Digital multimeter instructions

1. Measurement of voltage

1. Measurement of DC voltage, such as batteries, walkman power supplies, etc. First, insert the black test lead into the "com" hole and the red test lead into the "V Ω" hole. Select the knob to a range larger than the estimated value (note: the values ​​on the dial are the maximum range, "V-" represents the DC voltage range, "V~" represents the AC voltage range, and "A" represents the current range), and then Connect the test leads to both ends of the power supply or battery; keep the contact stable. The value can be read directly from the display. If it displays "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 supply polarity. At this time, the red test lead is connected to the negative pole.

2. Measurement of AC voltage. The test lead jack is the same as the DC voltage measurement, but the knob should be turned to the required range at the AC gear "V~". There is no positive or negative distinction between AC voltage, and the measurement method is the same as before. Regardless of whether you are measuring AC or DC voltage, you must pay attention to personal safety and do not touch the metal parts of the test leads with your hands.

2. Measurement of current

1. Measurement of DC current. First 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 start measuring. Insert the multimeter into the circuit, keep it stable, and you can take a reading. If it displays "1.", then the range needs to be increased; if "-" appears on the left side of the value, it means that the current flows from the black test lead into the multimeter.

Measurement of alternating current. The measurement method is the same as 1, but the gear should be set to the AC gear. After the current measurement is completed, the red pen should be inserted back into the "VΩ" hole. If you forget this step and measure the voltage directly, haha! Your watch or power supply will "go up to the sky in a wisp of smoke" - scrapped!

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 measurement, but do not hold your hands at the same time. Contacting both ends of the resistor will affect the measurement accuracy - the human body is a conductor with high resistance but limited resistance. When reading, keep the test lead and the resistor in good contact; 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 above "2M" is "MΩ".

4. Measurement of Diodes

The digital multimeter can measure light-emitting diodes, rectifier diodes... When measuring, the position of the test leads is the same as for voltage measurement. Turn the knob to the " " position; connect the red test lead to the positive electrode of the diode, and the black test lead to the negative electrode. At this time, the forward direction of the diode will be displayed. pressure drop. The voltage drop of Schottky diodes is about 0.2V, that of ordinary silicon rectifiers (1N4000, 1N5400 series, etc.) is about 0.7V, and that of light-emitting diodes is about 1.8~2.3V. Replace the test leads. If the display shows "1.", it is normal, because the reverse resistance of the diode is very large, otherwise the tube has been broken down.