Multimeter

A multimeter (from Latin Multus "a lot", and ancient Greek μέτρον métron " tool for measuring " ), also called multimeter is an electrical engineering measurement device that can be used for multiple metrics and in different temperature ranges.

The basic equipment of a multimeter is one of its usefulness as a voltmeter and ammeter. In general, it is switchable between DC and AC size measurements. Are also common features as a resistance meter.

Primary distinction is made between digital and analog multimeter. Pure analog multimeter play since the 1990s in the practical measurement technique a diminishing role and are increasingly being replaced for reasons of price by digital multimeter. In addition to the oscilloscope is the multimeter is one of the most important measurement and diagnostic tools in electronics and electrical engineering. Because of its relatively low purchase price and the wide spectrum of applications, it is also widely used in electronics hobbyists and DIYers.

Digital Multimeter

With digital multimeters, the signal is electronically added by an analog- to-digital converter and displays the measured value as a numerical value. The measuring ranges extend generally from 200 mV to 1000 V and 20 uA to 20 Amps Digital Multimeters have in the voltage measurement usually a high internal resistivity of 1 to 20 M, 10 M is standard. The relative error bound is usually less than 1%, depending on the measuring range, the DC voltage ranges they is quality appliances usually below 0.2%.

The measurement of current is performed by measuring the voltage across the switchable shunt resistors. Measuring resistance is attributed to the measurement of voltage due to a reversible constant current source.

Advantages of digital multimeters are the relatively simple mechanical construction and reproducible mass production electronic components, which they are already relatively inexpensive to buy, usually cheaper than a good analog device. The operation is very simple by displaying the units on the display and by avoiding multiple scales. Furthermore, some digital devices have protection circuits against overloads and polarity reversal. Easy device can enter the voltage measurement range automatically select (Auto- range function ). Against shocks and they are relatively insensitive, since no sensitive mechanism may be damaged.

Because of the internal electronics for signal processing and display on the display digital multimeter are always dependent on a supply from a battery, AC adapter or solar cell.

Some devices also have opportunities for measuring frequencies, capacitance, inductance and transistor and diode characteristics. With built-in or external sensors are possible with some devices also humidity, noise or temperature measurements. A continuity buzzer is incorporated in almost all digital devices.

Analog Multimeters

For analog multimeters reading on a pointer instrument with multiple scales for different measuring ranges is displayed. The readout values ​​are represented by discrete graduations, intermediate values ​​can be interpolated. The error limits of analog gauges can be quite less than one percent of the full scale value for high-quality devices. As a crucial component that provides the display, usually comes a moving coil instrument used.

The measuring ranges of Drehspulgeräten extend so as at voltages from 100 mV to 1000 V for direct current of 100 uA to 10 A, high-quality devices have partially even smaller areas on. Analog multimeters have can lead a much lower internal resistance than digital multimeter, what with high-impedance voltage sources to measurement errors ( circuit influence) for voltage measurement as a rule. The influence of the internal resistance for current and voltage measurement can be reduced by built-in amplifier, whereby such analog multimeter for voltage measurement achieve a high internal resistance, which may correspond to digital multimeters.

For resistance measurement, the current is measured which can flow through the resistor, a built-in battery. The relationship is highly non- linear; the measurement is only suitable for coarse -looking statements. Even with resistance measurement can be used to scale linearization at very high quality appliances, an amplifier electronics.