fbpx

How Do I Use a Multimeter to Check Voltage

Updated on: December 11, 2018

Overview

These tips will show you exactly how to use a digital multimeter (DMM), a vital device that you can utilize to detect circuits, discover other individuals’s digital designs, as well as also check voltage. Hence the ‘multi’-‘meter’ or multiple dimension name.

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

Every fixer must understand their means around a multimeter, which has simply north of a zillion uses for testing electronic parts and circuits.

In this tutorial we’re going to show you how to utilize a multimeter. This tutorial is primarily addressed for beginners that are starting in electronic devices as well as have no idea just how to make use of a multimeter as well as just how it can be beneficial. We’ll discover the most typical functions on a multimeter and just how to measure current, voltage, resistance and also exactly how to examine continuity.

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

A multimeter is a measurement device definitely needed in electronic devices. It combines 3 crucial attributes: a voltmeter, ohmeter, and ammeter, and in many cases continuity.

The tool allows you to understand what is going on in your circuits. Whenever something in your circuit isn’t functioning, it will certainly assist you repairing. Below’s some circumstances in electronics tasks that you’ll discover the multimeter helpful:

  • is the switch turn on?
  • is this cord conducting the power or is it broken?
  • exactly how much current is streaming with this led?
  • just how much power do you have left on your batteries?

What would multimeters measure?

Mostly all multimeters can measure voltage, current, and also resistance.

Quite a few multimeters have a continuity check, leading to a loud beep if two points are electrically linked. This is valuable if, for instance, you are building a circuit and also connecting wires or soldering; the beep shows everything is linked and nothing has come loose. You can additionally use it to make certain two things are not attached, to assist stop brief circuits.

Various multimeters likewise have a diode check function. A diode resembles a one-way shutoff that only allows power flow in one instructions. The specific feature of the diode check can vary from one type to another. If you’re functioning with a diode and can’t tell which method it goes in the circuit, or if you’re unsure the diode is working appropriately, the check attribute can be rather convenient. If your DMM has a diode check function, read the handbook to figure out specifically just how it functions.

Advanced models may have various other functions, such as the ability to measure and also identify various other electrical components, like transistors or capacitors. Since not all multimeters have these features, we will not cover them in this tutorial. You can review your multimeter’s handbook if you need to utilize these attributes.

What Do All the Symbols Mean?

There’s a lot taking place when you take a look at the selection knob, but if you’re just mosting likely to be doing some standard stuff, you won’t also utilize fifty percent of all the settings. In any type of situation, below’s a rundown of what each sign indicates:

Direct Current Voltage (DCV):once in a while it will certainly be represented with a V– instead. This setting is utilized to measure straight current (DC) voltage in things like batteries.
Alternating Current Voltage (ACV): Sometimes it will certainly be represented with a V ~ rather. This setting is used to measure the voltage from alternating current sources, which is virtually anything that links into an outlet, as well as the power coming from the outlet itself.
Resistance (Ω): This determines exactly how much resistance there is in the circuit. The lower the number, the simpler it is for the current to flow through, and the other way around.
Continuity: Usually signified by a wave or diode icon. This merely tests whether a circuit is complete by sending an extremely small amount 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 triggering a problem– discover it!
Straight Current Amperage (DCA): Similar to DCV, however rather than offering you a voltage analysis, it will certainly tell you the amperage.
Straight Current Gain (hFE): This setup is to check transistors and also their DC gain, however it’s mainly worthless, given that a lot of electricians as well as enthusiasts will certainly utilize the continuity check rather.

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

Once more, you most likely won’t also use fifty percent of the setups revealed, so do not obtain bewildered if you only understand what a few of them do.

Just how to Use a Multimeter

For starters, let’s discuss a few of the various parts of a multimeter. At the really basic degree you have the gadget itself, together with two probes, which are the black and also red wires that have plugs on one end and also steel tips on the various other.

The tool itself has a screen on top, which gives you your readout, and also there’s a big selection knob that you can spin around to select a details setting. Each setup may additionally have various number values, which are there to measure different toughness of voltages, resistances, and amps. So if you have your multimeter set to 20 in the DCV section, it will measure voltages up to 20 volts.

Your DMM will certainly also come with two or 3 ports for connecting in the probes:

  • COM port represent “Common”, and also the black probe will certainly constantly link into this port.
  • the VΩmA port (in some cases represented as mAVΩ) is simply an acronym for voltage, resistance, and also current (in milliamps). This is where the red probe will certainly plug into if you’re measuring voltage, resistance, continuity, and also current less than 200mA.
  • the 10ADC port (occasionally signified as simply 10A) is made use of whenever you’re measuring current that’s greater than 200mA. If you’re uncertain of the current draw, begin with this port. On the various other hand, you would not use this port in any way if you’re measuring anything besides current.

Warning: Make certain that if you’re measuring anything with a current higher than 200mA, you plug the red probe right into the 10A port, rather than the 200mA port. Or else you could blow the fuse that’s within the multimeter. Furthermore, measuring anything over 10 amps might blow a fuse or damage the multimeters as well.

Your measurement tool may have entirely separate ports for measuring amps, while the other port is specifically simply for voltage, resistance, and also continuity, but many cheaper multimeters will share ports.

Anyway, allow’s begin in fact making use of 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 cable as some instances to get you started and also knowledgeable about utilizing a multimeter.

Parts of a Multimeter

Multimeters have four components:

  • Display: this specific is where the measurements are displayed
  • Selection Knob: this picks what you wish to measure
  • Ports: this is where you connect in the probes
  • Probes: a multimeter includes two probes. Normally, one is red and also the various other is black.
Read Also:  Best All Around Multimeter

Ports

  • “COM” or “–” port is where the black probe should be attached. The COM probe is conventionally black.
  • 10A is used when measuring huge currents, more than 200mA.
  • µAmA is utilized to measure current.
  • permits you to measure voltage and resistance and also test continuity.

COM

COM mean usual and also is usually linked to Ground or ‘-‘ of a circuit.The COM probe is traditionally black however there is no distinction in between the red probe as well as black probe besides color.

10A

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

Selection Knob

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

Probes

Two probes are plugged into 2 of the ports on the front of the system. The probes have a banana type connector on completion that connects into the multimeter. Any kind of probe with a banana plug will deal with this meter. This enables various kinds of probes to be made use of.

Probe Types

There are several types of probes readily available. Right here are a few of our faves:

  • Banana to Alligator Clips: These are wonderful cables for linking to big wires or pins on a breadboard. Great for doing longer term examinations where you don’t need to have to hold the probes in position while you manipulate a circuit.
  • Banana to IC Hook: IC hooks function well on smaller ICs and legs of ICs.
  • Banana to Tweezers: Tweezers are handy if you are requiring to check SMD elements.
  • Banana to Test Probes: If you ever damage a probe, they are cheap to replace!

Measuring Voltage

To start, allow’s measure voltage on a AA battery: Plug the black probe into COM and the red probe right into mAVΩ. Establish to “2V” in the DC (straight current) range. Virtually all portable electronic devices use straight current), not alternating current. Attach the black probe to the battery’s ground or ‘-‘ as well as the red probe to power or ‘+’. Squeeze the probes with a little pressure against the favorable and also unfavorable terminals of the AA battery. If you’ve got a fresh battery, you need to see around 1.5 V on the display screen (this battery is new, so its voltage is somewhat greater than 1.5 V).

You could 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 setting to V with a wavy line if you’re measuring AC voltage or to the V with a straight line if you’re measuring DC voltage.
  2. See to it the red probe is attached to the port with a V following to it.
  3. Link the red probe to the positive side of your component, which is where the current is originating from.
  4. Connect the COM probe to the other side of your component.
  5. Review the value on the display.

Pointer: to measure voltage you need to connect 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 wish 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 recognize that you’ll have approximately 1.5 V. So, you need to choose a range with the selection knob that can review the 1.5 V. So you ought to choose 2V when it comes to this multimeter. If you have an autorange one, you do not have to fret about the variety you need to pick.

Start by activating it, connecting the probes right into their respective ports and afterwards establishing the selection knob to the highest possible number value in the DCV section, which in my situation is 500 volts. If you don’t know at the very least the voltage variety of the point you’re measuring, it’s always an excellent concept to begin with the greatest value first and also after that work your method down up until you get an exact reading.

In this instance, we understand the AA battery has a very reduced voltage, yet we’ll begin at 200 volts just for the benefit of instance. Next, place the black probe on the unfavorable end of the battery and also the red probe on the positive end. Take a look at the analysis on the screen. Considering that we have the multimeter set to a high 200 volts, it shows “1.6” on the screen, meaning 1.6 volts.

Nonetheless, I desire an even more accurate analysis, so I’ll move the selection knob reduced to 20 volts. Below, you can see that we have an even more exact reading that hovers 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 checking, the multimeter would certainly just read “1”, signifying that it’s strained. So if I were to set the knob to 200 millivolts (0.2 volts), the 1.6 volts of the AA battery is excessive for the multimeter to handle at that setup.

Regardless, you may be asking why you would need to check the voltage of something to begin with. Well, in this instance with the AA battery, we’re checking to see if it has any juice left. At 1.6 volts, that’s a fully-loaded battery. However, if it were to read 1.2 volts, it’s close to being pointless.
In a much more useful situation, you could do this kind of measuring on an auto battery to see if it could be dying or if the generator (which is what charges the battery) is going poor. A reading between 12.4-12.7 volts implies that the battery remains in good shape. Anything lower which’s evidence of a passing away battery. Moreover, start your automobile up and also rev it up a little bit. If the voltage does not enhance to about 14 volts or two, then it’s most likely that the alternator is having problems.

Overload

What occurs if you pick a voltage setup that is also low for the voltage you’re trying to measure? Nothing negative. The meter will just show a 1. This is the meter trying to inform you that it is overloaded or out-of-range. Whatever you’re trying to read is also much for that particular setup. Attempt transforming the multimeter knob to a the following highest possible setting.

Selection Knob

Why does the meter knob read 20V and also not 10V? If you’re aiming to measure a voltage much less than 20V, you transform to the 20V setup. This will enable you to check out from 2.00 to 19.99. The first figure on lots of multimeters is only able to display a ‘1’ so the ranges are restricted to 19.99 rather than 99.99. Therefore the 20V max array as opposed to 99V max variety.

Measuring Resistance

Plug the red probe into the ideal port and turn the selection knob to the resistance section. Then, attach the probes to the resistor leads. The way you connect the leads does not matter, the result is the exact same.

Normal resistors have color codes on them. If you do not understand what they suggest, that’s ok! There are a lot of on the internet calculators that are very easy to utilize. Nonetheless, if you ever discover on your own without internet gain access to, a multimeter is extremely helpful at measuring resistance.

Pick a random resistor as well as set the multimeter to the 20kΩ setup. Then 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 check out among 3 points, 0.00, 1, or the real resistor value.

Read Also:  Arduino Electronics Best Clamp Multimeter

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

If the multimeter checks out 1 or shows OL, it’s overwhelmed. You will need to attempt a greater mode such as 200kΩ mode or 2MΩ (megaohm) mode. There is no harm if this take place, it merely indicates the range handle needs to be readjusted.

Should the multimeter checks out 0.00 or virtually absolutely no, then you need to lower the setting to 2kΩ or 200Ω.

Keep in mind that several resistors have a 5% tolerance. This suggests that the shade codes might indicate 10,000 Ohms (10kΩ), however due to inconsistencies in the manufacturing procedure a 10kΩ resistor could be as low as 9.5 kΩ or as high as 10.5 kΩ. Do not stress, it’ll function simply fine as a pull-up or general resistor.

Generally of thumb, it’s uncommon to see a resistor much less than 1 Ohm. Bear in mind that measuring resistance is not best. Temperature level can affect the checking out a lot. Likewise, measuring resistance of a device while it is physically installed in a circuit can be really challenging. The surrounding components on a motherboard can substantially affect the analysis.

The mockup normally resembles with a basic clock running off of a AA battery. On the silver lining, the cord going from the battery to the clock is separated. We just put our 2 probes in between that break to complete the circuit again (with the red probe connected to the source of power), just this moment our multimeter will certainly review out the amps that the clock is pulling, which in this instance is around 0.08 mA.

While a lot of multimeters can additionally measure alternating current (AC), it’s not really a good suggestion (especially if its online power), since AC can be hazardous if you end up slipping up. If you require to see whether or not an electrical outlet is working, utilize a non-contact tester instead.

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

TIP: to place the multimeter in series, you require to place 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 cable in your circuit. If you disconnect the multimeter, your circuit will not work.

Before measuring the current, be sure that you’ve connected in the red probe in the best port, in this case µAmA. In the example below, the exact same circuit of the previous instance is used. The multimeter belongs to the circuit.

Continuity

If there is really reduced resistance between two points, which is less than a few ohms, both points are electrically linked and also you’ll listen to a constant sound. If the audio isn’t continuous or if you don’t hear any kind of audio in all, it suggests that what you’re testing has a defective link or isn’t attached at all.

CAUTION: In order to test continuity you need to turn off the system! Turn off the power supply.

Touch the 2 probes together and, as they are linked, you’ll listen to a constant sound.To examination the continuity of a cord, you just need to attach each probe to the wire pointers.

Continuity is a wonderful way to check if two SMD pins are touching. If your eyes can’t see it, the multimeter is usually an excellent second testing source. When a system is not working, continuity is one more point to aid fix the system.

  • Set your multimeter to the continuity setup making use of the selection knob.
  • The readout on the display will immediately read “1”, which indicates that there isn’t any kind of continuity. This would certainly be right since we haven’t attached the probes to anything yet.
  • Next, make certain the circuit is unplugged as well as has no power. After that attach one probe to one end of the wire as well as the various other probe to the other end– it does not matter which probe goes on which end. If there is a total circuit, your multimeter will either beep, reveal a “0”, or something besides a “1”. If it still reveals a “1”, after that there’s an issue and also your circuit isn’t total.
  • You can additionally examine that the continuity attribute deals with your multimeter by touching both probes to every various other. This completes the circuit and also your multimeter must allow you understand that.

A continuity test tells us whether 2 things are electrically connected: if something is continual, an electrical current can stream easily from one end to the various other.

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

Changing the Fuse

One of one of the most typical errors with a new multimeter is to measure current on a bread board by probing from VCC to GND. This will right away brief power to ground through the multimeter creating the bread board power supply to brown out. As the current rushes via the multimeter, the internal fuse will certainly heat up and then stress out as 200mA moves via it. It will happen in a fraction of a second and also without any genuine audible or physical indication that something is wrong.

Keep in mind that measuring current is carried out in series (disturb the VCC line to the breadboard or microcontroller to measure current). If you try to measure the current with a blown fuse, you’ll most likely notice that the meter reads ‘0.00’ which the system does not switch on like it needs to when you connect the multimeter. This is because the interior fuse is broken and works as a busted cable or open.

To alter the fuse, find your useful dandy mini screw vehicle driver, and also begin securing screws. The parts and also PCB traces inside the multimeter are created to take various quantities of current. You will damage and also potentially wreck your multimeter if you unintentionally press 5A via the 200mA port.

There are times where you need to measure high current gadgets like an electric motor or home heating element. Do you see both areas to put the red probe on the front of the multimeter? 10A on the left as well as mAVΩ on the right? If you try to measure even more than 200mA on the mAVΩ port you run the risk of blowing the fuse. However if you make use of the 10A port to measure current, you run a much lower danger of blowing the fuse. The compromise is level of sensitivity. As we spoke about above, by making use of the 10A port as well as knob setting, you will just be able to read down 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 enough. If you’re trying to measure extremely low power (mini 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 begin measuring the globe around you. Really feel totally free to start using it to address many concerns. A digital multimeter will answer lots of concerns concerning electronics.

A multimeter is a necessary device in any kind of electronic devices laboratory. In this guide, we’ve revealed you How To Use a Multimeter. You’ve discovered how to measure voltage, current as well as resistance, and also how to examine continuity.