Instructions for using a multimeter
The following is an example of an MF30 multimeter to illustrate its reading. The first scale line indicates the resistance value, with infinity at the far left end and zero at the right end. The scale in the middle is uneven. Resistance gear has R × 1. R × 10. R × 100, R × 1K, R × For each gear of 10K, indicate the indication of the scale and multiply it to obtain the actual resistance value (in ohms).
For example, using R × Measure the resistance at gear 100, and the pointer indicates "10", so its resistance value is 10 × 100=1000, i.e. 1K. The second scale line is shared between the 500V and 500mA ranges. It should be noted that the indication principle of the voltage and current ranges is different from the resistance range. For example, the 5V range indicates that this range can only measure voltages below 5V, while the 500mA range can only measure currents below 500mA. If it exceeds the range, it will damage the multimeter.
Attention: When using a multimeter, it should be placed horizontally. Insert the red pen into the+hole and the black pen into the - hole. When testing the current, use the current range instead of misusing the voltage range or resistance range. Otherwise, it may cause the fuse inside the multimeter to burn, or it may cause damage to the meter head. Without knowing the range beforehand, try measuring with the maximum range and then disconnect the measuring circuit before shifting gears. Do not switch the range online. If there is a rapid deviation of the watch needle to the bottom, the circuit should be immediately disconnected for inspection.
Finally, there is another rule, which is to set the range switch of the multimeter to the highest level of AC voltage after use, in order to prevent damage caused by others accidentally measuring the 220V mains voltage. Remember the fine tradition left by this senior generation!
Use Cases
Taking the MF30 multimeter as an example, this article introduces its usage. Preparation before use
Firstly, before using a multimeter, one must be familiar with the function of the range selection switch. What should be tested clearly? How to test? Then turn the range selection switch to the position where the test gear is required. Do not mistake the gear position. For example, mistakenly setting the selection switch to the current or resistance range when measuring voltage can easily burn the meter head.
Secondly, observe whether the watch needle is in the zero position before use. If the zero position is not specified, a screwdriver can be used to adjust the mechanical zero adjustment screw on the meter head to reset the watch needle (usually not necessary to adjust it every time). The red pen should be inserted into the positive socket, while the black pen should be inserted into the negative socket.
When measuring voltage, the meter probe should be connected in parallel to the circuit being tested. Select a suitable range position based on the approximate value of the circuit being tested. The maximum value of each dry battery cell is 1.5V, so it can be placed in the 5V range. At this point, 500 of the full scale reading on the panel should be taken as a reading of 5. That is, shrink by 100 times. If the watch needle points at the 300 scale, it reads 3V. Note that the value indicated by the tip of the range switch is the corresponding value of the full scale reading of the needle on the meter head. When reading the meter, simply convert it accordingly to read the real value. https://www.dgdqw.com Except for the resistance range, all range switches should read the measurement results using this method. In actual measurement, when the approximate value of the measured voltage cannot be determined, the switch can be turned to the maximum range first, and then the range can be reduced to the appropriate position step by step. When measuring DC voltage, attention should be paid to the positive and negative polarity. If the probe is connected in the wrong direction, the probe will strike back. If you don't know the positive and negative polarity of the circuit being tested, you can set the range of the multimeter to the maximum range and quickly try it on the circuit being tested. By observing how the stylus is deflected, you can determine the positive and negative polarity.
