POWER SUPPLY

Power Supply is reference to source of electrical power. A device or system that supplies electricalor other types of energy to an output load or group pf loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to other.
This term covers the power distribution system together with any other or secondary sources of energy such as :

• Conversion one of form of electricel power to another desired form and voltage. this typically involves converting 120 or 240 volt AC supplied by a utility company to a well-regulated lower lower voltage DC for electronic device. For example, see switched-mode power supply, linear regulator, rectifier and inverter (electrical).
• Batteries
• Chemical fuel cells and other form energy storage system
• Generators or alternators (particularly useful in vehicles of all shapes and sizes, where the enginee has torque to spare, or in semi-portable units containing an internal combustion engine and generator) (For large-scale power supplies, see electricity generation). Low voltage, low power DC power supply units are commonly integrated with the devices they supply, such as computer and household electronics.

Contraints that commonly affect power supplies are amount of power they can supply, how long theycan supply it without needing some kind of refueling or recharging, how stable their output voltage or current is under varying load conditions, and whether they provide continuous power or pulse.
They regulation of power supplies is done by incorporatingcircuitry to tightly control the output volatage and/or current of the power supply to a specific value. The specific value is closely maintained despite variations in the load presented to the power supply's output, or any reasonable voltage variation at the supply's input. This
kind of regulation is commonly categorised as a Stabilized power supply.

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