Digital multimeters, or DMMs, come in a wide variety of shapes and sizes, perhaps more than any other instrument category. DMMs are primarily used in field environments where portability and battery power are important, where maintenance technicians and maintenance personnel can quickly and easily make basic voltage, current, and resistance measurements as they travel from one location to another. For these applications, resolution, accuracy, measurement speed or connection to a computer are not as important as battery life, durability and size.
As you might expect, benchtop multimeters are larger than handheld DMMs, since benchtop multimeters are primarily used in designer benches or automated system test racks. Engineering educators, researchers, product designers, and test engineers of all types are users of benchtop DMMs. For these users, sensitivity, accuracy, wide range, maximum functionality, measurement speed, and connection to a PC are even more important.
The desktop DMM has multiple interfaces for connecting to a computer and other instruments.
Desktop DMMs have all of these features, offering 5½ to 8½ digit resolution, well above the typical 3½ to 4½ digit resolution of handheld DMMs. Benchtop DMMs have sensitivities as low as 100nV, 0.1μΩ, and 1pA, compared to 10μV, 0.1Ω, and 0.01μA for high-end handheld DMMs. A good handheld DMM has a DCV accuracy of 0.05%, while a desktop DMM can achieve 0.0025% DCV and better.
Desktop DMMs are much more sensitive than handheld DMMs.
Desktop DMMs are usually used for automated testing and require an interface to use a computer to control the DMM and send and receive data. Automated tests often require fast measurement rates and the ability to sample complex waveforms, as shown in the figure below. If the maintenance technician’s job is to keep the electrical system running, he doesn’t need any of these functions. And these benchtop capabilities are critical for scientists, designers, and test engineers.
Benchtop DMMs provide fast measurement rates and can sample complex waveforms.
Both handheld multimeters and benchtop multimeters serve specific applications and therefore offer very different features and functions. For Tektronix and Keithley, our focus is on meeting the needs of scientists, designers and test engineers, and we are proud to offer the broadest range of benchtop and system DMMs in the industry. Tektronix product models cover 5½ digit resolution to 8½ digit resolution.
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