Updated on: December 9, 2018
This guide will show you how to use a digital multimeter (DMM), an indispensable device that you can utilize to diagnose circuits, find out about other individuals’s electronic layouts, and to use a southwire multimeter. Therefore the ‘multi’-‘meter’ or numerous measurement name.
One of the most basic points we measure are voltage and also current. A multimeter is also great for some standard peace of mind checks and troubleshooting. Is your circuit not functioning? Does the switch job? 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 recognize their way around a multimeter, which has just north of a zillion utilizes for screening electronic components as well as circuits.
In this tutorial we’re going to show you exactly how to make use of a multimeter. This tutorial is primarily resolved for newbies who are starting out in electronics and also have no concept exactly how to utilize a multimeter and also just how it can be valuable. We’ll explore one of the most typical functions on a multimeter as well as just how to measure current, voltage, resistance and just how to check continuity.
What is a multimeter and why do you require one?
A multimeter is a measurement device absolutely essential in electronic devices. It integrates three necessary attributes: a voltmeter, ohmeter, and also ammeter, as well as in some instances continuity.
The tool allows you to understand what is taking place in your circuits. Whenever something in your circuit isn’t functioning, it will certainly assist you fixing. Right here’s some circumstances in electronic devices tasks that you’ll find the multimeter beneficial:
- is the switch activate?
- is this cord performing the power or is it damaged?
- just how much current is moving with this led?
- just how much power do you have left on your batteries?
What should multimeters measure?
Almost all multimeters can measure voltage, current, and also resistance.
A lot of multimeters have a continuity check, resulting in a loud beep if 2 things are electrically linked. This is useful if, as an example, you are building a circuit and linking cables or soldering; the beep suggests everything is attached as well as absolutely nothing has come loose. You can also use it to make certain 2 things are not attached, to assist avoid brief circuits.
Various other multimeters also have a diode check function. A diode is like a one-way valve that just allows electrical energy flow in one instructions. The exact feature of the diode check can differ from one type to another. If you’re dealing with a diode and also can’t tell which way it enters the circuit, or if you’re not certain the diode is functioning correctly, the check attribute can be fairly handy. If your DMM has a diode check feature, read the manual to figure out specifically just how it functions.
Advanced models could have various other functions, such as the capability to measure and also determine other electrical parts, like transistors or capacitors. Since not just about all multimeters have these attributes, we will certainly not cover them in this tutorial. You can review your multimeter’s manual if you need to make use of these features.
What Do Each Of the Symbols Mean?
There’s a whole lot going on when you take a look at the selection knob, however if you’re just going to be doing some basic things, you won’t also make use of half of all the setups. Regardless, right here’s a rundown of what each sign indicates:
Direct Current Voltage (DCV):In some cases it will be signified with a V– rather. This setting is used to measure direct current (DC) voltage in points like batteries.
Alternating Current Voltage (ACV): Sometimes it will certainly be signified with a V ~ rather. This setting is utilized to measure the voltage from alternating current resources, which is virtually anything that links into an outlet, along with the power originating from the electrical outlet itself.
Resistance (Ω): This gauges just how much resistance there is in the circuit. The reduced the number, the less complicated it is for the current to move with, as well as the other way around.
Continuity: Usually signified by a wave or diode icon. This merely checks whether or not a circuit is total by sending a very small quantity of current through the circuit and also seeing if it makes it out the other end. Otherwise, then there’s something along the circuit that’s creating a problem– locate it!
Straight Current Amperage (DCA): Similar to DCV, however instead of offering you a voltage analysis, it will certainly tell you the amperage.
Direct Current Gain (hFE): This setting is to check transistors and also their DC gain, yet it’s mostly ineffective, considering that most electrical experts and hobbyists will certainly utilize the continuity check instead.
Your multimeter may also have a dedicated setup for checking the amperage of AA, AAA, as well as 9V batteries. This setting is typically denoted with the battery sign.
Once more, you possibly won’t also utilize half of the setups shown, so don’t get overwhelmed if you just understand what a few of them do.
Exactly how to Use a Multimeter
For starters, allow’s look at a few of the various parts of a multimeter. At the really basic level you have the gadget itself, along with 2 probes, which are the black and red cables that have plugs on one end and also metal ideas on the various other.
The tool itself has a screen at the top, which provides you your readout, and there’s a big selection knob that you can rotate around to pick a particular setup. Each setup may also have various number worths, which exist to measure various staminas of voltages, resistances, and amps. So if you have your multimeter set to 20 in the DCV section, it will certainly measure voltages as much as 20 volts.
Your DMM will certainly likewise have two or three ports for plugging in the probes:
- COM port stands for “Common”, as well as the black probe will certainly always plug into this port.
- VΩmA port (sometimes signified as mAVΩ) is merely an acronym for voltage, resistance, and current (in milliamps). This is where the red probe will plug right into if you’re measuring voltage, resistance, continuity, as well as current less than 200mA.
- the 10ADC port (sometimes signified as simply 10A) is made use of whenever you’re measuring current that’s greater than 200mA. If you’re not exactly sure of the current draw, start with this port. On the various other hand, you would not utilize this port whatsoever if you’re measuring anything aside from current.
Caution: Make sure that if you’re measuring anything with a current greater than 200mA, you connect the red probe into the 10A port, rather than the 200mA port. Otherwise you might blow the fuse that’s within the multimeter. Furthermore, measuring anything over 10 amps can blow a fuse or damage the multimeters too.
Your measurement tool might have completely separate ports for measuring amps, while the other port is especially just for voltage, resistance, as well as continuity, but many cheaper multimeters will certainly share ports.
Anyway, allow’s start really using a multimeter. We’ll be measuring the voltage of a AA battery, the current draw of a wall clock, as well as the continuity of a basic cord as some instances to get you started and familiar with utilizing a multimeter.
Components of a Multimeter
A multimeter has actually four parts:
- Display: this particular is where the measurements are displayed
- Selection Knob: this selects what you intend to measure
- Ports: this is where you connect in the probes
- Probes: a multimeter comes with 2 probes. Usually, one is red and also the other is black.
- “COM” or “–” port is where the black probe should be connected. The COM probe is conventionally black.
- 10A is used when measuring large currents, more than 200mA.
- µAmA is utilized to measure current.
- VΩ enables you to measure voltage and also resistance and also test continuity.
COM represent typical as well as is often attached to Ground or ‘-‘ of a circuit.The COM probe is traditionally black but there is no distinction in between the red probe as well as black probe other than color.
10A is the unique port used when measuring big currents (higher than 200mA).
The selection knob allows the customer to establish the tool to read different things such as milliamps (mA) of current, voltage (V) and resistance (Ω).
Two probes are linked into two of the ports on the front of the system. The probes have a banana type connector on completion that links into the multimeter. Any probe with a banana plug will certainly function with this meter. This allows for various sorts of probes to be made use of.
There are many different kinds of probes readily available. Here are a few of our faves:
- Banana to Alligator Clips: These are fantastic cables for attaching to large cables or pins on a breadboard. Great for performing longer term examinations where you don’t have to need to hold the probes in location while you control a circuit.
- Banana to IC Hook: IC hooks work well on smaller sized ICs as well as legs of ICs.
- Banana to Tweezers: Tweezers come in handy if you are requiring to check SMD elements.
- Banana to Test Probes: If you ever break a probe, they are low-cost to replace!
To begin, allow’s measure voltage on a AA battery: Plug the black probe into COM and the red probe into mAVΩ. Set to “2V” in the DC (straight current) variety. Almost all portable electronics utilize direct current), not alternating current. Link the black probe to the battery’s ground or ‘-‘ and also the red probe to power or ‘+’. Press the probes with a little pressure against the favorable as well as adverse terminals of the AA battery. If you’ve obtained a fresh battery, you must see around 1.5 V on the display screen (this battery is brand-new, so its voltage is somewhat more than 1.5 V).
You could measure DC voltage or AC voltage. The V with a straight line means DC voltage. The V with the wavy 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 linked to the port with a V beside it.
- Attach the red probe to the positive side of your component, which is where the current is coming from.
- Attach the COM probe to the various other side of your component.
- Read the worth on the display screen.
Pointer: to measure voltage you need to attach your multimeter in parallel with the component you intend 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 example we’re going to measure the voltage of a 1.5 V battery. You know that you’ll have about 1.5 V. So, you must select a variety with the selection knob that can check out the 1.5 V. So you need to choose 2V in the instance of this multimeter. If you have an autorange one, you don’t need to stress over the array you require to choose.
Begin by switching on it, plugging the probes into their respective ports and afterwards setting the selection knob to the highest number worth in the DCV area, which in my case is 500 volts. If you don’t understand a minimum of the voltage variety of things you’re measuring, it’s always a good idea to begin with the greatest value initially as well as after that function your way down until you obtain an exact analysis.
In this case, we understand the AA battery has a really reduced voltage, however we’ll begin at 200 volts simply for the purpose of instance. Next off, position the black probe on the negative end of the battery and also the red probe on the positive end. Have a look at the analysis on the screen. Since we have the multimeter set to a high 200 volts, it reveals “1.6” on the screen, indicating 1.6 volts.
Nonetheless, I desire a more precise reading, so I’ll relocate the selection knob lower down to 20 volts. Here, you can see that we have an even more accurate reading that hovers between 1.60 and also 1.61 volts. If you were to ever before set the selection knob to a number worth less than the voltage of the point you’re testing, the multimeter would certainly just review “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 take care of 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 instance with the AA battery, we’re inspecting to see if it has any type of juice left. At 1.6 volts, that’s a fully-loaded battery. Nonetheless, if it were to check out 1.2 volts, it’s close to being pointless.
In a more sensible scenario, you can do this sort of measuring on a vehicle battery to see if it could be dying or if the generator (which is what bills the battery) is going poor. An analysis between 12.4-12.7 volts means that the battery is in good form. Anything reduced which’s evidence of a passing away battery. In addition, start your car up and rev it up a little bit. If the voltage does not enhance to about 14 volts or so, after that it’s likely that the alternator is having issues.
What takes place if you pick a voltage setup 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 attempting to check out is way too much for that specific setting. Attempt altering the multimeter knob to a the following highest possible setting.
How come does the meter knob checked out 20V as well as not 10V? If you’re wanting to measure a voltage much less than 20V, you resort to the 20V setting. This will certainly permit you to check out from 2.00 to 19.99. The initial number on many multimeters is only able to show a ‘1’ so the arrays are limited to 19.99 rather than 99.99. Therefore the 20V max array rather than 99V max variety.
Plug the red probe right into the ideal port and turn the selection knob to the resistance area. Then, connect the probes to the resistor leads. The means you link the leads does not matter, the result is the very same.
Normal resistors have shade codes on them. If you do not recognize what they mean, that’s ok! There are a lot of online calculators that are easy to use. However, if you ever before discover on your own without net accessibility, a multimeter is extremely helpful at measuring resistance.
Choose out a random resistor and also set the multimeter to the 20kΩ setting. Then hold the probes versus the resistor legs with the same quantity of pressure you when pushing a trick on a keyboard.
The meter will review one of 3 things, 0.00, 1, or the actual resistor worth.
In this instance, the meter reviews 0.97, implying this resistor has a value of 970Ω, or concerning 1kΩ (remember you remain in the 20kΩ or 20,000 Ohm setting so you require to relocate the decimal three locations to the right or 970 Ohms).
If the multimeter checks out 1 or presents OL, it’s overwhelmed. You will need to attempt a higher setting such as 200kΩ mode or 2MΩ (megaohm) mode. There is no harm if this happen, it merely implies the variety knob requires to be changed.
Whenever the multimeter reviews 0.00 or virtually zero, then you require to lower the setting to 2kΩ or 200Ω.
Keep in mind that lots of resistors have a 5% resistance. This suggests that the color codes may show 10,000 Ohms (10kΩ), but as a result of discrepancies in the manufacturing procedure a 10kΩ resistor might be as low as 9.5 kΩ or as high as 10.5 kΩ. Do not worry, it’ll function simply great as a pull-up or general resistor.
Generally of thumb, it’s uncommon to see a resistor less than 1 Ohm. Keep in mind that measuring resistance is not best. Temperature can influence the checking out a whole lot. Likewise, measuring resistance of a device while it is literally mounted in a circuit can be extremely challenging. The bordering parts on a motherboard can substantially affect the reading.
The mockup normally looks like with a fundamental clock running of a AA battery. On the positive side, the cord going from the battery to the clock is separated. We just place our 2 probes in between that break to complete the circuit again (with the red probe attached to the source of power), only this time our multimeter will read out the amps that the clock is pulling, which in this instance is around 0.08 mA.
While a lot of multimeters can likewise measure alternating current (AC), it’s not truly an excellent suggestion (specifically if its online power), since AC can be harmful if you end up slipping up. If you require to see whether or not an outlet is functioning, utilize a non-contact tester instead.
To measure current you need to bear in mind that parts in collection share a current. So, you require to attach your multimeter in series with your circuit.
IDEA: to position the multimeter in collection, you require to place 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 wire in your circuit. If you separate the multimeter, your circuit will not work.
Before measuring the current, make certain that you’ve connected in the red probe in the appropriate port, in this instance µAmA. In the instance below, the very same circuit of the previous instance is made use of. The multimeter becomes part of the circuit.
Check for Continuity
If there is extremely low resistance in between 2 points, which is much less than a couple of ohms, the two points are electrically linked and also you’ll hear a constant audio. If the noise isn’t constant or if you do not listen to any type of noise whatsoever, it indicates that what you’re testing has a damaged link or isn’t attached in any way.
WARNING: In order to test continuity you must turn off the system! Turn off the power source.
Touch both probes with each other as well as, as they are attached, you’ll listen to a continual sound.To test the continuity of a cable, you simply require to link each probe to the wire ideas.
Continuity is a fantastic method to examine if 2 SMD pins are touching. If your eyes can not see it, the multimeter is usually a terrific 2nd testing resource. When a system is not working, continuity is another thing to help repair the system.
- Set your multimeter to the continuity setup using the selection knob.
- The readout on the display will promptly read “1”, which indicates that there isn’t any continuity. This would certainly be right given that we have not linked the probes to anything yet.
- Next off, make certain the circuit is unplugged and has no power. Then connect one probe to one end of the cord and the other probe to the other end– it matters not which probe goes on which end. If there is a total 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 your circuit isn’t full.
- You can likewise check that the continuity feature services your multimeter by touching both probes to every other. This finishes the circuit and your multimeter must let you know that.
A continuity test tells us whether two points are electrically linked: if something is continuous, an electrical current can flow easily from one end to the various other.
If there’s no continuity, it implies there is a break someplace in the circuit. This might indicate anything from a blown fuse or poor solder joint to an improperly wired circuit.
Altering the Fuse
Among one of the most common errors with a brand-new multimeter is to measure current on a bread board by penetrating from VCC to GND. This will right away brief power to ground with the multimeter causing the bread board power supply to brownish out. As the current hurries with the multimeter, the internal fuse will heat up and afterwards wear out as 200mA streams via it. It will certainly occur in a flash and without any kind of actual distinct or physical indication that something is wrong.
Bear in mind that measuring current is carried out in collection (disrupt 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 see that the meter reviews ‘0.00’ and also that the system does not transform on like it must when you attach the multimeter. This is because the interior fuse is damaged as well as acts as a damaged cable or open.
To change the fuse, find your useful dandy mini screw driver, as well as begin obtaining screws. The components and PCB traces inside the multimeter are developed to take various amounts of current. You will harm as well as perhaps wreck your multimeter if you unintentionally press 5A with the 200mA port.
There are times where you need to measure high current tools like an electric motor or burner. Do you see the 2 places 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 risk of blowing the fuse. Yet if you use the 10A port to measure current, you run a much lower threat of blowing the fuse. The compromise is sensitivity. As we spoke about above, by using the 10A port and also handle setup, you will just be able to review down to 0.01 A or 10mA. A lot of systems make use of greater than 10mA so the 10A setup as well as port functions well enough. If you’re attempting to measure extremely low power (micro or nano amps) the 200mA port with the 2mA, 200uA, or 20uA can be what you require.
You’re currently prepared to use your digital multimeter to begin measuring the globe around you. Do not hesitate to start utilizing it to respond to numerous inquiries. A digital multimeter will answer several inquiries concerning electronic devices.
A multimeter is a necessary tool in any electronics laboratory. In this guide, we’ve shown you How To Use a Multimeter. You’ve learned exactly how to measure voltage, current and also resistance, and also just how to examine continuity.