Siren
Physics 30 Circuits
What it Does
• When the push button (momentary switch) is held down for
10 to 15 seconds, a timing circuit of capacitors and resistors
that "feeds back" the output to input starts slowly rising in
pitch, known as oscillation.
- A siren is based on these oscillators or tone generators.
• The energy in the circuit is stored in the various capacitors,
until finally, the energy is released and continues through
the circuit.
• The time it takes to charge the capacitors (known as the
time constant) creates a slow buildup of the oscillator's
frequency, which then produces the siren noise.
How It Looks.....
capacitor
integrated circuit
transistor
momentary switch
capacitor
resistor
capacitor
What it sounds like....
Follow this link (or copy and paste
it )to see a video of the siren in
action:
http://physics64748738394.piczo.
com/?cr=3
Siren Circuit Diagram
Measurements (Voltage)
Voltage of entire
system= 6.67 V
While holding the switch When siren is on
(Volts)
(Volts)
1 Meg ohm resistor
5.17
5.09
100 ohm resistor(f4-e8) 0.0469
0.05
100 ohm resistor(f11-e9)0.0469
0.00
100 ohm resistor (j13j22)
0.00
0.00
47 ohm resistor
0.00
0.00
470 ohm resistor
0.249
0.247
100 µf capacitor
(C15-C19)
5.80
3.14
100 µf capacitor
(e10-g20)
0.0844
0.22
.047 µf capacitor
0.651
0.44
220 µf capacitor
1.37
1.27
Measurements (Total Current)
Before pressing the
switch
While pressing the
switch
After pressing the
switch
0.0054 Amps
0.0021 Amps
0.022 Amps
Measurements (Resistance)
Resistance (Ohms) Ω
100 µf capacitor (c15-c19)
230 000 +
100 µf capacitor (e10-g20)
289 000 +
0.047 µf capacitor
94 000 +
220 µf capacitor
122 000 +
Orange jumper
0.9
Blue jumpers
1.1
Yellow jumper
1.0
Brown jumper
1.2
LM 386NIC
17400
Momentary switch
313 000
Transistor
341 000
Paper clips
1.2
* We also worked with
resistors with already
indicated values of 100 Ω,
470 Ω, 47 Ω and 1 Meg Ω
but we must note that the
values could have varied
throughout the process,
depending on their
tolerance.
*the capacitors
would continue to
climb as more
energy was being
stored.
What is an Integrated Circuit?
• An integrated circuit is a miniature electronic circuit.
• It can contain up to billions of electric components- on a
silicon chip.
What does it do?
They are used to enhance/optimize the operation of electronics.
Can function as: an amplifier, oscillator, timer, counter,
computer memory, microprocessor.
1.http://www.sciencedaily.com/articles/i/integrated_circuit.htm
2.http://www.techterms.com/definition/integratedcircuit
How it works(generally):
• It consists of semiconductor devices, and passive components such
as diodes, transistors and microprocessors.
• Diodes-helps the circuit function as they regulate flow in the cicuit.
• Transistors-they help in keeping the voltage stable and can store
voltage for amplification.
• Microprocessors-provides the circuit with memory to follow a set of
given rules.
• Voltage dividers are often used to provide a different voltage than
what is coming from the power source (to provide the
amplification). These dividers are often made through the use of
resistors.
• *Integrated circuits can contain millions of these types of
components.
1.http://en.wikipedia.org/wiki/Integrated_circuit
2.midmarket.techtarget.com/sDefinition/0,,sid183_gci213503,00.html
3.http://www.articlealley.com/article_89315_10.html\
4.http://www.electronics-manufacturers.com/info/circuits-and-processors/integrated-electronic-circuit
html
LM 386NIC
Circuit diagram of the LM386N
specifically
The LM386N specifically:
The LM 386N specifically functions as a low voltage (below 9 V) audio amplifier.
o The "L" in LM386n means "linear". This means that the integrated circuit has
the ability to take in any value and output a different one.
• How it works:
• The gain* is internally set to 20 to
keep external part count low, but the addition of an external
resistor and capacitor between pins 1 and 8 will increase the
gain to any value from 20 to 200.
• The inputs are ground referenced and the output automatically
• chooses to one-half the voltage supply. The power drain is only 24
milliwatts when using a 6 volt supply.
• Refer to the diagram on the previous side to see where the gain,
output, input etc is located.*
*Gain(a measure) refers to the circuit's ability to increase the
power or amplitude from a signal from the input to the
output. When the word "gain" is used, it often refers to the voltage
gain.
• This integrated circuit is very adaptable due to the pins 1
and 8 (we can change the gain)
How?
• 1. If pins 1 and 8 are open, the resistor (1.35KΩ) will set
the gain at 20.
• 2. If a capacitor is put between 1 and 8 and bypassing the
resistor, the gain will go up to 200.
• 3. If a resistor is put in series with the capacitor, the gain
can vary from 20 to 200.
• Other external components can be placed in parallel
• with the internal feedback resistors to modify the gain
and frequency response for individual applications.
http://www.biltek.tubitak.gov.tr/gelisim/elektronik/dosyalar/6/LM386.pdf
http://en.wikipedia.org/wiki/Gain
What are resistors?
In our particular project, we use
resistors with values of 1meg ohm,
100ohm(x3), 470ohm, and 47ohm.
What they do:
• Resistors are used to restrict the flow of electric
current. They have units of ohms (Ω=j*s/c^2).
• They enable us to have multiple components on the same
circuit while using the same power source (without having to
change the voltage), even though the components operate
differently.
1. Zitzewitz, Elliot, Haase, Harper, Herzog, Nelson, Schuler, Zorn
2009. Physics: Principles and Problems. Glencoe/McGaw-Hill.
How they work:
•
Since current is dependent on resistance according to Ohms law of I=V*R,
the resistors are used to change the current of the circuit, or part of the circuit
(the higher the resistance, the lower the current).
• It absorbs some of the electrical energy running through it and releases it as
heat. Removing some of this energy will slow down the current.
• All materials naturally have some sort of resistance, but resistors are often
made of carbon or copper composed material because carbon and copper are
known to have a noticeable resistance against current. It has resistance
because of it's atomic makeup. Depending on a materials atomic strucure,
the electrons can either move easily through them or not. For example, if the
particles in the material are bonded in a way that the electrons inside the
atoms are fully occupied, there are no free electrons to carry and electric
current. This specific example would have high resistance.
http://www.play-hookey.com/dc_theory/components_resistors.html
http://www.explainthatstuff.com/resistors.html
Continued..
The strength of the resistor is dependent on....
1. The length: the longer the resistor, the more resistance it has
since the electrons have that much farther to fight the
resistance.
2. Cross sectional area: the bigger the area, the less resistance
since there is more room for the electrons to flow through
(increasing current).
3.Temperature: the hotter it is, the more resistance there is
because it is harder for electrons to pass the other particles that
are moving quickly.
4. The type of material: different types of material have different
resistances (as already explained).
1. Zitzewitz, Elliot, Haase, Harper, Herzog, Nelson, Schuler, Zorn. 2009. Physics:
Principles and Problems. Glencoe/McGaw-Hill.
The Colors
What is the color code?How does it work?
• Most resistors have four bands of color.
1st band = gives the first digit.
2nd band = gives the second digit.
3rd band = indicates the number of zeros.
4th band = indicates it's tolerance (how close it is to it's actual
noted resistance).
For example....
The yellow band=4
The purple band=7
The brown band= one zero
so...it has a resistance of 470 Ω (one that we specifically used
in our circuit).
http://www.kpsec.freeuk.com/components/resist.htm
What is a breadboard?
• A breadboard is often used to make temporary circuits. No
soldering is needed so connections and components can be
changed easily and quickly.
What does it do?
-It acts as a base for
a temporary circuit. It
allows for connection
between the
components, wires
etc.
http://www.kpsec.freeuk.com/breadb.htm
How does it work?
• It's made up of an insulating material with rows and columns
containing conductive points where the components can be
inserted.
• The terminals of components are inserted into the
breadboard, and into the conductive strips underneath.
• Each terminal goes into a different strip so that there is no
short circuit.
• Connections are made between components when they are
added along the same conductive strip.
• It's on the positive and negative strips (located on the two
outer sides of the board) where the power supply is
connected.
1.http://www.tech-faq.com/breadboard.html
Transistor 2N3503
What it is:
- A transistor is a semiconductor device used to switch
electronic signals and to amplify.
- Made of a solid piece of semiconductor material with three
terminals: an emmiter, a base, and a collector. This is known is
a bipolar junction transistor.
• Can control it's output in proportion to the input signal (amplifier)
• Can also be used to turn current on or off in a circuit (electrically
controlled switch), where the amount of current is determined by other circuit
elements.
2N3503:
• small signal transistor
• Application of transistor- medium power, general purpose
• Central Semiconductor
How it works:
- A voltage or current applied to one
pair of the transistor's terminals
(base, collector, or emmiter) changes
the current flowing through another
pair of terminals.
- By starting at the base, a small
current can control or switch a much
larger current between the collector
and emitter terminals.
Circuit image of a bipolar junction transistor
- Because the output power can be
much more than the input power, the
transistor provides amplication of a
signal. This property is called "gain"
Transistor 2N3053:
Amplifier circuit, common-emitter configuration.
http://en.wikipedia.org/wiki/Transistor
http://www.museumoftechnology.org.uk/nimage
s/A1433_tn.jpg
Different types of capacitors
Capacitors
What is it:
- A device used to store charge in an electrical circuit
- Used in timing circuits because it takes time for a capacitor to fill with
charge.
- Used to smooth varying DC supplies by acting as a reservoir of
charge. They are also used in filter circuits because capacitors easily
pass AC signals but they block DC signals.
-There are many types of capacitors but they can be split into two
groups, polarized and unpolarized
• Electrolytic capacitors are polarized and they must be
connected the correct way round, + or - (ex: the 100uf
capacitor-blue ones we used)
• Small value capacitors are unpolarized and may be connected
either way; high voltage rating (ex: the 470uf and 0.47 uf capacitor
we used)
How it works:
- Two conductive plates, each with a terminal and separated by a nonconductive material called a dielectric. The dielectric can be any nonconductive material that can keep the plates of the capacitor from
touching. The size of the plates and the type and size of the material
determines the capacitance of the capacitor.
- The plates are connected to two terminals that provide for
“communicating” with the rest of the electrical circuit.
- Electrons from the battery enter the capacitor from the “negative”
terminal of the battery
- The capacitor holds the energy and gives up electrons to the
“positive” terminal of the battery. When fully “charged” the capacitor has
the same voltage as the battery it is connected to.
- The energy is then released to be used by the rest of the circuit
Capacitor Diagram:
Measure of Capacitor
• Capacitance: a measure of a capacitor's ability to store
charge.
- A large capacitance means that more charge can be stored.
ex: The 470 uf, 100 uf, and 0.47 uf capacitors used in the circuit all hold
different amounts of charge
Why uf?
- Capacitor electron storing ability is measured in Farads (f).
- One Farad is actually a huge amount of charge
(6,280,000,000,000,000,000 electrons to be exact), so we usually rate
capacitors in microfarads (uF = 0.000,001F)
http://encyclobeamia.solarbotics.net/articles/capacitor.html
http://www.kpsec.freeuk.com/components/capac.htm
http://www.thegeminigeek.com/how-capacitors-work/
http://www.essortment.com/hobbies/electronicsques_sjra.htm
Momentary Switch
What is it?
- An electrical component that can break an electrical
circuit, interrupting the current or diverting it from one conductor
to another.
- Can be both manual (ex. light switch) or automatic ( ex.
stopping of certain machines)
• Momentary: switch returns to its normal position when
released; used to change a circuit only while you are
interacting with it. Ex: doorbell, siren
How it works:
Electrical Contacts:
- can be in one of two states:
either 'closed' meaning the
contacts are touching and
electricity can flow between
them, or 'open', meaning the
contacts are separated and
nonconducting.
Circuit Diagram of Switch
Spring inside the momentary switch
- has a spring holding the
contacts apart. When you
press the button, you
overcome the spring and
press the contacts together,
creating a complete circuit.
http://www.e-f-w.com/community/images/content/snake-eyes_2/se2_spring_switch.jpg
http://en.wikipedia.org/wiki/Switch
http://www.ehow.com/about_6110467_momentary-switch-work_.html
Comet Trails-Science
A comet truly has two trails- one due to the dust particles, and one due to ionized gas
from the comet coma. We will be focusing on the second trail.
• When entering the inner solar system, solar radiation makes materials of the comet
vaporize and leave the nucleus (the head).
• The streams of gas and dust then forms a huge atmosphere around the comet called
the coma.
• The sun's radiation pressure and the solar wind(charged particles around the solar
magnetic field) is what causes this trail to form. These gas molecules are often ripped
apart by solar ultraviolet light, resulting in the loss of electrons and thus
becoming ions.
• The ions are also formed through the solar wind-where a proton removes an electron
from the atom.
• The trail is straight because they ions are initially travelling at a the velocity at which
they were produced. The solar magnetic field then carries them at 10 to 100 km/s,
which makes them travelling straight.
• The trail appears blue because the most common ion formed is CO+, which emits 400
to 460 nm wavelenghts (the blue spectrum).
1.http://www.windows2universe.org/comets/tail.html
2.http://earthsci.org/fossils/space/comets/comet.html
3.http://earthsci.org/fossils/space/comets/comet.html
4.http://en.wikipedia.org/wiki/Comet#Coma_and_tail
Comet Trails-Technology
What technologies are used to study this concept?
• Of course since these comets occur a long ways away from
the earth, scientists use telescopes to observe comets and
their trails.
• A popular telescope used by scientists is the Hubble Space
Telescope:
-It can observe near-ultraviolet so the scientists can observe
the ultraviolet act on the gas from the comet to create the ion
trail.
-It also has a spectrograph which seperates light into it's
component colors (the different wavelenghts). From this, they
are able to tell that the most common ion in a comet trail is
CO+.
-It provides photographs so the scientists are able to study the
length, etc. of the trails.
1. http://hubblesite.org/the_telescope/hubble_essentials/
Comet Trails- Society
History:
• 1577- Tycho Brahe shows that comets were not in the atmosphere, but rather
they were very far away, even further than the moon.
• 1704- Edmund Halley to actually fully explain the way comets work
• 1456, 1531, 1607, and 1682- Documentation of the same comet, known as
Halley's Comet; led to many scientific discoveries concerning comet trails
Society:
• Collisions between comets and planets or moons were common in the early Solar
System
• Many scientists believe that comets hit the Earth 4 billion years ago, which brought
the vast quantities of water that now fill the Earth's oceans
• The detection of organic molecules in comets has led some to believe that comets
may have brought the precursors of life—or even life itself—to Earth
• Comet Trails can be admired by many people
http://burro.astr.cwru.edu/stu/comets.html
http://en.wikipedia.org/wiki/Comet#Collisions
Comet Trails- Environment
Comet Trails have very little effect on the Environment, but the comet
itself can be very destructive
There are many environmental effects from the impact of a comet with the Earth. These
effects depend mainly on:
the characteristics of the asteroid or comet (size, speed,
mass, material composition and strength, trajectory)
o the characteristics of the impact site (land, ice or ocean,
latitude, types of rocks)
o the climatic conditions (stage of ice age, association with
other impacts, seasons - for smaller impacts).
o
Environmental Damage:
• Dust and debris fallout
• Earthquakes, hurricanes and tsunami from impact
• Acid Rain
• Global Greenhouse heating from water and CO2
• Plant growth and extinctions; Global Crop failures which can lead to
food shortage
http://www.windows2universe.org/comets/tail.html
http://news.bbc.co.uk/2/hi/science/nature/8179895.stm
Electric Motors-Science
• An electric motor converts electrical energy into mechanical energy.
• A big part of an electric motor is the use of magnets and magnetism.
• The use of the magnets is what produces the motion of the motor since
opposite charges attract, and like repel (a fundamental law of electricity).
• In the motor, there is a field magnet (permanent) with a North and South end.
• Then there is the armature/rotor (an electromagnet-magnetized by running an
electric current through a wire) with a North end.
• The North end of the field magnet will repel the rotor, while the South end will
attract it, therefore creating that half-turn rotational motion.
• The battery is simply then flipped (the direction of the flow of electrons is
changed) to reverse the magnetic field.
• If this field is reversed at just the right moment at the end of each half turn, the
motor should spin freely.
1.http://www.howstuffworks.com/motor.htm/printable
2.http://electronics.howstuffworks.com/motor4.htm
Electric Motors-Technology
Electric motors are used in many technologies:
1. The split phase electric motor (used for frequent stopping
and starting) is used in fans, blowers and office machines.
2. The capacitor start electric motor (has a capacitor in
series=improved starting torque) is used in compressors,
pumps, air conditioners and conveyors.
Technologies used in the motors:
1.Magnets: an object made from material that is magnetized. It
has it's own constant magnetic field.
-electromagnet= made from a coil of wire that acts as a magnet
as electric current passes through it.
-field magnet=simply provides a magentic field for the electric
motor.
http://sawdustmaking.com/ELECTRIC%20MOTORS/electricmotors.html
http://en.wikipedia.org/wiki/Magnet
http://dictionary.die.net/field%20magnet
Electric Motors-Society
The history behind electric motors:
• 1832- the first direct current electric motor able to turn machinery was
invented by William Sturgeon. The zinc used in it was too expensive for
society, so it was unsuccessful.
• 1873- modern DC motor was made by Zenobe Gramme by accident as he
connected an older invention to a simliar unit, creating a motor. This electric
motor was the first successful in the industry.
• 1886- the first practical DC electric motor was invented by Frank Sprague. It
didn't spark and it would keep constant under variable loads.
• 1888- Nikola Tesla invented the first AC electric motor that was practical to
society.
• Electric motors truly revolutionaized the industry. People no longer had to
rely on using shafts, belts etc.
• Electric motors allowed for ease of use and improved efficiency.
• They replaced human and animal muscle power in the agriculture area as
well. It replaced tasks such as pumping water and handling grain.
1.http://en.wikipedia.org/wiki/Electric_motor#History_and_development
Electric Motors-Environment
Electric motors can be considered "green."
• They are being used in windmills (used to rotate the heads of
windmills 360 degrees to keep the blades in the wind's current) to
power communities.
• They are being used in gate-operated dams (used to open and
close the gates).
• They are being used in powered bicycles to reduce the amount of
driving.
• They are starting to replace internal combustion motors in vehicles
(gasoline engines). This is seen to reduce the amount of CO2
produced.
• This makes electric motors somewhat "green" since they are being
applied to technologies with a "green" motive behind them.
1.http://www.articlepros.com/Science-Technology/Alternative-Energy/article92478.html
2.http://advantage-environment.com/transporter/unique-electric-motor-forbicycles/
3.http://www.howstuffworks.com/electric-car.htm
Monorail Transit Systems- Science
A monorail is a rail-based transportation system based on a
single rail, which acts as its sole support and its guideway.
• powered by electric motors, contact wires or electrified channels
attached to or enclosed in their guidance beams.
• Driving power is transmitted from the driving motor by propeller
shafts via a double reduction gearbox to the wheels.
• Braking is an air operated system in conjunction with dynamic
braking. "Failsafe" mechanisms are in place in case of air pressure
failure.
• The heart of the train's electrical system is the main control
package, which controls all acceleration and deceleration functions
• Trains are powered by 600 volts DC, obtained from contact rails
(positive and negative), running beside the support beam and
picked up by current collector areas installed under the monorail
cars
Monorail Transit Systems- Technology
There are many different systems used in monorails:
Electric Motors-see previous slides
Propeller Shafts- a component for transmitting torque and rotation, usually used
to connect other components of a drive train that cannot be connected directly
because of distance, like the monorail
Reduction Gear- an arrangement by which an input speed can be lowered for a
requirement of slower output speed, with same or more output torque. Used in
ships, monorails, etc.
Air Operation System- the use of air pressure to brake; more efficient vs.
conventional fluid brake systems
Running Gear:
Voltage of traction power supply
Interior power supply
Continuous DC control for motion and braking
Traction motors 4 DC motors/train
Traction motor power
600VDC
24V
4DC motors/train
50kW
Monorail Transit
Technology behind the Monorail System
Monorail Suspension Technology
Monorail Transit Systems- Social
History:
• 1820- The first monorail was made in Russia in by Ivan Elmanov
• 1821- the world's first monorail to carry passengers, as well as the first railway
line to be opened in Hertfordshire
• 1879- a "one-rail" system was proposed independently by Haddon and by
Stringfellow, which used an inverted "/\" rail.
• 1950s- the ALWEG straddle design emerged, followed by an updated
suspended type
• 1960's to 1980's-major monorails were installed at Disneyland in California, in
Florida, Seattle, Japan, and many other locations.
Social Aspect:
• They are quiet, since modern monorails use rubber wheels on a concrete
track, causing minimal distractions
• Not physically capable of derailing, unless the track itself suffers a
catastrophic failure, which is unlikely
• Less expensive to build, resulting in a low impact on the economy
• aesthetically pleasing and a new mode of transportation
Monorail Transit Systems- Environment
Monorails can be classified as "Environmentally Friendly"
• Reduce the foreign fossil fuel that we import from different
countries.
• Reduce CO2 emissions because it is a more efficient
transportation system; non-polluting mechanism because
it produces no exhaust emissions along the route
• Quick construction time and small footprint results in less
disruption to the surrounding environments
• The guide way requires minimal cut and fill, earthwork, or
tunnels, resulting in minimal impact on the natural terrain
• The monorail is whisper quiet, creating no disturbances
http://www.monorails.org/tMspages/TPindex.html
http://en.wikipedia.org/wiki/Monorail
http://www.monorails.org/tmspages/TPAlwpr.html
http://www.brighthub.com/engineering/mechanical/articles/47267.aspx
http://en.wikipedia.org/wiki/Drive_shaft
http://www.meneren.com/projects/transportation/Environment.html
Monorail System still
allows the natural
environment