Coil Gun Project

1
Coil Gun Project
David Weaver Wonderful start. Some things to
fix, however

• By
• Carly Davis, Daniel Martell, Steve Brown, And Joe
  Kempton
• (Team-The Ligers)

2
Parts Placement (Front)

• FL-Flash Lamp
• S1-Charge Switch
• S2-Shutter Contacts
• C2-Main Capacitor
• (-)()-Battery Contacts

3
Parts Placement (Back)

• T1-Step Up Transformer
• T2-Trigger Coil
• NE-Neon Indicator Lamp
• FL-Flash Lamp
• Q1, Q2, Q3-Transistors
• R1, R2, R3-Resistors
• C1, C2, C3- Capacitors
• D1 D2- Diodes

4
Schematic
5
Phase 1- Charge
David Weaver Voltage doesnt flow. Got the
Ohms Law kinda of messed up too. Think I V/R

• Pushing the charge switch, this starts Phase 1 by
  allowing a voltage from the battery to flow
  through a conductor that is directly proportional
  to the electric current and inversely
  proportional to that conductors resistance. This
  links back to Ohms Law.
• The current and magnetic current from the
  inductor coil create an oscillator that flows
  into the transistor.
• After the transistor collects the electrical
  energy, it then sends it over to the transformer
  for amplification.
• The inductors within the transformer increases
  the voltage and then sends into the capacitor. To
  keep the energy from escaping, the energy flows
  through a diode before it gets to the capacitor.
• Once the capacitor is fully charged, the charge
  phase is over and the indicator light has now
  turned on.
• We are now ready for Phase 2- Discharge

David Weaver What is magnetic current.
David Weaver What does this mean?
David Weaver Need more detail of how the
oscillator works, Lenzs Laws role, etc.
6
Phase 2- Discharge

• This phase is initiated after the flash lamp on
  the switchboard is illuminated, signifying that
  the capacitor is charged.
• As the flash button is compressed the capacitor
  joins the second transformer which intensifies
  the voltage of the current.
• Because of Faradays Law the voltage increases,
  caused by a changing magnetic field. (see slide
  13 for details)
• Faradays Law is an exact predecessor of Lenzs
  Law, which initiates the Launch phase

David Weaver What does this mean?
David Weaver Your slides arent numbered Turn
this into a link so readers can go there if they
want to???
7
Phase 3- Launch
David Weaver What?

• The current it creates, produces its own magnetic
  field that opposes the change in magnetic flux
  through the coil which repels the BB from the
  coil and barrel.
• Lenzs Law account for the Launch phase (see
  slide 13)

David Weaver I dont quite get this
David Weaver Dont tease me, tell me!
8
Key Terms and Definitions

• Charge- An excess or deficiency of electrons.
• Current- The direction in which positive charges
  would flow.
• Conductor- A material or object that permits an
  electric current to flow easily.
• Insulator- A material that is a poor conductor.
• Semiconductor- Any of a class of solids whose
  electrical conductivity is between that of a
  conductor and that of an insulator.
• Resistor- A device that has electrical resistance
  and that is used in an electric circuit for
  protection, operation, or current control.
• Capacitor- Consists of two oppositely charged
  plates. Used to store energy.
• Battery- Converts stored chemical potential
  energy into electrical energy.
• Electrical Potential- The potential unit of
  charge associated with electric field. Usually
  measured in Volts

David Weaver As I said in the syllabus Your
goal is to show how the topics apply to your
project, you are not to define the term or give
some theoretical description of it. Assume that
your audience knows what the topic is, you just
need to show how it applies to your project.
9
Key Terms and Definitions Contd
David Weaver Ditto

• Ohms Law- The voltage drop from one point to a
  second point of a device capable of conducting
  electricity are proportional at a given
  temperature.
• Coulombs Law, indicates the magnitude and
  direction of electrostatic force that one
  stationary, electrically charged object exerts on
  another.
• Inductance is a measure of the amount of magnetic
  flux produced for a given electric current.
• Voltage, or the potential difference across a
  conductor when a current is passed through, is a
  measure of the strength of an electrical source.
• Resistance- A measurement of the degree to which
  an object opposes the passage of an electric
  current. The unit of measure for resistance is
  the Ohm.

10
Key Terms and Definitions Contd
David Weaver Ditto the ditto

• Electric Field- The electric force per unit
  change.
• When a magnetic field moves through a metal
  conductor, electrons are dislodged from their
  orbits. The difference between the charges in
  the conductor is equal to voltage.

11
The Importance of Inductors
David Weaver Inductors dont generate magnetic
fields, moving charge does. Coils concentrate
the mag field.

• Description
• Inductors are coiled lengths of wire that store
  up energy by generating magnetic fields
• An inductor can store energy in its magnetic
  field, and resist any change in the amount of
  current flowing through it.
• An inductor is an electromagnet

• How they work
• A fluctuating magnetic field, generated by
  fluctuating electric current, will cause a
  voltage change in a conductor.
• This is the boost, or initial current, that
  allows out coil-gun to function.
• The transformer in our circuit is made up of 2
  inductors, this is where the voltage from the
  battery is amplified
• This intense current provides energy to the
  various components of the circuit

David Weaver Huh?
David Weaver Why do they resist change?
David Weaver We boost the voltage but reduce the
current by and equivalent amount.
12
Magnetism vs. Electromagnetism
David Weaver No need to define

• Magnetism
• Permanent
• Law of Poles like magnetic poles repel each
  other, unlike magnetic poles attract each other
  (North and South)
• Electromagnetism
• Temporary, needs a source of power
• The interactions between electronically charged
  particles and magnetic fields (electron flow from
  negative to positive)
• 
  Circular, perpendicular
• 
  magnetic field
• The electrical current passing through the
  magnetic wire from the inductor will generate a
  magnetic field, via electromagnetism.

David Weaver There is NO interaction between
electrically (not electronically) charged
particles and magnetic fields. Charges interact
with charges and magnets with magnets.
13
Ode to the Laws
David Weaver If you can use the math, do so. If
not, then dont.

A moving magnetic field is necessary in order for
electromagnetic induction to occur. (phase 2)

• Faradays Law of Induction
• The emf induced in a coil depends on the time
  rate of change of the number of magnetic fields
  through all the loops
• or
• Lenzs Law
• An induced emf in a coil has a direction, or
  polarity, such that the current it creates
  produces its own magnetic field that opposes the
  change in magnetic flux through that coil.
• Amperes Law
• The sum over elements of the component of the
  magnetic field along the direction of the
  element, times the element length, is
  proportional to the current that passes through
  the loop
• or

David Weaver Need a bit more detail here
The induced current produced in the conductor
always flows in a direction so that it opposes
the change that is producing it. This is the
force that actually pushes the bb out of the
straw. (phase 3)
David Weaver What is emf?
Describes all of the ways that electrical current
can make magnetic fields. This is the magnetic
field that is created inside the straw of our
gun. (phase 1)
14
Graphical Analysis

I(A)
(V)
Time (ms)
Time (ms)
A Voltage (V) vs. Time (ms) graph shows that over
time the voltage is increased. Especially after
it crosses the second transformer. Then it
decreases after the Capacitor is Discharged The
current, I(A) vs. Time (ms) graph would show that
due to increased resistance over time the current
does go down.
David Weaver Why does the resistance increase?
15
Conclusion

• In the end, the whole experiment gave the group
  an application in which laws, theories, and terms
  could be applied to.
• Overall, this project was a fun experience.

16
Works Cited

• www.jeffhove.com
• www.howstuffworks.com
• www.coilgun.org
• www.wikipedia.org
• www.dictionary.com
• Wilson, Jerry D., and Anthony J. Buffa. College
  Physics. 5th ed. Vol. 2. New Jersey Pearson
  Education, Inc., 2003. 513-991.