A Safe

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A Safe Environment
Thematic Brief
A Door-Bell / Security System for the Partial
Hearing
Ordinary Level
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Theme A Safe Environment
There is an increased awareness of the importance
of safety in the home for both adults and
children. Items such as personal alarms, child
locks, burglar alarms, warning devices,
temperature alarms etc. help to create a safer
environment. Design Brief With reference to
the above theme, design and make a device that
will improve personal safety in the home. The
device must incorporate a mechanical or
electrical or electronic system.
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Theme A Safe Environment

• There is an increased awareness of the importance
  of safety in the home for both adults and
  children. Items such as personal alarms, child
  locks, burglar alarms, warning devices,
  temperature alarms etc. help to create a safer
  environment.
• Design Brief
• With reference to the above theme, design and
  make a device that will improve personal safety
  in the home. The device must incorporate a
  mechanical or electrical or electronic system.
• I have decided to carry out some research on the
  following topics
• Personal Alarms
• Burglar Alarms
• Child Locks

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(1) Analysis, Research Investigation
Safety Concerns for!
Elderly
Children
Fire!
Security!
Handicapped
Single People
I have decided to focus on the handicapped
environment!
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(1) Analysis, Research Investigation
Safety Concerns for!
Elderly
Hearing Disability
Handicapped
Visually Impaired
Wheelchair Bound
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(1) Analysis, Research Investigation

• Associated Problems
• awareness of caller - door bell / knocking!
• telephone ringing
• television / radio
• cooker alarm
• smoke alarm
• intruder
• dog barking

I have decided to investigate a visual/vibrating
indicator to indicate to the impaired hearing
that someone is at the door.
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(1) Analysis, Research Investigation

• I have decided to carry out some research on the
  following areas
• Personal Alarms
• Burglar Alarms
• Warning / Signalling Device

The number of personal attacks particularly on
the elderly and young women is quite frightening
in today's society. Therefore there is a need
for some type of small convenient device that
could be easily carried, triggered with ease and
would send out a loud audible tone to catch the
attention of passers-by!
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(1) Analysis, Research Investigation
A Domestic Burglar Alarm The idea of an intruder
alarm is to simply try and deter a potential
burglary occurring at your premises, and to an
extent research shows that it works. A burglar
does not want any attention his/her aim is to
access the property with as little fuss as
possible. If the alarm system is triggered or
activated a loud sound attracts
attention! Warning Device I may consider
researching some type of warning or signalling
devices such as hazzard lights safety
tractors, cycling, walking etc. or a device to
aid the handicapped?
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(1) Analysis, Research Investigation
Design 1 Existing Solutions This alarm is
designed to be worn around the neck or strapped
to the wrist for convenience. It is very
compact, small in size and quite robust. The
casing is made from ABS, nylon etc, and the
manufacturing process is probably injection
moulded however this shape could be easily made
using the school vacuum forming machine and using
rigid polystyrene plastic. The shape or design is
quite simplistic and uninspiring. Design 2
Existing Solutions This personal attack alarm
opposite also performs exactly the same function
producing a high pitched sound dB120 for a short
time warning off an attacker or an alarm! I like
the relief detail that I feel enhances the visual
impact!
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(1) Analysis, Research Investigation

Design 3 Existing Solutions Specification
(must dos) Compact, lightweight, plastic casing,
robust, aesthetically pleasing, relatively low
cost etc.. This alarm is designed to activate
when the cord is pulled. The cord is easily
accessible. The cylindrical shape lends itself
to accommodate the round batteries. This design
is very small and probably quite comfortable to
wear around the neck. The wearer can be assured
that the device is always readily at hand and
not left in the handbag or in the car!
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(1) Analysis, Research Investigation
A Domestic Burglar Alarm
This diagram shows the different locating zones
in and around the home for the many different
alarm devices that could be fitted to help
provide better security sensors, motion
detectors, monitor
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(1) Analysis, research investigation - existing
products
An existing product in the market place The Evo
D413 is a wireless door bell/flasher system for
use throughout the home and garden. The bell push
is fitted to your door like any conventional door
bell, but the chime/flasher unit is wireless
making it fully portable up to a range of 200
metres. This system is also designed with the
hard of hearing in mind with a flashing light
built in for use instead of the chime. I like
the range that this device provides however the
LED light output may be difficult to see and the
circuit appears to be quite complex!
Evo D413 Wireless Flashing Door Bell Kit for the
hard of hearing
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(1) Design Specification Door-Bell / Security
Type of device will require either something
flashing or moving? Some type of Mechanical or
Electronic system. My Design Brief My
intention is to design and manufacture a device
which will signal to a partial hearing person
that someone is at the door. I also wish to
include a security alarm that indicates an
intruder has entered the property.
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(1) Design Specification Door-Bell / Security

• Design Specification
• the device should be operated by a standard
  door-bell push button
• when the button is pressed the device should
  continue to operate for
• a minimum of 10 -15 seconds
• the visual output signal must be easily seen
  indicating someone at the door
• a visual signal must indicate should an intruder
  enter the house
• if the device is operated by electronics it
  should be powered by low voltage d.c. (less
  than 12V)
• the device should be easily manufactured in the
  school workshop
• the product should be attractive, easily serviced
  and maintained
• the product should be strong and withstand sudden
  shocks.

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(1) Design Specification Door-Bell / Security

• Design Specification continued
• the product / device should hold a TV remote
  control
• the unit should be compact, stable and match the
  room surroundings
• the product should be environmental friendly.

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(2) Project Management
Proposed Timeframe - Time - 49 class periods
to complete the portfolio manufacture
the product
Budget - I have estimated that 10 euro should
cover the total production costs However my
research will be helpful when costing materials
and my chosen design may also impact on the final
cost.
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Circuit 1 Systems Design Ideas

• Pros
• a very simple circuit which provides
• oscillating sound and flashing light / LED
• Cons
• operator might only press the door button
  momentarily
• Needs to sound and flash for at least 10
• seconds

A very basic electronic circuit design
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Circuit 2 systems design ideas

• Pros
• a very simple latching circuit which uses a
  relay to create a latch
• Light will continue to flash until the door is
  opened (SW 2)
• No electricity is used until the switch (SW1) is
  pressed
• Cons
• when no one at home light will continue to flash
  and sound - power wastage
• Relays can stick over a period of time

A basic electronic circuit design
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Circuit 3 systems design ideas

• Pros
• a simple latching circuit using a thyristor
• Light will continue to operate until the door is
  opened (SW 2)
• This circuit design is more reliable than a relay
• Cons
• when no one at home light will remain on wasting
  battery power.

A basic electronic circuit design
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Circuit 4 systems design ideas

• Pros
• this basic circuit design uses a capacitor to
  keep the light flashing for approximately 10
  seconds
• Cons
• capacitor timing tends to be inaccurate
• slight current drain through LED and transistor.

A basic electronic timer circuit design
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Circuit 5 systems design ideas

• Pros
• this circuit design uses a 555 IC timer to keep
  the light on for approximately 10 seconds
• Cons
• A constant on light is not as noticeable as a
  flashing one
• slight current drain through 555 IC

An electronic (555) IC in Monostable mode
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Circuit 7 systems design ideas

• Pros
• this circuit design uses two 555 timers to keep
  the light flashing and buzzer sounding for
  approximately 10 seconds
• Button only needs pressed momentarily to activate
  cycle
• Cons
• slight current drain through 555 IC

Completed real view PCB
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Circuit 6 systems design ideas

• Pros
• this circuit design uses a 555 IC timer to keep
  the light and buzzer on for approximately 10
  seconds
• Cons
• A constant on light is not as noticeable as a
  flashing one
• slight current drain through 555 IC

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Circuit 5 systems design ideas
This circuit provides a delayed visual indication
when a door bell switch is pressed. In addition,
a DPDT switch can be moved from within the house
which will light a lamp in the door bell switch.
The lamp can illuminate the words "Please Wait"
for anyone with walking difficulties.
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Circuit 4 systems design ideas

• This circuit also satisfies the conditions for
  the security / door bell situation-
• SW 2 on LED D1 flashes
• capacitor charges and provides current to the
  LED for approximately
• 15 seconds
• If SW 3 micro / proximity switch (fitted into
  the door) is activated D2
• flashing LED indicated an intruder has entered.

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Circuit 5 optimum electronics systems design

• This circuit also satisfies the conditions for
  the security / door bell situation-
• SW 1 on and SW 3 door bell on Bulb BL1 on
• thyristor latches keeping BL1 on indicating
  someone at the door
• SW4 pressed BL1 off current by-passes
  thyristor switching this
• component to its insulating state
• If SW 2 micro / proximity switch (fitted into
  the door) is activated D3
• flashing LED indicates that an intruder has
  entered.

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Circuit 5 optimum electronics systems design
PCB converted using Circuit Wizard
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(3) Design Ideas Security / Door Bell Indicator

• Location of unit?
• Near the TV as this would be central in the room?
  The casing should also be a
• decorative unit / product
• Worn on body would be ideal but this would
  require infrared / radio which is too complex an
• electronic system.
• My Design Brief
• My intention is to design and manufacture a
  device which will signal to a partial hearing
• person that someone is at the door. I have
  decided to design the systems casing or
• housing as a TV remote control holder or stand as
  this often is in a convenient location
• and easily seen in the living room. An output
  light will indicate when someone is at the
• door. I also intend to design some type of
  security alarm to indicate that an intruder has
• entered the house.

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(3) Design Ideas Security / Door Bell Indicator
Location of unit Near the TV as this would be
central in the room?
Caller calls at the door and rings bell
The unit is placed near the TV In a central
location.
a) A flashing light signal indicates that
someone Is at the door b) A flashing light of a
different colour flashes if an intruder enters
the house.
A TV remote holder/stand Could be duel purpose?
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(3) Design Ideas Security / Door Bell Indicator
Location?
Alarm!! An intruder has entered
Someone at the door
I feel the best location for this product is near
the TV which tends to be the focal point in the
living room.
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Concepts Early Ideas Casing Design
supporting the TV remote control
Side view end view
Some type of stand made from acrylic plastic?
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Concepts Early Ideas Casing Design
supporting the TV remote control
Gouging from a solid piece Of wood
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Concept 1 Early Ideas Casing Design
Holder for the TV remote control
Designing from a solid block of wood
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Concept 1 Solid Modelled - 3D CAD
Casing made from solid beech This design could be
manufactured using the CNC. Access for the
battery pcb will must be considered!
I may decide to manufacture this design Using
the
press-mould method.
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Concept 2 Solid Modelled - 3D CAD
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Concept 2 Solid Modelled - 3D CAD
The remote control sits on the acrylic rest the
large LED provides the flashing output when
someone rings the door bell.
I drew my inspiration from the shape / profile
of the remote control.
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Concept 3 Solid Modelled - 3D CAD
This a simplistic casing design that may be
vacuum formed or press moulded. The remote
control is located in the recess.
LED light output
Inspiration taken from !!!
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(3) Selection of Optimum Solution / justification
Justification I have selected this design as it
satisfies all the points raised in my
specification- the device should be operated by
a standard door-bell push button My electronic
circuit demonstrates that when the door is forced
open or when the door bell is pushed flashing
light/s provide a signal to the user when the
button is pressed the device should continue to
operate for a minimum of 10 seconds The
capacitor in my circuit acts like a battery and
provides current to flow to the output for a
required time the visual output signal must be
easily seen indicating someone at the door I
have inserted flashing LEDs into the TV remote
control and I find they are easy to see
particularly when placed on the TV remote stand
centrally in the room
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(3) Selection of Optimum Solution / justification
a visual signal must indicate should an intruder
enter the house When an intruder forces the
door open the proximity or micro switch / magnet
in the door holding the switch open is released
and makes contact bring the circuit on flashing
LED on if the device is operated by
electronics it should be powered by low voltage
d.c. (less than 12V) The device is powered by
a d.c. 12V battery the device should be easily
manufactured in the school workshop All the
making process using acrylic plastic such as
drilling, filing, bending, gluing etc can be
carried out in the workshop the product should
be attractive, easily serviced and maintained I
feel the product looks good because of the
contemporary design and the colourful acrylic
material and I also feel it fits into the
domestic environment quite well.
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Concept 3 sketch development
I will require some type of robust stand and
base to house the remote securely?
Some type of fabricated housing would conceal the
battery and pcb and add stability?
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Concept sketch development
I like the idea of a housing so I have designed
this simplistic shape. I have used a cylinder cut
and faced on the centre lathe and sawn in two for
the semi-circular end and glued this to the
formed u shape. This part is transparent so
that the pcb and battery are visible. I thick
this will provide a modern look!
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3D CAD Solid Model of my chosen design
assembled view
exploded view
Optimum Solution
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Optimum Solution
Partial Hearing / Security Door Bell Indicator
master / re-set switch
Manufacturing
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(4) Working Drawings
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(4) Working Drawings
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(4) Working Drawings
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Materials Production Planning
Manufacturing Processes Time approx,
1 Manufacture of pcb by chemical bath or CNC - surface machining Class periods 1
2 Assembly soldering of pcb / testing 1-2
3 CAD drawings of former/mould design (not a manufacturing process) 3
4 CNC Manufacture of former 1
5 Hand finishing/sanding of former 1-2
6 Vacuum forming of former 1
7 Manufacture of bezel for split mould 1-2
8 Assembly of casing 1
9 Testing the finished product 1
10 Evaluations write-up!

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Materials Production Planning
Part Materials Processes
1 Base Acrylic / plastic / fabrication
2 Collar Acrylic / plastic / fabrication
3 Top Acrylic / plastic / fabrication
4 Stand Acrylic / plastic / fabrication
5
6
7 pcb Copper clad board
8 Pcb mount
9 LEDs 3 x 5mm LEDs
10 PPP 3 Battery PPP 3 Battery
11 Liquid solvent cement
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Environmental Impact
As I stated earlier the material that I intend
using for my housing design is acrylic plastic.
Plastics are made from oil which is a fossil fuel
and unfortunately as the price of oil increases
then so will the cost of plastics. Another
disadvantage of this type of plastics is that
acrylic is not biodegradable and therefore
plastic takes many years to disintegrate.
However many types of plastics can be recycled
and have alternative uses. Sign makers use
acrylic because it is easily to machine, is
lightweight and does not corrode. Off-cuts can be
used for school projects. An alternative
material would have been wood which I had thought
of. Certain types of wood can look well and
could easily blend in with domestic surroundings.
Wood can also be recycled, reused for heating
and is biodegradable.
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Production Realisation
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Evaluation critical reflection
I was quite pleased with the visual appearance of
the finished model and I enjoyed making the
product. However I feel I am now just ready to
start all over again and do a better job! My
research materials helped me and the reference
materials I collected inspired the final design.
Google images is great for looking at other ideas
/ existing products particularly of TV remote
control holders. I also researched mobile phone
holders to get ideas. The acrylic plastic was
quite easy to cut, file, glue and polish and
overall I had no problems using this material.
Fortunately no finishing was required on this
material just polishing the edges on the buff.
The liquid solvent cement was clean and easy to
use in the assembly of the stand.
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Evaluation critical reflection
My teacher showed me how to use the burette
opposite which applies the liquid solvent cement
precisely. Bending the acrylic was also quite
easy I used the hot wire bending machine for
sharp bends and the strip heater for the larger
radii. I struggled with my time management
despite having a plan. If I was involved in a
major project like this again I would plan my
time better!! In the future the TV may be
developed to include some type of house security
indicator providing a signal when an intruder has
enter the property?
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Location Partial Hearing / Security / Door Bell
Indicator
TV remote control holder / plus a security alarm
and door-bell indicator.
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Alternative Solution Idea 2
Partial Hearing / Security Door Bell Indicator
Idea 2
Manufacturing
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Alternative Solution Idea 3
Partial Hearing / Security Door Bell Indicator
Idea 3
Manufacturing
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Research Partial Hearing Door Bell
Indicator - House Security!
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Analysis, research investigation - existing
products
www.deaf.ie/IDSinfo/Deaftech.htm
www.kimododreams.com/lette/?cat6 http//www.mi
tedu.freeserve.co.uk/Circuits/Misc/deafdoorbell.ht
m www.homecontrols.com/.../pgrfnbr/503/sesent/00
answers.yahoo.com/question/index?qid20070528..
http//www.angelfire.com/co3/NCFS/science/dangerou
sdecibels.html
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