Category Archives for How To & Tips

How to use a Multimeter to Test a Solder Joint

There is nothing more frustrating when finishing a large electronics project then finding out that your project doesn’t work as intended. The causes for this can vary wildly, but a bad solder joint is one of the more common reasons for circuitry failure. As such, you should follow these steps to verify that each new solder joint is good before continuing with your project.

A word on quality components

Many challenges associated with soldering, especially for newcomers, can be overcome by using a quality soldering iron. Features such as a quality build, sufficient wattage (50+ Watts), temperature control, and using an appropriate tip for the job can all make using a soldering iron much easier. We recommend the guides and reviews at Discover the Best Soldering Iron if you are looking for assistance with choosing a soldering iron or related accessory.

Visual Inspectionsolder-joints

It may sound like common sense, but visually inspecting the solder joint should be your first step. Inspect the joint with a magnifying glass and move or wiggle the component to check for stability. Remove and re-solder components that feel loose. Also verify that the pad is filled with solder, but not overfilled. The pad and the lead should be completely covered with solder and you shouldn’t be able to see through the hole the lead passes through.

Also check for Shiny solder, which indicates that the solder was melted and re-cooled properly. Generally solder that didn’t reach a hot enough melting temperature will appear cloudy when re-cooled. This tip doesn’t apply to all solder, however, so take it with a grain of salt. (Some of the newer lead-free solder will always appear cloudy).

Last, make sure that the cooled solder isn’t touching another pad, which will create a short and cause your circuit to not operate as expected.

Test with a Multimeter

Checking for Resistance


Set the dial on your multimeter to the Ohm function. Sometimes it will be labeled “Ohm x 1K”. The icon for Ohms looks like an upside down U or a set of headphones.

Touch the leads of your multimeter together before beginning. You should get a zero reading, indicating there is zero resistance between the leads currently.

Now, touch the positive lead of your multimeter to some part of the wire ahead of the solder joint. Then touch the negitive lead to the end of the post of the connector on the other side of the solder joint. Your meter should read zero. If you see any kind of resistance, it likely reflects a bad solder joint.

Checking for Continuity

test-continuity-with-multimeterYou can also use the continuity function on your multimeter to test a solder joint. First, set your multimeter to continuity mode (looks like sound waves going out left to right in a cone shape). Touch the leads together and make sure the multimeter beeps.

Now, touch the leads to two points on opposite sides of your solder joint. The multimeter will beep if there is continuity detected. This means that conductive material (i.e. your solder joint) is connecting the points between your leads and that the solder joint is good from a continuity standpoint. If the multimeter does not beep, you do not have continuity.

multimeter for cars

How To Use an Automotive Multimeter

What is a multimeter and how is it used?

Multimeters are very common tools in the home and in businesses, particularly automotive organizations.

They are used very frequently for a wide range of tasks when checking your car for problems.

Another name for a multimeter is a volt/ohm meter (VOM). This electronic device is used for measuring. It combines a number of different functions in one easy-to-use handheld piece of kit.

Multimeters measure

  • Amps
  • Volts
  • Resistance

multimeter readings

Almost all models come with a circular dial. This allows you to choose the type of measurement you require. Current, voltage and resistance are the most regular options. Some of the more advanced variants will stretch to measuring continuity and can also be used for testing diodes.

Although there a number of types of multimeter, we can split them in two and think of manual multimeters and auto ranging multimeters. The difference is much like that between manual and automatic cars: the manual requires rather more input from the user.

With the manual version, you choose the range of input. The auto ranging type come with some selections on its dial. Depending on the information received through the equipment’s probes, this machine will guess on your behalf.

4 simple ways to use your multimeter with a car at home

We will look here at some of the most basic ways in which you can use your multimeter for car-related problems.

Remember, opt for a digital model and look out for one which comes with plenty of attachments. They will be useful when working on your car.

multimeter for cars1) Testing a car battery

Sometimes you can guess that your battery is starting to run low on power. With a multimeter you can easily check this suspicion.

Make sure you wear safety glasses and also a sturdy pair of gloves. Car batteries have chemicals which can be extremely dangerous if you are not adequately protected.

Flip open the hood and locate your battery. Refer to the manual and disconnect the cables from the battery.

Use a setting of 20V DC for an accurate reading.

Hook up the multimeter’s red probe with the battery’s positive terminal. Connect the black probe to the negative terminal.

Wait a few seconds and read the meter: it’s as simple as that!

If you have a 12V battery then you’ll need a minimum of 9.6V in order for it to receive a charge. This may not even be enough and you may need a new battery.

Note: A 12V battery which is fully charged and is not connected to the car should show test results of between 12.4V and 12.7V.

2) Testing a car alternator

If all is well with the battery then testing the alternator is a smart move.

Wear gloves and glasses again and keep yourself well clear of moving parts.

Set the multimeter to 20V DC.

Ensure that the battery is connected but the engine switched off.

As when testing the battery, connect red to positive and black to negative.

With the car off the reading should be 12.5 – 12.8V if there’s no issue with the battery. Start up the engine. You should now see the multimeter reading between 13.8V and 14.8V if you the alternator is functioning perfectly.

As a final test, if you flick the heater blower to high and turn on the headlights, you’ll notice a slight drop in voltage before the reading returns to the above range. (This is assuming that the alternator is working OK.)

3) Testing the wires on your speakers

Imagine this situation…

You have the dash open, the stereo removed and also the door panels. The speakers are just about to be replaced but you realize that you are not sure which is positive and which is negative.

Get out your multimeter!

Put your stereo on with the volume low.

Set the multimeter to 20V DC. Place the negative probe on to one of the chassis grounds. Get the speaker and put the positive probe on one of the terminals.

The one with voltage is positive. Job done!

4) Checking the ohms on your subwoofer

 Many people today have car entertainment systems featuring powerful subwoofers.

As these subs are bridged and ready to go, you must be careful. When you want to connect the wires from the sub to amp, it’s crucial that they are correctly wired.

Hook up both ends of the multimeter to the amp’s speaker terminals.

Set the multimeter to 200 ohms (Ω) and you can check that the ohm level of the sub tallies with the rating of the amplifier.

Using a multimeter for car diagnostics

car multimeter

Think of automotive electrical systems as much like a support framework. The diagnosis of electrical problems is helped considerably by a multimeter. It’s absolutely crucial, in fact.

The digital style is much preferred. It works to much lower tolerances than an analogue version. Digital multimeters also have high impedance circuits.

Here are some ways in which a multimeter is used to check up on things…

Airflow meter

  • This is located in the outlet of the air cleaner top cover. Disconnect the wiring and remove it
  • Check the resistance of the airflow meter using your multimeter set to ohms against the specifications for your vehicle

Coolant temperature sensor

  • You’ll find this in the cylinder head
  • As the sensor temperature increases, the resistance values will decrease. The same is true in reverse
  • With the ignition switch off, disconnect the wiring plug from the intake air temperature sensor
  • Check the resistance between the terminals. With a cool engine it should be between 2.0 and 3.0 kohms
  • Warm up the engine and test again. The resistance should now be 400 to 700 ohms
  • Renew the sensor if these results are not correct

Fuel temperature sensor

  • This sensor is another thermistor like that used for a coolant temperature sensor. This just means that the value of resistance changes with the temperature
  • This sensor can be found in the fuel pump body
  • Turn off the car and disconnect the wiring
  • This value has quite a wide range, anywhere between 0.5 and 3.0 ohms is absolutely fine. If you find values outside these parameters you’ll need to replace the fuel pump itself

Camshaft position sensor

  • This is on a support bracket at the right-hand rear of the cylinder head
  • Disconnect the wiring and test for resistance consulting the specs in your manual. These values vary so pay close attention


These are just a few of the uses for an automotive multimeter. You can also use one to test fuel pressure and turbo pressure sensors, those sensors found in the accelerator pedal or crankshaft, the fuel pressure limiter, electronic driving units and a wealth of other situations.


With a multimeter, you can very quickly and easily diagnose a wide range of automotive problems.

No commercial garage could do without a multimeter and it also pays to have one stored at home to assess simple problems if things are not working as they should.

Have a look here for some reviews of the best digital multimeters – remember that this type is best for using with cars.

This simple-looking piece of kit is highly versatile. The more you learn about it and the more you use it, the more different ways you will find to put it into action.


What Is a Multimeter and How Does It Work?

In a world powered by electricity, few things are more useful than a multimeter or Volt-Ohm meter (VOM for short).

These useful tools can read voltage, current, and resistance. These are all are essential when working with electricity. Electricians, electronic experts, mechanics and many other specialists working with electricity use multimeters on a regular basis.

There are two types of multimeters: analog and digital.

An analog multimeter has a moving pointer that will point out voltage and the other things being measured. This analog measure is called an ammeter.

Digital multimeters, on the other hand, use a digital display and measure things electronically.

These days, digital units are more common than analog. However, analog multimeters are still preferable in some cases such as measuring electric currents that can rapidly change. Analog units are simply more responsive.

Getting Into the Nuts and Bolts of a Multimeter


So how does a multimeter actually work?

Both analog and digital multimeters measure voltage in similar ways. At the heart of every multimeter is a set of circuits. Basically, when you tap into a current of electricity, the electricity will flow through the circuits and will be measured.

Electricity is essentially “converted” into voltage. This voltage is then measured by the circuits and the output is displayed. The electricity is passed through what is called a shunt. This shunt measures resistance of the voltage that develops across the circuitry.

Needless to say, the actual operation of multimeters is very complex and experts have spent their entire careers just working out measurement processes.

Most people won’t ever have to worry about how a multimeter works internally, they simply need to know that it does work and also what the output means.

How To Use a Multimeter?

A multimeter measures more than just volts. At a minimum, a multimeter will measure volts with a voltmeter, amps with an ammeter, and ohms with an ohmmeter. In fact, this is where a “multi” meter gets its name. It measures multiple things. You can still buy and use individual testing tools but most people now just use a multimeter because it displays more information.


Probe tips will be connected to a circuit so that it can measure the flow of electricity going through the circuit. The electricity is then passed into the multimeter’s own circuits where it is measured.

Circuits are complex systems that allow electricity to flow through them. Circuits will also direct and utilize the electricity to accomplish certain things such as powering a computer.

Reading a Multimeter


Most digital multimeters are equipped with a screen that displays four digits. Once the probes are connected to a circuit, electricity can flow through the probes and into the multimeter. The multimeter will then display the volts on the four digit space. The number shown is the voltage.

If you misconnect the tips and put them on backwards, the multimeter will still measure the volts. You will, though, get a negative sign in front of the numbers.

Voltage is very important for batteries, circuits and other things. If the voltage is wrong, the circuit may simply not work. This occurs because circuits are designed to operate with certain voltages.

A volt is a standardized unit of potential electrical conduction. A volt tells you how much “electrical production” a specific thing has. In more technical terms, it measures the resistance of one ohm when one ampere flows through it.

The higher the voltage, the stronger the flow of electricity. When it comes to circuitry and electronic systems, too low a voltage may simply not be enough to power the system.

What if the voltage is too high? It can overpower the system and even cause the circuit to break. In extreme cases, the circuit might actually end up melted or catch on fire!

Think of a house. If a house gets struck by a bolt of lightening, and the house isn’t equipped with the circuitry to deal with the sudden surge in electricity, all of the extra electricity could flow into the electronics in the house and fry them. This is why many houses are now equipped with “surge protectors” that will stop and handle the extra flow of electricity.

When it comes to working with circuits, experts have to be very careful to make sure that the appropriate volts of electricity are being used. They use multimeters to test this. Multimeters also help them troubleshoot and find where the voltage is too high or too low.

Things To Consider Before Buying A Multimeter

If you are looking to buy a multimeter for your electrical troubleshooting tasks, there are certain key things you need to consider.

You need the right information to ensure that you are getting the smartest deal and the best bargain.

Some crucial elements to bear in mind include the features, ease of use, how to use the multimeter, cost and overall design (whether it’s portable or too large). Some of these considerations are based on what you want to accomplish with the multimeter.

Read on for more information on the things you need to give think about before buying a multimeter.

Things To Consider Before Buying A Multimeter


Obviously, one of the first questions that pops up in your mind when buying a multimeter is, “How much should I pay?” Multimeters vary in terms of brand and price; some are very affordable while some others at the higher end of pricing. But to give you an idea, you can spend anywhere between $50 and $500. Usually, the calibrated multimeters are more expensive than ones that are not calibrated. However, you may need it to be calibrated on a yearly basis to keep it very accurate. This additional expense can quickly outflank the initial cost.

Usually, cheaper models are designed with only basic features and may not have the extended functionality that comes with the more expensive ones. Handheld multimeters are a good example of cheaper options. But it is advisable to buy a high quality product with all the right features if you are a professional. You don’t want your customers to be disappointed with your service due to the use of inaccurate reading material. So, a bench top multimeter is ideal for most professional troubleshooting jobs.

What features are you looking for?

The feature of the multimeter are paramount.

Before you invest, understand what you are looking for to select the multimeter that will best serve that need. If you want a simple functioning meter with just basic features to help you accomplish simple tasks, you can settle for a product with straightforward measuring features.

However, if you are a professional who require a wide range of choices with a multimeter, it is better to settle for a more feature-rich product.

Usually, digital multimeters tend to be more accurate with more measuring features such as current, resistance, DC and AC voltage, capacitance and continuity. Most high quality units come with features which include data acquisitions, removable data storage, adjustable sample rating, auto ranging and DB ratings.

There are varying ways you can use a multimeter just as the name implies. You can use a multimeter on switches, power sources, components, motors and batteries. An auto-ranging feature is another excellent feature that high quality multimeters have. With an auto-ranging feature, you will be able to select different range of voltages since you will be dealing with a very flexible device. It is great for wiring systems and detecting computer malfunctions.

Brands and Quality

The brand of multimeter you buy is also very important.

In most cases, you will find good models made by high quality brands. Good brands want to maintain their standards and they would not want to manufacture products with poor quality design. The best brands of multimeters always maintain high quality control.

So, when you are ready to buy a multimeter, do not neglect to look at the best brands and see what they offer before you make your purchase. Known brands provide superior products that are more efficient and highly accurate for all kinds of electronic troubleshooting. They boast the highest customer ratings and reviews on retail websites such as Amazon.

Before you buy a multimeter, make sure to search for the best brands and settle for the product with the best measuring ability.


There are different options available for you if you are looking for a high quality multimeter to buy.

Before you settle for one, always try to conduct your research and select the product with the highest ratings and reviews on retail websites. Select the meter with the best features based on your needs and the kind of task you want to accomplish.

If you conduct proper research before buying a multimeter, you will be able to select the ideal model that will help you accomplish your task more effectively.

How To Use A Multimeter Effectively

If you want to learn how to use a multimeter effectively, you are certainly in the right place.

A multimeter is a three-in-one electrical measuring device. It measures electric current (amperes), resistance (ohms) and voltage (volts).

Using a multimeter in making various measurements is a simple procedure provided you are conversant with electrical terms and multimeter features. However, using a multimeter to measure voltage is not the same as how you will use it to measure resistance or the current measurement. Each measurement has its specific settings.

Before proceeding with any measurements using your multimeter, ensure that you practice all necessary safety precautions to be on the safe side. Remember you are dealing with electricity which is something that can cost you your life if not properly handled. Look over the battery and ensure it has enough charge. Do not at any point measure resistance with the power on. Also do not conduct measurements above the meters rated voltage.


Another important thing is to ensure that you know the parts of the meter involved in measurements and the denotations. Familiarize yourself with the leads, the position of the function dial, the connection ports and the different readings for the three functions.

It is better to be safe than sorry.

How To Use A Multimeter Effectively


Voltage measurements

Voltage refers to the electrical potential of a device – that’s the electric pressure in a circuit. Voltage is measured in volts with measurements denoted in V. Also, there are AC voltage and DC voltage where AC refers to alternating current with DC referring to direct current.

Voltage is measured using the voltmeter function. The first step is to switch the multimeter function to the volt setting denoted as ‘V’. Next, locate the test leads and connect them to the multimeter. There are two leads (red and black). Connect the red lead to the terminal labeled VΩ (red input terminal) while the black lead you connect to the common terminal labeled COM. The common terminal connection remains for both the amp and ohm measurements.

Once you have connected the leads correctly, you can now measure voltage. Attach the leads in the following order: the red lead to the terminal with higher potential and the black lead to the terminal with lower potential.


Resistance is measured in ohms and denoted as Ω. Resistance refers to the level to which an electric current is opposed through a conductor. To measure resistance, you will first need to disconnect the power and wiring of the circuit you intend to measure. This disconnection is to ensure that you are not exposed to electrical hazards or dangers.

Once this is done, turn the function dial to ohm (Ω) on the multimeter to provide ohms readings. Next connect the red lead to the terminal indicated VΩ and, once again, the black lead to the common terminal (COM). At this point, the screen should be displaying ‘OL’ (meaning overload). Now, to be able to measure the circuits resistance, connect both leads (red and black) to the specific circuit.

With this method, you will be able to get the ohms readings that indicate how much resistance is available in that circuit.

Measuring current

If you measure current, it means that you measure the flow of electricity charge in a circuit. Current measurement is given in amps. It can be very dangerous if attempted when an open circuit is above the rated voltage of the meter. The standard rating is 300mA.

To measure current, you should set the multimeter to the ammeter function labeled A. After this, you connect the test leads to the terminals in a slightly different manner from the ohms and volts measurements. For amp measurement, you connect the red lead to the terminal reading 300mA and the black lead to the common terminal (COM).

After correct connection of the leads to the multimeter, attach the meter to the circuit where you will have to break the circuit open and attach the multimeter in series between the open points to acquire amp readings.

With this simple guideline on how to use a multimeter, you should be able to achieve accurate readings and efficiency with your meter.

With a multimeter, you do not have to carry a separate ammeter, voltmeter and ohmmeter whenever you are going to work. You can perform all the above measurements with a single multimeter only with a difference in the settings.

Make work easier by adding a multimeter to your toolkit.