How does the switching power supply circuit not interfere with others and how is it not interfered with by others
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.
The main function of this filtering circuit is to filter out interference pulses from the power grid, prevent the impact of interference pulses on the switching power supply components, and also prevent the oscillation pulses generated by the switching power supply during operation from being sent back to the power grid, causing interference to other electrical appliances in use.
That's why the capacitors here are called safety capacitors. For the safety of the power grid and power supply, it is stipulated that the switching power supply must be equipped with this filtering circuit, just like the compensation capacitors in the electrical cabinet. Capacitors and inductors together form a protective wall, which not only protects the switching power supply itself from harm, but also prevents it from causing interference to the power grid.
