How to Use a Harbor Freight Multimeter

Updated on: December 15, 2018

The Intro

These guidelines will reveal you how to make use of a digital multimeter (DMM), a vital device that you can make use of to identify circuits, learn more about various other individuals’s electronic layouts, and also even harbor freight multimeter. For this reason the ‘multi’-‘meter’ or several dimension name.

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

Every fixer needs to recognize their means around a multimeter, which has simply north of a zillion uses for screening electronic elements and also circuits.

In this tutorial we’re mostly likely to show you exactly how to utilize a multimeter. This tutorial is primarily resolved for novices who are starting in electronic devices as well as have no idea just how to use a multimeter and exactly how it can be useful. We’ll explore one of the most usual attributes on a multimeter as well as exactly how to measure current, voltage, resistance as well as exactly how to inspect continuity.

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

A multimeter is a measurement tool absolutely required in electronic devices. It combines 3 vital functions: a voltmeter, ohmeter, and also ammeter, and also in many cases continuity.

The tool enables you to understand what is going on in your circuits. Whenever something in your circuit isn’t working, it will certainly aid you repairing. Below’s some situations in electronic devices jobs that you’ll discover the multimeter helpful:

  • is the button on?
  • is this cable conducting the electrical power or is it broken?
  • just how much current is streaming via this led?
  • exactly how much power do you have left on your batteries?

What would multimeters measure?

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

A bunch of multimeters have a continuity check, leading to a loud beep if two things are electrically connected. This is valuable if, for instance, you are building a circuit and also attaching cords or soldering; the beep indicates everything is connected and also absolutely nothing has come loose. You can also utilize it to ensure two points are not connected, to aid protect against short circuits.

Some multimeters likewise have a diode check feature. A diode resembles a one-way valve that just allows electricity flow in one direction. The exact feature of the diode check can differ from one type to another. If you’re collaborating with a diode as well as can’t inform which means it enters the circuit, or if you’re unsure the diode is functioning appropriately, the check attribute can be fairly helpful. If your DMM has a diode check function, read the handbook to discover precisely how it works.

Advanced models could have various other features, such as the capability to measure and determine other electric parts, like transistors or capacitors. Given that not just about all multimeters have these features, we will not cover them in this tutorial. You can read your multimeter’s guidebook if you need to utilize these attributes.

What Do All Of the Symbols Mean?

There’s a lot taking place when you look at the selection knob, but if you’re only going to be doing some standard things, you will not also utilize fifty percent of all the settings. In any type of situation, below’s a rundown of what each sign suggests:

Direct Current Voltage (DCV):quite often it will certainly be signified with a V– rather. This setting is made use of to measure direct current (DC) voltage crazes like batteries.
Alternating Current Voltage (ACV): Sometimes it will certainly be signified with a V ~ instead. This setup is utilized to measure the voltage from alternating current resources, which is practically anything that connects right into an electrical outlet, along with the power coming from the electrical outlet itself.
Resistance (Ω): This gauges just how much resistance there is in the circuit. The reduced the number, the simpler it is for the current to move through, as well as the other way around.
Continuity: Usually signified by a wave or diode symbol. This just checks whether or not a circuit is total by sending out a really percentage 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 creating a problem– find it!
Straight Current Amperage (DCA): Similar to DCV, but as opposed to offering you a voltage analysis, it will inform you the amperage.
Straight Current Gain (hFE): This setting is to test transistors as well as their DC gain, but it’s primarily pointless, since the majority of electrical contractors and also enthusiasts will use the continuity check instead.

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

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

How to Utilize a Multimeter

For starters, let’s look at a few of the different parts of a multimeter. At the really basic level you have the device itself, along with 2 probes, which are the black and also red cable televisions that have plugs on one end and also metal suggestions on the other.

The tool itself has a display screen at the top, which offers you your readout, as well as there’s a big selection knob that you can spin around to pick a particular setup. Each setting might additionally have different number worths, which exist to measure different toughness of voltages, resistances, and amps. So if you have your multimeter collection to 20 in the DCV area, it will certainly measure voltages as much as 20 volts.

Your DMM will likewise come with 2 or three ports for connecting in the probes:

  • COM port mean “Common”, and 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 plug right into if you’re measuring voltage, resistance, continuity, and also current less than 200mA.
  • the 10ADC port (sometimes signified as just 10A) is utilized whenever you’re measuring current that’s greater than 200mA. If you’re uncertain of the current draw, begin with this port. On the other hand, you would not use this port at all if you’re measuring anything aside from current.

Caution: Make sure that if you’re measuring anything with a current greater than 200mA, you plug the red probe right into the 10A port, instead of the 200mA port. Otherwise you can blow the fuse that’s inside of the multimeters. In addition, measuring anything over 10 amps can blow a fuse or damage the multimeter as well.

Your measurement tool could have totally separate ports for measuring amps, while the various other port is particularly simply for voltage, resistance, and continuity, but the majority of less expensive multimeters will certainly share ports.

Anyway, allow’s get started in fact utilizing a multimeter. We’ll be measuring the voltage of a AA battery, the current draw of a wall surface clock, as well as the continuity of an easy cord as some instances to get you started and also acquainted with making use of a multimeter.

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Parts of a Multimeter

Multimeters are composed by 4 vital sections:

  • Display: this particular is just where the measurements are shown
  • Selection Knob: this picks what you want to measure
  • Ports: this is where you plug in the probes
  • Probes: a multimeter includes two probes. Typically, one is red as well as the various other is black.


  • “COM” or “–” port is where the black probe needs 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.
  • allows you to measure voltage as well as resistance and examination continuity.


COM mean typical and also is often attached to Ground or ‘-‘ of a circuit.The COM probe is conventionally black yet there is no distinction in between the red probe as well as black probe besides shade.


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

Selection Knob

The selection knob permits the user to establish the tool to read different things such as milliamps (mA) of current, voltage (V) and also resistance (Ω).


2 probes are connected right into two of the ports on the front of the device. The probes have a banana type connector on completion that connects into the multimeter. Any kind of probe with a banana plug will work with this meter. This permits for different kinds of probes to be utilized.

Probe Types

There are several kinds of probes offered. Here are a few of our faves:

  • Banana to Alligator Clips: These are excellent cable televisions for attaching to large wires or pins on a breadboard. Great for doing longer term examinations where you don’t have to have to hold the probes in position while you adjust a circuit.
  • Banana to IC Hook: IC hooks function well on smaller sized ICs and legs of ICs.
  • Banana to Tweezers: Tweezers are helpful if you are requiring to examine SMD parts.
  • Banana to Test Probes: If you ever damage a probe, they are inexpensive to replace!

Measuring Voltage

To begin, allow’s measure voltage on a AA battery: Plug the black probe into COM as well as the red probe into mAVΩ. Establish to “2V” in the DC (straight current) variety. Nearly all portable electronic devices make use of direct current), not alternating current. Link the black probe to the battery’s ground or ‘-‘ and also the red probe to power or ‘+’. Squeeze the probes with a little pressure against the favorable and also adverse terminals of the AA battery. If you’ve obtained a fresh battery, you ought to see around 1.5 V on the display screen (this battery is brand-new, so its voltage is somewhat greater 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 curly line means AC voltage.

To measure voltage:

  1. Set the mode 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. Ensure the red probe is connected to the port with a V next to it.
  3. Connect the red probe to the silver lining of your component, which is where the current is coming from.
  4. Attach the COM probe to the various other side of your component.
  5. Review the value on the screen.

Idea: to measure voltage you have to connect your multimeter in parallel with the component you intend to measure the voltage. Putting the multimeter in parallel is positioning each probe along the leads of the component you desire 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 pick a variety with the selection knob that can check out the 1.5 V. So you should choose 2V when it comes to this multimeter. If you take an autorange one, you don’t need to stress over the array you require to choose.

Start by activating it, plugging the probes right into their corresponding ports and also after that establishing the selection knob to the greatest number worth in the DCV area, which in my situation is 500 volts. If you do not know at the very least the voltage series of things you’re measuring, it’s constantly an excellent idea to begin with the highest worth initially and also after that work your way down until you get an accurate reading.

In this instance, we understand the AA battery has a very low voltage, but we’ll begin at 200 volts simply for the sake of example. Next off, place the black probe on the adverse end of the battery as well as the red probe on the favorable end. Have a look at the analysis on the display. Given that we have the multimeter collection to a high 200 volts, it shows “1.6” on the display, indicating 1.6 volts.

However, I desire an even more precise analysis, so I’ll move the selection knob reduced down to 20 volts. Below, you can see that we have a more exact analysis that floats in between 1.60 and 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 testing, the multimeter would just read “1”, representing that it’s overwhelmed. 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 deal with at that setting.

All the same, you might be asking why you would certainly require to check the voltage of something to begin with. Well, in this instance with the AA battery, we’re inspecting to see if it has any juice left. At 1.6 volts, that’s a fully-loaded battery. Nevertheless, if it were to read 1.2 volts, it’s close to being unusable.
In a more practical situation, you might do this sort of measuring on a cars and truck battery to see if it may be passing away or if the alternator (which is what bills the battery) is spoiling. A reading between 12.4-12.7 volts implies that the battery remains in excellent form. Anything lower which’s proof of a passing away battery. In addition, start your automobile up as well as rev it up a bit. If the voltage does not increase to around 14 volts or two, after that it’s likely that the generator is having concerns.


What takes place if you choose a voltage setting that is also low for the voltage you’re trying to measure? Absolutely nothing negative. The meter will just display a 1. This is the meter attempting to tell you that it is overloaded or out-of-range. Whatever you’re trying to review is way too much for that certain setup. Try transforming the multimeter handle to a the following highest setup.

Selection Knob

Why does the meter knob checked out 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 certainly permit you to review from 2.00 to 19.99. The initial digit on lots of multimeters is only able to show a ‘1’ so the arrays are restricted to 19.99 instead of 99.99. Hence the 20V max variety as opposed to 99V max variety.

Measuring Resistance

Plug the red probe right into the ideal port and also turn the selection knob to the resistance area. Then, attach the probes to the resistor leads. The method you link the leads does not matter, the outcome coincides.

Normal resistors have color codes on them. If you don’t understand what they imply, that’s ok! There are lots of on-line calculators that are simple to make use of. However, if you ever before locate yourself without web gain access to, a multimeter is really useful at measuring resistance.

Choose an arbitrary resistor as well as set the multimeter to the 20kΩ setup. Then hold the probes against the resistor legs with the same quantity of pressure you when pressing a secret on a keyboard.

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

In this case, the meter reads 0.97, meaning this resistor has a worth of 970Ω, or regarding 1kΩ (remember you remain in the 20kΩ or 20,000 Ohm setting 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 strained. You will certainly need to try a greater mode such as 200kΩ mode or 2MΩ (megaohm) mode. There is no injury if this take place, it merely means the range handle needs to be adjusted.

Should the multimeter reviews 0.00 or nearly zero, after that you require to reduce the mode to 2kΩ or 200Ω.

Bear in mind that several resistors have a 5% tolerance. This means that the shade codes may show 10,000 Ohms (10kΩ), but since of disparities in the manufacturing procedure a 10kΩ resistor can be as reduced as 9.5 kΩ or as high as 10.5 kΩ. Don’t fret, it’ll work simply fine as a pull-up or basic resistor.

Generally of thumb, it’s unusual to see a resistor much less than 1 Ohm. Keep in mind that measuring resistance is not ideal. Temperature can affect the reading a great deal. Additionally, measuring resistance of a gadget while it is literally set up in a circuit can be really tricky. The surrounding elements on a motherboard can greatly impact the analysis.

The mockup normally resembles with a basic clock running off of a AA battery. On the silver lining, the cable going from the battery to the clock is separated. We simply place 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 read out the amps that the clock is pulling, which in this situation is around 0.08 mA.

While most multimeters can additionally measure alternating current (AC), it’s not actually a good suggestion (specifically if its online power), considering that AC can be unsafe if you wind up slipping up. If you need to see whether or not an outlet is functioning, utilize a non-contact tester instead.

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

SUGGESTION: to place the multimeter in series, you require to place the red probe on the lead of a component and the black probe on the following component lead. The multimeter acts as if it was a wire in your circuit. If you separate the multimeter, your circuit won’t work.

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


If there is extremely reduced resistance in between 2 points, which is much less than a few ohms, the two factors are electrically linked and also you’ll hear a constant sound. If the sound isn’t constant or if you don’t hear any type of sound at all, it means that what you’re testing has a malfunctioning link or isn’t connected in all.

WARNING: To examine continuity you ought to turn off the system! Turn off the power supply!

Touch the 2 probes together and also, as they are attached, you’ll listen to a continuous sound.To test the continuity of a cable, you just require to attach each probe to the cable tips.

Continuity is a wonderful method to evaluate if two SMD pins are touching. If your eyes can not see it, the multimeter is typically a wonderful second testing resource. When a system is not functioning, continuity is another point to help fix the system.

  • Establish your multimeter to the continuity setting making use of the selection knob.
  • The readout on the screen will instantaneously read “1”, which implies that there isn’t any kind of continuity. This would be right because we have not attached the probes to anything yet.
  • Next, ensure the circuit is unplugged and has no power. Then attach one probe to one end of the wire and the various other probe to the various other end– no matter which probe goes on which end. If there is a total circuit, your multimeter will certainly either beep, reveal a “0”, or something besides a “1”. If it still reveals a “1”, then there’s a trouble and also your circuit isn’t full.
  • You can also check that the continuity function services your multimeter by touching both probes to every other. This finishes the circuit as well as your multimeter must let you know that.

A continuity test informs us whether 2 things are electrically connected: if something is continuous, an electric current can move easily from one end to the other.

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

Changing the Fuse

Among one of the most usual mistakes with a new multimeter is to measure current on a bread board by probing from VCC to GND. This will right away short power to ground through the multimeter triggering the bread board power supply to brownish out. As the current rushes through the multimeter, the internal fuse will heat up and after that stress out as 200mA moves with it. It will occur in a flash as well as with no actual audible or physical indicator that something is incorrect.

Remember that measuring current is carried out in series (disrupt the VCC line to the breadboard or microcontroller to measure current). If you try to measure the current with a blown fuse, you’ll probably see that the meter reviews ‘0.00’ as well as that the system doesn’t turn on like it must when you connect the multimeter. This is since the interior fuse is damaged as well as acts as a busted cable or open.

To change the fuse, locate your useful dandy mini screw driver, and start obtaining screws. The parts and 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 mistakenly press 5A through the 200mA port.

There are times where you require to measure high current tools like a motor or burner. Do you see the 2 locations to place the red probe on the front of the multimeter? 10A left wing as well as mAVΩ on the right? If you try to measure greater than 200mA on the mAVΩ port you run the risk of blowing the fuse. But if you use the 10A port to measure current, you run a much reduced threat of blowing the fuse. The compromise is sensitivity. As we spoke about above, by utilizing the 10A port and handle setup, you will just have the ability to review down to 0.01 A or 10mA. A lot of systems make use of more than 10mA so the 10A setting as well as port works 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 require.


You’re currently ready to use your digital multimeter to begin measuring the globe around you. Really feel totally free to begin using it to address several questions. A digital multimeter will certainly respond to numerous questions about electronics.

A multimeter is a crucial device in any type of electronics laboratory. In this guide, we’ve shown you How To Use a Multimeter. You’ve learned just how to measure voltage, current as well as resistance, as well as just how to check continuity.