Structure of Multimeter (Type 500)
The multimeter is composed of three main parts: meter head, measuring circuit and changeover switch.
(1) header
It is a high-sensitivity magnetoelectric DC ammeter. The main performance indicators of the multimeter basically depend on the performance of the meter head. The sensitivity of the meter head refers to the DC current value flowing through the meter head when the pointer of the meter head is deflected at full scale. The smaller the value, the higher the sensitivity of the meter head. The greater the internal resistance when measuring voltage, the better its performance. There are four scale lines on the meter head, and their functions are as follows: the first line (from top to bottom) is marked with R or Ω, which indicates the resistance value. When the switch is in the ohm block, read this scale line. The second bar is marked with ∽ and VA, indicating the AC, DC voltage and DC current value. When the transfer switch is in the AC, DC voltage or DC current gear, and the range is at a position other than AC 10V, read this scale Wire. The third line is marked with 10V, which indicates the AC voltage value of 10V. When the switch is in the AC and DC voltage range and the range is at AC 10V, read this scale line. The fourth bar, labeled dB, indicates the audio level.
(2) Measurement line
The measurement circuit is a circuit used to convert various measured objects into tiny DC currents suitable for meter measurement. It is composed of resistors, semiconductor elements and batteries. It can convert various measured objects (such as current, voltage, resistance, etc ), different ranges, after a series of processing (such as rectification, shunting, voltage division, etc.), it is unified into a certain amount of tiny DC current and sent to the meter for measurement.
(3) Transfer switch
Its function is to select a variety of different measurement lines to meet the measurement requirements of different types and ranges. There are generally two transfer switches, marked with different gears and ranges.
Fourth, the meaning of the multimeter symbol
(1)∽ means AC and DC
(2) V-2.5KV 4000Ω/V means that for AC voltage and 2.5KV DC voltage block, its sensitivity is 4000Ω/V
(3) A-V-Ω means that current, voltage and resistance can be measured
(4) 45-65-1000Hz indicates that the operating frequency range is below 1000 Hz, and the standard industrial frequency range is 45-65Hz
(5) 2000Ω/V DC means that the sensitivity of the DC block is 2000Ω/V
