1. Interference caused by external factors

Introduction to headphone socket: External electromagnetic interference enters the 2.5 headphone socket power supply through radiation or is input into the socket power supply through a power cord. This kind of interference can be divided into the following two types.

1) Natural sources of interference. For example, the phenomenon of lightning discharge and the interference noise of celestial electricity such as sunspots and cosmic rays in the universe, the former has a short duration but high energy, while the latter has a wide frequency range.

2) Human interference source. With the rapid development of modern science and technology, electronics, power electronics, and electrical equipment have begun to be widely used. The high-density, wideband electromagnetic signals generated during their operation fill the entire space, forming a complex electromagnetic environment.

Especially transient electromagnetic interference, with high voltage amplitude (several hundred volts to thousands of volts), fast rise speed, short duration, and strong randomness. In addition, radar, navigation, communication and other equipment generate radio noise with a wide frequency range and high interference intensity.

2. Interference caused by internal components of the power supply

A socket power supply is a type of power supply that rectifies power frequency AC into DC, then converts it into high-frequency AC through a switching circuit, and then rectifies it into stable DC. As a result, there are several types of noise: high-order harmonic noise generated by the distortion of the rectified wave of a 2.5 headphone socket power supply; The wideband electromagnetic interference noise caused by the rapid changes in current and voltage of switching devices during high current and high voltage conduction and cutoff; Surge current spikes and high-frequency oscillation noise generated during the turn-on and turn off process of rectifier diodes; In addition, there are electromagnetic interference noise caused by oscillations at the input end of the output filter due to transformer leakage inductance, distributed capacitance, and filtering capacitance.