Resistance is one of the most used basic components in electronic equipment, mainly plays the role of current limiting, voltage dividing, pull-up/pull-down, etc. Common types include carbon film resistors, metal film resistors, patch thick film/film resistors, cement resistors, and precision resistors.

The selection focuses on three parameters: resistance, accuracy (tolerance) and rated power. The pull-up resistance of ordinary digital circuits is generally 4.7kΩ ~ 10kΩ, and the accuracy is 5%; while analog circuits such as sampling, reference, and op-amp feedback are recommended to use metal films or thin film resistors with 1% or more accuracy.

There should be sufficient margin in terms of power, and the actual power consumption should not exceed 60% ~ 70% of the rated power. In the development of microcontrollers, reset circuits, led current limiting, button pull-up, etc. will use resistors, and reasonable selection can effectively reduce the power consumption and heat generation of the whole machine.