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Problem Situation
Burglar Alarm Project
PROBLEMSITUATION
An Alarm company is developing a simple low cost security system for use in a new blockof small flats
The pressure mat gives a high (1) output when stood on.
The alarm arm switch is incorporated into the the front door key lock. Locking the doorwill set the alarm giving signal high (1).
A Reed switch and magnet are mounted on the door and frame and gives a low(0)signal when the door is opened
The electronic control sub-system is based on a combinational logic circuit whichoperates the alarm via a transistor
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Design Brief
Burglar Alarm Project
Design an electronic logic control sub-system to process the signal from the
Inputs in order to operate the Alarm buzzer as described above
DESIGNBRIEF
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Systems Approach
Burglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceSelection
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Systems Approach
PROCESSINPUTOUTPUT
Any device or system can be analysed interms of INPUT, PROCESS & OUTPUT
The universal System Diagram
Burglar Alarm Project
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Burglar Alarm Project
The universal System Diagram
Burglar
AlarmINPUT
OUTPUT
A) Arm Key Activated
B) Burglar Through Door
C) Burglar Through Window
Z) SCARY SOUND ENERGY
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The system diagram can be broken down into a subsystem diagram:
Burglar Alarm Project
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A
B
C
ZSCARYSOUNDENERGY
Arm Key Activated
Burglar Thru Door
Burglar ThruWindow
System Boundary
Subsystem
Inputs
Subsystem
Outputs
Process
Subsystems
ReedSwitch N/C
Micro
Switch N/O
PressureSwitch N/O
Inverter OR
AND LATCH DRIVER
BUZZER
Sub System Diagram
Manual Reset
D
Push ButtonN/O
Burglar Alarm Project
System
OUTPUTS
System
INPUTS
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Systems ApproachBurglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceSelection
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Burglar Alarm Project
The System Must:
1) Detect a Burglar entering through the door or the window
2) Enable owner to disable it to go about their businesswithout setting it off
3) It must give a continuous audible warning to deterburglars, and should be reset by owner
4) It should be low cost, reliable and durable
5) Sensor should be unobtrusive
SPECIFICATION
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Systems ApproachBurglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceSelection
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Burglar Alarm Project
SIMULATION LINK
http://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Burglar Alarm Project
SIMULATION LINK
http://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Burglar Alarm Project
SIMULATION LINK
http://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Burglar Alarm Project
SIMULATION LINK
http://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Burglar Alarm Project
A(Arm Key)
B(Reed Switch)
C(Pressure Mat)
Buzzer
0 0 0 0
0 0 1 0
0 1 0 0
0 1 1 0
1 0 0 1
1 0 1 1
1 1 0 0
1 1 1 1 SIMULATION LINK
http://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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Systems ApproachBurglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceSelection
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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MicroSwitch N/O
ReedSwitch N/C
PressureSwitch N/O
Burglar Alarm Project
Selection of Resources
For detecting pressure under mat whenburglar comes through window
For detecting when door is lockedArming the alarm
For detecting when the door is open.(This switch is high when the door is closed)
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Integrated circuits consist of plastic cases filled with electronic circuitry.There are many resistors, transistors and other components packed intothe chips. There are literally thousands of ICs on the market, all designedto do different jobslogic gates, amplifiers, timers, etc.In this work we will be using the TTL (transistortransistor logic) range ofchips.
TTL chips require a stable 5V supply to work properly. (Great difficultieswill be met if any other voltage is used.) Any unconnected pinsautomatically go to logic 1. In other words, if a wire connected to a pinis connected to the 0-volt rail (logic 0), it will go to logic 0. If the wire isdisconnected from the 0-volt rail it will go to logic 1. However, it is good
practice to connect pins to high or low as needed.
All TTL chips have a four-digit code number, which always starts with 74.For example, a 7400 is a quad two-input NAND chip.Although the chip contains complex circuitry, the internal wiring can beshown as simple logic circuits with the inputs and outputs of each logicgate shown. This is called a pin-out diagram.
Burglar Alarm Project
Selection of Resources
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OR (TTL 7432) NOR (TTL 7402)
AND (TTL 7408) INVERTER (TTL 7408)
Burglar Alarm Project
Used to detect when the arm key is activatedAND a burglar is in the system
Used to detect when a burglar comesthrough the Door OR through the window
2 cross coupled Nor Gates make an SRFLIP-FLOP Keeping the output high if a
burglar closes the door or steps off the mat
Inverts out put from N/C reeds switch todetect when Door is open
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Systems ApproachBurglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceSelection
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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DATA ON TTL 74HC04 INVERTER CHIP
Burglar Alarm Project
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DATA ON TTL 74HC32 OR CHIP
Burglar Alarm Project
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DATA ON TTL 74HC08 AND CHIP
Burglar Alarm Project
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DATA ON TTL 74HC02 NOR CHIP
Burglar Alarm Project
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Systems ApproachBurglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceSelection
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt8/10/2019 Electronics - Burglar Alarm Project
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BREAD BOARD
Burglar Alarm Project
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BREAD BOARD
Burglar Alarm Project
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BREAD BOARD
Burglar Alarm Project
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BREAD BOARD
Burglar Alarm Project
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RESET
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Systems ApproachBurglar Alarm Project
PROBLEMSITUATION
DESIGNBRIEF
SYSTEMANALYSIS
SPECIFICATION
SOLUTION
ResourceS l ti
Build & Test
ComputerSimulation
DATA SHEETS
Evaluation
http://e/Simulation1.cythttp://e/Simulation1.cythttp://e/Simulation1.cyt