Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil. 

In this power supply, this stage has four Y capacitors and one ferrite coil more than required (plus an X capacitor after the rectifying bridges), however it doesn’t have an MOV, which is the component in charge of removing spikes coming from the power grid.

ASUS Atlas A-45GA 450 W power supplyFigure 8: Transient filtering stage (part 1)

ASUS Atlas A-45GA 450 W power supplyFigure 9: Transient filtering stage (part 2)

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.