When it comes to analysing electrical and electronic circuits, there are two major analysis tools to help get the job done. These two tools are the Multimeter and Oscilloscope. However, these two tools have different functionalities and most of the time they are not interchangeable. If you are after a tool to help you get the job done, knowing the difference between the two is essential. Below are some key differences and similarities between a multimeter and oscilloscope. For a more in-depth look, keep reading the rest of the article.
A note before continuing, the multimeter that will be discussed is the newer digital multimeters, not its analog counterpart (which is rarely used anymore).
Multimeter vs Oscilloscope
- Multimeters display data using numbers, oscilloscopes display data visually (lines, waveforms, etc)
- Multimeters have higher resolution with the ability to display data up to 8 digits of data for voltage, current, or resistance.
- An oscilloscope can display signals visually in the form of waves and lines (which can help distinguish if a signal is AC or DC).
- Multimeters are much more portable than oscilloscopes (however, there are newer portable versions of the oscilloscope).
- Multimeters are used for more general purpose measurements. Oscilloscopes are used for more in-depth analysis as well as troubleshooting systems that contain complex signals.
- Oscilloscopes are faster and have wider measurement bandwidths compared to multimeters.
- Multimeters are used for initial measurements. Oscilloscopes are used for further analysis.
- Multimeters can measure voltage (AC and DC), current (AC and DC), resistance, frequency, capacitance, diode test, temperature and continuity.
- Oscilloscopes can measure voltage (AC and DC), frequency/period, and phase angle.
Functions of a Multimeter
Multimeters come in a range of complexities and will vary in the number of functionalities. However, below is a list of the most common functionalities of multimeters.
Voltage (AC and DC)
Multimeters have the ability to measure both AC and DC voltages. This makes them an essential tool for any type of electrical or electronic circuit.However, there are limits to how much voltage the multimeter can measure, so you will have to check its maximum ratings before using it for a particular application.
You can measure voltage between two points in a circuit, or across a component.
Current (AC and DC)
Just like voltage, multimeters can measure both AC and DC currents. Again, each multimeter will have its own limit as to how much current it can handle.Being able to measure current allows you to see if a component is receiving the right amount of current, how much current is being consumed, if there are random spikes in current, etc.
Every piece of material has some sort of resistance and a multimeter has the capability to measure resistances of any type of material (specifically conductors). But, resistance measurements yield more than just measuring the resistance of components. It can tell us the condition of a circuit or component as well (some components resistance deteriorates over time, while others increase. Both these are unwanted scenarios)
Continuity is a function of a multimeter that lets you test the presence of a complete path between two points in a circuit or wire. For example you can test the continuity of wire to see if it has any breaks somewhere in the middle even if it is fully insulated (however, the ends have to be exposed).
The digital multimeter has the capability of providing temperatures in both Degrees Celsius and Degrees Farhanheit. Depending on the need of the application, there are multiple varieties of probes available for temperature measurement.
In the electrical world current is divided into Direct Current (DC) and Alternating Current (AC).
Alternating currents are represented by a Sine wave which involves currents that vary in magnitude and polarity.
The frequency in the electrical world defines the number of times a sine wave of an alternating current repeats itself within a certain time period.Circuits and electrical components are designed to operate at a certain fixed or variable frequency. If they are subject to different frequency values, the circuit will not operate as intended. Multimeters have a Frequency function to ensure all values are correct.
Voltage, current, and resistance form the basic building blocks of electrical and electronic circuits. However, there are many other factors that play a part in the overall working with one of them being Capacitance.
Multimeters can measure the capacitance of a capacitor (as well as other components).
Finally we have the Diode test.A diode is a two terminal, semiconducting device that only allows current to flow in one direction. The diode test function on a digital multimeter allows you to analyse a diode to ensure it is fully functional.
Functions of an oscilloscope
Let’s take a look at the different functions of an oscilloscope. Again these are the most common ones that you will find.
Voltage (AC and DC)
Just like the multimeter, the oscilloscope comes with Voltage measuring capabilities.However, the oscilloscope is able to provide a time-based measurement of voltage, which means it can display how the voltage waveform changes with time. Another addition is that it can measure peak-to-peak voltage, which is the measurement of a voltage waveform from the maximum peak to the minimum peak ( more associated with AC voltages). The oscilloscope can measure both AC and DC voltages.
Frequency and Period
AC applications come with waveforms and varying frequencies. Another important factor is Period which defines the amount of time it takes a signal to complete one cycle.
Frequency and Period are reciprocals of each other; 1/ Period equals the Frequency, and 1/Frequency equals the Period. An oscilloscope can visually display the waveforms on screen which can show you how many times a wave repeats itself within a 1 second time interval.
The Phase Angle of a sine wave describes the angle at which one wave ‘Leads’ or ‘Lags’ another wave. It is the relationship between two sine waves of the same frequency plotted on the same reference axis.An oscilloscope can show you the sine waves of two signals and their phase angles.
Multimeter vs Oscilloscope: Level of analysis
The level of analysis required for a particular job is going to determine whether a multimeter or oscilloscope is needed. If the job just requires general purpose testing of voltage, current, resistance, etc, to get a quick analysis of the situation, then the multimeter is the perfect tool. However, if you find there are problems that need a more in-depth look, and further analysis, then the oscilloscope is the perfect tool.
However, saying so, an oscilloscope is limited by the number of measurements compared to a multimeter.
Multimeter vs Oscilloscope: Cost and availability
Now that we have covered the functions of both the multimeter and oscilloscope, let’s take a look at a cost comparison of the two as well as their availability. When it comes to multimeters, you can get your hands on a cheap multimeter (ranging from $15) without any hassle. More likely than not, your local hardware store will have one.
However, with cheap multimeters comes cheap quality as with anything in life. While they do a decent job, they use cheaper materials which don’t last very long.
Depending on your circumstances and how often you use the multimeter will ultimately determine how much you fork out for a multimeter.
Oscilloscopes on the other hand, cost a bit more which is due to their overall complexity of design and components used compared to the multimeter. Also, you are less likely to find one at your local hardware store.
Multimeter vs Oscilloscope: Ease of use
When it comes to ease of use, both devices have a learning curve. However, the oscilloscope comes with a steeper curve compared to the multimeter.While the multimeter has a lot of functions, it is quite intuitive using them. You just have to be aware of things like the maximum voltage and current ratings, and how to connect the probes to a circuit when testing voltage (parallel), or current (series).
The oscilloscope does take some time to get your head around as you need to learn things like interpreting the different waveforms, setting voltage divisions, understanding triggering, capture rate, duty cycle, rise time, etc.
Multimeter vs Oscilloscope: Portability
Applications that require testing, diagnosis, and analysis are not restricted to a workshop benchtop. You might be an electrician at a house inspecting wiring, or an engineer at a clients worksite designing a new manufacturing plant.Therefore, having a measurement tool that you can take with you is crucial. This is why the portability of a multimeter and oscilloscope is necessary.
The multimeter is quite small by nature and can fit easily into any tool bag making it very portable.
If we went back about 10-15 years, an oscilloscope would have been limited to a workshop bench. They were quite large and not very portable.However, nowadays there are options for portable oscilloscopes that almost resemble a multimeter so you can take them with you on the go.
Multimeter vs Oscilloscope: Display
Finally, we have the Display.
Both devices come with a display that lets you interpret information. But, their displays are quite different in the way they display this information.The multimeter is restricted to only displaying numbers of the electrical parameters you are measuring (which can vary in the number of digits depending on the manufacturer).
Oscilloscopes have a more complex display due to the fact that they display more information (such as the voltage waveforms, time periods, etc.) which require more interpretation and analysis.
Multimeter vs Oscilloscope; which is the best option?
The job you are needing to conduct analysis on will be the determining factor on whether the multimeter or oscilloscope is the right option for you. Below is a table with different conditions and which is the right tool for the job.
|Multimeter or Oscilloscope?
|Need a wide variety of measurements (voltage, current, resistance, capacitance, etc)
|General purpose measurement
|Multimeter and Oscilloscope
|Ease of use
|Signals are more complex
|Need higher speeds