How to choose the resistor in the power adapter?

Resistors are a very common component in power adapters. The sub-circuits usually function as voltage dividers and current dividers. Recently, the shortage of resistors and capacitors and the rise in prices are also very troublesome. So what should we pay attention to when choosing resistors?
First of all, the resistance and error of the resistor must be selected correctly:
1. Pay attention to the limit parameters of the resistor;
2. General-purpose resistors should be preferred;
3. Select according to the characteristics of the circuit;
4. Select the resistor according to the size of the circuit board;
5. Learn about sensitive resistors, thermistors, and photoresistors;
6. Varistor: The biggest feature of a varistor is that when the voltage applied to it is lower than its threshold "UN", the current flowing through it is extremely small, which is equivalent to a closed valve. When UN is exceeded, the current flowing through it surges, which is equivalent to the opening of the valve. Utilizing this function, it is possible to suppress the abnormal overvoltage that often occurs in the circuit and protect the circuit from damage caused by overvoltage.
As a manufacturer of power adapters, we must have a full understanding of components. Only in this way can we choose materials and match them to produce high-quality power products.