Maintaining a Constant DC Power Supply
Luis Garcia
April 2, 2010
Team 3
Abstract
Energy dissipated in an electrical or electronic circuit or device per unit of time is
known as the electrical power (electrical power is usually measured in watts).
Electrical energy supplied by a current to an appliance enables it to do work witch
could provide some other form of energy. The difficult part will be manipulating the
electrical power to only output the power needed to power a certain component.
Transformers and voltage regulators could be a reliable form of manipulation to the
power that needs to be outputted.
Objective
To have a constant output voltage from either an AC power supply or a DC power
supply. Also converting an AC power supply to a DC power supply in order to
simplify the system.
Introduction
Power is an essential part in today’s world. Power is needed by everyone to run
televisions, printers, computers, cars, etc. If different constant power supplies could
be implemented from just one source of power, then people could run what they
need at the power they need. First we need to know that power is equal to voltage
multiplied by current. Current comes in either AC or DC and most circuits use DC to
be able to run. Having a simple transformer could turn my AC source into a DC
source.
Background
The power that arrives at someone household travels as AC (alternating current).
On the other hand there is DC (direct current). DC is very useful since the output
voltage is steady witch is applied to the circuits. Most components at someone’s
house hold runs on DC, but AC is what arrives at the wall sockets. Once someone
plugs a plug to their wall socket a AC to DC conversion is made.
PST - SP24AS
A PST - SP24AS is a transformer that converts an AC signal to a DC signal. This
transformer in particular takes a range of 85 volts AC to 265 volts AC and outputs a
steady 24 volts DC.
Figure 1: PST - SP24AS
Linear Regulators
The LM7805 is a voltage regulator that takes a DC voltage (in a range of up to 30
volts and gives a constant 5 volts DC. This is a very simple and great component
since it is very simple to implement.
Figure 2: LM7805
L7815CV is another voltage regulator and both LM7805 and L7815CV look the same
and work the same. The only difference is that one outputs a 5 volts DC and the
other outputs a 15 volts DC.
Conclusion
The final design will have linear voltage regulators and a transformer, basically AC
voltages will be converted to DC with the transformer. Once in DC the linear voltage
regulators will be implemented to have a constant voltage output and our
components will be able to run. The whole system will not take much space and will
be very easy to implement.