Hello there, If you are starting your career or your passion for electricians, you must know about all of the tools we use through our work. Today in this article I am going to teach you all the basics about multimeters. After reading this article you will become a master of multimeters.
I put some best multimeter links which I recommend you buy if you don't have one right now.
In this tutorial I will cover some topics -
- DC voltage
- AC voltage
- Resistance
- DC current
- Continuity
- Diodes
- Battery
- Frequency
- and etc.
Multimeter options
There are many different types of multimeters in the market. But we commonly use analog and digital versions. Analog multimeters use a dial to measure all things, and this is too horrible and time-consuming. But in the case of digital multimeters, they are easy to use. and yeah you can buy them cheaper to expensive. Hardly anyone uses the analog one anymore. So I am not going to cover them. But, If you wanna know about analog multimeters I'll make an article on it.
We use digital multimeters all the time, and in today's generation, you have to know how to use digital multimeters. They are very easy to use and believe me, it will make your work a lot easier.
We have two main types of multimeters, one is manual range and another one is auto range. There are some pros and cons to them,
Here are my multimeter recommendations :
- Professional Multimeter- https://amzn.to/4ansHPz
- Good Multimeter- https://amzn.to/4ajS7xk
DC Voltage
DC Voltage is represented by this symbol. You will find it on your multimeter. We find DC electricity in many types of batteries, solar panels, DC power supply, etc. DC current flows in one direction. You can think of it like flowing water in a pipe. That is why when you want to, measure DC voltage, the oscilloscope shows a straight line and that is why we use his symbol.
1st you have to know the terminals.
one is red and another is black.
This red one is positive the black one is negative and it is a common terminal.
In the case of a manual range multimeter, you will notice there are three holes at the bottom side. One is common and the other is volt, ohm, diode, and amp.
To measure DC voltage you have to connect the black lead to the COM terminal of the multimeter. and the red lead into the V terminal.
Now you have to select the correct range for measurement. It`s very easy you just need to select the number.
But there are so many numbers and letters, which one should you choose?
look there are 200m(200mV), 2000m(2V), 20,200,600 ratings. So if you want to measure a battery voltage that is rated 12v or any DC power supply that is rated below 20v, then turn the dial and set it to 20.
For small projects like lemon batteries, salt batteries, or low voltage applications, you can select 2V or 200mV according you.
Now you have to connect the COM lead to the negative side of the battery or the power supply and the red lead to the positive one. If you change its polarity, you will notice there a (-) sign will appear before the voltage rating. so please connect it properly.
Remember we can measure only the difference in voltage between two points, if we try to measure the same point we won`t get any reading on the display. Because there is no voltage difference.
AC Voltage
The electric socket or outlet of our home contains the AC voltage. AC means basically Alternating Current. This means the current doesn't flow in a straight direction. It changes its direction of flow back and forth.
Not only electric outlet but also inverters, alternators, or AC generators produces AC voltage.
You can think of it like the tide of the sea, and that is why our oscilloscope shows this beautiful sine wave, and this is why we use this symbol.
This is a much higher voltage than a battery and electricity is very dangerous and may be fatal sometimes.
So you should be qualified and you must have followed the safety procedures.
You can buy a socket tester (neon) or a digital one which shows voltage also, that will be much safer to use.
Now in case of measuring the AC voltage, you have to turn the dial and select the AC voltage section of your multimeter. In manual range multimeters you will find 200 and 600v ratings. So if your area voltage is below 200v like 120v AC then you select the 200v AC setting and if your outlet is 230v, then you have to select the 600v AC setting.
1st of all you can test your socket with the socket tester, and you can find where is the live port. During the measuring of AC voltage no need to look at the correct direction, because it al after all alternating.
You Can Click here if you want to know more in detail about power outlet and power sockets.
Now put the leads into the power socket and you will get your voltage reading.
Resistance
Resistance is represented by these symbols and it is the unit of resistance, which is called the ohm. It is a Greek alphabet. It means basically how easily electrons can pass easily through something.
You notice electron flows easily through copper, for a better understanding, copper is highly conductive, which means electricity passes through copper very easily. But in the case of Rubber electricity does not flow that well, and that means rubber resists the flow of electrons, so here rubber is the resistance.
Commercially they use carbon to make resistance because carbon can tolerate high temperatures and it behaves as a resistance.
To measure resistance value with a multimeter is very easy,
1st of all put the black lead into the COM terminal and the red one into the OHM-rated terminal. now select the proper measuring section,
If you want to check resistance, whether is good or bad, you need to learn resistance color coding and how to know the resistance value. Click Here
For example, I am going to measure 6.5k Ohm resistance, so I have to set the dial to 20k and then tap the leads to the resistance, now you can notice some digits appear, and you will see the right value.
In the case of auto range multimeters, you just need to select the resistance section by rotating the dial and then tap the leads to the resistant and you will see its value.
Current
Current is a measurement of how many electrons are flowing through a particular point of a wire. Its unit is Amp.
You already know the symbols of direct current and alternating current. In normal manual range multimeters you will find only the DC current setting. But in the case of clamp meters or automatic range multimeters, you will find the AC current setting.
Let`s learn how to measure the current
1st of all you need to connect the black lead into the common terminal and the red one into the A terminal. Now you need to connect your probes in series with the load and you have to select the right value.
In the case of a clamp meter, you have to select the correct AC or DC current setting, and put the clamp on a single wire, if you put it on a wire which contains 3 phases or live and neutral then you will not get any result.
Continuity
We use this continuity setting to test whether two points are connected or not, if so, it means electricity can flow.
To use this setting, simply connect the black lead to the COM terminal and the red one to the continuity terminal.
If you don't find any continuity terminal but your multimeter has this function, then you put the red lead into the V terminal.
Now the display will show OL or Open Loop Or it may show 1
it means the leads are not connected anywhere.
Tap the leads together, and it will beep. and the display may show 0 ohms. if you have a cheaper one then your meter may show some ohm.
Now you can use it to test a break in a circuit or wire. You can test whether the switch operating correctly or not, and you can test cables over a long distance.
It is important to know, that we can get false readings sometimes, if we try to test between these two points which are clearly broken the meter will find an alternative route and indicate continuity.
So you must consider this and isolate where possible.
The continuity test doesn't work with high-resistance circuits,.
Frequency
In the case of AC voltage, you can measure the frequency. But not all multimeters have this function, 1st of all you have to check if your multimeter has this function or not.
Frequency is basically the alternation of current through the wires back and forth according to time. Suppose in a wire electrons flow back and forth 60 times in a second. that means it is 60Hz frequency.
Hz means hertz, it is the unit of frequency.
To measure it, you have to connect the black lead to the COM terminal and the redone into the V terminal.
Now turn the dial and set the frequency setting, or if your meter has a separate dedicated button for frequency then press it. You can check the correct frequency on the display.
Remember, turn the power off before disconnecting the meter, otherwise, your meter may be damaged.
Diodes
Diodes are basically valves, which allow the electrons to flow in only one direction.
To test them Put the black lead into the COM terminal and the red lead into the diode symbol.
Now turn the dial and select diode mode.
If we connect the leads like this and turn the meter on, you will notice the display shows OL,
Now tap the leads on the terminals of the diode if the display again shows OL then change its polarity, you will get some reading.
LEDs are also diodes, they just emit light. The full name of LED is LIGHT EMITTING DIODES
In this same way you can check LEDs and while checking LED may produce a small light.
Batteries
We need to test our batteries, if they are damaged or in good condition.
Connect your back lead to the COM terminal and the red lead to the V terminal. then turn the dial and set it to 20, most of the batteries are in between 20v but if you are checking a battery pack then make sure to check the rated voltage of that battery pack,
Now tap the black lead on the negative terminal of the battery and the red one on the positive terminal of the battery. you will see a reading on the display. and it is the current voltage of that battery.
If your battery is a 3.7v LI-ion battery then you may get a 3.9-4.1v reading on a multimeter in case of the fully charged battery. If your battery is 12v Battery then you may get 13.4v or almost 14v reading.
Watch the Full Multimeter tutorial On my YOUTUBE channel. Click Here
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