Power Supply

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:

Power Supply 9 Volt 2 Amp

12 Volt DC Power Supply

12 Volt DC 30 Amp Power Supply

13 Volt 20 Amp PS

Symmetrical Power supply 15 Volt

Power supply voltage variable with L200

Power supply 12V (switched) 2A

12V UPS

Adjustable PS with LM338

Operation:
The adjustment is given by the multi-turn potentiometer 5K, the voltimeter LCD (200V) and amperimeter LCD (200mV) require external power, 9V batteries can be used.