Digital multimeters are one of the most widely used and trusty electronic test instruments. With a wide variety of market retailers and an extensive range of advanced products to choose from, buying a digital multimeter can be a daunting shopping experience. So, to help your buying process consider the following eleven factors which can help you select the best multimeter for your application.
1.Digital Multimeters Vs. Analogue Multimeters
Although a multimeter can be digital or analogue, the digital multimeter is the most modern and extensively used model.
Digital multimeters are more accurate than analogues, but in the past, they were not ideal for measurements that change rapidly. This is because digital multimeters must first take in analogue data and then convert to digital data, resulting in a tiny delay in readings.
Despite this drawback, and especially with improved update rates, overall digital multimeters are a much superior product in the modern world. They offer better accuracy, much easier interpretation of readings and added functionalities over an Analogue. Modern DMM update rates now vastly improved and functions such as analogue bar graph mode to emulate an analogue meter on even fast-changing signals.
Due to the high demand for testing equipment and digital multimeters, there are dozens of digital multimeters brands in the market, making selecting the finest digital multimeter for your needs difficult. Even if you don't need all the latest advanced features, it's a good idea to invest in a high-powered digital multimeter from a reputable manufacture to ensure your digital multimeter will last for many years to come.
2. Auto Range Vs. Manual Range
When comparing the auto and manual range multimeters, the auto range multimeter is far more user-friendly. But if you're a newbie or on a tight budget, a manual range metre is the way to go.
Auto-range will connect to the device automatically and pick the required parameter to measure, then switch it on to display the reading/value on the screen, choosing the range on its own, without requiring manual adjustment.
For a manual metre, one must turn the knob every time, which is inconvenient when working with several components and quantities for a project. Using this manual metre while working with several components and values for a project is unproductive. As a result, the auto range is the ideal option for a majority of activities.
3. Accuracy and Handheld vs Benchtop
When taking multimeter readings, accuracy is defined as the maximum allowable error. Although most multimeters, particularly digital multimeters, will offer accurate reading values, it is necessary to examine them thoroughly before utilising the device in a project.
For example, a 0.5% DC volt accuracy with 4000–6000 counts are acceptable for many applications, but anything less than this indicates the digital multimeter is unreliable for professional readings.
If high accuracy is required and field or battery use is not essential, then a bench DMM may be considered. As in general, the main benefit of a bench DMM vs handheld is better accuracy, higher resolution, better stability, and features such as connection to a PC and 4 wire resistance measuring capability for measuring low resistances not possible on a handheld 2 wire measuring DMM.This is especially valid now where good quality bench DMM offerings from companies such as Rigol and GW Instek etc., are relatively low cost for the performance they offer.
A True RMS DMM is an essential feature for accurately measuring AC voltages and currents in the "real world" with non-sinusoidal waveforms. The real world is full of AC powered devices that generate non-sinusoidal waveforms such as variable-speed motor drives, electronic ballasts, computers, HVAC, solid-state environments etc. An average reading DMM won't work for these now typical applications. A rule of thumb – if the DMM spec doesn't clearly state TRMS, it won't be – it will be an average reading DMM.
5. Range Limits
We have no idea what specifications you'll need for your projects, but before acquiring a digital multimeter, you should be aware of the device's range limits. For example, if the metre can't measure current in milliamps, the device can't detect particular sensor current levels. When shopping, you should make sure you get a digital multimeter with ranges that will meet the needs of both current and future projects.
The following are some suggested digital multimeter ranges:
- Range for Resistance – Low Ohm to 20 MOhm
- Current Range – 10 uA to 10 A
- Voltage Range – millivolt to 600
6. Resolution or Display Counts
The digital multimeter's resolution, also known as display counts, refers to the total number of digits displayed, from lowest to highest. The best digital multimeter has a larger number of digits.
Reading resolution on a spec sheet can be confusing, so what exactly does 3 or 4 ½ digits, 5 digit, 5 ½ digit mean?Basically, a 3 ½ digit DMM can read 1999 on the display. The ½ digit is 1 maximum, so 4 ½ digit is 19999, 5 ½ digit 199999.
Resolution may also be displayed as "counts", such as a 4000 count or 40000 count DMM. This just means first digit maximum is a 4, and all others can go to 9, so a 4000 count DMM can measure up to 4999.
In general, a high count is preferred but is more expensive and may not be needed depending on the application.
7. Features of Safety
Anyone working with electronic gear should always prioritise their safety. When searching for a professional digital multimeter to measure greater DC or AC voltages, safety features, particularly CAT safety precautions, should be required.
The rule of thumb here is the higher the CAT rating, the better the insulation of the unit and leads, and safer the unit is measuring higher voltages or currents where there is more power – e.g. overhead mains line work typically requires CAT IV. Working on electronic circuits may only need CAT I or CAT II. Also, with a specified CAT rating, there will be a Voltage quoted next to it, e.g. CATIII 600V or CAT III 300V. Selecting a meter based on a CAT rating really depends on what is being measured and where the measurements are taking place.
8. Input Resistance
A digital multimeter's input resistance is the resistance it provides to a connected device across the probes. When measuring Voltages, a digital multimeter will perform better if it has a greater input resistance as this allows it to measure signals with minimal loading to the circuit under test. In general, 1MOhm or above is specified on all DMM's for an optimal value for a digital multimeter input resistance.
9. Battery Time
When using the digital multimeter daily, a battery life of around 1000 hours would be preferable for the greatest results.
When choosing a Multimeter, you will also want to select a unit with additional measuring capabilities for your own measuring application.
Measurement capability of things like battery test, diode test, temperature measurement, transistor test, and continuity test and functions such as analogue bar graph, auto-range, true RMS, PC interface with logging software may make it far more useful than a multimeter without these.
Digital multimeters are available in a wide price range, ranging from $10 to $3500, depending on the bands and features offered. In addition, a higher-priced digital multimeter will have more durable and accurate findings than a lower-priced digital multimeter. While also, a workstation multimeter will be more costly than a portable multimeter.
Check how often you'll be using a digital multimeter to see what features you will require. If you're just going to use the digital multimeter once in a while, go for a lower-cost option. If you expect to use the digital multimeter more frequently, go for a more costly, more durable design.
Source Your Next Digital Multimeter at Emona Instruments
No matter if you need a digital multimeter for hobbyist requirements or professional applications, Emona Instruments stocks an extensive inventory of high-powered digital multimeters from industry-leading suppliers to suit any customer requirements. The digital multimeters Emona Instruments stocks includes:
- Rigol's DM3000 Series benchtop digital multimeters – DM3068, DM3058 and DM3058E – are designed for efficient and accurate bench testing with added features great for production line applications.
- GW Instek provides high precision benchtop digital multimeters with industry-leading response times. Models include the GDM-8261A, GDM-8245 and GDM-8255A.
- Metrel offers a wide range of digital multimeter models, all suitable for virtually any general-purpose or hobby work. Including a pocket digital multimeter MD-1150, a range of handheld digital multimeters MD-9020, MD-9030, MD-9040, MD-9050 and MD-9060. Plus, an insulation and continuity digital multimeter MD-9070.
- Time Electronics offers the benchtop digital multimeter 5075, designed for precision, performance, and functionality, making them ideal for automatic testing and fault diagnosis.
- LT Lutron offers a Watt Meter digital multimeter DW-6163 for direct readings of AC WATT (true power) value.
Whether you are looking for high-quality electronic test and measure instruments, test and tag instruments, state of the art 3D printers, 3D printer accessories or engineering teaching & research equipment, Emona supplies only globally trusted manufacturers.
Emona Instruments caters for a range of budgets, functions and technologies, suitable for R&D professionals, production lines or the classroom. Each of our products, from digital multimeters, Markforged metal printers through to Formlabs SLA resin printers, the Emona team is ready to help you choose the best product for your application with expert advice.