In this article we’re going to cover multimeters! We’ll talk about how to use them to measure voltage, current, resistance, and continuity. We’ll go over what to look for in a multimeter, where to buy one, and some other great information!
Deciding Which Multimeter to Buy?
In today’s marketplace, multimeters are literally everywhere. You can get even buy one at the Dollar Store! Of course they are also available at Wal-Mart, Target, Best Buy and most other big box retailers. The best deals are generally online at Amazon and NewEgg.
Features to Look for in Multimeters
When deciding which multimeter to buy, you’re going want at least these basic features in any multimeter you buy: Voltage, Resistance, Continuity. We will discuss what each of those do later in the article. I’d personally recommend getting a meter that supports capacitance and temperatures if you can spend a couple of extra dollars. Those features come in pretty handy.
Next up, take a look at the accuracy of the meter. Most meters are somewhere around +/- 2%. I wouldn’t get anything less than that. Again, if you can afford a meter with better accuracy I would do so, but +/- 2% is going to be good enough for most things the home hobbyist will run into.
The next thing to look for is a good display. You’d be surprised how much difference a large, easy to read, high contrast display makes when working on electronics. Many times you’ll be looking at the screen out of the corner of your eye while working on small circuit boards and a small fuzzy screen is going to frustrate you to no end. Don’t cheap out on the screen!
Lastly, look for automatic ranging. The last thing you want to do is mess around with having to set the range of your meter before every measurement. The good news, I haven’t seen a meter in a while that doesn’t have auto-ranging that fits our previous criteria and features.
Our Choice of Which Multimeter to By for the General Hobbyist
To make things simple, we’ve picked a multimeter for you that meets all of our criteria and features. It’s cost effect and will service you well. Of course, cost effective is different for different people. There are many multimeters available for $10, but they will have terrible accuracy, a fuzzy tiny screen (they are even digital at all), and will cause you all kinds of grief down the road. To get a decent multimeter you’ll need to spend between $45-$65 dollars. Of course, there are multi-hundred dollar meters for those who have special needs. Again, we’re looking fo the best multimeter for the hobbyist and average buyer.
Our choice is the Greenlee Autoranging DM-45. It meets all of our requirements at the lowest price of our three recommendations. It will likely last you a lifetime and keep up with anything you throw its way.
Other good choices include the Klein Tools MM600 Autoranging (another staff favorite, we own two), and the Triplett 9007-A Multimeter. They’re both solid meters and meet all of our requirements, albeit at a slightly higher cost point.
The Basics of Using a Multimeter
So before we go to much further into deciding which multimeter to buy, let’s start our exploration of multimeter basics with measuring voltages. Next to checking continuity, measuring voltage will be the most common task you do with your multimeter.
Measuring DC Voltage
Before you can measure voltage, you need to make sure your meter is configured properly. Starting with the cables, make sure the black lead is in the jack labeled COM or COMMON. Next, place the red probe in the jack labeled voltage. Make certain it is not in the plug labeled AMPS or AMPERES. You run the high risk of damaging your meter, or at the least blowing a fuse in your meter if you use the wrong jack..
Next, set the dial to measure DC voltage. The DC voltage icon is usually a V, followed by a solid line over a dashed line.
To get a voltage reading, set touch the black probe to the GND (or -) terminal of a battery. Touch the red probe to the positive (or +) terminal the same battery. You should get a voltage reading of the battery. If its a 9V battery and fully charged you’ll see approximately 9 volts on the display.
Now, reverse the wires. Instead touch the black probe against positive terminal and the red probe against the negative terminal. You should get a negative reading on your multimeter! Reversing the meter probes is safe to do and will never cause damage to your meter or the device you’re checking. In fact, its great way to figure out polarity when you the terminals are not marked on a board!
Measuring AC Voltage
Set the dial to the AC voltage setting. The AC voltage icon on a multimeter is usually represented by a V~. Just like in measuring DC voltage, connect the red lead to the jack labeled Voltage. Touch the probes to the AC voltage source that you want to measure. You can insert the leads into a common AC all socket in your home. As long as you don’t touch metal parts of the probe or short them out this is perfectly safe to do. In North America you should get a reading of approximately 120 volts.
Most multimeters share the same jack for voltage and resistance. Make sure the red lead in the jack labeled ohms for resistance if your meter has a separate jack, and then set the dial to the resistance setting. The resistance setting will look the like Ohm symbol.
There is no polarity involved in resistance so you can touch either lead to either end of the circuit, component, or resistor you want to measure. The resistance value in ohms will be shown on the screen.
Continuity means that there is a good connection between any two points in the circuit. As with voltage and resistance above, most meters use the same voltage/resistance jack for continuity. Place the red lead in the jack for continuity and then select the continuity setting on your multimeter. The continuity symbol will look like a diode symbol.
The best way to test the continuity function is by touching the probes together. This will cause the multimeter to beep, indicating continuity is good. You can use the continuity function to check if for breaks in cables, or breaks in traces on circuit boards. This is a fantastic troubleshooting tool and is probably the most common use of the multimeter by most home hobbyist.
Most multimeters are going to require you to move your red lead to the AMPS connection for measuring current. Many multimeters have two. The first jack is for currents up to 10 amps and the second is for currents up to 400 milliamps. You’ll most likely start with 10 amps jack. If you find your measuring something below 400ma and need more accuracy, you can simply move the lead to the other jack. Some meters also require you to move the setting dial to a mA setting.
Once you’ve set the dial to the amps or milliamps setting its time to measure current! Measuring current is a little trickier than the rest of things. I can’t just touch the probes to a terminal or component and get a reading. The multimeter bust be place in series in the circuit so that the circuit flows through the multimeter. This may mean cutting a wire and splicing the multimeter in-line.
Additional Thoughts on Buying your First Multimeter
So as you work through which multimeter to buy for your needs, I hope this gives you some insight and helps you make the right decision. Just remember not to cheap out on this purchase. A $10 meter will not serve you well and you’ll always regret it. A good multimeter will be something that you’ll keep for a lifetime and I guarantee you’ll find many uses for, whether in your hobbyist projects, or in your day to day life as your fix things around your home or auto!
Be sure to leave a comment below with your tips on multimeters and your favorite meter!