Download Output Devices - Cabarrus County Schools

Output Devices
Objectives
Upon completion of this unit the student will be able to:
1. Describe electrical output devices
2. Operate output devices using AC and DC current sources.
3. Relate voltage value to output device operation
Background
An electrical output device is any piece of equipment powered by
electricity. Output devices convert electricity into light, sound, heat or
motion. Output devices found in homes include lamps, clocks, radios,
televisions, game systems, microwaves, corded drills and power tools.
Output devices found in schools and businesses include intercoms,
photocopiers, FAX machines, computers and other various kinds of
machinery – all powered by electricity.
People depend heavily on electrical output devices. When power goes
out during a bad storm, people have trouble moving around their homes in
the dark. Without clocks, they may be late for school or work (unless they
use their cell phone as a back-up). They may not even be able to cook or
heat/cool their home (without the use of a generator). If a business loses its
electrical power, almost no work can get done.
Output devices are often called loads in circuits. Bigger loads
require more voltage to operate, just as heavier packages require more
strength to lift. The source voltage must always be the same as or less
than the load voltage rating. High voltages destroy small loads.
Two basic kinds of output devices, lamps and LED’s change
electricity into lights. Lamps provide light for indoor and outdoor
spaces. They also help machine operators run a machine by indicating if
the power is on or if a certain job is being done.
The MB100 Kit uses a lamp to indicate that the power is on. A car
dashboard has lamps to indicate if turn signals or high beam lights are
on. Some cars also have lamps to indicate if the battery or oil pressure
is low or if the engine is overheating. These indicator lamps help the
operator (drive) know what is happening in the car.
An incandescent
lamp (light bulb)
uses electricity to
heat us a thin piece
of conducting wire
called filament. The
filament gets so hot
that it glows
brightly, producing
light.
Incandescent Light Bulb
• Making of an incandescent light bulb
Fluorescent Lights
Fluorescent lights work a little differently. These lights do not
contain a filament. Instead, electricity flows through a conducting gas
tube, making it glow. Fluorescent lights stay cooler that incandescent
lamps because the gas in them glows easily. They also use less
electricity than incandescent lamps.
How it Made
LED
LED’s also produce light, but not enough to light up a room until now. LED’s
were usually just used as indicators lamps on machinery. The red numbers on a
digital clock are formed by several long, thin LED’s. With technology we have been
able to integrated multi-LED’s to create individual light bulbs.
The name LED comes from light emitting diode. An LED is made from a
semiconductor material. Just as lamps electricity is converted into light.
Currently the LED lamp is popular due to it's efficiency and many believe it
is a 'new' technology. The LED as we know it has been around for over 50 years.
The recent development of white LEDs is what has brought it into the public eye as
a replacement for other white light sources.
Common uses: indication lights on devices, small and large lamps, traffic
lights, large video screens, signs, street lighting(although this is still not
widespread)
Advantages:
-Energy efficient source of light for short
distances and small areas. The typical LED
requires only 30-60 milliwatts to operate
-Durable and shockproof unlike glass bulb lamp
types
-Directional nature is useful for some
applications like reducing stray light pollution on
streetlights
Disadvantages:
-May be unreliable in outside applications with
great variations in summer/winter
temperatures, more work is being done now to
solve this problem
-Semiconductors are sensitive to being damaged
by heat, so large heat sinks must be employed
to keep powerful arrays cool, sometimes a fan is
required. This adds to cost and a fan greatly
reduces the energy efficient advantage of LEDs,
it is also prone to failure which leads to unit
failure
-Circuit board solder and thin copper
connections crack when flexed and cause
sections of arrays to go out
-Rare earth metals used in LEDs are subject to
price control monopolies by certain nations
-Reduced lumen output over time
Large LED array designed for use as a street lamp. A massive
aluminum heat sink is needed with the high wattage LEDs
OLED
What is an OLED?
OLED (Organic Light Emitting Diodes) is a flat light emitting technology, made by placing a series of
organic thin films between two conductors. When electrical current is applied, a bright light is
emitted. OLEDs can be used to make displays and lighting. Because OLEDs emit light they do not
require a backlight and so are thinner and more efficient than LCD displays(which do require a white
backlight).
Uses: Lamps - short distance indoor lamps (produces a diffused light).
Displays - small: phones and media devices and large: televisions, computer monitors
Advantages:
-The units are lighter than traditional LEDs and can be made thinner as well
-OLEDs can provide a more energy efficient alternative to LCD computer and television monitors
-Can be used in a myriad of new applications in which lighting technology has never been used before
Disadvantages:
-The cost of OLEDs is still high and each unit produces less lumens than a normal LED
-The technology is still under development so the life of the OLED is being researched as new materials are
used and tested each year. Until more research is done we will not know how these lamps with new materials
compare with established technology.
LED and OLEDs
LEDs and OLEDs - How it Works, Inventors
The Future of Illumination and Display's
Motors
A motor is a device which
converts electrical energy into
mechanical energy (rotating energy).
There are two basic parts to an
electric motor. An iron rod, or
armature, is mounted to the shaft.
The armature has wire wrapped it
creating a coil. This wire is called the
armature coil. The armature coil is
mounted so it can rotate between the
poles of a magnet.
Motors
Current flowing through the coil turns the armature into a
electromagnet. The magnetic field produced by the magnet then causes the
coil to rotate. It rotates until its north pole is closest to the south pole of the
magnet. If current always flowed in the same direction, the coil would not
continue to rotate, however, a motor that runs on direct current (DC) has a
commutator. The commutator is a reversing switch that rotates with the coil
and reverses the direction of current every half turn of the coil. This reversal
causes the poles of the electromagnet to switch. Now, two poles will be
together, causing the coil to rotate another half turn. The commutator
reverses the current direction again, and the coil rotates another half turn.
All this happens very quickly, making the armature coil spin around creating
electrical energy. This electrical energy causes the motor shaft to rotate. The
rotation of the motor shaft creates the mechanical energy used to do work.
DC MOTOR
DC Motor, How it works?
Brushless DC Motor, How it works?
Buzzers & Speakers
• Buzzers and speakers are output devices that convert electricity into
sound. A buzzer makes a constant sound. A speaker, on the other
hand, can produce music and speech sounds.
Buzzers
Both buzzers and
speakers use electricity to
make a diaphragm
vibrate. In the buzzer, the
diaphragm is usually a
very thin sheet of
semiconducting plastic.
When electricity flows
through the it, it vibrates
and the buzzer sounds.
Speaker
A speaker is a bit more
complex. A magnet and an
electrical coil are used to
create motion in a speaker,
just like a motor. The motion
is very rapid vibration of a
diaphragm to create sound,
something like a buzzer. This
diaphragm is shaped like a
cone to help make many
different kinds of sounds.
Without other electrical
components, a speaker can
make only a buzzing sound.
This sometimes is called
“white noise”.
Speaker & Microphones
• The difference between a speaker and a microphone is that a speaker
is used to produce sound and a microphone is used to pick up sound.
They are basically made the same way. Both can reproduce or pick up
sound. Speakers, however, cannot run on DC voltage. DC voltage will
damage the speakers. The MB100 Kit is protected so that a student
cannot damage the speaker using DC voltage.