If you’re doing any kind of electrical work, no matter what the application is; one of the best tools you can have at your disposal is a multimeter. If you’re just getting started, here’s how to use one and what all those confusing symbols mean. In this guide, we will show the basics of a multimeter and the uses of a multimeter.
What is a Multimeter?
A multimeter is a measurement tool undeniably necessary in electrical work. It combines three important features: a voltmeter, ohmmeter, and ammeter, and in some cases continuity. A multimeter allows you to know what is going on in your circuits. Whenever your circuit isn’t working, the multimeter will help you troubleshooting.
Different Parts of a Multimeter
If you are a beginner and this is your first time using a multimeter then it’s very important to know the parts of a multimeter. A multimeter has three parts:
- Selection Knob
The display usually has four digits and it has the ability to display a negative sign. Some multimeters have illuminated displays for better viewing in low light situations. The selection knob allows the user to set the multimeter to read different things such as milliamps (mA) of current, voltage (V) and resistance (Ω).
The COM port stands for Common, and the black probe will always plug into this port. The VΩmA port sometimes denoted as mAVΩ is simply an acronym for voltage, resistance, and current (in milliamps). This is where the red probe will plug into if you’re measuring voltage, resistance, continuity, and currently less than 200mA. The 10ADC port sometimes denoted as just 10A. It is used whenever you’re measuring the current that’s more than 200mA.
Multimeter Symbols and Meaning
There’s a lot symbol available at the selection knob on a multimeter. But if you’re only going to do some basic stuff then you won’t even need to use half of all the settings. In any case, here’s a rundown of what each symbol means on my multimeter:
- Direct Current Voltage (DCV): Sometimes it will be denoted with a V– instead. This setting is used to measure direct current (DC) voltage in things like batteries.
- Alternating Current Voltage (ACV): Sometimes it will be denoted with a V~ instead. This setting is used to measure the voltage from alternating current sources, which is pretty much anything that plugs into an outlet, as well as the power coming from the outlet itself.
- Resistance (Ω): This measure how much resistance there is in the circuit. The lower the number, the easier it is for the current to flow through, and vice versa.
- Continuity: Usually denoted by a wave or diode symbol. This simply tests whether or not a circuit is completed by sending a very small amount of current through the circuit and seeing if it makes it out the other end. If not, then there’s something along the circuit that’s causing a problem—find it!
- Direct Current Amperage (DCA): Similar to DCV, but instead of giving you a voltage reading, it will tell you the amperage.
- Direct Current Gain (hFE): This setting is to test transistors and their DC gain, but it’s mostly useless since most electricians and hobbyists will use the continuity check instead.
How to Use a Multimeter?
A multimeter is used for different purpose like measuring voltage (volts), current (amps) and resistance (ohms). Now we will show you how you can measure current, voltage, resistance using a multimeter.
You can measure DC voltage or AC voltage. The V with a straight line means DC voltage. The V with the wavy line means AC voltage. To measure voltage:
- 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.
- Make sure the red probe is connected to the port with a V next to it.
- Connect the red probe to the positive side of your component, which is where the current is coming from.
- Connect the COM probe to the other side of your component.
- Read the value on the display.
To measure current you need to bear in mind that components in series share a current. So, you need to connect your multimeter in series with your circuit. Before measuring the current, be sure that you’ve plugged in the red probe in the right port, in this case, µAmA. In the example below, the same circuit of the previous example is used. The multimeter is part of the circuit.
Plug the red probe into the right port and turn the selection knob to the resistance section. Then, connect the probes to the resistor leads. The way you connect the leads doesn’t matter, the result is the same.
Continuity testing is the act of testing the resistance between two points. If there is very low resistance (less than a few Ωs), the two points are connected electrically, and a tone is emitted. If there is more than a few Ωs of resistance than the circuit is open, and no tone is emitted. This test helps ensure that connections are made correctly between two points. This test also helps us detect if two points are connected that should not be.
A multimeter is an important tool in any electronics lab. In this Beginner’s Guide, we’ve shown you the basics of multimeter and uses. This guide is meant to be a starting point to get you up and running, and it’s very possible that some things shown above are different from your particular model.