(l) Measuring resistance. The multimeter's transfer switch should be placed in the appropriate range of electrical blocking (n-stop). The MF-47 multimeter and the 500-type multimeter have R x1Ω, R×lOΩ, R×lOOΩ.R×1kΩ_ and R×lOkΩ. When choosing the earning range, try to make the pointer at 2/3 of the full scale, the degree is more accurate. When measuring the large resistance, do not touch the two ends of the resistor or the metal parts of the two test leads at the same time, otherwise the human body resistance will be measured. The resistance values ​​are connected in parallel to make the measured values ​​inaccurate.
Before measuring the resistance, the ohm should be zeroed. After shorting the two test leads, see if the pointer of the watch refers to 0Ω on the right side of the dial. If the pointer is not adjusted to 0Ω, check the battery inside the watch. Is the power shortage?
When the multimeter is placed in the resistance file, the red meter pen is connected to the battery negative pole, and the black test pen is connected to the battery positive pole.
(2) Measure the DC voltage. Place the transfer switch in the appropriate range within the DC voltage (V) range. The MF-47 multimeter can directly switch the transfer switch to the appropriate range of the DC voltage block (V block), while the 500 type The multimeter needs to set the right selector switch to “AC voltage blockâ€, and then turn the left selector switch to the appropriate range of DC voltage (V).
The DC voltage of the MF-47 multimeter has 0.25V, 1V, 2.5V, 10V, 50V, 250V, 500V, 1000V for a total of eight ranges. The DC voltage of the 500 multimeter has 2.5V, 10V, 50V, 250V, 500V. A total of five ranges. The value indicated by the transfer switch is the corresponding value of the pointer full scale reading. For example, if the range is 250V, the full scale reading of the DC voltage on the dial is 250V. If the scale value of the pointer is at 100, the measured voltage value is 100V.
When measuring the DC voltage, the multimeter should be connected in parallel at both ends of the circuit under test. The black meter pen is connected to the negative pole of the tested power supply, and the red meter pen is connected to the positive pole of the tested power source. The polarity cannot be connected incorrectly, otherwise the pointer will impact or be bent in the opposite direction.
(3) Measure the AC voltage. The method of measuring the AC voltage and the reading method thereof are similar to the measurement of the DC voltage, and the difference is that the measuring AC voltage is that the meter of the multimeter does not distinguish between the positive and negative poles. When measuring the voltage, be careful that the selector switch should be placed in the appropriate range.
A general multimeter can only measure the AC voltage of a normal wave, but cannot be used to measure a non-sinusoidal voltage such as a triangle wave, a square wave, or a sawtooth wave. If the DC voltage value is superimposed on the measured AC voltage, measure it in series with a DC blocking capacitor with sufficient withstand voltage.
(4) Measure the DC current. The switch of the multimeter should be placed in the DC current block (A block). The DC current of the MF-47 multimeter has six ranges of 0.25mA, 0.05mA, 0.5mA, 5mA, 50mA and 500mA. When measuring, the switch can be directly dialed to the appropriate range. The DC current of the 500 multimeter has five ranges of 50uA, 1 mA, 10 mA, 100 mA, and 500 mA. When measuring, the right switch should be placed in the DC current block (A block), and the right switch should be placed. In the DC current block (A block) the appropriate range.
When measuring, the multimeter should be connected to the circuit under test, and the polarity of the test pen should be noted. The red test pen should be connected to the high potential end. The current value is read in the same way as the measured DC voltage.
The MF-47 multimeter and the 500 multimeter have measurement functions of 2500V (AC and DC) voltage and 5A DC current. When measuring, pull the red test lead out of the “+†end of the panel and insert the 2500V (AC and DC) voltage test jack or 5A DC current test jack.
(5) Measurement of transistor magnification. The MF-47 universal meter has the function of transistor magnification measurement. When measuring, first put the transfer switch in the ADJ gear, after the two test leads are shorted and zeroed, then turn the transfer switch to the corresponding jack on the hFE test socket (the high power transistor can lead its electrodes out, then insert In the socket). The NPN tube is plugged into the “N†socket and the PNP tube is plugged into the “P†socket. The pointer will display the magnified value of the tube under test.
(6) Measure the decibel value. The decibel value is the power gain level unit. The MF-47 and 500 multimeters have a decibel value measurement function.
When measuring the decibel value, the multimeter should be placed in a 10V AC voltage range. The dB scale on the dial is -10~22dB, which is drawn in the voltage range of 10V AC voltage, and is only suitable when the voltage of the measured point is 10V AC voltage. If the measured voltage is high, the multimeter should be placed in the 50V, 250V, 500V range of the AC voltage block. If the decibel value is measured with a 50V AC voltage, the pointer reading should be +28dB; if the 500V AC voltage is used to measure the decibel value, the pointer reading should be added 34dB.
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