What does the internal structure of a multimeter consist of?

The internal structure of a multimeter is theoretically divided into three parts: meter head, measuring circuit and switching switch.

(1) Table header

The meter is usually a DC microammeter, and its working principle can be summarized as: "The deflection angle of the meter pointer is proportional to the current flowing through the meter." The primary function of the multimeter basically depends on the function of the meter. The sensitivity of the meter refers to the DC current value flowing through the meter when the meter pointer deflects full scale. The smaller this value, the higher the sensitivity of the meter. The greater the internal resistance when measuring voltage, the better its function.

The meter can be connected to various measuring circuits to measure various electrical quantities. By changing the switch, the meter and the measuring circuit can form a multimeter.

(2) Measurement line

The measuring circuit of a multimeter is a circuit used to convert various measured quantities into tiny DC currents suitable for measurement by the meter. It is composed of resistors, semiconductor components and batteries.

The measurement circuit of a multimeter is the basic part of the multimeter, which is composed of several measurement circuits such as multi-range DC voltmeter, multi-range DC ammeter, multi-range ohmmeter, multi-range AC voltmeter, etc. It can convert various measured quantities (such as current, voltage, resistance, etc.) and different ranges into a certain limit of tiny DC current through a series of processing (such as rectification, shunting, voltage division, etc.) and send it to the meter for measurement.

(3) Change the switch

The function of the change-over switch is to select various measurement circuits to achieve the selection of measurement types and ranges. The change-over switch is marked with different gears and ranges.