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1, according to the screen printing of the chip to determine the positive and negative poles
When designing the chip, engineers will use silk screen to mark the pin definition of the interface part. For the positive and negative power supply, V and GND are generally used to distinguish the positive and negative power supply. Therefore, first look at the screen printing on the board, through the screen printing content on the board can learn a lot of information, the correct understanding of the screen printing information of the circuit board is very important.
2, according to the polar components to determine the positive and negative poles
Polar components are polar and cannot be reversed when in use. Commonly used polar components are electrolytic capacitors, diodes and so on. Therefore, the positive and negative poles of the circuit can be determined by polar components. Taking electrolytic capacitor as an example, its positive electrode must be connected to the positive power supply, and the negative electrode must be connected to the GND, and the positive and negative electrodes of the circuit can be determined by identifying the pin of the capacitor.
3, according to the large area of copper coating to determine the positive and negative poles
In order to improve the anti-interference ability and reduce the impedance of the ground wire when designing the chip, the ground will be electrically connected by a large-area copper coating. If the circuit board is covered with copper, it is basically covered with GND as the network copper, and it can be judged that the large-area copper coating is the ground wire in turn.