The structure and symbol meaning of the multimeter
1, Structure of multimeter (500 type)
A multimeter consists of three main parts: the meter head, measuring circuit, and conversion switch.
(1) Header
The meter head is a highly sensitive magneto electric DC current meter, and the main performance indicators of a multimeter basically depend on the performance of the meter head.
The sensitivity of the meter head refers to the value of the direct current flowing through the meter head when the pointer deviates to full scale. The smaller this value, the higher the sensitivity of the meter head. The larger the internal resistance during voltage measurement, the better its performance.
There are four scale lines on the header, and their functions are as follows:
The first line (from top to bottom) is marked with R or Ω, indicating the resistance value. When the switch is in the ohm range, this scale line is read.
The second line is marked with ∽ and VA, indicating the values of AC and DC voltage and DC current. When the conversion switch is in the AC or DC voltage or DC current mode and the range is in other positions except for AC 10V, this scale line is read.
The third line is marked with 10V, indicating the AC voltage value of 10V. When the conversion switch is in the AC/DC voltage range and the measuring range is at 10V AC, this scale line is read.
The fourth item is marked with dB, indicating the audio level.
(2) Measurement line
A measurement circuit is a circuit used to convert various measured signals into small DC currents suitable for meter measurement. It consists of resistors, semiconductor components, and batteries. It can convert different measured signals (such as current, voltage, resistance, etc.) and different ranges into a certain limit of small DC currents through a series of processes (such as rectification, diversion, voltage division, etc.) and send them to the meter for measurement.
(3) Conversion switch
Its function is to select various measurement circuits to meet the measurement requirements of different types and ranges. There are usually two toggle switches, each labeled with different gears and ranges.
2, Symbol meaning
(1) ∽ represents AC/DC
(2) V-2.5KV 4000 Ω/V indicates a sensitivity of 4000 Ω/V for AC voltage and 2.5KV DC voltage range
(3) A-V - Ω represents measurable current, voltage, and resistance
(4) 45-65-1000Hz indicates a frequency range below 1000 Hz, with a standard power frequency range of 45-65Hz
(5) The sensitivity of the DC gear is represented by 2000 Ω/V DC, and the symbols on the clamp meter and rocker dial are similar to the above symbols
