How to use the multimeter
(1) Before using the multimeter, "mechanical zero adjustment" should be performed first, that is, when there is no electricity to be measured, make the pointer of the multimeter point to the position of zero voltage or zero current.
(2) In the process of using the multimeter, you cannot touch the metal part of the test pen with your hands, so on the one hand, it can ensure the accuracy of the measurement, and on the other hand, it can also ensure personal safety.
(3) When measuring a certain amount of electricity, it is not possible to change gears while measuring, especially when measuring high voltage or large current, more attention should be paid. Otherwise, the multimeter will be destroyed. If you need to change gears, you should disconnect the test leads first, and then go to measure after changing gears.
(4) When the multimeter is in use, it must be placed horizontally to avoid errors. At the same time, pay attention to avoid the influence of external magnetic field on the multimeter.
(5) After the multimeter is used, the transfer switch should be placed in the maximum block of AC voltage. If it is not used for a long time, the battery inside the multimeter should also be taken out to prevent the battery from corroding other devices in the meter.
When using an analog multimeter, insert one end of the two measuring probes into the measuring end according to the requirements of red to positive (+) and black to negative (-), and then confirm whether the pointer is at the "0" position. The pointer should line up with the end line on the left side of the dial, if not, make a zero adjustment. Before measuring the current and voltage, first estimate the range of the current and voltage to be measured, first set it in a larger gear, and then adjust it to a suitable gear to avoid burning out the multimeter due to excessive current.
When making measurements, the influence of the internal resistance of the multimeter should be considered. For example, in order to measure the voltage, the test leads should be connected to the circuit under test. At this time, the resistance in the multimeter also flows through the current, which has a certain influence on the measured value. When measuring the voltage at the same point, if different gears are used, the internal resistance of the multimeter will be different, and the degree of influence will also be different.
When measuring electronic circuits of transistors, it is better to select the internal resistance of 20kΩ/V in DC mode, and this value is usually marked on the dial of the multimeter. In addition, transistor circuits often need to measure low-value voltages, such as 0.1V. At this time, the selected multimeter should have a measurement range of 1V.
