Digital Multimeter Operation

Digital multimeters are popular among radio enthusiasts because of their advantages such as accurate measurement, convenient value acquisition, and complete functions. The most common digital multimeters generally have resistance measurement, on-off sound detection, and diode forward voltage measurement. AC DC voltage and current measurement, transistor amplification and performance measurement, etc. Multimeter current measurement Some digital multimeters have added functions such as capacitance measurement, frequency measurement, temperature measurement, data memory, and voice reporting, which greatly facilitates actual detection work. 
Digital multimeter operation guide 1. DC voltage measurement
1. Insert the black test lead into the COM jack and the red test lead into the V/Ω jack.
2. Set the function switch to the DC voltage range V-range, and connect the test lead to the power supply to be tested (to measure the open circuit voltage) or load (to measure the load voltage drop). The polarity of the end connected to the red test lead will be displayed on the display at the same time. (
Note:
1. If the voltage range to be measured is unknown, set the function switch to the maximum range and gradually decrease.
2. If the display shows only "1", it means over-range, and the function switch should be set to a higher range.
3. "" means do not measure voltages higher than 100. It is possible to display higher voltage values, but there is a risk of damaging the internal circuit. 0V
4. When measuring high voltages, pay special attention to avoid electric shock.
2. DC current measurement
1. Insert the black test lead into the COM jack. When measuring a current with a maximum value of 200mA, insert the red test lead into the mA jack. When measuring a current with a maximum value of 20A, insert the red test lead into the 20A jack.
2. Set the function switch to the DC current range A-range, and connect the test lead in series to the load to be measured. The polarity of the red test lead will be displayed while the current value is displayed.
Note:
1. If the current range to be measured is unknown before use, set the function switch to the maximum range and gradually decrease.
2. If the display shows only "1", it means over-range, and the function switch should be set to a higher range.
3. Indicates that the maximum input current is 200mA. Excessive current will burn out the fuse and should be replaced. The 20A range has no fuse protection and the measurement cannot exceed 15 seconds.
III. AC voltage measurement
1. Insert the black test lead into the COM jack and the red test lead into the V/Ω jack.
2. Set the function switch to the AC voltage range of V~ and connect the test lead to the power supply or load to be tested. The test connection diagram is the same as above. When measuring AC voltage, there is no polarity display.
Note:
1. Refer to DC voltage note 1.2.4.
2. "" indicates that a voltage higher than 700Vrms should not be input. It is possible to display a higher voltage value, but there is a risk of damaging the internal circuit.
IV. AC current measurement
1. Insert the black test lead into the COM jack. When measuring a current with a maximum value of 200mA, insert the red test lead into the mA jack. When measuring a current with a maximum value of 20A, insert the red test lead into the 20A jack.
2. Set the function switch to the AC current range A~, and connect the test leads in series to the circuit to be tested.
Note:
1. Refer to the DC current DCA measurement notes 1, 2, and
3. V. Resistance measurement
1. Insert the black test lead into the COM jack and the red test lead into the V/Ω jack.
2. Set the function switch to the Ω range, and connect the test leads to the resistance to be tested.
Note:
1. If the measured resistance value exceeds the maximum value of the selected range, the over-range "1" will be displayed. A higher range should be selected. For resistances greater than 1MΩ or higher, it will take a few seconds for the reading to stabilize. This is normal.
2. When the connection is not good, such as an open circuit, the meter displays "1".
3. When checking the impedance of the measured line, ensure that all power supplies in the measured line are removed and all capacitors are discharged. If there are power supplies and energy storage components in the measured line, the correctness of the line impedance test will be affected.
4. The 200MΩ position of the multimeter has 10 characters when short-circuited. When measuring a resistor, these 10 characters should be subtracted from the measured reading. If the display is 101.0 when measuring a resistor, 10 characters should be subtracted from 101.0. The actual resistance of the measured component is 100.0, i.e. 100MΩ.
VI. Capacitance Test
Before connecting the capacitor to be tested, note that it takes time to reset to zero each time the range is changed. The existence of drift readings will not affect the test accuracy.
1. Set the function switch to the capacitance range C (F)
2. Insert the capacitor into the capacitance test socket
Note:
1. The instrument itself has set protection for the capacitance range, so there is no need to consider polarity and capacitance charging and discharging during the capacitance test.
2. When measuring capacitance, insert the capacitor into the dedicated capacitance test socket (do not insert the test lead jack COM, V/Ω).
3. It takes a certain amount of time to stabilize the reading when measuring large capacitance.
4. Conversion of capacitance units: 1μF=106pFlμF=103nFVII
. Diode test and buzzer test1
. Insert the black test lead into the COM jack and the red test lead into the V/Ω jack (the polarity of the red test lead is "+"). Set the function switch to the "+" position and connect the test lead to the diode to be tested. The reading is the approximate value of the forward voltage drop of the diode.
2. Connect the test lead to both ends of the circuit to be tested. If the resistance value between the two ends is less than about 70Ω, the built-in buzzer will sound.