The Baidu entry's explanation for the multimeter is
"Multimeters are also called multiplex meters, multimeters, three-meters, multi-meters, etc. They are indispensable measuring instruments in power electronics and other sectors. They generally measure voltage, current, and resistance as their main purpose. Multimeters are divided into display modes Pointer multimeter and digital multimeter. It is a multi-function, multi-range measuring instrument. Generally, multimeters can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc. Some can also measure AC current and capacitance. , Inductance and some parameters of the semiconductor (such as β)"
Wikipedia explains the multimeter like this
A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current, and resistance. Analog multimeters use a microammeter with a moving pointer to display readings. Digital multimeters (DMM, DVOM) have a numeric display, and may also show a graphical bar representing the measured value. Digital multimeters are now far more common due to their cost and precision, but analog multimeters are still preferable in some cases, for example when monitoring a rapidly varying value.
These explanations are very comprehensive and some parts are not well understood. In fact, to put it bluntly, a multimeter is actually an instrument for measuring voltage, resistance and current.
Multimeters are divided into pointer type and digital display type in display mode.
This article takes the pointer type multimeter as an example, and uses several steps to describe how to use the multimeter correctly.
Pointer type multimeter
First, let’s first understand the degree on the multimeter dial.
1. V represents voltage, a wavy line represents AC (home circuit), and a straight or dashed line represents DC. The setting symbol of voltage in AC circuit is V ~, ACV, or VAC.
If the symbol of the voltage in the DC circuit is -V, V or DCV.
2. A means current, and there is also the difference between direct current and alternating current. a. ACA and AAC represent alternating current. a, a, DCA and ADC represent direct current.
3. The Greek letter Ω is the unit of resistance. In some multimeters, R is used to represent resistance.
4. If the multimeter you are using has the functions of DC+ and DC-, first adjust to DC+ when testing the direct current. If there is no change in the dial, you can switch to DC- without changing the positive and negative interface
5. Other symbols on the multimeter dial
))) means "continuity test". In this setting, if the two probes of the multimeter touch, the multimeter will sound an alarm
A crossed right arrow indicates "diode test", which is used to test whether the unidirectional circuit is connected
Hz stands for Hertz, used to measure the frequency of alternating current
–|(– Represents the current capacity
6. A general multimeter has three ports (holes). When measuring voltage and resistance, the minimum current port (usually milliampere) inserted into the port of the red wire
When measuring current, the port inserted into the end of the red wire must be within the value range. Usually the rated current of the low current circuit port is 200mA, and the high current port is 10A
Read the measured value of the multimeter
1. First find the correct scale on the multimeter. Usually, there are three arcs behind the pointer. These are three different types of scale displays, each with different parameters.
2. Adjust the knob to the corresponding voltage range according to the range
3. Estimate the value in the middle of the scale, as shown in the figure, the scale without a number in the middle is half.
4. When reading the value, the degree of the pointer and the scale setting of the multimeter should be combined. For example, if the multimeter is set to R x 100 and the pointer points to 50Ω, the actual resistance value is 100×50=5000Ω
Measure other, calculate the final value in this way
5. Supplement that the bottom dB of the multimeter is used to measure low-frequency AC signals.
The method of use is that if the meter is at ACV 50V, all dB readings must be added to 14. At ACV 100V, the reading is increased by 28, and at ACV 1000V, the reading is increased by 40.
When the effective voltage of resistance 0.775V passes through the 600 ohm resistance inside the meter, the measured dB number is zero.
Generally can also be used to measure TV signals.
I hope that a brief introduction to the multimeter can be helpful to everyone and be able to use the multimeter more proficiently.
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