How Does a Multimeter Work?

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If you do know even the tiniest bit about electronics, then you’ll concur to the fact that a multimeter is a must-have for anyone who wants to troubleshoot their electronic and electrical devices in the best way possible.

But how does a digital multimeter really work? Well, if you’re planning to get your first digital multimeter or you’ve just got your first one, this guide is definitely meant for you.

Here’s everything you need to know about the working of a multimeter from taking the electrical and electronic readings to the safety precautions you need to employ when using one.

Let’s get to it then, shall we?

How does a multimeter work
How does a multimeter work

Parts of a Digital Multimeter

Any basic or rather average multimeter has got 3 essential parts which include the display, the selection knob, and the ports.

Right at the top of the front face of a digital multimeter is the display. It is via the display that you are able to see the output of the readings you’re taking.

The selection knob or rather the dial is normally located below the display. Around the dial are different measuring stations and by turning it either clockwise or counter-clockwise, you can choose different measurements regarding what you’re troubleshooting.

Right below the selection knob is the ports. Normally, you’ll be getting three of these. One of them is the COM port which is also referred to as the ground port then there are also the mAVΩ and the 10A ports in which goes the red probe. The former is used when measuring current up to 200mA whereas the latter is used to measuring any current above this.

How do you handle different measurements?

When it comes to DIY electrical and electronic maintenance, here’s how you’ll best be able to handle different measurements using a digital multimeter.

Current Measurement

Being one of the trickiest units of measurement, you need to be really careful when measuring current since for starters, you’ll have to measure this in series.

First, you’ll want the black probe in the COM port and the red one in either the mAVΩ or the 10A port. Measuring current simply involves you interrupting the current flow in the circuit and you’ll, therefore, have to cut the power supply to the circuit under measurement.

Unless it is an auto-ranging multimeter, you’ll have to set the range yourself. First set the multimeter to 200mA and if you suspect that you’ll be measuring anything above this, have the red probe in the 10A port to avoid overloading the current and blowing the fuse.

You should be able to see an instantaneous current reading and, in some cases, the reading may fluctuate over time and then stabilize finally.

NOTE: Once you’re done with the current measurement, ensure the dial is at the DC voltage setting.

Voltage Measurement

Just as it was the case in current measurement, you should have the black probe in the COM port and the red one in the mAVΩ port for measuring voltage.

Since most electrical appliances use DC voltage (where the ‘V’ has a straight line), you should set the dial to ‘2V’ DC current. Unlike current measurement, voltage is measured in parallel i.e. the black probe on the negative terminal and the red one on the positive terminal.

You should have the dial set to a station that is slightly higher than the component you’re measuring e.g. if it’s a fresh battery, and you have the dial set at 1.5V, the reading on the display will be 1.5V which means that the voltage of the battery is slightly higher than this hence you should turn the dial to 2V to get the correct reading.

Measuring Resistance.

Don’t want to go through the hassle of having to master all the resistor color codes? A digital multimeter definitely has you covered.

Still having the probes as they were when measuring current, have the dial set on the least ohm measurement first and press the probe tips on either leg of the resistor (ensure the resistor is not connected to the main circuit ). If say you’re measuring a resistor that has a kilo-Ohm rating of 0.97. you should set the dial to 20 kilo-Ohms. If you get a 0.00 reading on the multimeter, then you’ll have to turn the dial to a lower reading.

If the above resistor is measured with the dial set to 200 ohms, then you’ll have a 1 displayed meaning that you’ll need to tune up the dial

Measuring Continuity

Continuity basically checks whether the circuit is closed or not. It is somewhat similar to measuring the resistance between two points.

By setting the dial to continuity mode (a diode symbol with a propagation symbol in front of it), touch the probes on either end of the circuit under testing. If the circuit is complete, you should hear a continuous beep and if otherwise, it’ll be silent.

In conclusion

Using a digital multimeter is quite simple and straightforward and anyone should pretty much be able to use one. If it’s your first time, you should pay close attention to the safety precautions to protect the multimeter, the circuit under measurement and you yourself as well.

Though it may seem somewhat difficult to find your way around using one, a few hours of practice should definitely make things easier.

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