How to Use a Multimeter Tester

Updated on: December 17, 2018

Contents

The Introduction

This guide will certainly show you just how to use a digital multimeter (DMM), a vital device that you can use to diagnose circuits, discover other people’s electronic designs, and also multimeter tester. For this reason the ‘multi’-‘meter’ or several measurement name.

One of the most standard things we measure are voltage and also current. A multimeter is likewise excellent for some standard peace of mind checks and also troubleshooting. Is your circuit not functioning? Does the button job? Put a meter on it! The multimeter is your very first protection when repairing a system. In this tutorial we will cover measuring voltage, current, resistance and continuity.

Every fixer should know their way around a multimeter, which has just north of a zillion makes use of for screening digital elements as well as circuits.

In this tutorial we’re going to reveal you exactly how to make use of a multimeter. This tutorial is primarily resolved for beginners that are starting out in electronic devices as well as have no concept exactly how to make use of a multimeter as well as how it can be beneficial. We’ll discover the most typical features on a multimeter as well as just how to measure current, voltage, resistance as well as exactly how to check continuity.

What is a multimeter and why do you require one?

A multimeter is a measurement tool absolutely necessary in electronic devices. It combines 3 essential functions: a voltmeter, ohmeter, as well as ammeter, and in some situations continuity.

The tool permits you to recognize what is taking place in your circuits. Whenever something in your circuit isn’t working, it will certainly assist you repairing. Right here’s some circumstances in electronic devices projects that you’ll locate the multimeter beneficial:

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

What should multimeters measure?

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

A few multimeters have a continuity check, leading to a loud beep if two things are electrically attached. This is valuable if, as an example, you are developing a circuit as well as attaching cables or soldering; the beep shows everything is linked and nothing has come loose. You can additionally use it to see to it two points are not attached, to assist prevent brief circuits.

Some multimeters likewise have a diode check function. A diode is like a one-way valve that just lets electrical power circulation in one instructions. The specific feature of the diode check can vary from one type to another. If you’re collaborating with a diode and also can’t tell which way it enters the circuit, or if you’re uncertain the diode is functioning correctly, the check function can be quite convenient. If your DMM has a diode check function, read the handbook to discover precisely just how it functions.

Advanced models might have various other features, such as the ability to measure and also recognize other electrical elements, like transistors or capacitors. Considering that not nearly all multimeters have these attributes, we will not cover them in this tutorial. You can review your multimeter’s manual if you require to make use of these functions.

What Do All Of the Symbols Mean?

There’s a great deal taking place when you look at the selection knob, but if you’re only mosting likely to be doing some fundamental stuff, you won’t even utilize fifty percent of all the setups. In any situation, here’s a run-through of what each sign means:

Direct Current Voltage (DCV):Occasionally it will certainly be denoted with a V– instead. This setup is utilized to measure straight current (DC) voltage crazes like batteries.
Alternating Current Voltage (ACV): Sometimes it will be represented with a V ~ rather. This setting is used to measure the voltage from alternating current sources, which is virtually anything that connects right into an electrical outlet, along with the power coming from the outlet itself.
Resistance (Ω): This determines just how much resistance there is in the circuit. The lower the number, the much easier it is for the current to flow via, as well as the other way around.
Continuity: Usually represented by a wave or diode icon. This merely examines whether a circuit is full by sending a really tiny amount of current with the circuit as well as seeing if it makes it out the various other end. If not, after that there’s something along the circuit that’s causing an issue– locate it!
Direct Current Amperage (DCA): Similar to DCV, but as opposed to offering you a voltage analysis, it will tell you the amperage.
Straight Current Gain (hFE): This setting is to examine transistors and also their DC gain, but it’s mainly ineffective, since many electrical experts and hobbyists will use the continuity check instead.

Your multimeter could additionally have a specialized setting for examining the amperage of AA, AAA, and also 9V batteries. This setup is normally signified with the battery icon.

Once more, you probably won’t also make use of fifty percent of the settings revealed, so don’t get overwhelmed if you only understand what a few of them do.

How to Use a Multimeter

For beginners, allow’s look at several of the different parts of a multimeter. At the really basic level you have the device itself, in addition to two probes, which are the black as well as red cables that have plugs on one end as well as steel ideas on the various other.

The tool itself has a display screen on top, which provides you your readout, and there’s a huge selection knob that you can spin around to pick a specific setup. Each setup might additionally have various number values, which exist to measure various toughness of voltages, resistances, and amps. So if you have your multimeter set to 20 in the DCV area, it will measure voltages approximately 20 volts.

Your DMM will certainly additionally come with two or three ports for connecting in the probes:

the COM port mean “Common”, and also the black probe will constantly connect into this port.
VΩmA port (often denoted as mAVΩ) is just an acronym for voltage, resistance, and also current (in milliamps). This is where the red probe will connect into if you’re measuring voltage, resistance, continuity, as well as current much less than 200mA.
the 10ADC port (often signified as just 10A) is used whenever you’re measuring current that’s even more than 200mA. If you’re uncertain of the current draw, begin with this port. On the various 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 greater than 200mA, you plug the red probe right into the 10A port, rather than the 200mA port. Otherwise you could blow the fuse that’s within the multimeter. Furthermore, measuring anything over 10 amps can blow a fuse or ruin the multimeter too.

Your measurement tool may have completely different ports for measuring amps, while the other port is particularly simply for voltage, resistance, as well as continuity, but most cheaper multimeters will share ports.

Anyhow, allow’s get begun actually making use of 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 straightforward cord as some instances to get you began and acquainted with making use of a multimeter.

Parts of Multimeters

Multimeters have four components:

Display: this particular is exactly where the measurements are displayed
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. Generally, one is red and also the various other is black.

Ports

“COM” or “–” port is where the black probe should be attached. The COM probe is conventionally black.
10A is used when measuring large currents, above 200mA.
µAmA is used to measure current.
VΩ allows you to measure voltage and resistance as well as examination continuity.

COM

COM represent common and is virtually always connected to Ground or ‘-‘ of a circuit.The COM probe is conventionally black yet there is no distinction between the red probe as well as black probe besides shade.

10A

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

Selection Knob

The selection knob enables the user to set the tool to read various points such as milliamps (mA) of current, voltage (V) and also resistance (Ω).

Probes

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 right into the multimeter. Any probe with a banana plug will certainly collaborate with this meter. This enables various sorts of probes to be used.

Probe Types

There are various sorts of probes available. Below are a few of our faves:

Banana to Alligator Clips: These are great cables for connecting to large wires or pins on a breadboard. Great for carrying out longer term examinations where you do not need to need to hold the probes in location while you adjust a circuit.
Banana to IC Hook: IC hooks function well on smaller sized ICs as well as legs of ICs.
Banana to Tweezers: Tweezers are handy if you are requiring to check SMD parts.
Banana to Test Probes: If you ever before break a probe, they are economical to change!

Measuring Voltage

To begin, let’s measure voltage on a AA battery: Plug the black probe right into COM and the red probe right into mAVΩ. Set to “2V” in the DC (straight current) array. Mostly all mobile electronic devices utilize direct current), not alternating current. Attach 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 positive as well as adverse terminals of the AA battery. If you’ve got a fresh battery, you ought to see around 1.5 V on the display (this battery is brand-new, so its voltage is somewhat greater than 1.5 V).

You can easily measure DC voltage or AC voltage. The V with a straight line suggests DC voltage. The V with the bumpy line indicates AC voltage.

In order to measure voltage take all these steps:

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.
Make sure the red probe is attached to the port with a V alongside it.
Link the red probe to the silver lining of your component, which is where the current is originating from.
Attach the COM probe to the opposite of your component.
Check out the worth on the screen.

Tip: to measure voltage you have to connect your multimeter in parallel with the component you wish to measure the voltage. Putting the multimeter in parallel is placing each probe along the leads of the component you want to measure the voltage.

Measuring a battery’s voltage

In this example we’re mosting likely to measure the voltage of a 1.5 V battery. You recognize that you’ll have around 1.5 V. So, you must pick an array with the selection knob that can read the 1.5 V. So you must choose 2V when it comes to this multimeter. If you have an autorange one, you do not need to bother with the array you need to choose.

Begin by turning on it, connecting the probes right into their corresponding ports and after that establishing the selection knob to the highest possible number worth in the DCV area, which in my instance is 500 volts. If you do not recognize at the very least the voltage series of the important things you’re measuring, it’s constantly a good concept to start with the highest possible worth initially and after that work your means down up until you get an accurate reading.

In this instance, we recognize the AA battery has an extremely reduced voltage, yet we’ll start at 200 volts just for the benefit of instance. Next off, position the black probe on the adverse end of the battery and the red probe on the favorable end. Have a look at the reading on the display. Because we have the multimeter set to a high 200 volts, it reveals “1.6” on the screen, suggesting 1.6 volts.

Nonetheless, I want an even more accurate reading, so I’ll relocate the selection knob lower down to 20 volts. Below, you can see that we have a more accurate reading that floats in between 1.60 and also 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 review “1”, indicating 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 way too much for the multimeter to deal with at that setting.

In any kind of situation, you might be asking why you would certainly require to evaluate the voltage of something to begin with. Well, in this situation 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. However, if it were to check out 1.2 volts, it’s close to being pointless.
In an extra practical circumstance, you could do this sort of measuring on a vehicle battery to see if it may be passing away or if the generator (which is what bills the battery) is spoiling. A reading in between 12.4-12.7 volts implies that the battery remains in good condition. Anything reduced which’s evidence of a passing away battery. In addition, start your automobile up and rev it up a little bit. If the voltage doesn’t raise to around 14 volts approximately, after that it’s most likely that the alternator is having issues.

Overload

What takes place if you pick a voltage setup that is as well reduced for the voltage you’re trying to measure? Absolutely nothing negative. The meter will simply show a 1. This is the meter trying to tell you that it is overloaded or out-of-range. Whatever you’re trying to review is way too much for that particular setup. Attempt altering the multimeter handle to a the next highest setting.

Selection Knob

How come does the meter knob read 20V as well as not 10V? If you’re aiming to measure a voltage less than 20V, you count on the 20V setting. This will permit you to check out from 2.00 to 19.99. The first digit on several multimeters is just able to present a ‘1’ so the arrays are limited to 19.99 as opposed to 99.99. Therefore the 20V max variety rather than 99V max variety.

Measuring Resistance

Plug the red probe right into the ideal port and turn the selection knob to the resistance area. Then, attach 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 recognize what they imply, that’s ok! There are lots of online calculators that are easy to utilize. However, if you ever locate on your own without net gain access to, a multimeter is extremely handy at measuring resistance.

Choose an arbitrary resistor as well as established the multimeter to the 20kΩ setup. After that hold the probes versus the resistor legs with the exact same quantity of stress you when pressing a secret on a key-board.

The meter will review one of 3 things, 0.00, 1, or the real resistor worth.

In this case, the meter reviews 0.97, meaning this resistor has a value of 970Ω, or concerning 1kΩ (remember you remain in the 20kΩ or 20,000 Ohm mode so you need to relocate the decimal three places to the right or 970 Ohms).

If the multimeter checks out 1 or shows OL, it’s overloaded. You will certainly require to try a greater setting such as 200kΩ setting or 2MΩ (megaohm) mode. There is no injury if this take place, it just suggests the range knob needs to be adjusted.

When the multimeter reads 0.00 or nearly no, then you require to reduce the setting to 2kΩ or 200Ω.

Remember that several resistors have a 5% resistance. This indicates that the shade codes may suggest 10,000 Ohms (10kΩ), but due to discrepancies in the production 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 just great as a pull-up or general resistor.

As a policy of thumb, it’s uncommon to see a resistor less than 1 Ohm. Bear in mind that measuring resistance is not excellent. Temperature level can affect the checking out a lot. Also, measuring resistance of a tool while it is literally mounted in a circuit can be very difficult. The bordering parts on a motherboard can substantially impact the analysis.

The mockup usually looks like with a standard clock running of a AA battery. On the positive side, the wire going from the battery to the clock is separated. We merely position our 2 probes in between that break to complete the circuit once more (with the red probe linked to the source of power), just this time our multimeter will certainly read out the amps that the clock is drawing, which in this instance is around 0.08 mA.

While many multimeters can also measure alternating current (AC), it’s not actually a great concept (especially if its live power), considering that AC can be dangerous if you wind up slipping up. If you require to see whether an electrical outlet is working, use a non-contact tester rather.

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

TIP: to position the multimeter in collection, you require to put the red probe on the lead of a component as well as the black probe on the following component lead. The multimeter acts as if it was a wire in your circuit. If you detach the multimeter, your circuit won’t work.

Prior to measuring the current, make certain that you’ve plugged in the red probe in the ideal port, in this case µAmA. In the instance below, the same circuit of the previous instance is utilized. The multimeter becomes part of the circuit.

Check Continuity

If there is very reduced resistance between 2 factors, which is much less than a few ohms, both points are electrically connected and you’ll hear a continuous noise. If the noise isn’t continuous or if you do not listen to any type of noise in all, it indicates that what you’re testing has a malfunctioning connection or isn’t linked in any way.

CAUTION: In order to evaluate continuity you should shut off the system! Turn off the power supply!

Touch both probes with each other and, as they are attached, you’ll listen to a continuous sound.To test the continuity of a cable, you simply need to connect each probe to the cord suggestions.

Continuity is a fantastic means to evaluate if 2 SMD pins are touching. If your eyes can not see it, the multimeter is typically a fantastic second testing resource. When a system is not working, continuity is another point to assist troubleshoot the system.

Establish your multimeter to the continuity setup using the selection knob.
The readout on the display will instantly review “1”, which implies that there isn’t any kind of continuity. This would be right given that we have not linked the probes to anything yet.
Next, ensure the circuit is unplugged as well as has no power. Then connect one probe to one end of the cord and the other probe to the various other end– it doesn’t matter which probe takes place which end. If there is a complete circuit, your multimeter will certainly either beep, reveal a “0”, or something other than a “1”. If it still shows a “1”, after that there’s a problem and also your circuit isn’t full.
You can additionally evaluate that the continuity function works with your multimeter by touching both probes to each various other. This completes the circuit and also your multimeter must allow you know that.

A continuity examination informs us whether 2 points are electrically linked: if something is constant, an electrical current can flow freely from one end to the various other.

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

Changing the Fuse

Among the most typical errors with a brand-new multimeter is to measure current on a bread board by penetrating from VCC to GND. This will quickly brief power to ground via the multimeter causing the bread board power supply to brownish out. As the current hurries with the multimeter, the interior fuse will warm up and after that stress out as 200mA moves through it. It will occur in an instant and without any genuine audible or physical sign that something is wrong.

Keep in mind that measuring current is performed in collection (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 probably observe that the meter checks out ‘0.00’ which the system does not transform on like it should when you attach the multimeter. This is since the interior fuse is damaged and also acts as a broken wire or open.

To change the fuse, find your convenient dandy mini screw driver, and begin securing screws. The elements and PCB traces inside the multimeter are made to take different amounts of current. You will certainly damage and possibly wreck your multimeter if you unintentionally push 5A through the 200mA port.

There are times where you need to measure high current tools like a motor or heating aspect. Do you see both places to place 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 danger of blowing the fuse. However if you make use of the 10A port to measure current, you run a much reduced threat of blowing the fuse. The compromise is level of sensitivity. As we chatted about above, by utilizing the 10A port as well as knob setup, you will only be able to review to 0.01 A or 10mA. Most of systems utilize greater than 10mA so the 10A setting and also port works all right. If you’re trying to measure really low power (micro or nano amps) the 200mA port with the 2mA, 200uA, or 20uA might be what you need.

Final thought

You’re now prepared to utilize your digital multimeter to start measuring the world around you. Do not hesitate to begin using it to address lots of concerns. A digital multimeter will answer numerous inquiries regarding electronic devices.

A multimeter is a crucial device in any type of electronic devices lab. In this guide, we’ve revealed you How To Use a Multimeter. You’ve discovered how to measure voltage, current and resistance, as well as just how to check continuity.