Comparison UNI-T UT61B vs Mastech MS8239C

The upper limit of the lower sub-range in which the device can measure DC voltage (see "Type of voltage").

The operating ranges of modern multimeters and other measuring instruments are usually divided into subranges. This is done for accuracy and convenience when measuring: for example, to assess the quality of AA batteries, you can set the subrange “up to 3 V” — this will give an accuracy of up to tenths, or even hundredths of a volt, unattainable when measuring with a higher threshold. The minimum constant voltage describes exactly the lower subrange, designed to measure the smallest voltage values: for example, if 2000 mV is indicated in this paragraph, this means that the lower subrange covers values \u200b\u200bup to 2000 mV (i.e. up to 2 V).

It is worth choosing according to this indicator taking into account the specifics of the planned application: for example, a device with low rates can be useful for delicate work, such as repairing computers or mobile phones, but for servicing the on-board electrical network of a car, especially high voltage sensitivity is not required.

The highest DC voltage (see “Voltage type”) that can be effectively measured with this instrument.

Compliance with this parameter is important not only for correct measurements, but also from a safety point of view. Measuring too high voltage can lead to malfunctions of the device, ranging from the operation of emergency protection (and it can take the form of a disposable fuse that requires replacement after operation) and ending with a complete failure and even fire. Therefore, it is impossible to exceed this indicator anyway. Yes, and choosing a device for maximum voltage is worth with a certain margin — at least 10 – 15%: this will give an additional guarantee in case of emergency situations. On the other hand, the margin should not be too large: a high constant voltage threshold can degrade the accuracy of measurements at low voltage, as well as affect the price, dimensions and weight of the device.

Note that most multimeters and other similar devices have several measurement ranges, with different maximum thresholds. So, for a safe measurement of voltage close to the maximum, you need to set the appropriate mode in the settings.

The upper limit of the lower sub-range in which the device can measure AC voltage (see "Type of voltage").

The operating ranges of modern multimeters and other measuring instruments are usually divided into subranges. This is done for accuracy and convenience in measurements: for example, to test a transformer that should output 6 V, it makes sense to set a subrange with an upper threshold of 10 V. This will ensure accuracy up to tenths of a volt, unattainable when measuring with a higher threshold. The minimum constant voltage describes exactly the lower subrange, designed to measure the smallest voltage values: for example, if 2000 mV is indicated in this paragraph, this means that the lower subrange covers values \u200b\u200bup to 2000 mV (i.e. up to 2 V).

If the device is purchased for measurements in stationary networks — household at 230 V or industrial at 400 V — you can ignore this parameter: usually, the minimum subranges are not used. But to work with power supplies, step-down transformers and various “thin” electronics served by low voltage alternating current, it makes sense to choose a model with a lower minimum voltage. This is connected not only with the measurement range: a low threshold, usually, indicates a good measurement accuracy at low voltages in general.

The largest alternating voltage (see “Type of voltage”) that can be effectively measured using this model. This parameter is important not only for measurements as such, but also for safe handling of the device: measuring too high voltage will, at best, trigger emergency protection (and it is possible that after that you will have to look for a new fuse to replace the burned one), at worst — to equipment failure or even fire. In addition, for safe measurements, a voltage margin is highly desirable — this is due both to the characteristics of the alternating current and to the possibility of various emergency situations in the network, primarily voltage surges. For example, for 230 V networks, it is desirable to have a device for at least 250 V, and preferably 300 – 310 V; detailed recommendations for other cases can be found in special sources.

Note that most multimeters and other similar devices have several measurement ranges, with different maximum thresholds. So, for a safe measurement of voltage close to the maximum, you need to set the appropriate mode in the settings.

Items included in the scope of supply other than the instrument itself.

— Battery. The power supply is necessary for the operation of the circuits of a digital device (see "Type"), and in analogue it is used for all measurements, except for voltage and current measurements. A battery as such a source is most often the most convenient (for more details, see "Power"); its presence in the kit eliminates the need to purchase a battery separately. At the same time, we note that the term "battery" in this case is very conditional — it can mean both a rechargeable element and a simple disposable battery. This point does not hurt to clarify before buying.

— Measuring probes. Styli are the basic tool needed for most measurements; in fact, the only type of instrument that can do without probes is oscilloscopes(see "Device"). The presence of probes in the kit is convenient, first of all, because such accessories are optimally suited for a specific device — an important point, given that modern multimeters can vary in design and size of the sockets for the probes.

— Data cable. Cable for connecting the device to a computer. The most popular connectors found in such cables are RS-232 (COM port) and USB, the specific option in each case should be specified separately. However, anyway, connecting to a computer provides many add...itional features — for example, automatic saving of measurement results or even comparison of measured parameters with reference ones; specific functionality depends on the model of the device and the software used.

— Case/case. Case for storing and carrying the device. Cases are usually called cases made of hard materials, cases are made of soft ones. Anyway, the case provides not only protection from dust, moisture, shock, etc., but also additional convenience — usually, it provides space not only for the device, but also for accessories for it (the same probes). At the same time, each type of case has its own advantages: the cases are durable and well protect the device from shocks, the cases are more compact both during use and during non-working hours. Of course, impromptu packaging can also be used for storage and transportation, but the complete case is at least more convenient, if not more reliable.

The type of battery used in the device. Note that the term “battery” in this case refers to all types of autonomous power sources - both rechargeable and disposable. These include: AAA, AA, C, “Krona”, A23, CR2032, etc.

- AA. Classic AA batteries, one of the most popular sizes these days. Available both in the form of disposable cells and in the form of rechargeable batteries; sold almost everywhere. The number of such batteries required to power a multimeter can be from 1 to 8, depending on the features of the device.

- AAA. “Mini-finger” or “little finger” batteries, similar to the AA batteries described above, but having reduced dimensions (and, accordingly, less power and capacity). However, given that many multimeters are also quite compact and their power consumption is low, this option is found in measuring instruments even more often than AA. The number of such elements in this case is usually from 1 to 4.

- “6LR61”. The batteries have a characteristic rectangular shape with a voltage of 9 V and a pair of contacts on one of the ends. High voltage contributes to the accuracy of measurements and allows even quite “gluttonous” models to use only one battery; so this option is quite popular in multimeters. Note that most often “Kronas”...are produced in the form of disposable cells, but if desired, you can also find batteries of this size.

- 6LR61 and AAA. Powered simultaneously from the two types of batteries described above. As a rule, each of these power sources is responsible for its own part of the functionality (for example, AAA for resistance measurements, Krona for testing transistors), and in the absence of one of the sources, only the capabilities directly related to it are unavailable. However, in general, such a combination is not particularly convenient and practical, which is why it is rare.

— Krona and AA. An option completely similar to the “6LR61 + AAA” described above - except that in this case, instead of “pinky” batteries, AA batteries are used. Also not popular.

— C. Cylindrical 1.5-volt elements. Available in two types - accumulators and batteries; similar in length to AA (50 mm), but almost twice as thick - 26 mm instead of 14 mm. As a result, they provide higher capacity and power supply, but due to their large size they are used mainly in advanced desktop devices. Moreover, many of these devices have an insulation test function, and the number of C batteries in them can be from 8 to 12 - this is necessary to create the high voltages used for such testing.

- A23. Cylindrical cells characterized by high voltage - 12 V, despite the fact that the size of such batteries is only 29 mm in length and 10 mm in size. Most often they are disposable batteries. In general, they are poorly distributed, which is why they are used relatively rarely in measuring instruments.

— LR44 / SR44. Miniature 1.5-volt batteries in the form of “tablets” with a size of 11.6 mm and a thickness of 5.4 mm. They are made only for disposable use; At the same time, simple and inexpensive alkaline batteries are marked with the “LR44” index, and more expensive and advanced silver-oxide batteries with the “SR44” index. In multimeters, as a rule, you can use both one and the other. In any case, due to their small size, the power and capacity of all such batteries is small, so they are used mainly in miniature devices - not designed for serious tasks and not having enough space in the case for more solid batteries.

- CR2032. Miniature button batteries with a voltage of 3 V, having a size of 20 mm and a thickness of 3.2 mm. Like LR44 / SR44, they are found mainly in small devices - incl. very miniature, made in the form factor of a pen or even a key fob; however, due to their larger sizes, they provide more advanced power characteristics, which is why they are noticeably more common. CR2032 elements are made only disposable.

— 18650. Removable lithium-ion batteries are cylindrical, 65 mm long and 18 mm in size. With an operating voltage of 3.7 V, they can also have a fairly high capacity. However, for a number of reasons, this option is not popular - it can be found in some advanced devices.

— Branded battery. Batteries created specifically for specific devices (or series of devices) and not related to standard sizes; often made non-removable. Such batteries can have more advanced characteristics than replaceable batteries, and they eliminate additional expenses - you do not need to regularly buy batteries (or a separate battery with a charger), it is enough to charge the existing power source from time to time. On the other hand, when the charge is depleted, such a battery cannot be quickly replaced with a fresh one - the only option is charging, and this requires an outlet and takes time, sometimes quite considerable. As a result, this method of nutrition has not become particularly widespread.