What are the methods of use of capacitance block of multimeter?

Last Update Time: 2019-03-01 11:53:27

Many digital multimeters now have capacitive barriers,which use 400Hz AC signals to detect voltages on capacitive reactance. Therefore, when measuring the capacitance, it is necessary to carry out short-circuit discharge and then detect the capacitance.

The capacitance block of the digital multimeter can also be used to judge the quality of the crystal oscillator. Usually, the resistance value of the electrical barrier detection should be ∞, that is, the high position display "1", and then the capacitance block can be used to detect, which can read out a numerical value. This value is the equivalent capacitance of the crystal oscillator. The frequency of the crystal oscillator is different, the detected capacitance is not the same, the higher the frequency, the smaller the capacitance.

In addition, the capacitance of the digital multimeter is used to block the sinusoidal signal of 400Hz, which can be used as a signal source during maintenance.

 

2.Choose the appropriate range and correct reading side.

First,estimate the range of values to be measured. Before using the digital multimeter, we should estimate the range of the measured value, and choose the range close to the full scale as far as possible in order to improve the accuracy of the measurement. For example, test a 1.5 V dry cell on 2, 20, 200 and 1000V blocks, respectively, as shown in Table 1.

      

Range

2

20

200

1000

Displayed Value

1.492

1.49

1.5

2

Table 1.Measurement of 1.5 V dry cell voltage in different gear


This shows that the accuracy of measuring with 2V block is the highest.

Second,show the value is relatively stable before reading. When the digital multimeter is measured, the value of the display screen will beat, which is normal and should not be read until the display value is relatively stable (1 / 2 s). In addition, the measured point and the table pen contact poor or oxide, dirt and so on, will also make the display screen for a long period of time jump phenomenon. Dirt should be removed first so that the pen is in good contact before measuring.

Third,shift should not be too hard, too fast. The digital multimeter's range conversion switch has a lot of baffles (DT-890 type has 30 measuring gappers), and the bit-distance between two adjacent gears is very small. The hand feeling in use is not as obvious as the analog multimeter, so it is easy to cause jump gear and wrong dialing. When using, shift should not be too fast.

This article is from Allicdata Electronics Limited.