General Purpose Diodes are two-terminal electronic components that allow current to flow in only one direction, from an anode (+) to a cathode. They are used for applications such as fast switching, low power rectification, current regulation and polarity protection.
The 1N400x (or 1N4001 or 1N4000) series is a family of popular 1A general-purpose silicon rectifier diodes commonly used in AC adapters for common household appliances. This device number series is available in the DO-41 axial package and similar diodes are available in SMA and MELF surface mount packages.
The 1N540x (or 1N5400) series is a similarly popular family of diodes for higher-current 3A applications. These diodes are typically available in the larger DO-27 axial package to dissipate heat better. Please refer to below WEET product list of General Purpose Diodes.