How to use a multimeter

A multimeter is a relatively practical and easy-to-learn testing tool. Multimeters are divided into pointer type and digital multimeters. Digital multimeters have quickly become popular due to their excellent performance and low price. In addition to the functions of a pointer meter, digital multimeters can also be used to measure capacitance, frequency, temperature, etc.; and they display readings in digital form, making them more convenient to use.

    From the appearance, the upper part of the multimeter is the LCD screen, the middle part is the function selection knob, and the lower part is the test lead jack, which is divided into "com" - the common end or "-" end and "+" end, as well as a current jack, a transistor β value jack and a capacitance jack. Now let's talk about the specific usage. 1. Voltage measurement

 1. Measurement of DC voltage, such as battery, Walkman power supply, etc. First, insert the black test lead into the "com" hole and the red test lead into the "V Ω". Turn the knob to a range larger than the estimated value (note: the values ​​on the dial are all the maximum range, "V-" indicates the DC voltage range, "V~" indicates the AC voltage range, and "A" is the current range), then connect the test leads to the power supply or both ends of the battery; keep the contact stable. The value can be read directly from the display. If it shows "1.", it means that the range is too small, so you need to increase the range before measuring. If "-" appears on the left side of the value, it means that the polarity of the test lead is opposite to the actual power polarity, and the red test lead is connected to the negative pole.

V‑g,E0te$wqv0  2. Measurement of AC voltage. The probe jack is the same as that of DC voltage measurement, but the knob should be turned to the AC range "V～". There is no positive or negative difference in AC voltage, and the measurement method is the same as before. Whether measuring AC or DC voltage, pay attention to personal safety and do not touch the metal part of the probe with your hands.

2. Current Measurement 

 1. Measurement of DC current

5{N0z)F*u(u0First  insert the black test lead into the "COM" hole. If you measure a current greater than 200mA, insert the red test lead into the "10A" jack and turn the knob to the DC "10A" position; if you measure a current less than 200mA, insert the red test lead into the "200mA" jack and turn the knob to a suitable range within DC 200mA. After adjustment, you can measure. Connect the multimeter in series to the circuit, keep it stable, and you can read the value. If it shows "1.", then increase the range; if "-" appears on the left side of the value, it means that the current flows from the black test lead into the multimeter.

 2.   The measurement method of AC current is basically the same as that of DC current, but the gear should be set to AC gear. After the current measurement is completed, the red pen should be inserted back into the "VΩ" hole. 3. Measurement of resistance   Insert the test leads into the "COM" and "VΩ" holes, turn the knob to the required range in "Ω", and connect the test leads to the metal parts at both ends of the resistor. You can touch the resistor with your hands during the measurement, but do not touch both ends of the resistor with your hands at the same time, which will affect the measurement accuracy - the human body is a conductor with large but finite resistance. When reading, keep good contact between the test leads and the resistor; pay attention to the unit: the unit is "Ω" in the "200" gear, the unit is "KΩ" in the "2K" to "200K" gear, and the unit is "MΩ" above "2M". 4. Measurement of diodes

 Digital multimeter can measure light-emitting diodes, rectifier diodes, etc. When measuring, the position of the test leads is the same as that of voltage measurement. Turn the knob to the diode position; connect the red test lead to the positive pole of the diode and the black test lead to the negative pole. The forward voltage drop of the diode will be displayed. The voltage drop of the germanium diode is about 0.15-0.3V, the silicon diode is about 0.5-0.7V, and the light-emitting diode is about 1.8-2.3V. If the display shows "1." after replacing the test leads, it is normal because the reverse resistance of the diode is large, otherwise the tube has been broken down.

In addition, the multimeter also has the function of measuring capacitance, transistors, etc. In the maintenance of instruments and equipment, if we can use the multimeter skillfully, we can judge the instrument failure in time and give full play to the role of electronic instruments and equipment in maintenance work.