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. 

Resistance

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

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).

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. 

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.

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 with one of them being Capacitance.

Multimeters can measure the capacitance of a capacitor (as well as other components). 

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 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.

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: 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. 

The post Multimeter vs Oscilloscope - Which is better? appeared first on Electronic Guidebook.

They are development boards that include a microcontroller, power supply, inputs, outputs, Serial communication and much more.

You might have just purchased an Arduino, or are thinking about buying one to get stuck into the world of microcontrollers, electronics and programming. 

But, you might also be wondering whether you need a multimeter for an Arduino? While it is not necessary to have a multimeter when you start out with an Arduino, it is recommended that you do have one. Multimeters are great for troubleshooting problems that you might come across with your Arduino projects.

Also, Arduino development boards are not perfect. They are going to have some onboard problems sooner or later. 

Again, a multimeter is your best option at identifying the problem. 

What is an Arduino

Let’s take a deeper look at the Arduino. 

This will help you understand why you might require a multimeter. 

Below is one for the most common Arduino development boards; Arduino Uno.

As you can see the Arduino Uno has many components and parts that make up the development board which include;

• Power Input (barrel jack)
• 3.3V power input pin
• 5V power output pin
• Analog Input pins
• Digital Input/Output pins
• Reset Switch
• Microcontroller 
• USB port 

It is great for the beginner as you do not need to set up a microcontroller on a breadboard with a power supply and capacitors or resistors. 

It’s already all done for you on the development board. 

Inputs and outputs like LED’s, sensors, motors, displays can be connected to the digital pins as required. 

The Arduino can also be programmed using the USB port. It does not require complicated interfacing with a computer. 

What are the main uses of a multimeter

The multimeter is an electronic measuring instrument used on a daily basis by Electricians, Engineers, Hobbyists, DIYers and many others.

It has many functionalities but the main three are measuring Voltage, Current, and Resistance.

The most basic of multimeters should include these three measurements.

More complex multimeters can have more than just these three measurements which can include;

• AC (alternating current) voltage and amperage
• DC (direct current) voltage and amperage
• Resistance (ohms)
• Capacity (farads)
• Conductance (siemens)
• Decibels
• Duty cycle 
• Frequency (Hz)
• Inductance (henrys)
• Temperature Celsius or Fahrenheit 

Multimeters come in Analog and Digital versions, but analog multimeters are less common today due to their inaccuracy. 

The main use of a multimeter is to be able to diagnose and troubleshoot electrical and electronic circuitry. 

Finding faults and rectifying them is where the multimeter will be your best friend. 

Reasons why you might need a multimeter for an Arduino

When starting out on your journey with an Arduino, the projects you will be undertaking will be simple and troubleshooting will not necessarily require a multimeter. 

However, as you advance and the Arduino projects you embark on get more complex, you will no doubt require a multimeter to aid you in finding inevitable problems. 

We now know that a basic multimeter can measure the three basic electrical values which are voltage, current, and resistance. 

So let’s look at some reasons why you might want to invest in a multimeter to help with your Arduino.

Reason #1 why you might need a multimeter for Arduino: Testing Digital and Analog Pins

Ardnuinos come with a varying number of digital pins that can be used either as inputs or as outputs. 

Where inputs can include;

• Buttons
• Switches
• Sensors

And outputs can include;

• Motors
• Light Emitting Diodes (LED’s)
• Displays

Smaller components that require less current and voltage, can be powered by the 5 volts outputted at the digital pins.

However, if for some reason the digital pin does not seem to be powering whatever you have connected, you can use the voltage function of the multimeter to check what voltages are present at the digital pins.

Also, an Arduino will have designated analog pins where sensors can be connected to. 

A sensor will output voltages in analog form. 

However, arduinos only deal with digital data. 

The analog pins have the ability to convert the analog data to a digital form. 

Sometimes, the wrong digital values will be generated by software. 

You can see where the problem is by double checking the voltage at the analog pins and cross checking them with the digital values. 

Reason #2 why you might need a multimeter for Arduino: Testing Voltages

Initially your circuits will be confined to onboard the Arduino itself. 

But, sooner or later your projects will extend to outside of the Arduino, and onto something like a breadboard.

The more wiring and connections that are required, the more chances of error. These errors tend to show themselves as wrong voltages. 

Therefore fault finding when something is not working without a multimeter is going to be very very hard, and annoying.

Using a multimeter, the circuit schematic and a little electronic knowledge you should be able to find solutions to your problem in no time.

Reason #3 why you might need a multimeter for Arduino: Current consumption

If the next project you are undertaking requires a means of mobile power (like a battery), the circuit will need to be as efficient as possible to extend the life of the batteries. 

If you don’t know how much Current the system you are designing is consuming how will you know whether it is efficient or not?

Utilising the ability of the multimeter to measure current, you will be able to deduct if any improvements need to be made. 

Reason #4 why you might need a multimeter for Arduino: Resistance and Continuity

No matter whether you are a beginner or an expert, you are going to encounter a resistor or two, or a hundred.

These little buggers have many uses in an electronic circuit and come in a variety of shapes, sizes and resistance values. 

Even though resistors have colour bands on them which indicates what resistance value they are, it can get quite annoying trying to squint and constantly check the colours.

A workaround to this problem is using a multimeter (no surprises there)!

You will easily be able to tell what the resistance is of a resistor in any part of the circuit. 

Also, multimeter’s have another neat function which allows you to test Continuity.

This test allows you to see if two points of a conducting material are connected and therefore ‘continuous’ allowing the flow of current.

This is great for wires with insulation, or testing parts of a circuit that should be connected together. 

Can you get away with not having a multimeter initially?

When you initially start out with the Arduino, your projects are not going to be very complex. 

This might include projects such as reading button presses, blinking an LED, reading sensor values etc. 

The circuits involved with these are not too intense and only require a few connections. 

Saying this, you will still encounter problems. However, finding the cause of the problem and then the solution will be a bit easier. 

So, when starting out you do not need a multimeter.

But, it does not hurt to have one as part of your troubleshooting arsenal. 

Do you need an expensive multimeter for an Arduino?

No, you do not require an expensive multimeter.

When you are working with an Arduino, there are only a few measurements you want your multimeter to be capable of measuring; Voltage, Current, Resistance and Continuity. 

You can get multimeters that won’t break the bank which are still capable of performing these measurements so you can troubleshoot your Arduino and additional circuitry. 

The one thing you need to be aware of when selecting a multimeter is the ranges of voltages, and currents it can handle. 

It should be able to handle the voltage and currents of the Arduino and other circuitry. 

Final thoughts

So, you can see there are many reasons why you would want to invest in a multimeter when using an arduino.

It is a great tool for diagnosing and troubleshooting problems which are inevitable.

While you might not need a multimeter initially when starting out with an Arduino, it will prove useful as you progress in skill level and your projects get a bit more complex.

However, you do not need an expensive multimeter. A decent cheap one with the three basic measurement capabilities (voltage,current and resistance) should be just fine.

The post Do I need a multimeter for an Arduino? appeared first on Electronic Guidebook.

These quantities include things like current, voltage, resistance,capacitance, inductance and a whole list of others.

When designing a circuit, or testing a circuit for faults, you need to have a way of being able to measure these different quantities.  

Otherwise things could get messy real fast. 

An analog multimeter is an electronic and electrical measuring instrument that is used to measure a number of different electrical quantities.

The uses of an analog multimeter include;

• Measuring Voltage
• Measuring Current
• Measuring Resistance
• Transistor testing
• Diode testing
• Continuity test 

What is an analog multimeter

The Analog multimeter uses a needle that is placed on a numbered scale (that has a specified range), to display a number of different quantities as pictured in the image below. 

When the analog multimeter is used to measure these quantities, the needle is deflected depending on the force generated by the quantity being measured.

Inside the multimeter is a drum (which has a coil wound around it) between a pair of permanent magnets.

A magnetic field is induced, when a current passes through the coil. 

Since a magnetic field already exists due to the magnetic field, it reacts with the induced magnetic field causing a force which moves the needle. 

6 uses of an analog multimeter 

The analog multimeter has many different functions and uses, which make it a vital measuring instrument. 

Let’s take a look at the different uses of an analog multimeter. 

Use #1 of an analog multimeter: Measuring Voltage 

Voltage is one of the most important aspects of any electrical or electronic circuit.

It is the force that is generated by a power source (like a battery) that pushes electrons (current) around a closed circuit. 

In simple words voltage is electrical pressure.

Why is it important for an analog multimeter to measure voltage?

When an electrical or electronic circuit is built, it is created with components to work within a certain range of voltage values. 

This is because all components have minimum and maximum values within which they operate efficiently. 

Operating outside of these thresholds will cause the component to fail, which will also have a domino effect causing the rest of the circuit to fail.

So, having the ability to check that the right voltages are present between any two points in a circuit is needed. 

Also, if for some reason a component has stopped working, an analog multimeter can be used to check the voltage across it to see whether there is a Short or Open circuit.

Another great reason is checking the voltage of your power source. 

You might be powering your circuit with a power supply which is fine as it displays the voltage, but what if you are using batteries? How will you know if it is providing the right voltage to power your circuit.

Again that is where the analog multimeter’s voltage measuring function comes in handy.

Use #2 of an analog multimeter: Measuring Current

Those charged electrons that move around a circuit that receive the force from the voltage are also known as Current.

A more detailed description of Current would be the amount of charge that passes a given point in a circuit within a specific time period. 

The magnitude of the current is given in Amperes (A). 

Without getting into too much detail, the molecular structure of materials contains electrons. Depending on the material in question, the electrons can be held tightly or loosely. 

When the electrons move within a material it is known as current. How well and how many electrons move governs the substance’s ability to conduct electricity. 

Just like voltage, there are many reasons why it is essential to be able to measure current using an analog multimeter. 

One reason for measuring current is to see how much current a circuit or component consumes.

If you are designing a circuit that runs off a limited power source (like a battery), you want to be able to extend its lifetime as much as possible. 

While theory and calculation can give you an indication of how much current a circuit or component will consume, there are many factors that come into play in the real world.

You can use an analog multimeter to measure how much current is being consumed that will give a better indication than just theory alone.

The next reason is again along the same lines of measuring voltage. 

Like voltage ratings, electronic components have current ratings too. 

Exceeding these current ratings can cause irreversible damage. So having a way to measure how much current is being supplied to them using an analog multimeter is a necessity. 

Use #3 of an analog multimeter: Measuring Resistance

So, voltage is the force that pushes electrons, and current is the number of electrons that pass a given point.

Resistance is the ability of a material to resist current. 

Voltage, current and resistance are closely related, and make up the fundamentals of electricity. 

Their relationship can be summed by using Ohm’s law. 

Ohm’s law sums up the relationship between Voltage, Current and Resistance. The formula can be seen below. 

So the final piece of the puzzle is measuring resistance. 

If you want to decrease the current flowing in a circuit you will need to increase the resistance of the circuit and vice versa.

Everything in a circuit like a battery, wires, and electronic components have some sort of resistance which adds up to the overall resistance of the circuit. 

But, there are specific passive components known as Resistors that are created with a known resistance so you can increase or decrease the resistance of a circuit as desired.

Being able to measure the resistance using an analog multimeter lets you design a circuit as close to the desired resistance value as possible.

Since you cannot really know the resistance values of other components other than resistors, being able to measure their resistance is very helpful. 

While resistors have colour bands on them indicating their resistances, it can be time consuming trying to figure out what the value is. Sometimes it’s much easier to just use the analog multimeter to read the resistance. 

Use #4 of an analog multimeter: Continuity test

For a current to flow, it requires an unbroken path.

If that path is unbroken it will stop the flow of current within that circuit as can seen below.

Diagram A shows a circuit that has an unbroken path. Here current can flow without any interruptions.

The circuit in diagram B has a break in the circuit, therefore no current can flow. 

Circuits and components are connected together using wires of varying lengths, materials and diameters. 

However, these wires are shielded to protect us and other parts of the circuit. 

So, if you have a long thick wire that has a break somewhere in the middle, it is going to be very hard to know what the real issue is.

Analog multimeters have the ability to test the Continuity, which is the presence of a complete path that electrons can flow through. 

It not only can test the continuity of wires, but of switches, fuses, conductors and certain components. 

For example, you can test if a MOSFET is damaged or not not using the continuity test. 

When the leads of the multimeter are placed between the Source and Gate terminals of the MOSFET, there should be no continuity. 

An analog multimeter lets you know if there is continuity using an audible beeping sound.

Use #5 of an analog multimeter: Diode and Transistor  testing

Diodes are electronic components that can be found in almost every circuit.

Their most common applications include protection, rectification and switching. 

Unfortunately for the Diode, they tend to be the first to get damaged when a fault arises. So, having a way to test whether it has been damaged or not is essential.

Lucky for you and me, analog multimeters can test a diode to check it is functioning as it should be or whether it needs to be disposed of.  

The Light Emitting Diode (LED) is a type of diode which has the ability to emit light when forward biased. 

Just like a conventional diode, we can test a LED using an analog multimeter to see if it is working.

As well as the diode, the analog can be used to test the functionality of a Transistor. 

The Transistor is a semiconductor device used mainly to amplify or switch electronic signals and electrical power.

Testing a transistor using an analog multimeter follows a similar procedure to testing a diode. This is due to the fact that a bipolar transistor closely resembles back to back diodes.

Use #6 of an analog multimeter: hFE amplification test  

A hFE (Hybrid parameter forward current gain, common emitter) amplification is the  current gain of a transistor. 

This number represents the factor that the base current of the transistor is amplified to produce the output amplified current.

So, for example if a transistor had a base current of 1mA, and a hFE of 100, the output current at the collector of the transistor would be 100 mA.

Analog multimeters are equipped with a function that allows you to find out what a transistor’s hFE value is. 

Being able to test the hFE (gain) of a transistor comes in handy when you might have transistors lying around and aren’t too sure of hFE value. 

Applications of an analog multimeter

You can see the analog multimeter has many great uses and abilities. 

But, what applications are these functionalities commonly used for and who tend to use them?

Since the multimeter is a device that is primarily used with electricity, anyone who deals with electricity, would use the multimeter.

This can include;

• Electricians, 
• Electrical and Electronic Engineers
• Scientists
• Automotive Engineers
• Mechanics 
• Line installers and repairers

The main most common use for an analog multimeter is Fault Finding or Circuit Analysis.

As the name suggests, this involves finding faults in a circuit, wire, component etc, that is not working. 

There are many ways to approach fault finding, each with their own pros and cons depending on the circumstance.

Other than that, analog multimeters are also used in the design process of electrical and electronic systems to ensure components are functioning, as well as having the right values. 

Does an an analog multimeter have the same uses as a digital multimeter

The analog multimeter is less commonly used in the electrical and electronic field due to the rise of digital electronics. 

You can now use a Digital Multimeter (DMM) to perform the same tasks as its older counterpart.

However, they both have similar uses,  but each having its own pros and cons which I will discuss below. 

Difference between an analog and digital multimeter

When it comes to the multimeter, you have two options; Analog or Digital.

While both are used for the same purpose, they do have their differences.

So, before diving into what are the uses of an Analog multimeter, let’s quickly identify the main differences between an Analog and Digital multimeter.

Display – The first most obvious difference between an Analog and Digital multimeter is the display. The analog multimeter uses a needle to show the measured quantity, whereas the digital multimeter displays information in the form of digits. 

This is similar to the difference between an Analog and Digital clock.

Cost – The analog multimeter is less expensive compared to its digital counterpart due to the way that it is constructed and the components that it uses.

Accuracy – Since the analog multimeter uses a needle pointer to display values, this can increase the amount of parallax error when being read by the user giving it a lower accuracy.

Input Resistance – The input resistance of an Analog multimeter varies with range, while a digital multimeter stays constant for all ranges. 

The post 6 common uses of an analog multimeter appeared first on Electronic Guidebook.

Whether you are an experienced engineer, electrician, DIYer, electronic hobbyist etc, having a Multimeter is going to benefit you in many ways.

A multimeter is capable of more than one measurement which can include; Voltage, Current, Resistance and others depending on the complexity of the multimeter.

Of the many measurements, Voltage is one of the most common parameters it is used to measure.

But, the multimeter is not a perfect measuring instrument. 

Sometimes it might read the wrong voltage. 

You might be reading this because your multimeter is reading the wrong voltage. 

So, does that mean you need to dispose of your multimeter and get a new one?

Of course not! 

Below are some possible reasons why a multimeter is reading the wrong voltage:

• Low battery
• Faulty Leads
• Incorrect placement of probes
• Component failure
• Fuse blown 

For a more detailed description for each reason, read on. 

Note, make sure to always first try the standard procedure of turning your multimeter off and on and then checking to see if the wrong voltage is still being read. 

5 reasons why a multimeter is reading wrong voltage

Let’s take a look at each of the reasons why a multimeter is reading the wrong voltage in more detail.

Reason #1 a multimeter is reading the wrong voltage: Low battery

The first and most possible reason why your multimeter is reading the wrong voltage is because its battery has decreased below its nominal voltage. 

Electronic components, devices all work within a specific voltage range. 

Whether it be your mobile phone, calculator, toaster, Television and so on.

However, some of these devices have the luxury of being plugged into a wall outlet and being powered ‘infinitely’ (or until you stop paying your bills).

Other devices which are mobile in nature run of a limited power source such as a battery. 

A multimeter is a device that is mobile because it needs to be carried and used in different locations. 

Therefore it needs to be powered by batteries. 

This can cause issues with reading voltages when the batteries start to drop in power. 

A drop in battery voltage can cause the internal reference voltage to drop which then could cause the meter reading to be high.

So, if you are not getting normal voltage readings on your multimeter, replace the current batteries with newer ones and then check again. 

If you get normal readings, you know the old batteries have dropped past their nominal voltage. 

Even if you haven’t used your multimeter in a long time, the batteries could still potentially drop in voltage. 

So beware of that.

Reason #2 a multimeter is reading the wrong voltage: Faulty Leads

If you replaced the batteries with newer ones, and you are still getting the wrong voltage readings, then the next possible issue you could have is faulty leads.

To test your multimeter leads, set the multimeter to read resistance and then touch the probes together.

The resistance that should be displayed for multimeter leads that are functioning properly should be zero.

If for some reason the resistance reading is above one, or all over the place, your multimeter leads are faulty and could be the reason your multimeter is reading the wrong voltage. 

Try replacing the leads to see if that rectifies the issue.

Another issue could be that the probes are not connected properly to the multimeter. 

If there isn’t a proper connection, there won’t be a proper electrical conduction and therefore the wrong voltage will be displayed. 

So, make sure your multimeter probes are connected properly. 

Reason #3 a multimeter is reading the wrong voltage: User error

Ok, this reason comes down to user error.

User error involves the user (the person using the multimeter) not placing the multimeter leads on the right points of a circuit or battery. 

This might seem like a silly reason as to why a multimeter is reading the wrong voltage, but it is entirely possible and has happened to me plenty of times.

This could be caused by not reading the schematic right, or, placing it in the wrong place by mistake. 

Either way, double check that you are measuring the right parts of the circuit if your multimeter is reading the wrong voltage. 

Reason #4 a multimeter is reading the wrong voltage: Fuse blown

Fuses are used in the electrical and electronic field as a way of providing safety to currents that exceed the normal threshold of a device. 

This threshold can be different for different devices so there are fuses that can handle different levels of current.

When that current threshold is exceeded, the metal wire inside the fuse melts, disrupting the flow of current. 

Multimeters have a maximum current that they can handle.

So, to protect them and you from overcurrents, they are fitted with fuses. 

If you happen to use the multimeter to measure the current or voltage outside its maximum threshold, the fuse is going to break.

If the fuse is blown, your multimeter is not going to function properly and therefore display incorrect voltage values. 

If you want to know how to check if your fuse is blown and how to replace it watch the video below.

Reason #5 a multimeter is reading the wrong voltage: Component failure

The last possible reason why your multimeter could be reading the wrong voltage might not be an issue with the multimeter itself.

The issue could be with the electronic/electrical component that you are testing.

Electronic components are not perfect. They too are subject to failure. 

Below are a couple ways electronic components could fail;

• Exceeding the current or voltage rating of the component
• Electrostatic Static Discharge

If a particular component has failed, this could cause a wrong voltage reading on the multimeter when testing another part of the circuit (depending on the circuit itself of course). 

How to be certain your multimeter isn’t reading the wrong voltage

So, the multimeter displays a voltage that you are not expecting.

You might know what voltage it should be displaying, but how can you be certain that something is wrong with the multimeter?

If you have a power supply, set it to a voltage (that is within the range of the multimeter) and then use the multimeter to test the output voltage. 

If the voltage on the multimeter matches the power supply’s voltage, great! 

However, if the voltages do not match, you know you have a problem.

You might not have a power supply lying around though.

That’s fine.

Get yourself a new battery (AA, AAA, D-cell, 9V etc), and test the voltage. Since it is a new battery, the voltage when testing should be around the full capacity value of the battery. 

Again, if the multimeter is displaying the wrong voltage, you know you have a problem and can cycle through the 5 possible reasons to find the problem. 

How to avoid reading the wrong voltage with a multimeter

It can be quite a waste of time having to go through all the steps of figuring out why your multimeter is reading the wrong voltage. 

You might know the saying, “Prevention is the best cure”.

This is having habits or procedures in place that prevent a problem from arising in the first place.

Below are some things you can do to avoid the situation of your multimeter reading the wrong voltage for each of the 5 possible reasons mentioned earlier. 

Low battery

You cannot really control how your battery performs. 

But, you can control the quality of the batteries you buy for your multimeter. 

Invest in good quality batteries that will last longer. This will save you from always having to change the batteries of the multimeter (which will save you time and money).

Faulty Leads

Depending on how often you use the multimeter, and the way you use them, you will be twisting, turning, stretching them in every direction. 

This is going to cause some wear and tear on the multimeter leads which will no doubt cause them to fail in time.

So, to ensure longevity, make sure to handle the leads with care when using the multimeter.

User Error

Mistakes are going to be made.

We are human after all.

But, we can reduce the frequency at which we make errors when reading voltages on the multimeter with a few things we do before testing.

Never assume anything. Always make it a habit to read the schematic of the circuit you are reading to identify the right points where to place the multimeter leads.

Test more than once to see if you are reading the same voltage. 

You might have got it wrong the first time, so testing more than once will eliminate any doubt. 

Also, make sure you are making a proper connection with whatever you may be testing. 

Fuse blown

To avoid blowing the fuse of your multimeter, get to know your multimeter.

All multimeters have different maximum current and voltage ratings.

Read your multimeter’s manual, and familiarise yourself with its maximum voltage and current ratings. 

This will prevent you from testing any currents and voltages outside of the limits of your multimeter.

Component failure

Similarly with the multimeter, make sure to stay within the voltage and current limits of the components in your circuit.

Electronic components are also susceptible to damage via electrostatic discharge when you are handling them.

To prevent this follow the points below

• Keep electronics away from blowing air
• Keep electronics away from plastics and synthetic materials 
• Invest in an ESD mat (which is designed to drain static discharge away from you)

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