The commonly used thermoelectric part of switch power supplies has a dedicated anti-interference filtering circuit, which is generally not noticeable due to its obscurity. As for the specific location, it is the circuit behind the fuse and varistor. This combination is not easy to break, but essential. Today, we will talk about some common sense here.

This part of the circuit is not complex, usually composed of capacitors and inductors. Speaking of this, it is necessary to mention a basic knowledge - filtering circuits. Those with a slightly weak electrical foundation know that capacitors and inductors can form LC or π structure filtering circuits, Lc circuits can be composed of an inductor and a capacitor, and π filtering circuits are composed of two capacitors and one inductor. Because the architecture is similar to a π shape, they are vividly called π filtering circuits.

The anti-interference circuit feature of the switching power supply, which is composed of inductance and capacitance, is very obvious. It generally consists of an inductance similar to a small transformer in appearance and two square safety capacitors, which are basically not damaged here. Especially, the inductance rarely has open circuit faults, as it is connected in series in the circuit, so there is no short circuit in the inductance. Unless the power supply is particularly stable, the safety capacitor is also rarely burned and short circuited.