How To Use A Multimeter To Check Continuity

Updated on: December 15, 2018

Contents

Intro

These recommendations will show you how to utilize a digital multimeter (DMM), an indispensable device that you can utilize to diagnose circuits, find out regarding other individuals’s digital designs, and also to check continuity. Thus the ‘multi’-‘meter’ or numerous measurement name.

One of the most standard points we measure are voltage and current. A multimeter is additionally excellent for some basic sanity checks and also troubleshooting. Is your circuit not functioning? Does the switch work? Put a meter on it! The multimeter is your first protection when fixing a system. In this tutorial we will certainly cover measuring voltage, current, resistance and continuity.

Every fixer must know their way around a multimeter, which has simply north of a zillion makes use of for testing digital elements and also circuits.

In this tutorial we’re mostly likely to show you exactly how to utilize a multimeter. This tutorial is mostly addressed for beginners who are starting in electronic devices as well as have no suggestion how to utilize a multimeter as well as how it can be valuable. We’ll discover one of the most typical functions on a multimeter and how to measure current, voltage, resistance and also just how to examine continuity.

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

A multimeter is a measurement tool definitely required in electronic devices. It combines three essential features: a voltmeter, ohmeter, as well as ammeter, and in some instances continuity.

The tool allows you to recognize what is taking place in your circuits. Whenever something in your circuit isn’t functioning, it will certainly aid you troubleshooting. Right here’s some situations in electronic devices projects that you’ll locate the multimeter helpful:

is the switch on?
is this wire conducting the electrical energy or is it broken?
just how much current is moving via this led?
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.

Certain multimeters have a continuity check, causing a loud beep if 2 points are electrically attached. This is useful if, for circumstances, you are developing a circuit and connecting cables or soldering; the beep indicates everything is linked as well as nothing has come loose. You can additionally use it to make sure 2 points are not linked, to assist prevent brief circuits.

A couple of multimeters likewise have a diode check feature. A diode is like a one-way shutoff that only allows electrical energy flow in one direction. The precise feature of the diode check can vary from one type to another. If you’re collaborating with a diode as well as can’t inform which method it enters the circuit, or if you’re not exactly sure the diode is functioning effectively, the check attribute can be rather useful. If your DMM has a diode check function, read the guidebook to discover exactly just how it functions.

Advanced models might have various other functions, such as the capacity to measure and also determine other electric elements, like transistors or capacitors. Considering that not all multimeters have these attributes, we will not cover them in this tutorial. You can read your multimeter’s manual if you require to utilize these features.

What Do All Of the Symbols Mean?

There’s a great deal going on when you take a look at the selection knob, yet if you’re only mosting likely to be doing some fundamental things, you won’t also utilize half of all the setups. Regardless, right here’s a review of what each symbol means:

Direct Current Voltage (DCV):quite often it will be represented with a V– rather. This setting is used to measure straight current (DC) voltage crazes like batteries.
Alternating Current Voltage (ACV): Sometimes it will be represented with a V ~ instead. This setting is utilized to measure the voltage from alternating current sources, which is basically anything that connects into an outlet, along with the power coming from the outlet itself.
Resistance (Ω): This measures how much resistance there remains in the circuit. The reduced the number, the much easier it is for the current to move via, as well as the other way around.
Continuity: Usually represented by a wave or diode symbol. This just checks whether a circuit is complete by sending out an extremely percentage of current with the circuit and seeing if it makes it out the other end. Otherwise, then there’s something along the circuit that’s triggering a problem– discover it!
Straight Current Amperage (DCA): Similar to DCV, yet rather of giving you a voltage reading, it will certainly inform you the amperage.
Direct Current Gain (hFE): This setting is to test transistors and their DC gain, yet it’s primarily worthless, considering that the majority of electricians and also enthusiasts will certainly utilize the continuity check rather.

Your multimeter could also have a specialized setup for testing the amperage of AA, AAA, and 9V batteries. This setup is typically denoted with the battery sign.

Once again, you possibly will not even use half of the settings revealed, so don’t obtain overwhelmed if you just recognize what a few of them do.

How to Utilize a Multimeter

For beginners, allow’s look at several of the different components of a multimeter. At the extremely basic level you have the tool itself, along with 2 probes, which are the black as well as red cords that have plugs on one end and also metal tips on the various other.

The tool itself has a screen at the top, which offers you your readout, as well as there’s a huge selection knob that you can rotate around to pick a certain setup. Each setup might likewise have different number values, which exist to measure different staminas of voltages, resistances, as well as amps. So if you have your multimeter collection to 20 in the DCV section, it will certainly measure voltages approximately 20 volts.

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

COM port stands for “Common”, as well as the black probe will always link into this port.
VΩmA port (sometimes denoted as mAVΩ) is simply an acronym for voltage, resistance, and also current (in milliamps). This is where the red probe will certainly connect into if you’re measuring voltage, resistance, continuity, as well as current less than 200mA.
the 10ADC port (occasionally signified as just 10A) is used whenever you’re measuring current that’s greater than 200mA. If you’re unsure of the current draw, start with this port. On the other hand, you would certainly not use this port in all if you’re measuring anything apart from current.

Caution: Make sure that if you’re measuring anything with a current greater than 200mA, you connect the red probe right into the 10A port, instead than the 200mA port. Otherwise you might blow the fuse that’s within of the multimeter. In addition, measuring anything over 10 amps might blow a fuse or ruin the multimeter too.

Your measurement tool could have entirely separate ports for measuring amps, while the various other port is particularly simply for voltage, resistance, as well as continuity, however a lot of more affordable multimeters will certainly share ports.

Anyway, let’s get going really 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 basic wire as some examples to get you started and also acquainted with using a multimeter.

Components of a Multimeter

A multimeter is made up by 4 crucial areas:

Display: this is where the measurements are presented
Selection Knob: this picks what you wish to measure
Ports: this is where you connect in the probes
Probes: a multimeter comes with 2 probes. Generally, one is red and also the various other is black.

Ports

“COM” or “–” port is where the black probe ought to be attached. The COM probe is traditionally black.
10A is made use of when measuring huge currents, higher than 200mA.
µAmA is utilized to measure current.
VΩ enables you to measure voltage and resistance and examination continuity.

COM

COM represent common as well as is usually linked to Ground or ‘-‘ of a circuit.The COM probe is traditionally black however there is no distinction between the red probe and black probe besides shade.

10A

10A is the special port utilized when measuring huge currents (higher than 200mA).

Selection Knob

The selection knob allows the individual to establish the tool to read various things such as milliamps (mA) of current, voltage (V) and resistance (Ω).

Probes

Two probes are linked into 2 of the ports on the front of the device. The probes have a banana type adapter on the end that connects into the multimeter. Any probe with a banana plug will certainly deal with this meter. This enables various kinds of probes to be used.

Probe Types

There are several sorts of probes offered. Here are a few of our favorites:

Banana to Alligator Clips: These are fantastic cords for attaching to big cables or pins on a breadboard. Great for executing longer term tests where you don’t need to have to hold the probes in position while you manipulate a circuit.
Banana to IC Hook: IC hooks work well on smaller sized ICs and also legs of ICs.
Banana to Tweezers: Tweezers are useful if you are requiring to examine SMD components.
Banana to Test Probes: If you ever damage a probe, they are economical to change!

Measuring Voltage

To begin, allow’s measure voltage on a AA battery: Plug the black probe right into COM as well as the red probe right into mAVΩ. Establish to “2V” in the DC (straight current) variety. Mostly all portable electronics use straight current), not alternating current. Connect the black probe to the battery’s ground or ‘-‘ as well as the red probe to power or ‘+’. Squeeze the probes with a little stress versus the positive as well as unfavorable terminals of the AA battery. If you’ve got a fresh battery, you should see around 1.5 V on the display screen (this battery is 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 indicates DC voltage. The V with the curly line means AC voltage.

So as to measure voltage take all of these steps:

Set the setting 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.
Make certain the red probe is linked to the port with a V alongside it.
Link the red probe to the positive side of your component, which is where the current is originating from.
Link the COM probe to the opposite side of your component.
Read the value on the display screen.

Tip: 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 putting each probe along the leads of the component you intend to measure the voltage.

Measuring a battery’s voltage

In this instance we’re going to measure the voltage of a 1.5 V battery. You understand that you’ll have about 1.5 V. So, you must select a variety with the selection knob that can review the 1.5 V. So you should choose 2V in the instance of this multimeter. If you obtain an autorange one, you do not need to fret about the array you need to choose.

Start by turning on it, connecting the probes right into their corresponding ports and after that setting the selection knob to the greatest number worth in the DCV area, which in my case is 500 volts. If you don’t recognize at the very least the voltage variety of things you’re measuring, it’s always an excellent idea to begin with the highest value initially and also after that function your method down up until you get a precise reading.

In this instance, we understand the AA battery has an extremely reduced voltage, but we’ll start at 200 volts simply for the purpose of example. Next off, position the black probe on the unfavorable end of the battery as well as the red probe on the favorable end. Have a look at the reading on the screen. Considering that we have the multimeter collection to a high 200 volts, it shows “1.6” on the screen, meaning 1.6 volts.

Nevertheless, I want an even more precise analysis, so I’ll relocate the selection knob reduced to 20 volts. Here, you can see that we have an even more precise analysis that hovers between 1.60 as well as 1.61 volts. If you were to ever before establish the selection knob to a number worth less than the voltage of things you’re checking, the multimeter would just read “1”, indicating that it’s overloaded. So if I were to establish the handle to 200 millivolts (0.2 volts), the 1.6 volts of the AA battery is way too much for the multimeter to handle at that setting.

All the same, you could be asking why you would require to examine the voltage of something to begin with. Well, in this instance with the AA battery, we’re examining to see if it has any juice left. At 1.6 volts, that’s a fully-loaded battery. Nevertheless, if it were to check out 1.2 volts, it’s close to being pointless.
In a more sensible circumstance, you might do this sort of measuring on a car battery to see if it may be passing away or if the alternator (which is what bills the battery) is going poor. An analysis in between 12.4-12.7 volts means that the battery remains in great shape. Anything reduced and that’s proof of a dying battery. Furthermore, start your cars and truck up and rev it up a little bit. If the voltage does not enhance to around 14 volts or two, after that it’s most likely that the alternator is having issues.

Overload

What happens if you choose a voltage setting that is as well low for the voltage you’re trying to measure? Nothing bad. The meter will merely display a 1. This is the meter trying to inform you that it is overloaded or out-of-range. Whatever you’re attempting to read is as well much for that particular setup. Attempt changing the multimeter handle to a the following highest possible setup.

Selection Knob

Precisely why does the meter knob read 20V as well as not 10V? If you’re looking to measure a voltage less than 20V, you turn to the 20V setting. This will certainly enable you to read from 2.00 to 19.99. The initial digit on numerous multimeters is just able to show a ‘1’ so the varieties are limited to 19.99 instead of 99.99. Thus the 20V max variety as opposed to 99V max range.

Measuring Resistance

Plug the red probe into the appropriate port and also turn the selection knob to the resistance section. Then, link the probes to the resistor leads. The means you attach the leads doesn’t matter, the outcome coincides.

Normal resistors have shade codes on them. If you do not know what they mean, that’s ok! There are plenty of on-line calculators that are simple to use. Nonetheless, if you ever locate on your own without web gain access to, a multimeter is extremely handy at measuring resistance.

Choose out an arbitrary resistor and set the multimeter to the 20kΩ setup. Then hold the probes against the resistor legs with the exact same amount of stress you when pressing a secret on a keyboard.

The meter will certainly review one of three things, 0.00, 1, or the actual resistor value.

In this situation, the meter reads 0.97, suggesting this resistor has a value of 970Ω, or concerning 1kΩ (remember you are 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 reads 1 or presents OL, it’s overwhelmed. You will certainly need to attempt a greater setting such as 200kΩ mode or 2MΩ (megaohm) setting. There is no damage if this take place, it simply indicates the variety handle needs to be adjusted.

In case the multimeter checks out 0.00 or almost no, after that you need to lower the setting to 2kΩ or 200Ω.

Keep in mind that several resistors have a 5% tolerance. This means that the shade codes may show 10,000 Ohms (10kΩ), yet as a result of discrepancies in the production procedure a 10kΩ resistor might be as low as 9.5 kΩ or as high as 10.5 kΩ. Don’t fret, it’ll function just great as a pull-up or basic resistor.

Generally of thumb, it’s uncommon to see a resistor much less than 1 Ohm. Keep in mind that measuring resistance is not ideal. Temperature level can affect the checking out a great deal. Also, measuring resistance of a device while it is physically installed in a circuit can be really complicated. The bordering elements on a circuit board can substantially influence the analysis.

The mockup usually appears like with a standard clock running off of a AA battery. On the positive side, the wire going from the battery to the clock is broken up. We simply position our 2 probes in between that break to complete the circuit again (with the red probe linked to the power source), just this time our multimeter will certainly read out the amps that the clock is pulling, which in this situation is around 0.08 mA.

While many multimeters can additionally measure alternating current (AC), it’s not really a great idea (specifically if its online power), since AC can be harmful if you wind up slipping up. If you need to see whether or not an outlet is functioning, utilize a non-contact tester rather.

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

IDEA: to put the multimeter in series, you require to position the red probe on the lead of a component and also the black probe on the next component lead. The multimeter acts as if it was a wire in your circuit. If you disconnect the multimeter, your circuit won’t function.

Before measuring the current, make certain that you’ve connected at a loss probe in the ideal port, in this situation µAmA. In the example listed below, the same circuit of the previous example is made use of. The multimeter becomes part of the circuit.

Tests Continuity

If there is really low resistance between two points, which is much less than a couple of ohms, the 2 factors are electrically attached and also you’ll hear a continuous audio. If the noise isn’t continual or if you don’t hear any type of sound in any way, it means that what you’re testing has a faulty connection or isn’t connected in any way.

WARNING: In order to examine continuity you need to turn off the system. Turn off the power source.

Touch the 2 probes together as well as, as they are attached, you’ll listen to a constant sound.To examination the continuity of a wire, you simply require to link each probe to the cable pointers.

Continuity is a wonderful way to test if 2 SMD pins are touching. If your eyes can’t see it, the multimeter is usually a fantastic 2nd testing resource. When a system is not working, continuity is one even more thing to assist troubleshoot the system.

Establish your multimeter to the continuity setting making use of the selection knob.
The readout on the display will instantaneously check out “1”, which suggests that there isn’t any continuity. This would be right because we haven’t linked the probes to anything yet.
Next, ensure the circuit is unplugged and has no power. After that attach one probe to one end of the cord as well as the various other probe to the other end– it does not matter which probe takes place which end. If there is a full circuit, your multimeter will certainly either beep, show a “0”, or something besides a “1”. If it still reveals a “1”, after that there’s a problem as well as your circuit isn’t total.
You can additionally test that the continuity attribute works on your multimeter by touching both probes to each other. This finishes the circuit and your multimeter should allow you recognize that.

A continuity test informs us whether 2 points are electrically linked: if something is constant, an electrical current can stream openly from one end to the other.

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

Changing the Fuse

Among the most common blunders with a brand-new multimeter is to measure current on a bread board by penetrating from VCC to GND. This will immediately brief power to ground with the multimeter creating the bread board power supply to brownish out. As the current hurries with the multimeter, the interior fuse will warm up and afterwards shed out as 200mA flows with it. It will certainly take place in an instant and also with no real distinct or physical indicator that something is incorrect.

Bear in mind that measuring current is done in series (interrupt the VCC line to the breadboard or microcontroller to measure current). If you attempt to measure the current with a blown fuse, you’ll probably notice that the meter reviews ‘0.00’ which the system doesn’t activate like it should when you connect the multimeter. This is since the internal fuse is damaged and also serves as a busted cable or open.

To alter the fuse, find your convenient dandy mini screw driver, and also begin obtaining screws. The elements and also PCB traces inside the multimeter are made to take different amounts of current. You will damage as well as potentially ruin your multimeter if you accidentally push 5A with the 200mA port.

There are times where you need to measure high current tools like a motor or burner. Do you see the two areas to put the red probe on the front of the multimeter? 10A left wing and mAVΩ on the right? If you try to measure more than 200mA on the mAVΩ port you run the risk of blowing the fuse. However if you use the 10A port to measure current, you run a much lower threat of blowing the fuse. The compromise is level of sensitivity. As we discussed above, by using the 10A port and handle setting, you will just be able to check out down to 0.01 A or 10mA. A lot of systems utilize more than 10mA so the 10A setup as well as port functions well sufficient. If you’re attempting to measure very reduced power (mini or nano amps) the 200mA port with the 2mA, 200uA, or 20uA could be what you need.

Conclusions

You’re currently prepared to utilize your digital multimeter to start measuring the globe around you. Really feel totally free to begin using it to answer lots of inquiries. A digital multimeter will certainly respond to many questions about electronic devices.

A multimeter is a vital device in any kind of electronics lab. In this guide, we’ve shown you How To Use a Multimeter. You’ve discovered how to measure voltage, current and resistance, as well as just how to inspect continuity.