How to use the digital multimeter: First of all, you need to understand some basics, such as: power switch HOLD screen lock button, B/L is generally a backlight, secondly, you need to understand that the transfer switch V- or DCV means DC voltage block V~ or ACV AC Voltage block means A- or DCA DC current block means A~ or ACA means AC current block, Ω means electrical block, draw a diode symbol that is diode gear, also known as buzzer gear, F means capacitive gear , H represents the inductance block hfe represents the triode current amplification factor test block. Generally, the digital meter will have four jacks, namely: VΩ hole, COM hole, mA hole, 10A hole or 20A hole.
Measure DC voltage, AC voltage, resistance, capacitance, diode, triode, check circuit continuity, etc., insert the red test lead into the VΩ hole, and the black test lead into the COM hole.
To measure mA-level current or μA-level current, insert the red test lead into the dedicated mA current jack, and the black test lead into the COM hole.
Measure the current higher than mA level, insert the red test lead into the 10A or 20A hole, and insert the black test lead into the COM hole.
When measuring voltage, select the appropriate range. If you are measuring DC voltage, you should hit the DC voltage block V- (DCV). If you measure AC voltage, you should hit the AC voltage block V~ (ACV). Insert the red test lead. VΩ hole, the black test lead is inserted into the COM hole, and then connected in parallel to the circuit to measure the voltage. If you do not know how large the measured signal is, you must select the maximum range measurement. When measuring DC, it is better to consider the positive and negative electrodes, because the digital meter is not like a pointer meter. When measuring the DC signal, the measurement is reversed, and the needle is reversed.
When measuring the current, select the jack according to the size of the measured current. If measuring a small current, insert the red test lead into the mA hole and the black test lead into the COM hole. Connect the red and black test leads into the circuit to measure the current. If the measurement shows "1", indicating that the range is over-range, the measurement range should be increased. Generally, a 200mA fuse will be set in the mA hole. When measuring high current, the red test lead should be inserted. The 10A or 20A hole black test lead is inserted into the COM hole. The 10A hole or 20A hole is generally not designed for insurance. When measuring high current, you must pay attention to the time. The correct measurement time should be 10-15S. If it is measured for a long time, due to the current block Constantan or manganese-copper shunt resistors, overheating causes resistance changes, resulting in measurement errors.
When measuring resistance, first of all, hit the multimeter to the electrical barrier and select the appropriate range. If you do not know the resistance value of the measured resistance, you should select the maximum range, and then insert the red test lead into the VΩ hole and the black test lead into the COM hole, and connect it to the resistance. There is no positive and negative pole at both ends, because the resistance has no positive and negative pole. If the multimeter shows "1" during the measurement, you should use the maximum block to measure it again. If the maximum block is used to measure the resistance value of the resistance is still "1", it means The resistance is open circuit. If the resistance value of the resistance is found to be 001 during the measurement, it means that the resistance is internally broken down. When measuring the resistance, first short the test lead to measure the resistance value of the test lead wire, generally 0.1-0.3Ω, and the resistance value cannot exceed 0.5 If it exceeds Ω, it means that the 9V battery is caused by the low 9V power supply voltage of the multimeter, or it is caused by the loose contact between the cutter head and the circuit board. When measuring, do not hold the metal part of the test pen with your hands, so as to avoid entering the resistance of the human body. cause measurement errors.
When measuring the diode, use the diode gear. The open-circuit voltage of the VΩ and COM holes of the digital meter diode gear is about 2.8V. Insert the red test lead into the VΩ hole and the black test lead into the COM hole. Connect the red test lead to the diode anode and the black test lead to the negative electrode. Get the forward resistance value, otherwise measure the reverse resistance value of the diode, because in the digital meter, the red test pen contacts the positive electrode of the internal battery and is positively charged, while the black test pen contacts the negative electrode of the internal battery and is negatively charged, just opposite to the pointer meter, in the pointer meter In the electricity block, the red test pen contacts the negative electrode of the internal battery, and the black test pen contacts the positive electrode of the internal battery. If the forward resistance value is 300-600Ω and the reverse resistance value is 1000, it means that the tube is good. If the forward and reverse resistance values are both "1", the tube is open, and if the forward and reverse resistance values are both 001, it means the tube is broken. If the forward and reverse resistance values are similar, the quality of the tube is poor.
