Laser Tag Group

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Laser TagGroup 3

• Elisa Alfonso
• Navid Nowakhtar
• Jo-Anne Seignoret
• Layne Stein

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Project Objectives and Purpose

• Entertaining project focusing on integration.
• Functional gun and vest units.
• A base unit that keeps track of the score and
  determines the winner.
• Originally rendered audio samples programmed onto
  an audio chip.
• Wireless means of communication between the three
  modules.
• Interconnection of infrared, RF, and digital
  logic technologies.

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Aggregate Specifications

• Powered by 9V DC batteries.
• Vest and Gun per unit weight of less than 5 lbs.
• RF frequency of 433 MHz.
• Infrared transmission frequency of 40 KHz, with
  mitigated divergence of the signal (20 degrees).
• Range of infrared detection (10-25 ft).
• 14 shots prior to reload.
• 10-15s stasis mode after magazine has been
  extinguished.

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Aggregate Features/Functionality

• Team/player differentiation with the use of RF
  addresses.
• Vibration through the inclusion of small electric
  motors in the vest unit.
• Timed blinking lighting effects on the vest unit.

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Power Subsystem

• Administered by
• Elisa Alfonso

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Voltage Regulation

• Implemented a 9 volt battery and an LM7805
  regulator to control the voltage supply to each
  individual component.
• Almost all chips function at a 5 volt input (RF
  receiver).

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Voltage Drop
 

• A 9 volt battery has a life span of 500 mAh.
• Each separate module will be operated with a
  single 9V volt battery, allowing for a reasonable
  performance interval for the game.
• Battery operation times will vary, but will be
  within a stable confidence interval.

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RF Subsystem

• Administered By
• Navid Nowakhtar

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Transmitter/Receiver Requirements

• Power requirements less than or equal to 5V.
• Built-in encoder/decoder.
• Mitigated external interference.
• FCC approved frequency.
• Reception distance of 100 ft, indoor/outdoor
  fidelity.
• Direct PCB Mounting.
• Low Price under 10/unit.

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KH Series by LINX

• On-Board Encoder(TX)\Decoder(RX)
• 8 Parallel Lines Allow Direct Interface
• 310 Addresses for Security and Uniqueness
• No External RF Components Required
• Ultra-Low Power Consumption
• Compact Surface-Mount Package
• No Production Tuning
• 433 MHz (FCC approved frequency)
• 10.00 Transmitter/16.00 Receiver

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KH Series Transmitter

• Two major advantages over LC Series built-in
  encoder, and signal differentiation with address
  lines.
• Transmit enable line enables the on board encoder
  IC.
• Encoder detects logic states of data address
  lines, and formats a three word transmission
  cycle.
• Encoder creates a serial data packet that is used
  to modulate the KH transmitter.

Pin Layout of KH Series transmitter Courtesy of
LINX Technologies
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KH Series Receiver

• Built-in decoder, which translates transmitted
  signal.
• Address bits are checked against address settings
  of the receiving device.
• Once a match is confirmed, decoders output is
  set to replicate transmitter's button status.
• Design advantage only one receiver module
  required.

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Antenna Requirements

• Made for operation at desired frequency of 433
  MHz.
• No external RF components required to integrate
  antenna into modules.
• Direct PCB mounting.
• Price of under 3/unit.

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Antenna Alternatives

• Planar
• Loop

• Whip
• Helical

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Antenna Integration

• Chose planar antenna by LINX.
• Specifically designed for chosen
  transmitter/receiver.
• Performed well in testing.
• Disadvantage surface mount, required precise
  soldering to create successful PCB board.

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Audio Subsystem

• Administered By
• Layne Stein

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Sound Chip Requirements

• 5V Power Supply.
• Ability to program multiple sounds on one chip.
• Moderate quality audio reproduction.
• Audio input for homemade sounds.
• 10-12 seconds of recordable audio time.
• Direct PCB mounting.
• Memory recall without power.
• Low Price under 10/chip.

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Sound Chip Sample Rate-number of samples of a
sound that are taken per second to represent the
event digitally.
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Sound Chip

• Winbond ISD1212
• 5 KHz sample rate determined to be adequate for
  our purposes.

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Chip Design/Operation

• Recorded homemade (44.1kHz at 24 bit) sounds and
  edited them using Protools digital audio
  workstation.
• Edited existing sounds taken from internet.
• Used an analog connection from the Protools sound
  card output to the sound chip input.
• The binary position on the address pins A0-A7
  correspond to a place in time in the memory of
  the chip.
• Each sample recorded at a certain address must be
  played at that same address.

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Chip Sample Sound Table
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Record Mode
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Play Mode
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Speaker Requirements

• Impedance of 8/16 Ohms.
• Typical output of 12.2 mW.
• Manageable weight
• Small in size (less than 2 in diameter and 1 in
  depth.)
• Under 5/speaker cost.

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Speaker Selection

• Vest/Base
• GA0506
• 2 inches diameter
• 8 Ohms
• .5 Watt
• Gun
• GC0251K
• 14mm x 25mm
• 8 Ohms
• 1 Watt

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LM386 Amplifier Implementation

• Used on the vest, base, and gun units.
• Applied a voltage gain of 20 to all units.

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Amplifier/Sound Chip Schematic
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Infrared Subsystem

• Administered By
• Elisa Alfonso

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Infrared Emission Requirements

• Transmission frequency of 40 KHz.
• High-Power, long-range infrared emission.
• Straightforward modulation technique for
  obtaining required frequency.
• Very small to negligible divergence of infrared
  beam angle (i.e. small convergence angle).

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TSAL 7200, High Output, Long-Range Infrared LED

• 17 degree beam angle (great mitigation of beam
  divergence).
• Removes the need for lenses
• Wavelength of 940 nm.
• Compact (5mm in length).
• Very inexpensive 0.65 per LED.
• Perfect match for our chosen IC transmitter and
  detection module.

Courtesy of Rentron Electronics.
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IC Transmitter Advantages

• Can easily emit at desired frequency no external
  components required.
• Instant compatibility with 40 KHz detection
  modules.
• Relatively low cost compared to reliability of
  transmission.

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TX-IR 38/40 KHz Infrared Remote Control IC

• 8- Pin PIC microcontroller custom programmed as
  an infrared transmitter IC.
• Designed for infrared remote control
  applications.
• Can choose between 38 or 40 KHz by pin values.
• True or inverted serial input modes.
• Relatively low cost 6 per unit.

Courtesy of Rentron Electronics.
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TSOP1140 Infrared Detection Module

• Visible Cutoff resin that helps to eliminate
  interference from visible light sources.
• No external components requiredremoves the 40
  KHz carrier and outputs data directly.
• Low Cost 3 per unit.

Courtesy of Rentron Electronics.
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Transmitter Circuit
Courtesy of Rentron Electronics
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Receiver Circuit
Courtesy of Rentron Electronics
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555 Timer Circuits and Other Digital Logic

• Administered By
• Jo-Anne Seignoret

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555 Timer Stasis Circuit

• Monostable operation
• Used for when magazine is depleted.
• Instead of automatic reload, user must hold/pulse
  the guns reload button for 12s (within
  tolerance) to regain ammo.
• Simulative of a futuristic laser architecture.

Taken from www.andy-clarkson.me.uk/555/delay.html
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555 Stasis Interconnect
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555 Timer Regulating Circuit

• Provides a pulse for a specified time interval.
• Used in the gun module as the trigger control.
• Used in the vest to control the electric motor,
  and to control the RF transmitter.

Taken from http//www.andy-clarkson.me.uk/555/mono
.html
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555 Regulation Interconnect
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Astable Oscillating Circuit

• Used a 555 to build an astable circuit to control
  the pattern of LEDs on the vest modules.
• It oscillates with an
• Output high at t651.42 ms
• Output low at t325.71 ms
• Output frequency of 1.02 Hz
• Used in accord with an inverter to create a
  blinking led circuit.

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CD74HCT153E Binary Counter/7 Segment LED Driver

• CD74HCT153E Used to keep track of the amount of
  times the gun has been fired, and also tracks the
  number of hits for each player for the base unit.
• CD74HCT153E replaced the 74AC161, which was
  extremely unreliable in testing and caused a
  delay in integration.
• CD4511BC LED driver successfully tested by manual
  drive, and then integrated with a fully
  functional binary counter.

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Counter to Emitter
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Counter to Driver
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PCB Milling

• Administered By
• Jo-Anne Seignoret

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PCB Milling/Prototyping Issues

• Double sided PCB boards for all three modules.
• Connected the top and bottom layers of copper
  with the use of through-hole via pins.
• Added considerable cost to each module, as via
  supply was assumed to be provided.

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Prototype Casing

• Wanted a protective yet aesthetically pleasing
  casing.
• Casing made of lexan, which is protective but
  allows for good interaction with the prototype.

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Final Implementation Hurdles

• Two part process of inceptive schematic
  transformation into IsoPro was unexpectedly
  tedious and time consumingthis was a big
  learning experience for the group with respect to
  milestone management.
• Precision of surface mounted soldering called for
  additional patience and care.
• Resource projections constantly adjusted ad hoc,
  resulting in intermittent parts acquisition
  needs.

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Possible Improvements

• Use of a demultiplexer as opposed to a diode
  interconnect to feed the proper addresses to the
  ISD sound chip.
• Using relays to increase the size of the
  vibrating motors, which are hindered by the
  amount of current flowing through our chips.
• Encoder/decoder for infrared emission to further
  decrease infrared interference, and to serve as a
  second method of team differentiation.

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Administrative Content

• Administered By
• Navid Nowakhtar

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Project Budget
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Laser Tag Tips
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Laser Tag Tip 3

• When starting laser tag, maintain a foothold on
  the vest, preferably close to your chest area.

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Laser Tag Tip 2

• Hold gun over shoulder to achieve optimum aim.

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Laser Tag Tip 1

• Always have fun with laser tag!!!!!

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