The multimeter is a universal instrument for measurement. Measurements of voltage, current, resistance, as well as checking the wire for an open circuit.
For each of these measurements, special measuring instruments can be used, such as an ohmmeter, ammeter, and voltmeter. A voltmeter is used to measure voltage, a current meter is measured by an ammeter, an ohmmeter is used to measure resistance, but a multimeter is a universal device for measuring voltage, current and resistance.
Thus, an ohmmeter + ammeter + voltmeter = multimeter.
There are two basic types of multimeters: analog and digital.
In an analog multimeter, the measurement results are read by the movement of the hand (as on the clock) relative to the measuring scale, to which the values are applied: voltage, current, resistance. On many, especially Chinese, analog multimeters, the scale is not very conveniently implemented and the measurement can cause some problems. The popularity of analog multimeters is explained by their availability and price, and the main drawback is a significant error in the measurement results. In analog multimeters for more precise adjustment there is a special construction resistor, with the help of manipulations which can achieve a little more accuracy. However, in cases where more accurate measurement results are required, the use of a digital multimeter is prioritized. In addition, analog multimeters are almost everywhere discontinued. Want to choose the best multimeter? You must read another our article about it!
The main difference between a digital multimeter and an analog one is that the measurement results are displayed on a special screen (LED or liquid crystal). Digital multimeters have a higher accuracy of measurements and are distinguished by ease of use, since there is no need to understand all the subtleties of the calibration of the measuring scale, in contrast to analogue, analog devices. New multimeters with a graphic display have the ability to display a waveform, so they can even be attributed to the simplest oscilloscopes. Those. multimeter as it absorbs the properties of an increasing number of devices. In addition, some multimeters have the ability to work under computer control, transmitting measurement results to it for further processing (portable, as a rule, via RS-232 interface, and desktop ones - via GPIB).
So, what every multimeter should have. Any multimeter has from two to four sockets (in old Russian even more) and two outputs, black and red. The black conclusion is common (mass). Red is called potential output and is used for measurements. The socket for the general output is marked as com or simply (-), that is, a minus, and the output itself may have a so-called "crocodile" at the end, so that it can be hooked to the electronic circuit during measurements. The red pin is inserted into the socket which is marked with the symbols of resistance or volts (ft, V or +). In this case, if the number of sockets is more than two, then the others are usually intended for the red output for measuring the current and are marked as A (amperes), mA (milliamperes), 10A or 20A, respectively.
A multimeter switch is used to select one of several limits for measurements. For example:
Constant (DCV) and alternating (ACV) voltage: 10V, 50V, 250V, 1000V.
Current (mA): 0.5mA, 50mA, 500mA.
Resistances (Ω): X1K, X100, X10, which means multiplication by a certain value, are usually indicated in digital multimeters as standard: 200 Ω, 2 kΩ, 20 kΩ, 200 kΩ, 2 MΩ.
On digital multimeters, the measurement limits are usually larger, and additional functions are often added to them, such as a frequency meter, checking transitions of transistors, audible “ringing” of diodes, measuring capacitance of capacitors, and even a temperature sensor.
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