Power supply
A power supply is a device that
supplies electrical energy to one or more electric loads. The term is most commonly
applied to devices that convert one form of electrical energy to another,
though it may also refer to devices that convert another form of energy (e.g.,
mechanical, chemical, solar) to electrical energy. A regulated power supply is one that
controls the output voltage or current to a specific value; the controlled
value is held nearly constant despite variations in either load current or the
voltage supplied by the power supply's energy source.
Every power
supply must obtain the energy it supplies to its load, as well as any energy it
consumes while performing that task, from an energy source. Depending on its
design, a power supply may obtain energy from:
·
Electrical
energy transmission systems. Common examples of this include power supplies
that convert AC line voltage to DC voltage.
·
Energy
storage devices such as batteries and fuel cells.
·
Electromechanical
systems such as generators and alternators.
·
Solar power.
A power supply
may be implemented as a discrete, stand-alone device or as an integral device
that is hardwired to its load. In the latter case,
for example, low voltage DC power supplies are commonly integrated with their
loads in devices such as computers and household electronics.
Commonly specified
power supply attributes include:
How stable its
output voltage or current is under varying line and load conditions.
How long it can
supply energy without refueling or recharging (applies to power supplies that
employ portable energy sources).
Electrical generator
12V dc generator
An electricity generation, an electric generator is a
device that converts mechanical energy to electrical energy. A generator forces electric charge (usually carried by electrons) to flow through
an external electrical circuit.
Dynamo
The dynamo uses electromagnetic principles to convert mechanical rotation into pulsed DC through. A dynamo machine consists of a
stationary structure, which provides a constant magnetic field, and a set of
rotating windings which turn within that field. On small machines the constant
magnetic field may be provided by one or more permanent magnets; larger
machines have the constant magnetic field provided by one or more
electromagnets, which are usually called field coils.
Large
power generation dynamos are now rarely seen due to the now nearly universal
use of alternating current for power distribution and solid state electronic AC to DC power conversion.
But before the principles of AC were discovered, very large direct-current
dynamos were the only means of power generation and distribution. Now power
generation dynamos are mostly a curiosity.
Diode
The most common function of a diode is
to allow an electric current to pass in one direction (called the diode's forward direction),
while blocking current in the opposite direction (the reverse direction)
Battery
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first
battery (or "voltaic pile") in 1800 by Alessandro Volta and
especially since the technically improved Daniell cell in
1836, batteries have become a common power source for many household and
industrial applications. According to a 2005 estimate, the worldwide battery
industry generates US$48 billion in
sales each year, with 6% annual
growth.
There
are two types of batteries: primary batteries (disposable
batteries), which are designed to be used once and discarded, and secondary batteries (rechargeable
batteries), which are designed to be recharged and used multiple times.
Batteries come in many sizes, from miniature cells used to power hearing aids and
wristwatches to battery banks the size of rooms that provide standby power for telephone exchanges and computer data centers.
