Prepare a Design Specification Engineering Design By Brendan Burr
Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Table of Contents TABLE OF CONTENTS..... ........... ........... ........... ........... ......... ........ ....... ....... ....... ....... ........ ....... ...... ... 2 TASK 1...... ............ ........... ........... ........... .......... ........... ........... ........... ........... ........... ............ ........... ........... ........ ..3 Create a list of all the identifiable customer requirements for your chosen design. These customer customer requirements requirements should be drawn up into a simple Product Design Specification (PDS) or a User Requirement Specification Specifi cation (URS)..... ....... ....... ....... ....... ........ ....... ...... ..... .. 3 Solution:Solutio n:-.................................................. ............................................................... ........................ ...................... ............... ....3 3 TASK 2...... ............ ........... ........... ........... .......... ........... ........... ........... ........... ........... ............ ........... ........... ........ ..4 Determi ne the major Determine maj or design desi gn parameters. paramet ers...... ........... ........... ........... ........... ........ ... 4 Solution:Solutio n:-.................................................. ............................................................... ........................ ...................... ............... ....4 4 TASK 3...... ............ ........... ........... ........... .......... ........... ........... ........... ........... ........... ............ ........... ........... ........ ..8 Using appropriate reference sources such as catalogues, internet, books, etc obtain information on the design technology. Identify the techniques and technology required required in the manufacturing of your chosen product and similar products etc. Identify any relevant relevant standards that need to be applied for example BS safety standards for mains electricity etc............................................. ................................................... .............. .............. .............. ............... ............ .... 8 Solution:Solutio n:-.................................................. ............................................................... ........................ ...................... ............... ....8 8 TASK 4...... ............ ........... ........... ........... .......... ........... ........... ........... ........... ........... ............ .......... ........ ....... ... 10 Ensure that the design specification meets the customer requirements. ........................................... .................................... ............... ............... .............. .........10 Solution:Solutio n:-............................................ ............................................................ ........................... ..................... ................ ......10 10 CONCLUSION CONCLUSIO N..... ........... ............ ........... ........... ........... .......... ........... ........... .......... ......... ....... ....... ........ .... 11 Books............................................. .................................................... .............. .............. .............. ............. ...... 12 Catalogues Catal ogues..... ........... ............ ........... ........... ........... .......... ........... ........... ........... ........... ......... ........ ....... .....12 Websites Websit es..... ........... ........... ........... ........... .......... ........... ........... ........... ........... .......... ........... ........... ......... ......12
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BTEC Higher National Certificate in Electronics
Brendan Burr
Engineering Design
Task 1 Create a list of all the identifiable i dentifiable customer requirements for your chosen design. These customer customer requirements should be drawn up into a simple Product Design Specification (PDS) or a User Requirement Specification (URS). Solution:Performance Requirements:Operate at 9 Volts DC. Have a minimum cable reach of: 3 meters for power supply o 6 meters for audio leads o The device should monitor all inputs and automatically send the signal to the output, without any interference from the other inputs. The selected channel should be visible to the user. The device should use 3.5mm Stereo Jacks as the Input and Output connectors, to keep conformity with standard audio equipment. There should be a manual selector switch to select the following:o Automatic (connecting the PIC) o Individual Channels There should be a minimum of 4 Inputs. There should be a minimum of 2 Outputs. There should be an On/Off switch. Working Environment:The device should be able to operate internally at a temperature range of +5 to +40 deg C. Maintenance:The device should only need to be kept clean to ensure life longevity. Costs:The device should cost no more than £30.00. Quantity:This product is going to be a one off. Aesthetics / Ergonomics:Polymer or Metallic body shell. User friendly insertion / removal of headphone jacks. Size/Weight:Maximum weight of 1KG. (excluding ( excluding the power supply) Maximum size 150 x 150 x 100mm. Safety:Complies with all relevant Standards and Regulations. • •
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Task 2 Determine the major design parameters. Solution:Requirement Operate at 9V DC
Parameter
Materials This will have an implication on circuit components. •
Cost May be cheaper to get lower voltage components and power supply. Function Audio devices will have to be less than 6 meters away from the device. Device needs to be less than 3 meters away from the Power Supply. •
Cable Reach
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Cost The longer the cable the greater the cost. For this reason there may have to be shorter cables with the ability of an an extension. This, however, however, would increase increase the amount of Stereo Jacks required and therefore increasing the cost. Manu Manufa fact ctur ure e There will need to be a parameter to prevent cross feeding the signals, as there is a likelihood of scrambled noises if there are two or more sources. There will need to be a default input if there are two or more signals being received. Materials LCD displays are relatively inexpensive with programming relatively simple. LED’s could be used as an indicator i ndicator to which channel is in use. •
Moni Monito torr Inp Input uts s
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Display
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Manufacture LCD would be slightly more difficult to program and install. •
Performance LCD would make the unit look more professional but not increase performance. •
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Stereo Jacks
Cost •
Standard connector so it will be cheap.
Aesthetics Clean finish making the device look l ook professional. •
Safety •
User friendly, preventing injury.
Performance Fits the majority of standard audio devices. •
Layout •
Selector Switch
Enough room will have to be left for inputs, to prevent fouling of connectors.
Layout •
Switch will have to be in a user friendly fri endly place, so that ease of switching is available.
Materials Basic selector switch can be used, as there is no special requirement requested. •
Function It should only select one channel at a time, to prevent corrupting the programming. •
Cost •
Can be relatively cheap as the switch is a common component.
Aesthetics The switch will need to match the style of the rest r est of the device. •
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Inputs/Outputs
Cost •
The more inputs/outputs the greater the cost.
Layout •
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The more inputs/outputs the more cramped the layout will become. The more inputs/outputs the more complicated the circuit and program will become.
Performance With more inputs/outputs there is a better chance of the device meeting the key objective which is to prevent the need of messing with wires when an new device is to be listened to. •
Aesthetics Too many inputs/outputs will compromise the aesthetics Layout Should be next to the power supply input, to prevent confusion. •
On/Off Sw Switch
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Materials / Cost A simple cheap switch will be required. Materials Any components which may overheat will need heat sinks. •
Operating Temperature
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Manufacture / Layout The body of a metallic casing could be used as a heat sink. Materials Sealable container for the circuit, to prevent debris contaminating the circuit. Performance Can be unique and exactly to customer requirements, rather than based on market m arket research. Materials / Performance May have an implication if the parts required come to more than £30.00 then a compromise in performance may be necessary. •
Maintenance
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Quantity
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Cost
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Aesthetics The device may appear cheap and unprofessional if cheap plastics and components are used for the device. •
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Aesthetics / Ergonomics (Type of case)
Safety
If a metallic case is used then correct grounding will be necessary to prevent any static build up affecting the circuit components. Friendly insertion for Manufacture / Function inputs/outputs There needs to be a solid housing of the stereo jacks to meet this requirement. Safety Legal Implications / Performance Only designed for UK usage. Weight Materials / Layout Limit materials required by getting a suitable circuit and device layout. •
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Maximum Size
Limiting materials will save on weight, but getting lighter components may increase the cost required to produce the circuit.
Layout •
Layout will become more important with smaller devices.
Fabrication Will become more difficult with smaller devices. •
Cost / Materials Smaller packages may require smaller (more expensive) components. •
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Task 3 Using appropriate reference sources such as catalogues, internet, books, etc obtain information on the the design technology. technology. Identify the techniques techniques and technology required in the manufacturing of your chosen product and similar products etc. Identify any relevant relevant standards that need need to be applied for example BS safety standards for mains electricity etc. Solution:Design Technology: ECAD – Electronic Computer Aided Design will be used to design, develop and test circuits for for my device. I will be able to save save expense on on costly components by testing, and working out any problems before potentially causing damage and extra work. ECAD is used in industry to provide clarity in drawings as well as producing automatic layouts of a PCB can be produced, saving a large amount of time. They can also be used for integrating miniaturisation as the software can link the information to a CNC machine, to create IC’s wi th complex circuitry inside within a small package. MPASM (used for programming the PIC) – This is a programming software developed by Microchip Microchip Technology Technology Inc. It provides a platform platform for developing basic and flexible language code for Microchip’s PIC Microcontroller (MCU) families. The software compiles the code written by the user into a code which the PIC can understand. Project planning, development and publishing software (MS Project, Excel, Word, PowerPoint) – using the standard Microsoft Office software I will be able to plan and track my project. MS Project is an extremely extremely useful tool tool for monitoring project progress. progress. I will be using MS Excel to work out parts lists and calculate costs costs of the project. MS Word and PowerPoint PowerPoint will be used used to present ideas and my final presentation.
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Manufacturing nufacturi ng Techniques Techni ques and Technology: Soldering – this is going to be the standard way of connecting the circuit components to the circuit board. Component mounting – care and consideration will have to be taken when mounting the components components to the board. board. Best practice is to solder solder all of the smallest components on and work up by size, this way they will remain flat on the board and it will be easier to ensure a good electrical connection is made. PIC (Programming) – PIC technology provides a relatively simplistic way of delivering an output when when the input is in a certain condition. Instructions will be compiled to the chip and it will carry out those instructions, repeatedly. CNC – machines can be numerically controlled by computer software, allowing them (if there parameters allow them) to create components to a much smaller scale and even to greater tolerance that a human operator can ever get to. Relevant Standards: COSHH Regulations Health and Safety at Work Act 1974 IEEE Wiring Regulations If I was working in industry I would follow the above top level standards to produce my device. device. These, however, however, do not fit the customer customer requirements, so it will be difficult to implement them. I will be using various considerations when handling the electronic components, such as the use of Electrostatic Protection, to prevent static discharges from damaging IC’s. To prevent myself from getting injured, I will also wear the appropriate PPE (Personal Protective Equipment) when carrying manufacturing activities. Safety goggles will help prevent solder splatter from damaging my eyes, whilst safety boots will protect my feet from heavy falling objects.
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Task 4 Ensure that the design specification meets the customer requirements. Solution:My Design Specification has been written by following the Customer Requirements. This has enabled enabled me to clearly and and precisely identify parameters which I will follow through the design process. As I am the customer as well as the designer and manufacturer I can easily work out design issues. issues. In a more realistic project project (where I as a designer would be taking a project brief, with requirements, from somebody I may not know) there would be a substantial difference in difficulty when developing the Design Specification. This is because because there may be mixed messages messages when explanations are given and received, or somebody’s perception of an idea may be completely different than intended. It is easy for me to agree any modifications to the specification if there any design difficulties. However, I feel my parameter breakdown approach approach to each of the requirements is suited in identifying difficulties or considerations necessary when when implementing each requirement. Following a similar similar approach in future projects, I believe, will be an acceptable foundation when beginning the design work.
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Evaluation I feel I have produced a design specification which satisfies the requirements of the customer. The original idea for the project came because of the constant frustration of having to mess around around with wires when when using my “wireless” “wireless” headphones. headphones. I thought it would be good to be able to connect all of m y audio equipment to one device and let it sort out which piece of equipment I was using, rather than having to do it myself. The customer requirements were kept relatively broad and non-complex to allow me to have as much flexibility as possible, whilst maintaining some constraints. I believe I have done this within this assignment, as I am am comfortable that I will be able to move into the design stages of the project and resolve unforeseen problems whilst still following the guidance of the specification. For Task 1, I followed an example in Mike Tooley & Lloyd Dingle’s “Higher National Engineering” Textbook. Textbook. It exampled a make make belief company who wanted a drill mass produced produced for international international markets. Following this I managed to get headings for a variety of fields which I could then adapt to suit my project. For Task 2, I continued continued the example example in the same textbook. textbook. It had a small section about design parameters on one of the customer requirements. Making use of this information, I again adapted it to suit my project, keeping conformity throughout for the other requirements. In Task 3, I needed to think about areas such as the manufacturing side, before having undertaken undertaken any of the design work. Comprehending the required standards, before knowing what the full list of circuit components and connectors is, I found found a bit demanding. demanding. I managed to list a range of viable options to cover many aspects I believe I will need to use, hopefully this is acceptable. Task 4 I found to be a little littl e confusing, I have been ensuring that the specification meets the customer customer requirements whilst doing doing Task 2. I found it difficult to write about something I had been constantly doing, rather than something I had left until the end.
Conclusion To conclude, I feel I have covered the necessary requirements set out in this assignment. I also feel that I have a good foundation to begin my design work, based on this specification. This assignment made me think a little more in depth about some of the potential problems (parameters) I may face in the project, and taking these into consideration when designing I may be able to avoid them.
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Brendan Burr
BTEC Higher National Certificate in Electronics Engineering Design
Bibliography Through guidance from my lecturer, the following text books, catalogues and websites I was able to complete this assignment: Books Higher National Engineering (Mike Tooley & Lloyd Dingle) ISBN: 978-0-7506-6177-5 Catalogues N/A Websites http://ww1.microchip.com/downloads/en/devicedoc/33014j.pdf http://en.wikipedia.org/wiki/ECAD http://office.microsoft.com/en-gb/products/
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