William Farr Comprehensive School

School Postcode: LN2 3JB DCFS number:
Staff member who developed this case study: Ben Price
Email contact: benprice_iw@hotmail.com
School telephone: 01673 866900 No. on roll: approx. 1400 pupils
Brief pen picture of school: William Farr School is a rural 11-18 C of E fully comprehensive school set in the village of Welton-by-Lincoln. It has approximately 1400 pupils.
The D&T department is a lead subject in school which has Science College, Raising Achievement, T & L and Leading Edge status. William Farr has recently changed it’s specialism from Technology to Science and Design and Technology has since been made optional at GCSE.
The department has 5 full time teachers and two part time teachers, with 1 full time and 2 part time technicians. It has 2 workshops, 1 electronics lab, a CAD suite, a graphics suite, 2 food rooms, a 6th Form work room and a textiles room.
At Key Stage 3 pupils have two, one hour lessons where they carousel through Electronics, Food, Graphics, Resistant Materials and Textiles.
GCSE is now optional and students have the choice of Systems and Control Technology with Electronics, Food Technology, Graphic Products, Resistant Materials Technology and Textiles Technology. Pupils have two, one hour lessons one week, and three the next.
At A-Level students opt into Product Design (3D), Art Textiles or Art Graphic Design.

1. The Teacher CPD Course:

The Project Brief:
I intend to design and make an electronic device which will act as an audio amplifier from an external device, for example, an MP3 player. It should be able to be used with a range of MP3 players and have a stereo output. There should be some sort of visual output to give the user stimulation, interest and pleasure.
Specification:
Purpose
The device will be used to connect to a generic MP3 player and amplify the audio output.
Function
The product will use a PP3 battery to power an amplifier circuit, connected to a generic MP3 player. It will be connected through a jack socket.
User Requirements
It must be easy to change the battery to allow it to be manageable by the user. It must be able to be turned on and off so that you do not have to disconnect the battery, which could prove to be difficult and time consuming. It must be easy to connect to the generic MP3 player so it does not cause any difficulty and be time consuming. It should play in stereo so there is a better quality sound. It must show some form of visual output to give pleasure and interest to the user.
Performance Requirements
It should use a PP3 battery as these are readily available and use one battery rather than several, which would make changing it easier. It should use at least an 8watt speaker so that the volume is loud enough to be heard. It should use an Op-Amp as this has the ability to give greater gain than a set of Darlington pair transistors. It must use a jack socket so any pair of earphones can fit in, making it flexible with many users. It must show the circuit is on so the user is aware the battery is being drained.
Materials, Components and Size
The enclosure must be made of a Resistant Material so that it is durable, robust and long lasting which will give the user satisfaction. It must use standard electronic components which are readily available, making it easy to source. It must use expensive exterior components to give the overall appearance more class and an expensive feel. It must be no larger than 200mm by 200mm by 10mm, so it is of a substantial enough size, but not too small that it can be lost or look cheap.
Scale of Production and Cost
The PCB, PCB mask, and enclosure must be manufactured using industrial applications such as bubble etch tank, PCB software, laser cutter and 3D printer to ensure that the product is accurate and produced to a high quality.
Concept Sketches:
1. Electronic circuit development:
a) Circuit diagrams/schematics
Idea 1
b) PCB artwork
Idea 1
c) Program details
The Final Circuit Board:
Idea 2
Idea 3
Commentary: Both parts of the circuit consolidate my knowledge of electronics. I understand the Op-amp, but I am familiarising myself with smoothing capacitors. The PIC side of the board is what I teach in Year 9 with Genie08M, and at GCSE, I use Genie18+ with my students.

Although I had really wanted to produce a PCB which played in-stereo (two speakers), time limited me to a mono circuit (one speaker). I also wanted to push my knowledge in PICs, so I used a Genie08, which again, if I had more time would have preferred to challenge myself to a Genie14 or Genie18. The PIC is independent to the Op-amp circuit, but ideally, I would have like to link the two and get the LEDs to pulse to the beat of the music.

2. CAD/CAM Development:

CAD/CAM Post Processing

 

 

Final CAD Design:
CAM Manufacture:
Commentary: My ideas are usually a bit ‘blue sky’ and they have to be altered to fit. Although I was designing a product for children in Year 8 and Year 9, my product had to look modern, expensive and contemporary to mirror those on the market.

My initial idea would use an iPod docking station, but this would not lend it towards other types of MP3 players, so I substituted the iDock for a jack socket. I then realised that although a 3D Printer was available to use, my initial design would be too big and take up too much powder which was very costly. So it was back to the drawing board.

My design was then altered to be produced on a piece of Styrofoam on the Boxford Router. The void in the middle was substituted for an indented back, to incorporate one speaker, having decided to use one (mono) rather than two (stereo). That meant that the base of the product wouldn’t have to be as big because it wouldn’t have to house two speakers. The Styrofoam could be routed out, fillered and sprayed up to give it a professional look. Due to the complexity of curves, lines and deformed faces, the Boxford post processor software wouldn’t accept it. And I had to look for other ways to produce the product.

Then I decided to produce my design in slices by rapid prototyping the finished product in 3mm Medium Density Fibreboard. I did this by taking the 3D Pro/DESKTOP images and exporting it as an STL file and post processing it through a piece of software called Rapid Pro. It then output each slice as a 2D drawing saved as a PDF file which could be attached to my laser cutter back at school.

The finished product could then be cut out, fillered and sprayed up.

Although I wanted to use a piece of CAD/CAM hardware which pushed the boundaries, due to the complexity of the product, and time, I finished the product on the laser cutter I had in school, which was something I was familiar with.

2. The Student Scheme of Work

Aimed at Key Stage: 3 (Year 8 Gifted and Talented)
Estimated time available for project: 5 periods of 60 minutes (One day off timetable).
National Curriculum PoS covered by Scheme of work:

Brief: To design and make an amplifier including it’s casing, which can be attached to a generic MP3 player.

Context: Young people to listen to their music through their earphones, or expensive MP3 audio devices. These devices are not particularly portable and are quite expensive for a young person. A robust, durable casing is needed to house the PCB.

Specification:

  • It must connect to a generic MP3 player
  • It must be lightweight and portable
  • It must amplify the sound from a generic MP3 player
  • It must be made from resistant materials
  • It must have space for your own graphics
  • The battery must be able to be easily accessible
  • It must use resistant material processes to manufacture the casing
The Scheme of Work:

List the design decisions (from David’s Barlex’s Nuffield D&T pentagon) you will be asking pupils to make.

Conceptual – What does it do? Focussed practical task. Everyone makes a generic MP3 amplifier design due to a low knowledge and understanding of electronics.

Aesthetic - What does it looks like?
What colour will it be?
What sort of surface graphics will you apply?
Will you add any texture to the casing?
What images / fonts will you apply?

Marketing – Who is it for? What age range will it be for? (5-15) (16-20) (21-29) (30+)

Technical – How it works?
Inputs – Switches (Toggle, PTM, LDR, Reed, Tilt)
Process –Transistors, Darlington Pair, Op Amps
Outputs – LEDs, Loudspeaker

Constructional – How it fits together?
Wood
Metal
Plastic
Vacuum Forming
Laser Cutter
Soldering
Measuring & Marking
Individual Lesson Plans:
Student Outcomes:
Commentary:

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