How to use a multimeter to tell the difference between AC and DC voltage.
How to quickly distinguish whether a power source is DC or AC with a multimeter? In general, people can make a rough judgment based on intuition. For example, batteries are usually DC power, while the electricity on household sockets is usually AC power. However, if there is a power source plugged into a socket at home and the power label is missing, then it is necessary to consider how to distinguish whether the power source is AC or DC power.
It is easy to distinguish with an electric pen. If this article simply says that using an electric pen to distinguish itself is not very meaningful, it would be better to share a somewhat technical multimeter to distinguish whether the power supply is DC or AC.
For AC power, there is no distinction between positive and negative poles. When using a multimeter in AC mode to measure, the results are actually the same for both positive and negative sides. However, when using a multimeter in DC voltage mode to measure DC power, there is actually a "-" sign difference between the positive and negative sides. This can also distinguish between AC and DC, but there is still a problem. In order to use a multimeter to measure this result, it is necessary to know whether the power source is DC or AC, otherwise selecting the wrong mode will not display the result.
So we need to come up with another method. Assuming that the power source we are trying to distinguish is AC power, select a larger range AC gear for the multimeter, bend the black probe for about three turns, and hang the black probe in the air. It is best not to touch the head of the black probe with your hands. For the AC voltage gear, touching the black probe is not dangerous, but for the wrong AC gear, if you accidentally touch the black probe while the red probe is plugged into a socket, it is very dangerous. Therefore, for safety reasons, it is best not to touch the probe with your hands.
The next step is to insert the black probe into any socket of the power supply. If it is AC power, you will find that when one of the two electrodes of the power supply is inserted into one of the sockets, a number can be displayed. If this situation occurs, it means that the power supply is AC power, otherwise it is DC power.
How to quickly distinguish between AC and DC power supply with a multimeter?
But when you change the position of the pointer inserted into the power socket, the number can be displayed on the screen. If the number can be displayed, it means that the power supply is AC power supply. For DC power supply, no matter how you plug it in, there will actually be no voltage when inserting a pointer.
