Teach you to measure electronic components with a multimeter
First, start with the initial voltage measurement. The multimeter measures DC voltage, such as battery and digital equipment power supply, etc., insert the black pen plug into the COM port on the lower right of the multimeter, and the red pen plug into VΩ, and then turn the middle knob to the range with the largest estimated value ("V-" is DC voltage file, "V~" is AC voltage file, "A" is current file). The next step is to use the red and black pens to touch both ends of the battery/power supply. If the meter displays "1" at this time, the range is too small, continue to increase the range and measure. When the symbol "-" appears to the left of the value, it means that the polarity of the ratio is opposite to that of the battery/power supply.
The AC voltage measurement is the same as the DC voltage measurement, the difference is that the knob in the middle is the AC gear "V~", and the AC voltage has no positive or negative, so it can be measured according to the DC voltage measurement method. In addition, during use, do not touch the metal part of the red-black ratio with your hands.
To measure the current, you must also insert the black pen into the COM port first. There are large and small gears when measuring the DC current. If the measured current is greater than 200 mA, insert the red nose into the "10A" port, and at the same time turn the knob to the DC "10A" " file; if it is less than 200mA, insert the red nose into the "200mA" port, and turn the knob to a suitable range in DC 200mA. When measuring, connect the multimeter into the circuit in series, if the reading is "1", increase the range; if the "-" sign also appears, the current flows from the black pen into the multimeter.
AC measurement is the same as DC, the difference is that the knob is in the AC position. When measuring AC, you need to pay attention to a very important point: after the measurement, you must insert the red nose back into "VΩ", otherwise, if you accidentally measure the voltage, the meter will be damaged. , or the power supply is damaged.
When measuring resistance, insert two pens into the COM and VΩ ports respectively, and turn the knob to the appropriate range in "Ω". Then use a pen to touch the metal at both ends of the resistor. If the unit is "'200'", it is "Ω", while the 2K and 200K gears are "KΩ". Similarly, if the unit is above 2M, the unit is "MΩ".
When measuring diodes such as light-emitting diodes and rectifier diodes, use a red pen to connect the positive pole of the diode (if you don’t know the positive and negative poles of the diode, you can check how to identify the polarity of circuit board components), connect the black pen to the negative pole, and the diode will be displayed at this time. The forward voltage drop of Schottky diodes is about 0.2V, while ordinary silicon rectifiers are about 0.7V, and light-emitting diodes are between 1.8 and 2.3V. Exchange two pens, display "1", then the diode is normal (diode characteristics), otherwise, the diode is scrapped~
The measurement of the triode is the same as the principle of the diode. Here, assuming that the pin A is the base, touch the black pen to the pin A. At this time, the red pen touches the other two pins respectively. If the display is about 0.7V, replace the two Pen position, touch the other two pins with a black pen, if "1" is displayed at this time, then the A pin is consistent with the base we assume, otherwise it is two, and the triode is a PNP tube.
In addition to the base, the triode also has a collector and an emitter. To judge these two polarities, you can use the "hFE file" of the multimeter. Adjust the gear first, there is a row of small openings on the side of the gear, which are the measurement ports of the PNP tube and the NPN tube. According to the tube type judged in the first step, insert the base into the "b" port, and insert the other two pins into the "e" and "c" ports. At this time, you can read the β value from the multimeter. After reading, swap the two pins "e" and "c", then read, and compare the two readings, that is, the position of the largest pin is the same as "e" and "c". correspond.
