As shown in the above figure, the measurement parameters of the multimeter and the position map of the gear position are very clear. We will not make unnecessary explanations. Below we will pay attention to the three aspects of the measurement. explain:

The reason why we put the current and voltage together, because there are many similarities between the current and the voltage measurement, they differ only in the measurement position in the circuit when measuring. When measuring the current, the multimeter and the component need to be connected in series. In the circuit, when measuring the voltage, the multimeter needs to be connected in parallel in the circuit, and the position of the parallel connection is the two ends of the measured component.

Because the multimeter is a kind of artificial measurement device, so it has the requirements of DC and AC. We will focus on this aspect. What are the requirements for DC and AC measured by the multimeter? The multimeter can The measured direct current is designed similar to the dry battery output, which has the same current direction and constant current. The design of the alternating current is specifically for what we usually call the mains (ie 220V, 50HZ). This is called sinusoidal AC design, so this is very important when measuring the circuit, which is why many engineers find the voltage rise when measuring the current at the output of the rectifier bridge, because the rectifier bridge outputs this The direct current is sinusoidal alternating current, which does not meet the DC requirements of the multimeter and does not meet the requirements of the alternating current. According to the design principle of the multimeter, this indication is of no practical significance.

Everyone may also have doubts. If this is the case, then the application area of the multimeter is not very restrictive, but it is not, because most of the AC and DC electricity that we encounter in our lives are as described in the above two categories. The current and voltage at the output of the rectifier bridge, we usually think that the current and voltage of the input and output of the rectifier bridge are the same.

The diode position and resistance file of the multimeter are also very similar. It can be used to judge whether the circuit is short-circuited or not. The measurement of the diode is good or bad, but the measurement of the resistance value can only be measured by the resistance gear position, but the common points of both need to pay attention to The matter is the same. The difference between the diode position and the resistance file and the current and voltage is that when measuring the current and voltage, the multimeter is powered by the measured circuit, that is, it needs to be measured in the power supply circuit, and the diode and the resistance position. When measuring, the multimeter itself supplies power, and when measuring resistance and diode conduction, it is generally not to be measured in the power supply circuit. Usually, the component is measured separately, especially when measuring the diode, because it is usually connected to the diode. Is a varistor or a capacitor, which causes the measured measurement to lose meaning.