Measuring range and accuracy of multimeter
The multimeter changes the measurement items and measurement range through the knob of the conversion switch. The mechanical zero adjustment knob is used to keep the pointer in the left zero position at rest. The "Ω" zero knob is used to align the pointer with the right zero position when measuring resistance to ensure accurate measurement values.
The measurement range of a multimeter is as follows:
·DC voltage: divided into 5 levels -0-6V; 0-30V; 0-150V; 0-300V; 0-600V.
·AC voltage: divided into 5 levels -0-6V; 0-30V; 0-150V; 0-300V; 0-600V
·DC current: divided into 3 levels -0-3mA; 0-30mA; 0-300mA.
·Resistance: divided into 5 levels - R * 1; R*10;R*100;R*1K;R*10K
Measure resistance: First, short-circuit the meter bars together to deflect the pointer to the right, then adjust the "Ω" zero knob to make the pointer point exactly to 0. Then, touch the two meter bars separately at both ends of the measured resistor (or circuit), read the reading of the pointer on the Ohm scale line (the first line), and multiply it by the number on that scale to obtain the resistance value of the measured resistor. For example, if the resistance is measured in R * 100 gear and the pointer points to 80, the measured resistance value is 80 * 100=8K. Due to the dense readings on the left side of the "Ω" scale, it is difficult to see accurately, so the appropriate ohm range should be selected for measurement. Place the pointer in the middle or right of the scale line so that the reading is clear and accurate. Every time you shift gears, you should short-circuit the two gauge rods again and readjust the pointer to zero position in order to measure accurately.
Measure DC voltage: First estimate the magnitude of the measured voltage, then turn the conversion switch to the appropriate V range, connect the positive meter rod to the "+" end of the measured voltage, and connect the negative meter rod to the "-" end of the measured voltage. Then, based on the range number of the gear and the pointer on the DC symbol "DC -" scale line (second line), read out the magnitude of the measured voltage. If measuring with V300 volts, the indicated value from 0 to 300 can be directly read. If measuring with V30 volts, simply remove a "0" from the number 300 on the scale line to see it as 30, and then sequentially see numbers such as 200 and 100 as 20 and 10 to directly read the pointer indication value. For example, when measuring DC voltage in V6 voltage range and the pointer points to 15, the measured voltage is 1.5 volts.
Measure DC current: First estimate the magnitude of the measured current, then turn the conversion switch to the appropriate mA range, and connect the multimeter in series in the circuit as shown in the figure. At the same time, observe the scale line marked with the DC symbol "DC". If the current range is selected in the 3mA range, the number 300 on the surface scale line should be removed by two "0s" and regarded as 3, and then 200 and 100 should be regarded as 2 and 1 in sequence. This way, the measured current value can be read out. For example, when measuring the DC current in the 3mA range and the pointer is at 100, the current is 1mA.
Measuring AC voltage: The method of measuring AC voltage is similar to measuring DC voltage, but the difference is that AC voltage does not have a positive or negative distinction, so when measuring AC voltage, the meter rod does not need to be divided into positive and negative. The reading method is the same as the reading method for measuring DC voltage mentioned above, except that the number should refer to the pointer position on the scale line marked with the AC symbol "AC".
