Humans have been developing tools since the stone age. Tools to help us achieve tasks with more effectiveness and efficiency.
Nowadays, the world is filled with a multitude of tools across different disciplines to make our lives easier when it comes to completing a certain task.
Whether it be a hammer, ruler, scissors, shovel, drill, etc.
Sometimes, there are multiple tools to achieve the same job. For example, you have the traditional Hammer and Nail, or you could opt for a Nail Gun.
Each will have its own pros and cons depending on specific criteria.
The electrical and electronic world is no different. There are many tools available for specific and unique tasks.
The Multimeter and Oscilloscope are two very important measurement tools used extensively for analysing and diagnosing electrical and electronic circuits, components, devices, etc.
But, which is better?
It all really depends on the needs of the applications and other factors.
This article will dive deeper and take a closer look at both the Multimeter and Oscilloscope and see which application each is better suited for depending on a set of factors.
A deeper look at the multimeter
First off, in the blue corner; The Multimeter!
The multimeter is an electrical and electronic measurement tool used to measure a specific set of electrical properties. The main ones being; Voltage, Current and Resistance.
These three properties form the fundamentals of Ohm’s Law which is used to design electrical and electronic circuits.
The multimeter has come a long way from its humble beginnings.
Nowadays, there are two main types of multimeter; Analog and Digital.
A brief history of the multimeter
Analog multimeters, or earlier versions first showed up on the electrical scene in 1820. Back then they were known as Galvanometers.
They were limited to only detecting electrical current, and resembled a compass which had a needle that moved depending on the amount of current.
Fast forward 100 years, the first version of the modern day multimeter was created thanks to Donald Macadie.
His multimeter wasn’t limited to just measuring current, but could measure voltage and resistance as well.
Unfortunately, with the advancement of technology, analog devices were being replaced by digital counterparts and this was no different for multimeters.
This was possible with the rise of Semiconductors. A solid state voltmeter was in the development phase as early as the 1950s.
However, it wasn’t until 1977 when the Fluke 8020A became the first readily available digital multimeter.
Over the years, with the cost of manufacturing decreasing, the digital multimeter started to make its way to the forefront and was the go to multimeter.
The Fluke 8020B sold over 1 million units by the late 1980s.
Working principle of a multimeter
Note, while the analog multimeter paved the way, nowadays digital multimeters are the go to choice. So, later when comparing a multimeter and an oscilloscope, I shall be referring to the digital version of the multimeter.
The most noticeable difference between an analog and digital multimeter is the display.
While an analog multimeter uses a needle that physically moves, the digital version uses a Liquid Crystal Display (LCD) that displays values of voltage, current and resistance.
Also, there is no moving coil meter in a digital multimeter.
They use integrated circuits such as operational amplifiers, Analog to Digital Converters (ADC), Digital to Analog Converters (DAC), Microcontrollers, and/or Microprocessors.
Below are the sequence of steps that occur within a digital multimeter when it is subject to a current, voltage, resistance, etc at its input;
- Input is converted to a DC voltage within the ADC range
- ADC converts DC voltage to a digital value
- This values is displayed on the LCD screen
The steps mentioned above are more common for measuring voltage. To measure current and resistance, the digital multimeter implements techniques similar to those used by its analog counterpart (using series and parallel shunt resistors).
To measure current, voltage is measured across a known resistor.
For resistance measurement, voltage is measured across a resistor via a known resistance from a stabilised voltage in the meter.
Digital multimeters come equipped with a Positive (red) and Negative (black) terminals where multimeter probes are connected to.
A deeper look at the oscilloscope
Next, in the red corner we have; The Oscilloscope!
The Oscilloscope is an electrical and electronic measuring instrument used to measure varying Voltage, Frequency , Time Period and Phase .
It represents this voltage in a graph form, with the amplitude of the voltage on the y-axis and how the voltage varies with time on the x-axis.
A brief history of the Oscilloscope
The first ever known oscilloscope (or one that had similar working principles to the modern day version) dates back to around 1893.
It was created by a French physicist named Andre Blondel.
The device he created measured the intensity of alternating currents by means of a pendulum attached to a coil which recorded this information on a moving paper tape.
Due to the many moving parts associated with its construction, the recorded measurements were not very accurate.
Fast forward to 1897, and a man by the name of Karl Fedinand Braun invents the Cathode Ray Tube (CRT). This technology was recognised by a British company called A.C. Cossor which used the CRT for developing the oscilloscope in 1932.
Later, in 1946, Howard Vollum and Melvin Jack Murdock, would start a company known as Tektronix, which would go on to be the leading manufacturers in the oscilloscope scene.
Working principle of an oscilloscope
Just like multimeters, oscilloscopes come in Analog and Digital versions.
However, since analog oscilloscopes are not widely used anymore, I will concentrate on the digital version for the rest of the article.
Also, this way I will be comparing a digital multimeter and a digital oscilloscope.
The main purpose of the oscilloscope is to process, capture, display, analyze, and store the waveform and bandwidth of an input signal.
There are three classifications of digital oscilloscopes; Digital Storage Oscilloscope (DSO), Digital Phosphor Oscilloscope (DPO), and Digital Sampling Oscilloscope.
The most common of the three oscilloscopes is the Digital Storage Oscilloscope (DSO). So, let’s take a look at its working principle.
When an input is presented to the DSO, it processes it, stores it in memory and then displays it on screen.
It utilises digital processing techniques to capture, analyse, process, store and display the data. The signal can be displayed visually.
The block diagram below shows the different components and circuits inside the oscilloscope.
- The analog signal is sent through an amplifier (if the signal is too weak).
- The analog is signal is then digitised using the digitiser
- It is then stored in memory
- It is then reconstructed from a digital format to analog
- The Cathode Ray Tube (CRT) is used to display the analog data
- To display data in memory it will first need to be converted to analog data (as it is stored as digital data) before being displayed on the CRT.
Multimeter vs Oscilloscope
Now that we know a little bit about the multimeter and oscilloscope, let’s compare the two using a set of factors such as functionality, cost and availability, ease of use, portability and display.
Later I shall discuss which is best suited for an application as opposed to the other.
Multimeter vs Oscilloscope: Functions
First off, let’s take a look at the different functions that a multimeter and oscilloscope have to offer.
Functions of a multimeter
This measuring tool has come a long way since its early days of being limited to just measuring voltage and current.
Nowadays, the multimeter comes packed with a plethora of functions that give engineers, hobbyists, electricians, etc, a more insightful look when it comes to circuit analysis and diagnosis.
Below are the functions a typical multimeter will come equipped (note, the cheaper the multimeter the less probability it will have all these functions);
Functions of a multimeter: Voltage (AC and DC)
The first function that comes standard with every multimeter is Voltage.
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.
Functions of a multimeter: Current (AC and DC)
Next is Current, which is another function that comes standard with every multimeter.
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.
Functions of a multimeter: Resistance
Resistance is the final piece that completes the Ohm’s Law puzzle.
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)
Functions of a multimeter: Continuity
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).
Functions of a multimeter: Temperature
Multimeters now come with the added ability to measure Temperature.
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.
Functions of a multimeter: Frequency
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.
Functions of a multimeter: Capacitance
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.
One of them is Capacitance.
Multimeters can measure the capacitance of a capacitor (as well as other components).
Functions of a multimeter: Diode Test
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 functions available on an oscilloscope.
As mentioned earlier, there are many different types of oscilloscope available. Each will have its own unique characteristics and measuring capabilities.
However, the functions I am going to cover are the most common and standard that an oscilloscope will come equipped with.
Functions of an oscilloscope: 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.
Functions of an oscilloscope: Frequency and Period
We saw earlier that the electrical world is divided into AC and DC applications.
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.
Functions of an oscilloscope: Phase angle
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: 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 on 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 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.
Conclusion of Multimeter vs Oscilloscope: Which is better?
Since we are looking at a multimeter versus an oscilloscope, and have compared the different factors, it is time to see which one is better.
But, there is more to it than that.
When it comes to superiority, one is not more superior than the other. Rather, it all depends on the needs of the application and other circumstances which will determine which is more suited for that particular application.
Its suitability for a particular application will come down to the factors we just covered earlier.
If you need a measuring tool to measure a wide variety of electrical parameters that include, voltage, current, resistance, frequency, temperature, etc, the multimeter is the perfect tool. It is more suited for quick circuit diagnosis and analysis.
But, if you are dealing with more complex circuits, and need to do a more in-depth analysis of voltage waveforms, frequency, and phases (especially with AC applications), then the oscilloscope is going to have to be your weapon of choice. It is great for diving deeper after you have found a problem.
Sometimes having both can be advantageous. As you can use the multimeter to quickly identify problems at the surface, and then use the oscilloscope to dive deeper for further analysis.
The multimeter is great for general purpose electrical and electronic testing, while the oscilloscope is great for in-depth diagnosis and analysis.
It all comes down to your needs and how a multimeter or oscilloscope can help you achieve them.