 200mA port with the 2mA, 200uA, or 20uA could be what you require.

Final thought

You’re now prepared to use your digital multimeter to start measuring the world around you. Do not hesitate to start using it to address numerous questions. A digital multimeter will answer several inquiries regarding electronics.

A multimeter is an essential tool in any electronic devices lab. In this overview, we’ve revealed you How To Use a Multimeter. You’ve found out exactly how to measure voltage, current and also resistance, and also just how to examine continuity.