A multimeter measures current, voltage and resistance, which setting should be set?
I. Observe and understand the structure of the multimeter.
There are many kinds of multimeters with different shapes, but the basic structure and usage are the same.
On the multimeter panel, the king should have the head and selector switch. There are also ohm zero knob and pen jack. The following describes the role of each part:
(A) the head
Multimeter head is a sensitive ammeter. The dial on the head is printed with a variety of symbols, scales and values. Symbol A a V a Ω that the meter is a multi-meter can measure current, voltage and resistance. The dial is printed on a number of scales, the right end of which is marked "Ω" is the resistance scale, the right end of which is zero, the left end of the ∞, the distribution of scale values is uneven. Symbol "-" or "DC" for direct current, "~" or "AC " indicates AC, and "~" indicates a scale line shared by AC and DC. The lines of numbers under the scale line are the scale values corresponding to the different gears of the selector switch.
There is also a mechanical zero adjustment knob on the head of the meter, which is used to correct the pointer at the left end to point to the zero position.
(ii) Selection switch
Multimeter selector switch is a multi-position rotary switch. Used to select the measurement items and ranges. General multimeter measurement items include: "mA"; DC current, "V": DC voltage, "V": AC voltage, "Ω ": resistance. Each measurement item is divided into several different ranges for selection.
(iii) Meter pens and pen jacks
Meter pen is divided into red, black two. When using the red pen should be inserted into the jack marked "+", the black pen into the jack marked "-".
Second, the use of multimeter
(A) before the use of multimeter, should be done:
1. The multimeter is placed horizontally.
2. Should check whether the needle stops at the left end of the dial zero. If there is a deviation, a small screwdriver can be used to gently turn the mechanical zero adjustment knob on the head of the meter, so that the needle points to zero.
3. Insert the pen into the pen socket according to the above requirements.
4. Turn the selector switch to the corresponding item and range. Can be used.
(B) multimeter after use, should be done:
1. Pull out the pen.
2. Rotate the selector switch to the "OFF" file, if there is no such file, should be rotated to the maximum range of AC voltage file, such as "and 1000V" file.
3. If it is not used for a long time, the battery in the table should be removed to prevent the battery electrolyte leakage and corrosion of the internal circuit.
(A) Measurement of DC voltage
Measurement steps are:
1. Select the range. Multimeter DC voltage marked with "V", 2.5 volts, 10 volts, 50 volts, 250 volts and 500 volts five ranges. Select the range according to the size of the power supply voltage in the circuit. Since the supply voltage in the circuit is only 3 volts, the 10-volt range is selected. If you are not sure of the size of the voltage, you should first measure with the highest voltage gear, and gradually switch to a lower voltage gear.
2. Measurement method. Multimeter should be connected in parallel with the circuit under test. The red pen should be connected to the measured circuit and the power supply positive connection, the black pen should be connected to the measured circuit and the power supply negative connection.
3. Correct reading. Carefully observe the dial, DC voltage scale is the second scale line, with 10V file, the third line of figures available under the scale line directly read out the measured voltage value. Note that when reading, the line of sight should be directly to the pointer.
