Digital multimeter structure and use

Last Update Time: 2019-01-25 17:58:18

The structure of digital multimeter

The digital multimeter is a kind of instrument that converts the measured analog electric quantity parameter into a digital electric quantity parameter and displays it in digital form by using the principle of analog digital conversion. Compared with the pointer multimeter, it has the advantages of high precision, high speed, high input impedance, small influence on the circuit, convenient and accurate reading, and its appearance is shown in Figure 1.

480-001 Allicdata Electronics

Figure 1 digital multimeter profile

 

The use of digital multimeter.

First turn on the power, insert the black test lead into the “COM” jack, and insert the red test lead into the “V/Ω” jack.

1. Resistance measurement.

Adjust the switch to Ω, and connect the test leads to both ends of the resistor to display the corresponding value. If the maximum value "1" (overflow symbol) is displayed, it must be adjusted to the high resistance value until the display is valid value.

 

In order to ensure the measurement accuracy, when measuring the resistance on the circuit, it is best to disconnect one end of the resistor to avoid forming a loop in the circuit when measuring the resistance, which affects the measurement result.

Note: Online measurement is not allowed with power on. The power must be cut off before the measurement and the bulk capacitor is discharged.

 

2. "DCV"  - DC voltage measurement.

The test end of the test leads must be in reliable contact with the test end (parallel measurement). In principle, the measurement is gradually adjusted from the high voltage gear to the low voltage gear until the gear value is 1/3~2/3, and the indication value is a relatively accurate value.

Note: It is strictly forbidden to measure large voltages with small voltage gears. It is not allowed to adjust the transfer switch while the power is on.

 

3. "ACV" -AC voltage measurement.

The test end of the test leads must be in reliable contact with the test end (parallel measurement). In principle, the measurement is gradually adjusted from the high voltage gear to the low voltage gear until the gear value is 1/3~2/3, and the indication value is a relatively accurate value.

Note: It is strictly forbidden to measure large voltage with small voltage gear, and it is not allowed to adjust the transfer switch when power is on.

 

4. Diode measurement.

Adjust the forward voltage drop value by adjusting the transfer switch to the diode position, the black test lead to the negative pole of the diode, and the red test lead to the positive pole of the diode.

 

5. Measurement of transistor current amplification factor hEF.

Adjust the "hFE" value of the transistor by adjusting the transfer switch to the "hFE" position and selecting the "PNP" or "NPN" position according to the transistor being tested, and inserting the transistor correctly into the test socket.

 

6. Open circuit detection.

Adjust the switch to the gear with the buzzer symbol. The test end of the test leads reliably touches the test point. If the two are lower than (20 ± 10) Ω, the buzzer will sound, indicating that the line is open. If it does not ring, the line will not work.

 

 Note: Detection is not allowed while the circuit being measured is energized.

 

7. "DCA" -DC current measurement

When the 200mA is used, the red test pen is inserted into the mA jack; when it is greater than 200mA, the red test pen is inserted into the A jack, and the test end of the test lead must be in reliable contact with the test end (series measurement). In principle, the high current gear gradually adjusts the measurement to the low current gear until the gear value is 1/3~2/3, and the indication value is a relatively accurate value.

Note: It is strictly forbidden to measure large currents with small current gears. It is not allowed to adjust the transfer switch while the power is on.

 

 

If you want to know more, our website has product specifications for the digital multimeters, you can go to ALLICDATA ELECTRONICS LIMITED to get more information