Power supplies to build yourself

There are many types of power supplies.
Most are designed to convert AC line supply to an appropriate value for low-voltage circuits and other electronic devices, maintain and stabilize DC output. Power Supply, supplies electric power to an electrical load.
Common attributes:

• How stable is voltage and current output under in and load conditions;
• How many time work without "refueling" or "recharching" (when use portable energy sources);
• How many current and voltage can supply to its load. 

All PS obtain energy from a source which supply to load and, all consume some amount of energy to work.
Depending of its type, a power supply obtain energy from:

• Solar power;
• Generators and alternators (electromechanical systems);
• Batteries and Fuel Cells (energy storage);
• Electrical energy transmission systems, a common example, AC line voltage to DC voltage.

Some Power Supplies Diagrams: