Note when using a multimeter:
1. Identify the function of each gear of the multimeter.
2. Measure three--four resistances and record them.
3. Measure the AC voltage and record.
4. Measure the DC voltage and record.
Multimeter: Mainly used to measure AC and DC voltage, current, DC resistance, and transistor current amplification digits, etc. Now there are mainly two types of digital multimeters and mechanical multimeters.
1 digital multimeter
On the multimeter, you will see the conversion knob as shown in the figure, and the knob refers to the gear of the quantity.
V~: Indicates the gear of measuring AC voltage.
V-: Indicates the measurement of DC voltage gear.
MA: Indicates the gear of measuring DC voltage.
ΩR: Indicates the gear of measuring resistance.
HFE: Indicates the gear of measuring resistance.
The red pen of the multimeter represents the positive pole of the external circuit, and the black pen represents the negative pole of the external circuit.
Advantages: anti-magnetic. Easy to read, accurate digital display......
2 Mechanical multimeters
The appearance of the mechanical multimeter is different from that of the digital meter, but the shift knobs of the two are similar, and the gears are basically the same.
On the mechanical watch, you will see a dial as shown in the figure, and there are eight scales on the dial:
The scale marked with "Ω" is the scale used for measuring resistance.
Marked with "~" is the scale used to measure AC and DC voltage. DC current.
The one marked with "HFE" is the scale used to measure the triode.
Marked with "LI" is a scale for measuring the current. Voltage of the load.
Marked with "DB" is the scale for measuring the level.
3 Use of a multimeter
①Digital multimeter: hit the measurement gear before measurement. It should be noted that the range marked on the gear is the maximum value.
②Mechanical multimeter: The method of measuring current and voltage is the same as the mathematical formula, but when measuring negative voltage, the reading must be multiplied by the value on the gear to obtain the measured value. The measurement problem is 200X100=20000Ω=20K, the "Ω" ruler on the dial is from left to right, from big to small, while the others are from left to right, from small to big
4. Notes:
① Adjusting the "zero point" is only available for mechanical watches. Before using the watch, first check that the pointer is on the "zero position" at the left end. If not, you should slowly turn the "starting point zero" correction screw in the center of the case with a small screwdriver. , so that the pointer points to the zero position.
②When using the multimeter, the machine should be placed horizontally.
③Before the test, determine the measurement content, turn the range conversion knob to the corresponding gear of the measurement shown, so as not to burn the meter head, if you do not know the size of the measured physical quantity, start the test from a large range first.
④The test leads should be correctly inserted into the corresponding sockets.
⑤ During the test, do not rotate the gear change knob arbitrarily.
⑥After use, be sure to adjust the scale change knob without meter to the maximum range of AC voltage.
⑦When measuring the DC voltage and current, pay attention to the positive and negative electrodes of the voltage and the flow of the current, and it is correct when connecting with the test leads.
