(1) Correct use of pointer multimeter
1 The selection of measurement type and measurement range should be cautious. Whenever you pick up the meter and measure each measurement, you should check whether the position of the transfer switch is appropriate.
2 Connect the red and black bars to the "+" and "-" ends, respectively. In this way, when measuring, the red meter rod can be always in contact with the positive pole and the high potential of the object to be tested, so as to avoid pointing the finger.
(2) Correct reading
1 The scale corresponding to the scale is divided.
2 The scale should correspond to the indication of the transfer switch.
3 The pointer of the multimeter should be indicated on the 1/2~2/3 scale. Otherwise, the measurement range should be changed so that the most accurate reading is measured.
(3) Correct measurement
1 Note the following seven points when measuring resistance.
a. It must be zeroed before each measurement and zero after changing the ohms.
b. The measured resistance cannot be charged. If the circuit has a capacitor, the capacitor should be discharged first.
c. When measuring large resistance, you should not touch the conductive part by hand, otherwise it will bring serious error to the æ²J amount of crusting.
d. The current of the multimeter flows out from the "-" end, that is, the "-" end is the positive pole of the attached battery, and the "+" end is the negative pole of the attached battery.
e. When measuring the transistor resistance, the measurement range should be placed in R × 100 or R × 1k block. If the measurement is done with R × 1 or R × 10, the transistor may be burned out. If the measurement is performed with R × 10k, the transistor may be broken.
f. It is not allowed to measure the internal resistance of micro-ampere meters, galvanometers, standard batteries, etc. with a multimeter R×1, R×10 block.
g. When measuring the interval, the two bars should be prevented from short-circuiting and waste battery energy.
2 Note the following seven points when measuring current and voltage.
a. When measuring current, the multimeter is connected to the human circuit, the red bar is connected to the positive electrode of the object to be measured, and the black bar is connected to the negative electrode of the object to be tested.
b. When measuring the voltage, the multimeter is connected to the circuit, the red bar is connected to the high potential of the object to be measured, and the black bar is connected to the low potential.
c. When the range needs to be converted during the test, the rod should be removed from the test point to prevent the switch from being burnt due to sparking at the contact point.
d. If you do not know the size of the object to be measured, you should first place the multimeter in the maximum measurement range, and then gradually reduce the measurement range according to the deflection of the pointer.
e. When testing high voltage, it should be operated with one hand. First set the black bar to zero potential, and then use the same hand to touch the red bar to the measured end.
f. If the measured waveform is a square wave, a rectangular tooth wave, a triangular wave, etc., the measurement result has a large deviation.
g. After the measurement is completed, the multimeter's transfer switch should be placed at the highest voltage of the AC voltage.
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