What you’ll learn:
- 模拟功能与数字功能的关键差异。
- 每种类型的万用表最适合的应用。
Multimeters, from small handheld to more sophisticated benchtop models, are indispensable tools for testing electrical voltage, current, and resistance, and depending on the model, frequency and signal power. Some believe analog meters are inferior to digital, but that’s not the case in many real-world applications. So, dismissing analog out of hand would be a mistake.
Both types of meters have their pros and cons, but the feature gap is narrowing. The ubiquity of integrated circuits in all things electronic has led to a flood of lower-cost digital models. However, there are still times when a digital, analog, or hybrid analog/digital meter can be the right choice for the job(s).
Digital vs. Analog: The Feature Gap Narrows
在内部，模拟和数字多项式使用Ammeters测量Amperes电路的电流。模拟单元(Fig. 1), for instance, commonly rely on an electro-dynamometer to measure both ac and dc. Digital units(Fig. 2)利用电阻器和二极管等组件将信号转换为模数转换器（ADC）可以用来显示测量的信号值的值。
在功能方面，数字表通常提供更高的速度。数字表还消除了插值错误；没有运动部件可以破裂；并提供“自动范围”，以防止用户选择错误的范围（可以在模拟单元上完成此功能，但更为复杂），以防止仪表的错误和损坏。他们还可以测试连续性；电容器，二极管和晶体管；和频率，以及用于各种测试和测量功能的记录和导出数据。
Digital meters also have a few drawbacks, starting with their need for an external power source for all measurements. Typically, that means batteries, which cause LCD displays to dim as they lose charge. Moreover, they can record errors due to fluctuations, transients, and even extended use if the unit gets too warm.
虽然模拟仪表可能无法提供小型，便携式单元的准确性，而高级台/台式模拟单元可以在数字电表中提供准确性。模拟仪表不需要电流和电压测量的电源源（但要测量电阻）。模拟仪表也不太容易受到电噪声的影响；电压范围更大；并且非常适合调整调谐电路或可调式可调响应 - 数字电表并非如此。
实用类似：理想的现场
Hybrids aside, there are practical uses for traditional analog meters, especially in the field as opposed to laboratory uses. Applications range from commercial to industrial uses, particularly in the field in isolated conditions. Examples include monitoring minute value changes in automotive, as well as maintenance of geographically isolated assets in applications ranging from submersible well pumps to agriculture to marine/ship industry applications.
在该领域，这种电气调查通常涉及实时的动手观察。在这些情况下，“老式”模拟技术可能是最实用，最有生产力的选择。For example, because analog units don’t require power for many uses, a technician in the field can be more productive with analog by simply monitoring current through a wire, instead of having to “break open” the component being measured as with a digital meter.
Other applications that may “move the needle” toward an analog meter include rate-of-change observations. For example, if a measurement cycles from 0 to 9 amps, it’s easier to read a needle than the blur of rapidly changing values on a digital display.
在相关用途中，某些模拟单元提供了零中心功能，将针头置于刻度中间。当它向左或向右移动时，它很容易看待，而不是必须在单独的数字读数中显示的同时显示的正面和负值。
Hybrids for “Best of Both” Benefits
Analog and digital features are complementary, and in certain cases work well together—even in the same unit with hybrid analog-digital meters. Since the early 1980s, meters have been offered with both analog and digital features. Today’s hybrid analog/digital models further narrow the feature gap with traditionally digital features such as auto-ranging, data export, and other features that may offer a best-of-both worlds solution.
The real choice depends on the application. Prices, like functions, can vary from lower cost to laboratory models that go for thousands of dollars. Somewhere in the middle are meters for field use.
From inexpensive handhelds to thousands of dollars for calibrated, certified test-and-measurement laboratory models, choices abound for all uses.
