BTEC HNC - Engineering Design - Prepare a Design Specification

Prepare a Design SpecificationEngineering Design

By Brendan Burr

Brendan Burr BTEC Higher National Certificate in ElectronicsEngineering 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 requirements should be drawn up into a simple Product Design Specification (PDS) or a User Requirement Specification (URS). - 3 -

Solution:- - 3 -

TASK 2 - 4 -

Determine the major design parameters. - 4 -Solution:- - 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 in the manufacturing of your chosen product and similar products etc. Identify any relevant standards that need to be applied for example BS safety standards for mains electricity etc. - 8 -

Solution:- - 8 -

TASK 4 - 10 -

Ensure that the design specification meets the customer requirements. - 10 -Solution:- - 10 -

EVALUATION - 11 -

CONCLUSION - 11 -

BIBLIOGRAPHY - 12 -

Books - 12 -

Catalogues - 12 -

Websites - 12 -

2


Task 1

Create a list of all the identifiable customer requirements for your chosen design. These 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:

o 3 meters for power supplyo 6 meters for audio leads

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 the power supply) Maximum size 150 x 150 x 100mm.

Safety:- Complies with all relevant Standards and Regulations.

3


Task 2

Determine the major design parameters.

Solution:-

Requirement ParameterOperate at 9V DC

Materials This will have an implication on circuit components.

Cost May be cheaper to get lower voltage components and

power supply.Cable Reach 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.

Cost The longer the cable the greater the cost. For this

reason there may have to be shorter cables with the ability of an extension. This, however, would increase the amount of Stereo Jacks required and therefore increasing the cost.

Monitor Inputs Manufacture 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.

Display Materials LCD displays are relatively inexpensive with

programming relatively simple. LED’s could be used as an indicator to which channel

is in use.

Manufacture LCD would be slightly more difficult to program and

install.

Performance LCD would make the unit look more professional but

not increase performance.

4


Stereo Jacks

Cost Standard connector so it will be cheap.

Aesthetics Clean finish making the device look professional.

Safety User friendly, preventing injury.

Performance Fits the majority of standard audio devices.

Layout Enough room will have to be left for inputs, to prevent

fouling of connectors.Selector Switch

Layout Switch will have to be in a user friendly 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 of the

device.

5


Inputs/Outputs Cost The more inputs/outputs the greater the cost.

Layout 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

aestheticsOn/Off Switch Layout

Should be next to the power supply input, to prevent confusion.

Materials / Cost A simple cheap switch will be required.

Operating Temperature

Materials Any components which may overheat will need heat

sinks.

Manufacture / Layout The body of a metallic casing could be used as a

heat sink.Maintenance Materials

Sealable container for the circuit, to prevent debris contaminating the circuit.

Quantity Performance Can be unique and exactly to customer

requirements, rather than based on market research.

Cost Materials / Performance May have an implication if the parts required come

to more than £30.00 then a compromise in performance may be necessary.

Aesthetics The device may appear cheap and unprofessional if

cheap plastics and components are used for the device.

6


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 inputs/outputs

Manufacture / Function 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.

Cost Limiting materials will save on weight, but

getting lighter components may increase the cost required to produce the circuit.

Maximum Size 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.

7


Task 3

Using appropriate reference sources such as catalogues, internet, books, etc obtain information on the design technology. Identify the techniques and technology required in the manufacturing of your chosen product and similar products etc. Identify any relevant standards that 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 my device. I will be able to save expense 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 with complex circuitry inside within a small package.

MPASM (used for programming the PIC) – This is a programming software developed by Microchip Technology Inc. It provides a 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 useful tool for monitoring project progress. I will be using MS Excel to work out parts lists and calculate costs of the project. MS Word and PowerPoint will be used to present ideas and my final presentation.

8


Manufacturing Techniques 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 to the board. Best practice is to 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 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 RegulationsHealth and Safety at Work Act 1974IEEE Wiring Regulations

If I was working in industry I would follow the above top level standards to produce my device. These, however, do not fit the 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.

9


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 me to clearly 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. In a more realistic 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 there may be mixed 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 to each of the requirements is suited in identifying difficulties or considerations necessary when implementing each requirement. Following a similar approach in future projects, I believe, will be an acceptable foundation when beginning the design work.

10


EvaluationI 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 with wires when using my “wireless” headphones. I thought it would be good to be able to connect all of my 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 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. It exampled a make belief company who wanted a drill mass produced for 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 the example in the same 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 any of the design work. Comprehending the required standards, before knowing what the full list of circuit components and connectors is, I found a bit 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 confusing, I have been ensuring that the specification meets the customer requirements whilst 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.

ConclusionTo 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.

11


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.pdfhttp://en.wikipedia.org/wiki/ECADhttp://office.microsoft.com/en-gb/products/

12

http://office.microsoft.com/en-gb/products/

http://en.wikipedia.org/wiki/ECAD

http://ww1.microchip.com/downloads/en/devicedoc/33014j.pdf

BTEC HNC - Engineering Design - Prepare a Design Specification

Documents

Transcript of BTEC HNC - Engineering Design - Prepare a Design Specification